636 FXUS66 KSEW 190321 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 821 PM PDT Sun Oct 18 2026 .SYNOPSIS... A trough will be departing south and well offshore tomorrow into Tuesday, with zonal flow through the middle of the week. The next few mornings will be on the colder side for potential frosts, namely in the south Puget Sound and Chehalis Valley. A weak system is possible late in the week for light rain. && .SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... The latest forecast remains on track this evening with no updates. High clouds are moving onshore courtesy of the upper level trough transiting south, but far offshore. Low temperatures tomorrow morning will be in the mid 30s for areas including Olympia and south through the I-5 corridor. Mid 40s are expected elsewhere. Lows decrease a few degrees further into Tuesday morning for frost potential in the aforementioned areas but also the Cascades and valleys. Patchy morning fog will remain possible through early in the week and will be more likely in the valleys and typically fog prone locations. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Extended models and the ensembles are favoring Gulf of Alaska troughing to build on the deeper low moving into southern California Wednesday and beyond. Positioning of the low becomes less clear by Friday into next weekend but the indication as of now isn`t for much in the way of impactful weather. Some light rain may be possible Thursday into Friday. Snow levels during that time come down to around 4,000-4,500 feet, so some light snow flurries may be possible at these elevations and higher if precipitation does materialize. 21 && .AVIATION... Southwesterly flow aloft is expected tonight into Monday as an upper trough digs southward offshore. Increasing high level moisture later tonight is expected to limit areal coverage of low clouds on Monday morning with the exception of more fog prone locations in the Southwest Interior and extreme southern Puget Sound for the potential of IFR/LIFR conditions. Impacted terminals expected to improve by the afternoon, for widespread VFR conditions. Light northerly to calm winds tonight. Winds will shift more southerly Monday morning then transition back northerly in the evening. KSEA...VFR conditions will continue tonight. High and mid level moisture spreading in the region ahead of upper trough digging southward offshore. The expectation remains that this will limit fog development tonight and will keep low ceilings/vis out of upcoming TAF for now. Surface winds light and variable late tonight into Monday A.M. Winds will shift more southerly late Monday morning, before transitioning northwesterly after 19Z-21Z at 5-7 kt. 27/29 && .MARINE... A low pressure system passing southward well offshore will keep winds northerly or weakly offshore into Monday. Weak high pressure will remain across the waters into the middle of the coming week for rather quiet conditions. A larger swell train near 10-12 feet generated by active weather well offshore is expected to reach the coastal waters around Thursday along with an increase in onshore flow. A front may reach the waters toward the end of the week. 27 && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$

138 FXUS66 KPQR 190445 AFDPQR Area Forecast Discussion National Weather Service Portland OR 945 PM PDT Sun Oct 18 2026 .SYNOPSIS...Largely dry weather expected through midweek with temperatures remaining near to above normal for mid-October. Chances for wetter and cooler weather return late in the week. && .DISCUSSION...Now through Sunday...Tranquil early fall weather will continue into the workweek despite an upper-level trough approaching the coast through tomorrow. There remains good consensus that the trough will elongate and pinch off into a closed low well offshore which will ultimately drift south and away from the Pacific Northwest. Locally, cloud cover will increase this afternoon through tonight as the system makes its closest approach, which will stymie radiational cooling and mitigate frost concerns for most. The typical coldest spots in the far upper Hood River Valley near Dee and Parkdale, north Oregon Coast Range valleys around Vernonia and Grand Ronde, and peripheral valleys around the southern Willamette Valley (along the Middle and Coast Fork Willamette River and the McKenzie River) may see some areas at risk of developing frost, and those with agricultural interests or sensitive outdoor plants should take precautionary actions to prevent damage. Chances for rain from this system tonight through Monday are minimal, with the Cascade foothills and Coast Range south of US-20 having a 15-25% chance of light rain or drizzle accumulating to 0.01 inches. Otherwise, dry weather is expected with near-normal afternoon high temperatures in the 50s along the coast and in terrain, and 60s in inland valleys. As the closed low drifts south into California, light offshore flow on its northern flank will help clear skies and push temperatures some 10 degrees above normal Tuesday and Wednesday, when afternoon highs should reach the 60s along the coast and in terrain, and the low to mid 70s in inland valleys. Despite warm afternoons, clear skies overnight may allow for nightly areas of frost within inland valleys; those with agricultural interests or sensitive outdoor plants should continue to monitor the forecast for potential Frost Advisories. By the latter half of the workweek, the pattern looks to become more active, favoring a return to cooler and wetter weather. An upper-level trough looks track inland in conjunction with the aforementioned closed low in California, bringing chances for light rain from Thursday through early Friday, although potential rainfall amounts appear very low. There is increasing consensus that a more potent system may affect the Pacific Northwest sometime this weekend, possibly the first atmospheric river of the season. There are elevated chances for more substantial rainfall amounts, but uncertainty remains high at this longer lead time. -36 && .AVIATION...Through 06z Tuesday...A low pressure system dropping southward off the coast will spread mid and high level clouds across the region through 06z Tuesday. Expect light winds and predominantly VFR conditions across the area through this time period. It should be noted that around 40-50% of our high resolution weather models suggest a mixture of IFR and MVFR stratus will develop along the central coast of Oregon between 06-12z Monday before spreading eastward into the southern Willamette Valley towards 12-18z Monday. Confidence in this scenario is not high, but it does seem modestly plausible. Patches of stratus are just beginning to develop along the Cascade foothills, but these seem to be in the 4-7kft ASL range per ASOS observations. Will keep TAFS VFR for now for later tonight into Monday morning, but will be monitoring trends and additional guidance and may need to make amendments given the uncertainty. Also, dewpoint depressions are currently lowest at KAST and KEUG so fog concerns are highest at these airports if these sites continue to radiate out overnight. KPDX AND APPROACHES...A low pressure system dropping southward off the coast will spread plenty of mid and high level clouds across the region through 06z Tuesday. Expect predominantly VFR conditions and light winds through this time period. There is a 20% chance for MVFR or high end IFR conditions to develop in the 12-18z Monday timeframe, but suspect a large band of mid and high clouds just beginning to move overhead will minimize fog and low cloud chances in the vicinity of KPDX later tonight. && .MARINE...A continued west-northwesterly swell and weakening northerly winds will see seas of 8-9 ft today ease to 6-7 ft by early Monday morning. A system dropping southward well offshore will generate a stronger westerly swell arriving late Monday which will push seas to 8-11 ft, highest beyond 10 NM and south of Cape Falcon, where Small Craft Advisories have been hoisted from 5 PM PDT Monday through 5 AM PDT Tuesday before seas ease below 9-10 ft. Strengthening northerly flow in the wake of this passing system may support gusts peaking at 20-25 kt on Tuesday, potentially requiring an extension or expansion of the advisory if confidence in the coverage and duration of stronger winds increases. Conditions otherwise improve midweek as winds and seas ease, but a more active pattern looks to return late in the week. Increasing northwesterly winds and a northwesterly swell could push seas close to 10 ft again from Thursday into Friday, and a more potent weather system next weekend will also see increased chances for seas above 10 ft and gusty, potentially gale-force winds. -36 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory from 5 PM Monday to 5 AM PDT Tuesday for PZZ272-273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland

706 FXUS66 KMFR 190513 AFDMFR Area Forecast Discussion National Weather Service Medford OR 1013 PM PDT Sun Oct 18 2026 ...Updated Aviation Discussion... KEY MESSAGES... * Near normal temperatures expected for much of this week with Wednesday currently the warmest (slightly above normal). * Much of the measurable precipitation chances for Mon/Mon night have dwindled down to near zero except for trace amounts near the coast. There is also a low chance (5-15%) for a few light showers along and just of the Cascades, over the Siskiyous and western Siskiyou County on Monday. * Better rainfall chances expected Wednesday into Thursday with measurable amounts favoring northern California and eastside areas. * Isolated thunderstorm chances exist on Wednesday within these rainfall chances. && .DISCUSSION (Today through Saturday)... Overall, the weather continues to showcase an overall low impact forecast through next week. The upper level pattern continues to show mostly zonal flow aloft for today, but the flow will become more southwesterly tomorrow as a low approaches the region. Not expecting any measurable precipitation with this front Monday as it appears to be a dry front with QPF amounts essentially down to zero for much of the area. If any location does get rainfall, it would likely be for areas along and near the coast, but only very light amounts would be anticipated as the low stays offshore. Model consensus continues to stall the system out over the Pacific right before moving inland becoming a cut-off low. Then a split flow pattern develops with this low sagging south, and eventually making its way inland over southern California. As the low moves inland, moisture will advect northward into the forecast area on Wednesday. Models show modest CAPE values upwards around 500 J/kg for mainly eastside areas. This would allow for isolated thunderstorms to develop Wednesday afternoon with lightning being the main threat. Looking ahead towards the end of this forecast period, models do show the potential for another low to develop over the PacNW next weekend. This low will be associated with a colder airmass, and we could see light snowfall amounts along/near the Cascades and areas east of the Cascades Saturday night into Sunday morning. This is getting outside of this current forecast window but worth mentioning and watching going forward. At this time, not expecting any noteworthy amounts, but areas above 4500 feet could see around an inch, and areas above 6000 feet could see around 2 inches. && .AVIATION...19/06Z TAFs...VFR conditions will continue will continue tonight for most inland areas. IFR stratus is expected to fill in along coastal locations and areas of MVFR will develop in the Umpqua Valley later tonight and linger into the morning hours. Elsewhere, expect VFR. The chance of light showers on Monday is low with a 5-15% chance, mainly along and just west of the Cascades, over the Siskiyous and western Siskiyou county. VFR will prevail Monday afternoon. && .MARINE...Updated 830 PM PDT Sunday, October 18, 2026...Seas will gradually lower tonight into Monday and are dominated by west- northwest swell. South winds will increase on Monday as a low moves southward offshore but are expected to remain below advisory criteria. Then, Monday evening and night, west swell will build, becoming steep. Breezy to gusty north winds will develop on Tuesday and steep seas will linger, gradually lowering late Tuesday into Tuesday night. && .MFR WATCHES/WARNINGS/ADVISORIES... OR...CA...None. PACIFIC COASTAL WATERS...Small Craft Advisory from 6 PM Monday to 11 AM PDT Tuesday for PZZ350-356-370-376. && $$

428 FXUS66 KEKA 182124 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 224 PM PDT Sun Oct 18 2026 .KEY MESSAGES... * Colder temperatures with chances for interior frost this week. * Chances for isolated light showers and rain this week, particularly in southern and eastern Mendocino, Trinity, and Lake counties. && .SYNOPSIS...Below normal temperatures are expected for the next week as a cold front ushers in cooler air to the region. A few showers will be possibly on Monday. Occasional showers are expected in southern and eastern Mendocino, Trinity, and Lake counties later Tuesday into Thursday. && .DISCUSSION...Clouds remain entrenched along the coast today as the marine layer moistens ahead of an approaching area of low pressure. Coastal clouds will expand inland into coastal valleys and the marine layer should deepen overnight. As the area of low pressure approaches the area, high and mid level clouds will gradually increase resulting in mostly cloudy conditions for the entire forecast area by Monday into Tuesday. There is high confidence that this area of low pressure will never fully make it to the Northwest California coast and instead cut- off from the flow and drift south over the far eastern Pacific toward central and southern California. A few showers might form over eastern and southern portions of the forecast area Monday and Monday night, but generally dry conditions are expected as this low sinks south. Wrap around moisture on the north side of this low cloud bring some light rain to southern areas of the forecast area and in the higher terrain on Tuesday and Wednesday with a 10-30% chance of rain during that timeframe. Farther north and west dry conditions are currently forecast to continue during that time frame with potentially some light offshore flow aloft reducing coastal stratus Tuesday into Wednesday. As this low ejects northeast over central and southern California, there is some indication that a deformation axis could form on the northwest side of the low resulting in light rain in the southeastern potion of the forecast area on Thursday. Confidence in this remains low but is certainly a reasonable possibility with 30-40% chances of rain included in the forecast from Trinity County south through eastern Mendocino and Lake counties. Temperatures throughout Monday through Thursday are forecast to be 5-15 degrees below normal across the interior and around 5 degrees below normal at the coast. Dry conditions are likely to return on Friday as a ridge noses into Northwest California. Temperatures won`t change much but the overall weather conditions for the region should improve. The next question is whether a more active weather pattern could develop starting next weekend. Looking at cluster guidance, around 70% of the ensemble is showing a trough somewhere near the Northwest California coast and around 50% indicate the potential for notable rainfall. At this time the probabilities included in the forecast are around 30-40% Saturday and Sunday next weekend. It wouldn`t be a shock to see probabilities decrease considering the model tendency to be too strong with systems in the extended periods during the transition season. Stay tuned to see how this trends over the next few days. && .AVIATION...18Z TAF...Cloud cover has been very persistent along the coast today with IFR conditions at all coastal terminals. Satellite indicates that the stratus is already beginning to push back inland, thus it is unlikely to see any clearing today. Statistical guidance indicates the stratus should descend back toward the surface overnight reducing visibilities into LIFR, but an approaching area of low pressure would support the opposite of this to occur with ceilings remaining in IFR instead of LIFR but areas of drizzle developing. Either way, conditions are not expected to improve much through Monday morning. Farther inland VFR is expected to prevail away from the near coastal ridges and valleys. Increasing higher level clouds will develop ahead of this approaching area of low pressure overnight. && .MARINE...Northerly winds will decrease tonight as an area of low pressure approaches the waters. Southerly winds ahead of this system will increase on Monday but never get particularly strong as the low fails to make it fully toward the coast. Thus, small crafts are not going to be needed for the wind itself. However, this low will also bring in a mid-period westerly swell that will likely peak over 10 feet Monday night into Tuesday, which would be large enough for small craft advisories for all waters. Northerlies will redevelop on Tuesday and gradually strengthen and expand through the end of the week. Additional small craft advisories may be needed late in the week. && .FIRE WEATHER...An area of low pressure will slide south off the Northwest California coast through Monday night. What was originally looking like a decent shot for wetting rain across the area, is now looking much less likely through Tuesday. However, the system will bring cooler temperatures and higher humidity by Monday along with a bit of gusty northwesterly winds during the afternoon hours. Some wrap around moisture Tuesday through Thursday could bring rain to eastern and southern areas of the forecast area, but probabilities of wetting rains still remain less than 30%, highest in southern Mendocino and Lake counties. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 5 PM PDT this afternoon for PZZ470. Small Craft Advisory until 9 PM PDT this evening for PZZ475. && $$ NOTE: The full forecast discussion is now regularly issued between 10 am/pm and 1 pm/am. Additional updates will be issued as needed. Visit us at https://www.weather.gov/eureka Follow us on Facebook and Twitter at: https://www.facebook.com/NWSEureka https://www.twitter.com/NWSEureka For forecast zone information see the forecast zone map online: https://www.weather.gov/images/eka/zonemap.png

240 FXUS66 KMTR 190501 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1001 PM PDT Sun Oct 18 2026 ...New AVIATION, MARINE... .KEY MESSAGES... Updated at 753 PM PDT Sun Oct 18 2026 - Cooling trend continues through the end of the week - Beneficial light rain showers expected mid-week - Thunderstorms possible mid-week across southern Central Coast && .UPDATE... Issued at 753 PM PDT Sun Oct 18 2026 The cooler weather has arrived! Across the Bay Area and Central Coast, temperatures dropped 10-20 degrees within the last 24 hours with some spots experiencing up to a 30 degree drop. Accompanied with the lower temperatures is an increase in humidity. The marine layer has reformed with a current depth around 1500-2000 feet. Moderate, gusty onshore winds will help push stratus further inland tonight. So, enjoy the stratus while you can because it won`t last long! Tomorrow, temperatures are expected to drop another 10-20 degrees with gusts around 20 mph. Breezier locations may experience gusts up to 30-35 mph which gradually diminish Monday evening. && .SHORT TERM... Issued at 145 PM PDT Sun Oct 18 2026 (This evening through Monday night) 24 hour trends are cooler across much of the forecast area, due to cool air advection from the surface up through the lower levels of the atmosphere. Daytime highs today will peak close to October 18th normal highs. A pattern shift to long wave troughing is developing and the trough will usher in below to much below mid-late October normal temperatures during the upcoming week. Wet weather will accompany the trough by mid-week. && .LONG TERM... Issued at 145 PM PDT Sun Oct 18 2026 (Tuesday through next Saturday) The northern hemisphere long wave trough pattern contracted somewhat after late September 2026 (interestingly e.g. after the persistent far downstream Nor`Easter). Just what storms do, the north-south meridional temperature/energy exchanges temporarily reduced the meridional temperature gradient resulting in some contraction that increased the chances we`d have long wave ridging (and warm/hot spells) which we had at times in October. Warm/hot spells are most frequent here in Sep-Oct after a long dry summer, still relatively high sun angle and especially when coupled to (dry, downsloping) offshore winds. As mentioned a pattern shift to long wave troughing is taking place, not so much because of an expansion in long wave troughs rather the result of a now progressive zonal pattern entering the entire western CONUS. Strong polar jet stream winds on the back side of the trough will drive the trough south-southeastward from the Gulf of Alaska temporarily cutting off a 500 mb low ~ a few hundred miles to our west-southwest from late Monday night to Wednesday night. During this time the subtropical jet stream will merge with the polar jet stream near the base of the newly forming 500 mb cut-off low. The cold core low will dig deep passing over higher sea surface temperatures in contrast to the cold core low, steepening temperature lapse rates and instability and water vapor availability will cause showers and thunderstorms to form. The greatest instability will be over the coastal and offshore waters while the low approaches land during mid-week it`ll encounter marginal diurnal surface instability and much less if any land surface based instability at night. Precipitable water is forecast to reach near the 90th percentile during the mid week timeframe; cold air within the low will help result in measurable rain and any thunderstorm development will be "wet" rain producers (vs "dry" thunderstorms). As of current time, the southern half of the forecast area stands the best chance of highest measurable rain with lesser amounts to the north. Forecast rainfall amounts for Tuesday night through Thursday: 0.10" to 0.25" in the North Bay, 0.20" to 0.50" across the rest of the Bay Area and 0.33" to 1" across Monterey and San Benito counties. Southerly breezes will prevail, but the low will be wrapping cold air around from the south as well and daytime highs are forecast to remain below normal during the period. Far inland highs will struggle to reach 70F in rain cooled air Wednesday and Thursday. For late in the week dry weather will return along with an increase in daytime highs reaching back to the 70s inland Friday and Saturday with 60s closest to the coastline. && .AVIATION... (06Z TAFS) Issued at 1001 PM PDT Sun Oct 18 2026 MVFR stratus is building into the valleys of the greater SF Bay Area and patches around Monterey Bay with further expansion expected overnight. Clearing times Monday morning and afternoon will be rather late owing to an incoming trough that will lower temperatures and expand the marine layer. Gentle to moderate onshore winds will persist through Monday evening, when winds diminish and turn southerly. Low confidence in the stratus extent and ceilings beginning on Monday night owing to potential mixing out of the lower layers as the trough approaches. Any rain chances from the incoming trough come later on Tuesday, after the TAF period ends. Vicinity of SFO... MVFR ceilings persist through Monday morning. Moderate northwest winds will continue through Monday evening with strong gusts expected in the afternoon and evening hours with a more southerly component as the winds diminish Monday evening. Low confidence for stratus returning to the terminal Monday night. SFO Bridge Approach... Similar to SFO. Monterey Bay Terminals... MVFR ceilings at the terminals will clear late Monday morning or early afternoon. Gentle to moderate northwest winds prevail through Monday evening, with light southerly flow developing Monday night. && .MARINE... (Tonight through next Saturday) Issued at 1001 PM PDT Sun Oct 18 2026 Moderate to fresh northwesterly breezes will prevail through Monday, with hazardous conditions for small craft lingering at the inner coastal waters south of Pigeon Point through Monday morning. Winds will diminish and back to a gentle southerly breeze Tuesday and Wednesday before returning to moderate to fresh northerly breezes Thursday. Rough seas across the outer waters will subside to become moderate Monday, rebuilding to become rough Tuesday. Light rain showers are expected Tuesday through Thursday. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory until 3 AM PDT Monday for Pigeon Pt to Pt Pinos 0-10 nm. Small Craft Advisory until 9 AM PDT Monday for Pt Pinos to Pt Piedras Blancas 0-10 nm. && $$ SHORT TERM...Canepa LONG TERM....Canepa AVIATION...DialH MARINE...DialH Visit us at www.weather.gov/sanfrancisco Follow us on Facebook, X, and YouTube at: www.facebook.com/nwsbayarea x.com/nwsbayarea www.youtube.com/nwsbayarea

920 FXUS66 KOTX 182344 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 444 PM PDT Sun Oct 18 2026 .KEY MESSAGES... - Dry weather continues through at least the middle of next week with mild afternoon temperatures. - Breezy winds down the Okanogan Valley on Tuesday. - Cooler weather with increased precipitation chances arrive late next week. && .SYNOPSIS... Dry weather is expected into Wednesday, with variable cloud cover and mild temperatures. Cooler weather and increasing precipitation chances arrive late in the week. && .DISCUSSION... Tonight through Wednesday: Dry and mild weather is forecast. Limited cloud cover this afternoon and evening will give way to thickening middle and high clouds later tonight into Monday. Low pressure offshore digs south and draws some moisture over the region to bring these clouds. However the deeper moisture and better lift stay south, so the forecast remains dry. Clouds decrease going into Tuesday and Wednesday. Wind will be breezy Tuesday in the northerly flow through the Okanogan Valley to Waterville Plateau, with the deeper low to the south. Gusts of 15-25 mph are possible. Otherwise winds will be lighter. Highs will largely in the 60s Monday, warming to the mid-60s to low 70s Tuesday and Wednesday. Low will be the 30s to low 40s, with some upper 20s in sheltered valley. Wednesday night to Sunday: Low pressure continues to dig into California, while another trough with a more northerly track approaches the area and starts to draw moisture in. Clouds thicken and rain chances start to enter southeast WA/lower ID Wednesday overnight into Thursday. The best chances will be over southeast WA/lower ID but at least a moderate chances (30-50%) extends toward northeast WA and north ID. This will largely be due to moisture coming in from the south and wave moving along a boundary near the southeast CWA. Other rain chances will be found near the Cascades later Thursday into Thursday night with the approach of that northern system. The best chance of wetting rain (>=0.10") between Thursday and Thursday night is over southeast WA through the central and southern ID Panhandle at 50-70%. Thereafter we will have to watch how systems and moisture interact with the incoming northern system. Friday right now looks drier, save for some shower chances near the mountains. However westerly winds increase over the region with a wave moving in with gusts of 15-30 mph, stronger over the upper Columbia Basin to Waterville Plateau. With the incoming low the rain chances expand back out later Saturday into next Sunday, along with cooler temperatures. The spread between the 25th to 75th percentile in terms of high temperature remains modestly wide at 10-15 degrees and there is also a spread in snow levels, meaning confidence in the details wanes. With that said, cooler temperatures and lower snow levels are forecast Friday into Sunday which could bring them down to pass level. It could even be cold enough Saturday night into next Sunday AM for some rain/snow mix in some of the northern valleys and maybe around the metro. The chance of wetting rain (>=0.10") Saturday night is around 20-40%, lowest in the deeper basin; chances rise to around 30-50% Sunday locally near 60% in the Cascades. This is all to say, rain amounts are not only trace amounts but also not very heavy at this point. Snow chances come to the Cascades Saturday and starts to expand to the other mountains Saturday night into Sunday. In the 48-hour period between Saturday and Sunday night, models currently show about 2 inches of snow in the passes, locally around 3 to 4 possible at Sherman and Washington Pass. Right snow probabilities for 1" is around 30-40, near 60% near Washington Pass. Highs stay in the 60s Thursday, then cool to the 50s Friday into Sunday, locally the upper 40s Sunday. Lows will be in 30s to low 40s Thursday night/Friday AM, then upper 20s and 30s thereafter, with Saturday morning the coldest morning. Friday looks breezy across the region with west-northwest gusting 15-30 mph; next Sunday also has similarly breezy conditions over central WA. /Solveig && .AVIATION... 18Z TAFS: VFR conditions with light winds under 10 kts regionwide. High clouds will increase this evening with a broken to overcast cirrostratus deck developing overnight into Monday Morning. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence in VFR conditions. /JDC ----------------------- Confidence descriptors: Low - Less than a 30 percent chance Moderate - 30 to 70 percent chance High - Greater than a 70 percent chance For additional probabilistic information for NWS Spokane airports, please refer to the Aviation Dashboard on our webpage: https:/www.weather.gov/otx/avndashboard && .Preliminary Point Temps/PoPs... Spokane 39 61 40 66 39 67 / 0 0 0 0 0 0 Coeur d`Alene 39 62 40 66 40 67 / 0 0 0 0 0 0 Pullman 38 60 36 65 37 67 / 0 0 0 0 0 0 Lewiston 42 66 42 66 43 69 / 0 0 0 0 0 0 Colville 31 62 33 67 32 69 / 0 0 0 0 0 0 Sandpoint 37 61 38 65 37 66 / 0 0 0 0 0 0 Kellogg 39 64 41 66 39 68 / 0 0 0 0 0 0 Moses Lake 37 62 37 69 37 68 / 0 0 0 0 0 0 Wenatchee 43 63 44 67 44 68 / 0 0 0 0 0 0 Omak 38 63 39 67 39 69 / 0 0 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... WA...None. ID...None. && $$

187 FXUS66 KPDT 182243 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 343 PM PDT Sun Oct 18 2026 .KEY MESSAGES... - Warm and dry conditions through the next few days as an upper ridge prevails over the region. - Cooler, wetter pattern in the midweek with split flow entering the region. - Light mountain snow showers possible mid to late week (10-20%). && .DISCUSSION... Satellite and radar indicate clear and dry conditions across the region as upper level ridge persists and continues to push to the east. High temperatures will continue to get warmer through Wednesday (>90% chance) with MaxTs climbing up to 10 to 15 degrees above climatological average. The upper ridge will keep winds calm and light with just diurnal driven speeds through at least mid-week (70-90% chance). Weather becomes more active as a trough amplify`s from the Gulf of Alaska into the Pacific through the week. Guidance and clusters are in good agreement that the trough will dig south through mid-week and form a cut off low just off the shore of California. It will then move onshore of California (70-80% chance) then continue to push off into the east. Closer to home, another shortwave is moving off the coast of British Colombia and into the PacNW region the same time as the cutoff low is moving across California. This split-flow pattern will bring precip chances up late Wednesday into the rest of the week (40-70% chances) with it being a mostly rain dominant system. Current NBM snow level forecasts over the Wallowas late Thursday through early Friday morning advertise 5500 to 6000 feet with minimum snow heights around 4500 to 5000 feet. A 10-30% chance of light mountain snow showers exists for this scenario, with more areas of a mix of rain/show through the Wallowas and northern Blue Mountains. Depending of the strength of the shortwave above Washington state/British Colombia, a stronger shortwave could bring lighter snow showers to a wider coverage, but not anticipating anything greater than 0.05 inches of QPF (70-90% chance) with dry PWAT values less than 0.25 inches. Looking at the potential for winds, tight pressure gradients developing across the area will be bring breezy to windy conditions across much of the area (with the exception of Central Oregon). Elevated winds with gusts up to 30-35 mph shows 40-70% chances across the region. Upping to wind advisory thresholds (45 mph gusts or greater) secludes chances to the Dalles and other parts of the Cascade gaps with 20-50% chances. Guidance is in good agreement the weather system will push-off Friday with dry conditions developing with a short-lived ridge entering the region bringing some temporary relief before another shortwave crosses the region Saturday. Agreement is shaky at best going into the weekend with strength all over the place, including the impacts to the area. According to clusters, 22% brings a much weaker solution with a mostly rain dominant solution, while 50% advertise a stronger system with stronger cold air advection. Will need to monitor for snow and rain impacts over the next several days for this evolving forecast. && .AVIATION /00Z TAFS THROUGH 00Z TUESDAY/... VFR conditions and predominantly light, diurnally and terrain- driven winds of 10 kts or less are expected (90% confidence or higher) through the period. There is a low chance (20% or less) of light rain at BDN/RDM Monday afternoon. && .Preliminary Point Temps/PoPs... PDT 36 63 36 63 / 0 0 0 0 ALW 41 63 40 64 / 0 0 0 0 PSC 36 65 37 69 / 0 0 0 0 YKM 39 64 39 69 / 0 0 0 0 HRI 36 64 37 66 / 0 0 0 0 ELN 35 61 34 65 / 0 0 0 0 RDM 29 59 29 61 / 0 10 10 0 LGD 39 70 36 68 / 0 0 0 0 GCD 39 71 38 71 / 0 0 0 0 DLS 43 66 42 71 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... WA...None. OR...None. && $$ DISCUSSION...95 AVIATION...86

218 FXUS65 KREV 181900 AFDREV Area Forecast Discussion National Weather Service Reno NV 1200 PM PDT Sun Oct 18 2026 .KEY MESSAGES... * Breezy south to southwest winds will present minor impacts to fire, recreation, and travel on Monday. * Active weather returns with rain, mountain snow and thunderstorms all possible by Tuesday into Wednesday. * More fall-weather, including much cooler temperatures and chilly nights will stick around through the remainder of the week. && .DISCUSSION... Time to get out and enjoy the last couple of warm/dry days of the week. Temperatures will remain in the upper 60s and 70s this afternoon along with our typical breezy, westerly winds. An approaching Pacific storm brings a change to the weather pattern starting Monday that will nudge us to cooler/wetter conditions for the rest of the week. Winds - Winds will increase Monday afternoon with S/SW gusts of 25- 35 mph across NE California, E Sierra valleys, and far W Nevada. Ridgetop gusts will reach 50-70 mph at times through early Tuesday. Plan for some wind impacts Monday, including a few hours of elevated fire concerns, choppy lake recreation and possible restrictions for air/ground travel. The winds will lessen for much of the region on Tuesday as valley rain and mountain snow arrive, but gusty winds will persist in S Mono and Mineral counties into Wednesday. Precipitation?! - The Pacific storm will meander across the Sierra and western Nevada Tuesday through the rest of the week. Moist, southerly flow will advect moisture into the region resulting in increased potential for valley rain, mountain snow, and yes, even some thunderstorms. Blended guidance is hinting at a fairly high potential for widespread (much-needed) wetting rains and most of the area with a 50%+ chance of at least 0.25 inches of rain through Friday. Some areas could see enhanced precipitation totals, especially considering the rather high EFI signals for CAPE on Wednesday. The anomalous CAPE values paired with the upper level ascent of the trough increases confidence for thunderstorm potential (15-25% chances) Wednesday and Thursday. Snow levels will be pretty high with this warmer, sub-tropical origin storm. Snow levels around 7500-8000 ft will allow for wet snow accumulations along higher mountain passes in Mono County and Mammoth Mountain where there is 50-70% chance of 4+ inches of snow by Friday morning. If you have outdoor recreation plans or travel in the Eastern Sierra, then plan on snow impacting those activities. Weather will remain on the cool side through next weekend as the large scale trough remains a fixture across the West and the Eastern Pacific ridge is slow to return. -Lindaman && .AVIATION... Widespread VFR conditions persist through today with standard westerly breezes of 15-20 kts by this afternoon. Stronger S/SW winds arrive Monday with increased potential for minor LLWS and mountain wave turbulence concerns through Tuesday morning. The Pacific storm bringing the enhanced winds on Monday will finally pass through the West Tuesday-Wednesday. Plan on periods of valley rain and mountain snow that will lower CIGS/VIS at all area terminals. A 10-20% chance of thunderstorms on Wednesday may also bring sudden VIS reductions to area terminals. -Salas/Lindaman && .FIRE WEATHER... Winds will increase on Monday ahead of a Pacific storm approaching the West. South-Southwest wind gusts Monday afternoon will waver around 30 mph with localized gusts up to 40 mph for the Sierra north of Highways 50/88 into Plumas-Lassen and into northern Washoe County, and the Reno-Carson-Douglas-Storey area. Winds along with recent warm and dry conditions will lead to an elevated wildfire threat and may produce localized critical conditions Monday afternoon. By Tuesday night into Wednesday, the Pacific storm is projected to bring widespread wetting rainfall and high elevation snow. Most areas have a 40% chance or higher of receiving at least 0.25" of liquid between Wednesday and Thursday. For the eastern Sierra, plan on accumulating snow (3-8 inches) above 7500-8000 feet by Friday morning. -Lindaman && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$

352 FXUS66 KSTO 182113 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 213 PM PDT Sun Oct 18 2026 For additional details on weather and expected impacts over the next 7 days, please visit weather.gov/sto/briefing. .KEY MESSAGES... - Gradual cool down begins Sunday with renewed precipitation chances by the middle of next week. - Onshore flow returns Sunday evening, providing temperature relief and increased overnight/daytime humidity values Monday through next week. && .DISCUSSION... ...Rest of Today - Monday... Clear skies today with slightly cooler temperatures. High temperatures this afternoon are on track to be in the lower to mid 80s across the Valley floor, about 3 to 7 degrees lower than yesterday, with somewhat higher humidity levels. An approaching Pacific Northwest shortwave trough will bring increased onshore flow to the region by later this afternoon into the evening, with a fairly strong Delta Breeze gusting to 20 to 30 mph. Temperatures will be cooler tonight into Monday morning and overnight humidity recoveries will increase significantly, helping mitigate area fire weather concerns. Monday the trough will develop into a closed low off the Northern California coast. Daytime temperatures will be noticeably cooler than seen recently, with Valley highs ranging from upper 60s to low 70s over the Sacramento Valley and Delta, to the mid 70s in the northern San Joaquin Valley. Breezy onshore flow continues through the Delta into the evening, gusting to 30 mph, and over the Sierra gusting to 35 mph. Generally dry weather is expected, except for a slight chance of rain showers over the northern Coast Range. ...Tuesday-Thursday...Confidence has increased in a cool, unsettled pattern through the week. Ensembles continue to show the low pressure drifting southward along the coastline Tuesday, which may limit precipitation chances until the evening, with dry weather during the day and widespread rainfall overnight. Moisture will advect northward into the area on the east side of the low, with best potential for precipitation south of I-80 Tuesday night. Chances of precipitation continue Wednesday as the low opens into a shortwave and tracks eastward through California. Instability has trended higher, with a 20% probability of afternoon thunderstorms now projected over the Sierra. General storm total rainfall amounts range up to around 0.75" over the Sierra crest, down to 0.05-0.20" in the Valley and lower foothills, though confidence in specific amounts remains low, with model fluctuations. Snow levels are expected to remain around 9,000 feet initially, limiting any snow to the highest peaks. Snow levels drop to around 8,000-8,500 feet Wednesday night into Thursday, which could bring some light accumulations to higher Sierra passes, such as Sonora Pass and Ebbetts Pass, though even there travel impacts should be minimal. Cooler temperatures, higher humidity and precipitation will continue to decrease fire weather concerns. ...Friday - Weekend...Friday is trending dryer as the shortwave trough exits to the east, with just some light, lingering showers over the Sierra and southern Cascades in the morning. A brief period of eastern Pacific ridging should bring a shift to breezy northerly winds through the day into early Saturday. Humidity levels should remain relatively moist, limiting fire weather concerns. Most of the clusters are suggesting a trough pattern for the weekend, but range widely in the strength and location of it. Overall continue to expect a continuation of cool, below normal temperatures with unsettled weather. NBM is currently forecasting widespread precipitation for Sunday. && .AVIATION... VFR conditions prevail across interior NorCal next 24 hours. Surface wind gusts generally below 15 knots, except in Delta from around 21z today through 18z Monday where onshore flow is forecast to strengthen with west gusts up to 30 knots. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$

054 FXUS65 KMSO 181912 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 112 PM MDT Sun Oct 18 2026 .DISCUSSION... KEY MESSAGES: - Mild temperatures continue through Thursday. - Unsettled weather and cooler temperatures arrive Friday into next weekend. Mild weather will continue across the Northern Rockies through the middle of the week. Forecast models show a low pressure system stalling off the California coast by Monday, while the main storm track stays far to the north across Alaska and northern Canada. This will bring mild daytime temperatures, around 10 degrees above average, across the region. Most areas will remain dry today (Sunday) and Monday. However, a few showers are possible in north-central Idaho and southwest Montana on Tuesday and Wednesday as moisture moves north from the California coast. Computer models show varying solutions as a large low pressure system over Alaska and Canada moves south toward the Western U.S. Thursday and Friday. Most models suggest this system will combine with the low pressure area off the California coast, increasing the chance for rain and snow by Friday. While the exact track of these low pressure systems remains uncertain, confidence in a cooler and wetter pattern is high. By the end of the week, afternoon temperatures will be 10 to 20 degrees cooler than this weekend, returning to near normal for this time of year. && .AVIATION...Mostly clear skies and light terrain-driven winds are expected over the Northern Rockies for the rest of today and Monday. Light winds and clear skies tonight will allow patchy fog and stratus to develop in the valleys, especially along bodies of water. Any fog and stratus that develops will dissipate by 1700Z each morning. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$

381 FXUS65 KBOI 182324 AFDBOI Area Forecast Discussion National Weather Service Boise ID 524 PM MDT Sun Oct 18 2026 .UPDATE...Updated aviation discussion. && .KEY MESSAGES... - Warm and dry conditions through early Tuesday, with high temperatures 5 to 15 degrees above normal. - Chances for precipitation increase Wednesday through Friday, with cooler temperatures by the end of the week. && .SHORT TERM /Through Tuesday Night/... Issued 240 PM MDT SUN OCT 18 2026 A closed low approaching the Pac NW coast will turn south while still off-shore on Monday. This will enhance southerly flow over the region, pushing temperatures to 10-15 degrees above normal, while elevated and open terrain see wind gusts of 20 to 30 mph. Moisture increases on Tuesday, wrapping around the low as it drops off the central CA coast. With precipitable water reaching the 90th percentile, afternoon heating/instability will support a 10-15% chance of showers and thunderstorms over w-central Idaho mountains and higher terrain along the ID/NV border Tuesday afternoon. Southerly flow could push a shower/storm into the western Magic Valley (about a 10% chance). Otherwise mild and dry conditions will continue across the area. && .LONG TERM /Wednesday through Sunday/... Issued 240 PM MDT SUN OCT 18 2026 A sharp cooldown, precipitation, thunder, and winds are all in store as successive troughs of low pressure move through the area. Wednesday through Friday, a closed low off the coast of California will rejoin the broader flow as a trough amplifies over the Pacific Northwest. A slight ridge axis over the region will allow slight warming on Wednesday as clouds increase ahead of the approaching Californian low. Temperatures that afternoon will be 10-15 degrees above normal. Wednesday evening, precipitation chances begin to increase substantially to 50-70%. Broad cloud cover will inhibit instability, but the colder atmospheric mid-layer with still warm surface temperatures allow for a 10-20% chance of thunder Wednesday evening. Clouds, precipitation, and a colder airmass moving in drop temperatures to near normal on Thursday, with precipitation chances still 50-80% and just warm enough for a 10% chance of thunder that afternoon and evening. Before precipitation tapers off Friday evening, Friday morning the cold front passes, cooling temps to about 5 degrees below normal and bringing wind gusts up to 25-35 mph out of the NW. Winds remain strong through Friday evening. Over the course of the event, rainfall accumulation is forecast at 0.05-0.3 tenths in lower elevations, and 0.25-0.5 inches for mountain valleys. Mountain summits and ridges could see 0.5-1 inch of rainfall, and 1-4 inches of snow on summits above 8000 ft MSL. Snow is unlikely on mountains until Friday morning. Temperatures are forecast to be near normal Saturday through Sunday, with another significant upper-level trough looking to impact the area Sunday. Behind the earlier system, snow levels are lower at 6500 ft MSL. Precipitation on Sunday will fall as snow in mountain passes and the highest mountain towns if the temperature forecast holds steady. Also behind the earlier trough, mountain valley cold pools could support fog/stratus formation and allow snowfall in the valleys on Sunday. && .AVIATION /00Z Monday through Tuesday/... Issued 507 PM MDT SUN OCT 18 2026 VFR under high clouds. Locally reduced visibility due to smoke/haze. Surface winds: variable up to 12 kt. Winds aloft at 10kft MSL: SW 10-25 kt. KBOI...VFR. Surface winds: light NW or variable through sunset, transitioning to SE 6-12 kt overnight. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise AVIATION.....SH SHORT TERM...DG LONG TERM....JM

904 FXUS65 KLKN 182256 AFDLKN Area Forecast Discussion National Weather Service Elko NV 356 PM PDT Sun Oct 18 2026 .KEY MESSAGES... * Unseasonably warm continues through Tuesday afternoon * Cooling trend Thursday and Friday * Valley rain and mountain snow showers likely late Tuesday into Wednesday through Friday && .DISCUSSION... (This evening through next Saturday) WEATHER PATTERN OVERVIEW: Satellite loop is showing nothing in the way of cloud cover across northern and central Nevada this afternoon. Expect a cool night with lows in the 30s and clear skies. Dry and warm conditions continue to dominate in the short term as a dry pattern remains over the forecast area. High temperatures Monday and Tuesday afternoons are expected to be in the 60s and 70s. Overnight lows for Monday and Tuesday night will be in the 30s and 40s. All models are depicting an upper level low pressure system diving to the south from the Pacific Northwest states to just off the coast of western California late Tuesday. Light valley rain showers and mountain snow showers are expected to develop during the latter portions of the afternoon and overnight period. Winds will be breezy to locally windy with gusts of 25 to 40 mph. Highs will be several degrees cooler with readings in the 50s and 60s. Overnight lows will be in the 30s and 40s. A slow forward progression is in store for this storm system as it tries to move east across northern and central Nevada Wednesday and Thursday. Valley rain showers and mountain snow showers are again possible both days. The estimated three day forecast amounts for precipitation and snowfall are coming in around one-half to two-thirds of an inch of rainfall in the valleys with one to four inches across the highest elevations in the mountains. Afternoon highs both of these days will be in the 50s and 60s with overnight lows in the 30s and 40s. The system may be exiting east by the latter portions of the week. Highs will remain on the cool side with readings in the 50s and 60s and lows in the 30s. FORECAST CONFIDENCE & DEVIATIONS: No changes were made to the short term grids as NBM is handling the forecast well. Confidence in the forecast remains high through Monday. Confidence continues to be moderate with respect to the precipitation and temperature forecast next week. Low confidence on the chances of a cold front late next week. && .AVIATION... VFR conditions will be the predominate flight category across all terminals for the next 24 hours. No precipitation is expected today through Tuesday morning. && .FIRE WEATHER... High temperatures throughout Northern and Central Nevada through Tuesday afternoon will be two to four degrees above normal for this time of year. A cooling trend is expected Thursday and Friday. The next storm system will impact Northern and Central Nevada late Tuesday through Friday, resulting in periods of valley rain and mountain snow showers. Isolated thunderstorms are possible across the central fire zones Tuesday afternoon. Wind gusts will be around 20 to 25 mph Monday and Tuesday afternoon as well, though the northern zones will see minimum relative humidity values above fifteen percent Monday. && .LKN Watches/Warnings/Advisories... None. && $$ DISCUSSION...86 AVIATION...86 FIRE WEATHER...86