068 FXUS66 KSEW 200348 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 848 PM PDT Tue May 19 2026 .SYNOPSIS... High pressure aloft will begin to rebuild across Western Washington on Wednesday and remain in place into Friday for a return to some sunshine and warmer temperatures. The ridge will weaken over the upcoming holiday weekend for a cooling trend and a chance of rain by Memorial Day. && .SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... A building upper ridge on Wednesday will lead to clearing skies and warmer temperatures. The ridge remains firmly in place offshore into Thursday with low level onshore flow weakening. Interior temperatures will warm a few degrees, but coastal area temperatures will likely stay fairly static with night and morning clouds hanging around and an afternoon sea breeze. && .LONG TERM /FRIDAY THROUGH TUESDAY/... The upper ridge axis offshore begins to weaken on Friday with low level onshore flow picking up a notch late in the day. Interior temperatures should be similar to those of Thursday...upper 60s to mid 70s...while coastal areas remain mostly in the lower 60s. The ridge is expected to flatten by Saturday for slightly cooler temperatures to begin the weekend. The weekend looks like a tale of two halves. Ensemble height anomalies agree that a deepening upper trough over the Northeast Pacific will begin a transition toward cooler temperatures and possible precipitation, but the speed of transition is up for debate. In general, the Euro and Canadian suite of solutions are more agressive with the troughs arrival while the GFS is less so. Sunday should feature additional cooling and cloud cover with precip chances increasing areawide Sunday night into Memorial Day. 27 && .AVIATION... Upper ridging offshore will continue to lead to N/NW flow aloft over western Washington for the entire TAF period. Some differences in surface flow...while the majority of terminals are seeing westerly to northwesterly winds, PWT is favoring an easterly direction while BLI is more southerly. Speeds ranging 4-8 kts although HQM is running closer to 8-12 kts this evening. A universal transition to north to northwesterly winds expected by 06Z tonight and remaining that way into late Wednesday morning with speeds generally 5 kts or less. Most terminals expected to remain northerly, with some variations to the NE or NW, but will see speeds increase to range mostly 5-10 kts. VFR conditions hold court over the eastern half of the CWA while MVFR cigs in place from CLM and points west. Low clouds expected to push westward through the night with widespread MVFR expected by 12Z Wednesday morning /IFR for terminals more prone to lower cigs/. Lifting looks to kick in during the 18-20Z time frame with widespread VFR conditions returning. The strengthening ridge will make life difficult for any low-level clouds, scattering out the lower altitudes leaving only SCT to BKN high clouds by Wednesday evening. KSEA...VFR conditions this evening into tonight with W to NW winds 4 to 8 knots, becoming more northerly after 06Z. Mid to high level clouds before MVFR conditions return late tonight and lasting throughout Wednesday morning. VFR conditions returning around 18z- 20z. 18/Mazurkiewicz && .MARINE... Surface high pressure offshore will continue onshore flow throughout the area waters through majority of the week. A small craft advisory remains in effect for all outer coastal water zones, mainly for elevated seas. Can expect another westerly push down the Strait of Juan De Fuca tonight, where a small craft advisory is also in effect. Diurnally driven pushes down the Strait expected through the end of the week. A system on Friday and Saturday could bring a round of elevated seas and winds to the coastal waters. Coastal seas 6 to 8 feet this evening will increase to 8 to 10 feet tonight into Wednesday. Seas will then level to 7 to 9 feet throughout Thursday, before rising above 10 feet Friday and into the weekend. Mazurkiewicz/18 && .HYDROLOGY... The daily hydrology discussion has ended until the start of the next rainy season; it will only be updated during this time as needed. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory until 5 AM PDT Wednesday for Central U.S. Waters Strait Of Juan De Fuca-Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-East Entrance U.S. Waters Strait Of Juan De Fuca. && $$

459 FXUS66 KPQR 200541 AAB AFDPQR Area Forecast Discussion...UPDATED National Weather Service Portland OR 1041 PM PDT Tue May 19 2026 Updated aviation discussion. && .SYNOPSIS...Dry and benign weather is expected across the region through much of the next week with high pressure remaining in place over the Northeast Pacific. Weak systems aloft may bring enhanced cloud cover on some days, but rain chances are minimal. Uncertainty in the forecast increases Sunday into Monday as chances for precipitation return. && .DISCUSSION...Now through Monday night...Broad upper-level ridging continues to build over the Northeast Pacific with persistent northwesterly flow streaming onshore from the Gulf of Alaska. This pattern will remain largely the same through Wednesday, with weak upper shortwaves bringing marine air inland and allowing pockets of mist or drizzle along the coast through the overnight and early morning hours. Temperatures will remain seasonable, around 60 degrees on the coast and near 70 degrees along the I-5 corridor. As offshore ridging shifts east late in the week, temperatures will trend warmer, reaching the 60s to near 70 degrees on the coast and upper 70s to mid 80s inland. This will support widespread Minor HeatRisk excepting only the immediate coast and high Cascade crest. Chances for Moderate HeatRisk are 20-35% in Portland and the adjacent northern Willamette Valley, 5-20% in Salem and Albany/Corvallis, and 5% or less elsewhere. Concerns for hazardous weather otherwise remain low. Friday through the holiday weekend, uncertainty in the evolution and possible break-down of the upper-level ridge yields growing uncertainty in forecast temperatures and precipitation. In general, as the ridge deamplifies, temperatures are more likely to trend cooler through the period, especially by Monday. The 80%-confidence envelope (the difference between the 10th and 90th percentiles) in temperature widens from 8-13 degrees on Friday and Saturday to 13-19 degrees on Sunday and Monday along the I-5 corridor, with warmer scenarios resulting from a more persistent ridge and cooler scenarios from a more rapid break down. There continues to be greater consensus of an upper-level trough digging over the Northeast Pacific on Monday, supporting much cooler temperatures and 30-60% chances for rain across the region, with the highest chances to the north of US-20 and in areas of higher terrain. -36 && .AVIATION...Northwest flow over continues over the forecast area supporting a mix of MVFR conditions along the coast and VFR inland. The summer-like pattern supporting marine stratus along the coast and MVFR CIGs is expected to persist through the overnight hours. VFR conditions inland are expected for a few more hours before chances for MVFR conditions increase. Guidance suggests some stratus backbuilding into the Willamette Valley from the Cascade Foothills. Chances for MVFR CIGs inland increase after 08z with all terminals seeing a 30-60% chance through 16-18z, highest in the southern Willamette Valley around KEUG and in the eastern Portland metro. Conditions expected to improve back to VFR by mid to late morning inland and early afternoon along the coast. Light winds overnight, becoming north/northwesterly Wednesday morning between 5-10 kt. Could see some gusts to around 20 kt at KONP during the afternoon. KPDX AND APPROACHES...Mainly VFR conditions with a chance for a short period of MVFR CIGs earlier Wednesday morning. Guidance shows backbuilding clouds along the Cascades pushing eastward starting around 09Z Wed. 30-60% chance for MVFR conditions developing and impacting the eastern metro, mainly KTTD and KPDX with lower chances at KUAO and KHIO. If these conditions manifest, improvement towards VFR starting around 18Z Wed. Light winds overnight, becoming north/northwesterly 6-10 kt after 18z Wednesday. -19 && .MARINE...Northerlies are expected to persist through much of the week as the summer-like pattern settles in. Strongest winds are expected during the afternoon and evening periods as a surface thermal trough strengthens over the region. Therefore, have updated the current suite of Small Craft Advisories as gusts up to 25 kt are expected across all zones with the exception of PZZ251, this afternoon and Wednesday afternoon. Seas 6 to 9 feet are expected through the week as well. Chances increase on Thursday and Friday for widespread wind gusts for all marine zones. Small Craft Advisories are in place for the Columbia River Bar Wednesday morning due to strong/very strong ebb currents which will produce conditions hazardous to small craft. Strong/very strong ebb currents are possible during the morning hours each day this week. -42/DH && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory from 6 AM to 10 AM PDT Wednesday for PZZ210. Small Craft Advisory until 2 AM PDT Wednesday for PZZ252-253- 271-272. Small Craft Advisory from 4 PM to 9 PM PDT Wednesday for PZZ252-271-272. Small Craft Advisory from 1 PM to 9 PM PDT Wednesday for PZZ253. Small Craft Advisory until 9 PM PDT Wednesday for PZZ273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland

408 FXUS66 KMFR 200741 AFDMFR Area Forecast Discussion National Weather Service Medford OR 1241 AM PDT Wed May 20 2026 .DISCUSSION...High pressure and dry northwest flow aloft will keep dry weather going through the remainder of this week along with a warming trend. High temperatures today will be a few to several degrees above normal, but warmer air aloft will bring temperatures around 10-15F above normal from Thursday through the weekend. The air mass is pretty dry, but we`ll get marine pushes from time to time that will bring bouts of nighttime/morning stratus to the coast, coastal valleys and Umpqua Basin. One such marine push is occuring this morning, which could be deep enough to cause some spillover clouds to bank up against the Siskiyous around the Rogue Valley this morning, but that`s about it. By late Friday, models are showing a weak impulse offshore and some moisture/weak instability near the NorCal mountains (mainly south of here -- Sierra). This raises the idea of thunder, but the probability of anything occurring this far north is 10% or less. Same goes for Saturday pm/eve. As we maintain the dry airmass and breezy afternoons, there will be at least an elevated threat for fire weather conditions each day. However, fuel conditions per fire agencies reveal the overall fire weather threat will remain low to moderate. Given the low RH values and breezy winds each afternoon, people should exercise caution with any outdoor activities that could cause sparks or flames. Bottom line is that fire season was declared early this year, so these precautionary actions should already be in place, but its especially important when we have these elevated fire weather days. Looking ahead, there are indications that the ridge will begin to break down over the weekend, with the potential for a more robust trough to enter the Pacific Northwest around Memorial Day that could bring precipitation and cooler temperatures to the forecast area. Model suites still are not in solid agreement with this scenario, with several differences primarily in trough strength, but also its timing, so confidence is also still on the low side. This will warrant a close eye for those with plans for the Memorial Day holiday. Most inland areas should have a 5-10F cool down along with enhanced to locally gusty winds, and a chance of showers. && .AVIATION...20/12Z TAFs...A weak impulse is passing over the region this morning, with a marine push resulting in IFR/MVFR ceilings over the marine waters and along the coast, and eventually the coastal valleys and Umpqua Basin by daybreak, including at North Bend and Roseburg. Marine layer depth (up to around 5000 feet) allows for the potential for some clouds to form and bank up against the Siskiyous this morning. These may cause local terrain obscuration but should be VFR above Medford. Any low flight conditions will clear through the morning or even early afternoon, with VFR then expected for the remainder of the TAF period. Elsewhere, VFR conditions will prevail through tonight. && .MARINE...Updated 1200 AM PDT Wednesday, May 20, 2026...A thermal trough will bring gusty north winds and steep to very steep seas over the coastal waters through Friday night. Winds will be strongest and seas will be highest during the afternoons/evenings. Through this stretch, very steep seas of 10-12 ft are most likely south of Cape Blanco with steep seas (6-9 ft) north of Cape Blanco. Guidance shows winds will strengthen Wednesday/Thursday with the potential (35-55% chance) for gales (gusts) across portions of the southern waters, especially from around Gold Beach south. The pattern will ease some this weekend as an upper trough pushes in from the NW. This should bring lighter winds and lower seas, especially by Sunday. Model scenarios indicate another trough moving through Sunday night into Monday, but the strength of the trough is the main source of uncertainty at this time. We should get a better handle on this in the coming days. && .MFR WATCHES/WARNINGS/ADVISORIES... OR...CA...None. PACIFIC COASTAL WATERS...Hazardous Seas Warning until 11 PM PDT Friday for PZZ356-376. Small Craft Advisory until 11 PM PDT Friday for PZZ350-370. && $$

072 FXUS66 KEKA 192237 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 337 PM PDT Tue May 19 2026 .SYNOPSIS...Clear and dry conditions will remain through the week with a warming trend through Thursday. A weak and shallow marine layer will hang along shore. Temperatures will trend lower this weekend weekend. && .KEY MESSAGES... -Northerly winds are much lighter, but will be breezy in the afternoons close to shore. -Generally clear skies and dry conditions, even along shore, through the week. -Conditions will warm through Thursday with highs in the interior peaking near 90. && .DISCUSSION...Weak high pressure arching over the area has made for slowly warming and dry but otherwise benign weather. Clear skies in the interior and weak winds has allowed for highs to warm back into the mid and upper 80s. Similarly, a slowly building but diffuse marine inversion has made for cooler and hazy conditions along shore. High pressure will quickly but briefly build over the next couple days. Heat will peak around Thursday with above average interiors highs in the low 90s. HeatRisk, however, will be mostly minor. A sharper marine inversion combined with onshore flow will most likely support the formation of a a more proper, shallow marine layer the next few nights, but daytime clearing remains most likely (80%) each afternoon. Still, the coast will most likely keep highs below 70. High pressure will weaken again this weekend, allow for slight cooling and more marine influence to push inland. Most models show a stronger and more consistent layer of marine stratus forming around Humboldt Bay and other protected areas, aided by gentle but persistent onshore flow. Most ensemble members continue to show a trough dipping across the Pacific Northwest early next week. The trough, however, will most likely be dry with only light drizzle on the coast and some weak showers inland. Even on the far North Coast, the chance of wetting rain is less than 10 percent. /JHW && .AVIATION...(18Z TAFs)...VFR conditions are being observed at all terminals early this afternoon. Gusty northerly winds, especially at the coast, are likely this afternoon. CEC could see gusts nearing or exceeding 30 kts. Winds are likely to ease overnight. Lighter winds overnight may allow stratus to form near the coast. Prevailing, light east winds at ACV may keep this offshore, or keep impacts brief and periodic. Should there be impacts, the stratus is likely to be shallow with LIFR to IFR ceilings. CEC is likely to remain stratus-free as north winds prevail overnight. VFR conditions are likely for the interior areas overnight. JB && .MARINE...North winds remain strong, especially in the outer waters and around Point St. George and in the lee of Cape Mendocino. Gales are expected to continue in these areas for much of the work week. Steep to very steep, hazardous seas will also continue with wind waves of 8 to 13 ft at 8 to 10 seconds and a mid period northwest swell at around 5 to 7 ft. This swell has peaked and will subside over the coming days. A break in the winds is likely this weekend as a trough moves into the Pacific Northwest. Seas will also ease this weekend, and could be below 6 ft in the inner waters by Saturday evening. JB && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 10 AM PDT Thursday for PZZ450- 455. Gale Warning until 9 PM PDT Friday for PZZ470. Gale Warning until 10 AM PDT Thursday 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

156 FXUS66 KMTR 200537 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1037 PM PDT Tue May 19 2026 ...New SHORT TERM, LONG TERM... .KEY MESSAGES... Updated at 1036 PM PDT Tue May 19 2026 - Diurnally driven winds, with onshore winds during the afternoon and early evening. - Above normal temperatures continue through midweek with seasonal temperatures returning late week. - Warm and dry weather through Thursday leads to elevated fire weather concerns for the interior Bay Area and Central Coast. && .SHORT TERM... Issued at 1036 PM PDT Tue May 19 2026 (Tonight through Thursday) Little change in the forecast as high pressure slowly creeps into Northern California today. Satellite imagery this evening shows high clouds sliding down the West Coast, with much of the Bay Area likely seeing some cirrus. With the current data, temperatures look to be on track; however, if we`re not able to get radiational cooling, our temperatures for tonight might be low/cool. This would be because the clouds act as blanket, allowing less heat to escape at night. It`ll be something to keep an eye on over the next few hours. In terms of Wednesday, if you guessed, "No pattern change. Ha, this means another day of warmer weather", you`d be correct! A potential fly in the ointment is if the marine layer attempts to manifest around 500 feet. This might keep temperatures a few degrees cooler along the immediate coast, but elsewhere temperatures should be similar to Tuesday, perhaps a few degrees higher. && .LONG TERM... Issued at 1036 PM PDT Tue May 19 2026 (Thursday night through next Tuesday) No major changes to the extended forecast. Upper level troughing looks to keep hold over the western US, while the Pacific high pushes even more into northern California on Thursday. With the high being a bit more pronounced, another warm day will be on tap. After that, guidance has flow becoming quasi-zonal for a brief period before troughing returns on Friday. The marine layer looks to be around 500ft on Thursday, deepening to around 1000ft by Friday and then lasting through the weekend. With onshore flow, a deeper marine layer, and troughing through the weekend the NBM`s temperatures are bit too warm. Opted to start trending towards slightly cooler temperatures given the ensembles and cluster analysis. But there is a chance ridging wins out and temperatures might warmer. Definitely something to keep an eye on over the next few days. && .AVIATION... (06Z TAFS) Issued at 926 PM PDT Tue May 19 2026 Currently VFR at all terminals with the exception of MVFR at HAF. Winds may become calm and/or light and variable overnight. Low to moderate confidence in IFR conditions developing at terminals tonight - the most likely timeframe is 12Z to 16Z. Coastal terminals will be at greatest risk with risk decreasing for bayshore and interior terminals, respectively. Higher confidence in IFR conditions returning tomorrow night. Vicinity of SFO...Currently VFR with northwesterly flow. Moderate to high confidence in VFR and diurnal winds prevailing through the TAF period. Low probability for sub-VFR conditions to develop at the terminal tonight as the compressed marine layer will be unable to penetrate the San Bruno Gap. Reasonable worst case scenario is stratus sneaks through the Golden Gate Gap and brings FEW/SCT to the north side of the terminal. SFO Bridge Approach...The San Mateo Bridge Approach has a lower probability of sub-VFR conditions. Monterey Bay Terminals...Currently VFR and calm at MRY and VFR with northerly flow at SNS. Confidence has increased in sub-VFR conditions developing at the terminals tonight, especially for MRY. Ceilings will likely be on the cusp of IFR/LIFR. && .MARINE... (Tonight through next Monday) Issued at 926 PM PDT Tue May 19 2026 Hazardous conditions for small craft will continue through Wednesday for the northern outers due to rough seas and strong northerly breezes. Elsewhere, moderate to fresh northwesterly breezes and moderate seas will prevail. Conditions improve into the weekend as seas and northwesterly breezes become moderate. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory until 3 PM PDT Thursday for Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...KR LONG TERM....KR AVIATION...Sarment MARINE...Sarment 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

555 FXUS66 KOTX 200722 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 1222 AM PDT Wed May 20 2026 .KEY MESSAGES... - 10-30% chance of pop up showers and isolated thunderstorms northeastern WA and north Idaho Wednesday afternoon. - Conditions trend drier and warmer through the workweek regionwide, with periodic breezy winds for the Cascades and central WA. - 90% chance for a cooling trend into early next week with chances for precipitation and breezy conditions. && .SYNOPSIS... Showers with isolated thunderstorms will continue Wednesday afternoon in northeast Washington and north Idaho. Precipitation chances decrease and afternoon highs trend warmer through the workweek, climbing into the high 70s and 80s by Friday and continuing through the weekend. Breezy winds are expected at times through the Cascade gaps and across the western Columbia Basin. There is high confidence for cooler and unsettled conditions to return early next week. && .DISCUSSION... Today through Sunday: A shortwave in southern Alberta will bring a dry cold front from the north Wednesday evening. There will be a 10- 30% chance for showers and isolated thunderstorms in northeast Washington and north Idaho this afternoon as a 110 kt jet streak dives in from central BC and into north central Washington. Instability will be maximized around the ID/MT border in the late afternoon with around 300-600 J/kg of surface based CAPE. Farther west in northeast Washington, drier boundary layer conditions will lead to higher cloud bases thus less available surface based CAPE. Effective bulk shear will be weak around 15-20 kt so expect single cells. Main risks with these cells will be gusty outflows up to 30 mph, isolated lightning, and small hail around pea size. Farther west this afternoon and early evening, there will be elevated fire weather conditions with dry and breezy north winds 10-15 mph down the Okanogan valley, eastern Waterville Plateau, and northern Basin. Behind this system, the Inland NW will be mild with above normal 500 mb heights through Saturday thanks to high pressure off the coast. Temperatures will climb from the upper 60s to low 80s today to the high 70s to upper 80s by Friday and through the weekend. Sunday through Wednesday: Changes are coming as the ensemble clusters indicate a 90% chance of a trough in the Gulf of Alaska diving south towards the Pacific NW Sunday and Monday. This will bring a cooling trend early next week and chances for rain and high elevation snow. There is still a 3000 ft spread for the 10th to 90th percentile snow levels in the Cascades Monday and Tuesday. The colder solutions have snow levels around 3500-4500 ft and the warmer solutions having snow levels around 6500-7500 ft. This period will need to be monitored for folks headed out into the high backcountry for potential light snow. /db && .AVIATION... 06Z TAFs: VFR conditions expected through the period. Showers and isolated thunderstorms will spark across northeast Washington and north Idaho again Wednesday afternon with breezy outflow gusts around 25 kt. Winds will be fairly light but shift towards northerly component in the afternoon as south-north pressure gradient increases with a dry front passage from the north. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence in VFR conditions the next 24 hours. ----------------------- 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 70 43 71 46 76 49 / 20 0 0 0 0 0 Coeur d`Alene 68 42 71 47 74 49 / 20 10 0 0 0 0 Pullman 66 41 68 44 73 46 / 10 10 0 0 0 0 Lewiston 71 46 74 48 78 51 / 0 0 0 0 0 0 Colville 73 37 76 43 79 46 / 20 0 0 0 0 0 Sandpoint 67 40 70 45 73 47 / 20 10 0 0 0 0 Kellogg 67 41 72 45 75 47 / 30 20 0 0 0 0 Moses Lake 77 48 78 48 82 52 / 0 0 0 0 0 0 Wenatchee 77 53 78 54 82 57 / 0 0 0 0 0 0 Omak 77 47 78 50 82 54 / 10 0 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... WA...None. ID...None. && $$

259 FXUS66 KPDT 200510 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1010 PM PDT Tue May 19 2026 .KEY MESSAGES... - Isolated showers today and Wednesday, mainly over the mountains - Breezy to locally windy westerly winds through the Cascade gaps today - Warming through the week && .DISCUSSION... Through Saturday, warming temperatures and mostly dry conditions are forecast region-wide as an upper-level ridge of high pressure will likely (95 percent confidence) build into the region from the Pacific and dominate the weather. A couple weak shortwaves coupled with modest diurnally induced instability (surface-based CAPE of a up to a couple hundred J/kg from forecast soundings) may facilitate some isolated showers, mainly over the mountains through Thursday, but PoPs are low (15 percent or less). Breezy to locally windy westerly winds are forecast through the Cascade gaps today, but not anticipating a need for any wind headlines. Late Wednesday through Thursday, a reversal to mostly light easterly to northeasterly (offshore) winds is forecast as a shortwave trough digs south across the northern Plains and Rockies, just clipping the edge of our forecast area. Considerable uncertainty in the 500-hPa pattern is present in ensemble solutions by the weekend and early next week, with the majority of the variance in solutions explained by timing and magnitude differences regarding the arrival of a trough or closed low from the Pacific. Ensemble trends have been towards a closed low for the Pacific Northwest sometime between Monday and Tuesday, but run-to-run and ensemble-to-ensemble differences are still quite significant and forecast confidence is lower than average. Ensemble clustering tools did not run today, so can`t provide any more details about scenarios at this time. The NBM has westerly winds returning to the region by late Friday, persisting through the weekend and into early next week. There are low chances (10-40 percent) of reaching advisory- level winds Saturday and Sunday through wind-prone areas of the lower elevations, primarily the eastern Columbia River Gorge, north-central Oregon, the foothills of the Blue Mountains, and the Kittitas Valley. By Monday, chances increase to 20-60 percent across the same areas. Of course, the magnitude of winds will be tied to the synoptic pattern, and given the uncertainty (see paragraph above), can`t really talk about much confidence in forecast details yet. && .AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...VFR conditions to prevail through the period. Breezy winds continue at sites DLS/PDT/PSC for the next couple hours tonight, with light and diurnally driven winds developing after 07-08Z. Otherwise, light winds at all other sites through the period. Lawhorn/82 && .Preliminary Point Temps/PoPs... PDT 46 73 46 76 / 0 0 0 0 ALW 50 73 49 76 / 0 0 0 0 PSC 49 78 51 81 / 0 0 0 0 YKM 47 79 50 80 / 0 0 0 0 HRI 48 76 49 79 / 0 0 0 0 ELN 43 73 45 75 / 0 0 0 0 RDM 37 73 39 77 / 0 0 0 0 LGD 40 70 41 73 / 0 0 0 0 GCD 39 73 39 75 / 0 0 0 0 DLS 50 77 51 83 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... WA...None. OR...None. && $$ DISCUSSION...86 AVIATION...82

268 FXUS65 KREV 200704 AFDREV Area Forecast Discussion National Weather Service Reno NV 1204 AM PDT Wed May 20 2026 .KEY MESSAGES... * Temperatures warm to around 5-10 degrees above normal by mid to late week. * Warming temperatures will support afternoon cumulus buildups near the Sierra, with low-end thunder chances Thursday into the weekend. * Afternoon west breezes continue this week, with somewhat stronger breezes possible by Memorial Day into Tuesday. && .DISCUSSION... Chances to hit 90 in W NV and 80 in the Tahoe Basin this weekend has quickly dropped to near zero as a shortwave impacts the area. More details on that in subsequent paragraphs. For now, highs will be 5-10 degrees above average with afternoon temps topping out in the mid 80s and 70s for valleys and higher elevations, respectively. Typical west winds and dry conditions will prevail for much of the area through at least Friday. For the Sierra and Sierra Front, we`re seeing chances for showers and thunderstorms this week. Surface heating will allow for cumulus buildups along the higher terrain today, continuing through Friday. Thursday, those buildups will mature into shower chances, mainly south of the Tahoe Basin through Mono county. Thunderstorm chances remain below 5% and CAPE values barely reach 50 J/kg. Some precip may fall out of the sky with those juicier clouds (model soundings do show inverted-V profiles, though), but any accumulations will be light. Friday looks to be more impactful with afternoon shower and thunderstorm chances expanding into the Tahoe Basin and the Sierra Front. CAPE values increase to 100-200 J/kg, with PWATs increasing to 0.5-0.6". Isolated shower chances with the occasional lightning strike may bring impacts to recreation. Remember, when thunder roars, go indoors! Model agreement remains mixed as we look towards the weekend; they agree on a shortwave, but not necessarily the placement nor the timing of said shortwave. Additionally, the models are having difficulty resolving just how deep the shortwave may get. This could bring additional impacts for the holiday weekend, including gustier winds and isolated thunderstorms. Check back here for more concrete details as we get closer. -Giralte && .AVIATION... VFR conditions are expected through the week with no significant visibility or precipitation impacts at the main terminals. Winds remain typical for late May, with afternoon west to southwest breezes most days. Peak gusts will generally remain around 15-25 kt. Afternoon cumulus buildups are possible near the Sierra crest west of MMH Wednesday, with low-end isolated shower or thunderstorm chances Thursday into the weekend near the Sierra, northeast California, and far western Nevada. Impacts will be limited to isolated mountain obscurations and possible gusty, erratic winds. -Johnston/Giralte && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$

623 FXUS66 KSTO 191820 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 1120 AM PDT Tue May 19 2026 .KEY MESSAGES... - Warm and dry weather prevails through the week and into the weekend with areas of Moderate HeatRisk Wednesday-Friday - Periodically breezy onshore winds return by Thursday; strongest west-southwest winds in the Delta and vicinity locations && .DISCUSSION... ...Today and Wednesday... As troughing over the Great Basin/Desert Southwest ejects eastward through the middle of the week, winds will continue to lessen relative to the past weekend. As ridging builds in offshore of the Pacific Northwest, a deepening trough over SoCal/Baja will leave interior NorCal underneath nebulous split flow mid to late week. Despite this, rising heights aloft will introduce gradually warming temperatures and areas of Moderate HeatRisk beginning on Wednesday. As a result, high temperatures in the 90s are expected in the Valley, with 70s to 80s at higher elevations. ...Thursday into the Weekend... As the split flow pattern and higher heights aloft persist into the end of the week, warm temperatures and Moderate HeatRisk look to stick around through Friday. Warmest temperatures, into the mid to upper 90s in the Valley, are anticipated on Thursday before gradually cooling toward and into the weekend. Despite some ensemble uncertainty, broad troughing aloft is on track to build in over the weekend helping to reinforce breezy onshore winds and temperatures nearer to normal for mid to late May. While periodically breezy onshore winds are expected to develop by Thursday evening, strongest winds are currently on track this weekend into early next week. && .AVIATION... VFR conditions are expected over the next 24 hours. Light northerly winds less than 10 kts expected through the afternoon, becoming light and variable after 00z Wednesday. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$

574 FXUS65 KMSO 191937 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 137 PM MDT Tue May 19 2026 .DISCUSSION... KEY MESSAGES: - Scattered showers today with a few thunderstorms possible over the higher terrain. - A system dropping into central Montana on Wednesday will push a boundary southward through western Montana driving thunderstorm activity through the afternoon and into the evening. - Dry and increasingly warm conditions return later in the week, temperatures nearing 80 degrees(or warmer) by the weekend for many locations. - Watching Monday for potential fire weather concerns in southwest Montana ahead of the next system. A west-northwesterly flow will promote scattered, disorganized showers across the region through the rest of the day today. Instability remains modest resulting in low (~10%) probabilities for thunderstorm development except in the higher terrain (40%). Precipitation amounts will remain light, generally under 0.15 inches for those that do see a shower. For Wednesday, an incoming closed low will track southward into central Montana. The western edge of this low will enhance a due- northerly flow across western Montana and push a boundary southward through the region. Showers and thunderstorms will organize along this feature with initiation in the Flathead Valley around and after noon eventually reaching the Missoula/Bitterroot valleys and points south closer to 5:00 pm and into the evening. There is a 40% chance of lightning with these storms in any area with shower/storm development along with the primary threats of graupel, small hail, and erratic outflow winds of 25-35 mph. Behind Wednesday`s system, high pressure builds across the Northern Rockies, ushering in a quiet, dry, and warming trend to end the workweek. By Saturday and Sunday, temperatures will peak in the upper 70s and low 80s across most valley locations (warmer in the lower river valleys of Idaho). Ensemble clusters suggest a potential breakdown of this ridge by Monday. If this materializes, the combination of a warm, dry weekend followed by increasing pre-frontal winds could elevate fire weather concerns particularly across southwest Montana. && .AVIATION...A slightly unstable west-northwest flow will result in scattered light showers and vicinity showers across most terminals this afternoon and evening. Brief, localized reductions to MVFR visibility and ceilings are possible under any passing showers alongside mountain obscurations across the higher terrain. While the probability of lightning is low today (around 10% for valleys), it is non-zero. Otherwise, expect noticeably gusty surface winds this afternoon with west-northwest gusts of 15-20 kt subsiding after sunset. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$

287 FXUS65 KBOI 200606 AFDBOI Area Forecast Discussion National Weather Service Boise ID 1206 AM MDT Wed May 20 2026 .UPDATE...Updated aviation discussion. && .KEY MESSAGES... - Mostly dry with temperatures warming through Friday. - Well above normal temperatures over Memorial Day Weekend. Gusty winds and a few mountain showers on Memorial Day. - Turning cooler with gusty winds and increasing chance of precipitation starting Tuesday. && .SHORT TERM /Through Thursday Night/... Issued 157 PM MDT TUE MAY 19 2026 Our region will remain positioned on the western edge of upper level troughing through Thursday. While the focus of organized precipitation will remain to our east, daytime instability will support widespread cumulus buildups over the mountains as seen this afternoon. There`s a slight chance that showers could develop from the cumulus field across e-central Oregon and w-central Idaho mtns each afternoon. Localized gusty winds will be possible from showers or more robust cumulus (with or w/o precipitation). Shower chances briefly increase to 15-25% in the w-central Idaho mtns and s-central Idaho zones Wednesday night in response to a passing shortwave trough. Otherwise it`s dry and temperatures are on the way up, leaving behind any frost/freeze concerns for the Snake Plain. By Thursday high temperatures will be several degrees above normal. && .LONG TERM /Friday through Tuesday/... Issued 157 PM MDT TUE MAY 19 2026 A ridge of high pressure will build over the Western US by the end of this week, bringing generally clear, warm and dry conditions to the region through Monday. Temperatures will be about 10-15 degrees above normal. The ridge will reach peak strength on Sunday, with high temperatures near 90F in the Treasure Valley. By Monday, models indicate that an upper level low moving into the Pacific Northwest will begin to increase chances for precipitation. The upper level trough will move inland on Tuesday, with about half of the models showing that the trough will evolve into a closed low over the Pacific NW by Tuesday or Wednesday. In either scenario, temperatures will cool down 10-20 degrees by Tuesday increasing winds and chance of showers and thunderstorms (20-30% chance). && .AVIATION /06Z Wednesday through Thursday/... Issued 1159 PM MDT TUE MAY 19 2026 VFR. Scattered to broken middle and high clouds. Isolated rain showers in the central Idaho mountains and in southern Twin Falls County after 20Z. Surface winds variable less than 10 kt, becoming WNW 10-20 kt after 20Z. Gusts to 25 kt in the Snake Basin east of KBOI after 20Z. Winds aloft at 10kft NW 15-20 kt. KBOI...VFR. Scattered to broken clouds AOA 15kft. Surface winds SE 5-10 kt, becoming WNW 10-20 kt after 20Z. && .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.....LC SHORT TERM...DG LONG TERM....JB

281 FXUS65 KLKN 200727 AFDLKN Area Forecast Discussion National Weather Service Elko NV 1227 AM PDT Wed May 20 2026 .KEY MESSAGES... * Warming trend Wednesday through Sunday * High temperatures throughout Northern and Central Nevada Sunday afternoon about ten degrees above normal for this time of year && .UPDATE... Issued at 1212 AM PDT Wed May 20 2026 No changes have been made to the forecast. && .DISCUSSION... (This afternoon through Monday) WEATHER PATTERN OVERVIEW: A trough of low pressure will remain in the vicinity of Eastern Nevada this afternoon through Wednesday. An atmospheric disturbance will dive southward along the trough of low pressure Wednesday night and Thursday. Precipitation associated with this atmospheric disturbance should remain northeast of Elko County. Zonal flow aloft will prevail Thursday night and Friday. A ridge of high pressure will build northwestward across the Silver State this weekend into early next week. A warming trend is expected Wednesday through Sunday. By Sunday afternoon, high temperatures will be around ten degrees above normal for this time of year. FORECAST CONFIDENCE & DEVIATIONS: High forecast confidence regarding a warming trend Wednesday through Sunday. Moderate forecast confidence in high temperatures Sunday afternoon about ten degrees above normal for this time of year. No deviations from the NBM model output. && .AVIATION... VFR conditions today and tonight at all terminals. Mostly sunny early this morning with increasing clouds late this morning through the early evening hours. Generally SCT-BKN FL100-120, BKN-OVC FL200. Diminishing clouds later this evening and overnight. Light NW winds of 5-10kts gusting 10-15kts, occasionally variable. && .FIRE WEATHER... Light NW winds 5 to 10 mph gusting to around 15 mph this afternoon. There is a 15% chance of showers and 5% chance of thunderstorms in northern FWZ 470 near Jackpot this afternoon, though any precipitation would be less than a couple hundredths of an inch or just virga. Otherwise dry and storm-free across all zones. Temperatures will be trending warmer through the weekend. && .LKN Watches/Warnings/Advisories...None. && $$ DISCUSSION...96 AVIATION...96 FIRE WEATHER...96