761

ACUS01 KWNS 210048

SWODY1

SPC AC 210047



Day 1 Convective Outlook

NWS Storm Prediction Center Norman OK

0647 PM CST Mon Jan 20 2025



Valid 210100Z - 211200Z



...NO THUNDERSTORM AREAS FORECAST...



...SUMMARY...

The risk for thunderstorms appears negligible across the U.S.

tonight.



...01Z Update...

Cold surface ridging has become entrenched across much of the

interior U.S. through much of the Gulf Basin and offshore western

Atlantic coastal waters.  This will become reinforced overnight

across the southern Great Plains through middle and southern

Atlantic Seaboard, downstream of a pair of digging short wave

troughs, where confluent mid-level flow will be maintained to the

northwest of a prominent ridge centered over the subtropical western

Atlantic.



In advance of the southwestern of the two perturbations digging

within positively tilted larger scale troughing, currently across

the Southwest and adjacent international border vicinity, warm

thermal and moisture advection is ongoing above the cold

surface-based air across the western Gulf of Mexico into

northwestern Gulf coast vicinity.  This is supporting increasing

precipitation offshore of the lower Texas coast, which is forecast

to expand northeastward and eastward across much of the northwestern

Gulf/Gulf Coast region by late tonight.



Model forecast soundings continue to suggest that elevated

destabilization, rooted within the 800-700 mb layer, is possible

ahead of developing weak surface troughing as far northwest as the

upper Texas coast by 12Z Tuesday.  The NAM soundings, in particular,

continue to indicate profiles which could become supportive of

convection capable of producing lightning.  However, based on the

objective calibrated guidance of both the NCEP SREF and HREF,

probabilities for this still appear less than the minimum 10 percent

threshold for a categorical thunder area.



..Kerr.. 01/21/2025



$$






                

                        

582

ACUS02 KWNS 201703

SWODY2

SPC AC 201702



Day 2 Convective Outlook

NWS Storm Prediction Center Norman OK

1102 AM CST Mon Jan 20 2025



Valid 211200Z - 221200Z



...NO THUNDERSTORM AREAS FORECAST...



...SUMMARY...

Thunderstorms are not forecast on Tuesday through Tuesday night.



...Synopsis...

Thunder potential will be nil across much of the CONUS during the D2

period. Deep convection will be relegated to the Gulf, initially

over the west-central portion before spreading towards the southeast

part late. The slimmest of elevated buoyancy (MUCAPE below 100 J/kg)

along the Upper TX to LA Gulf Coast may coincide with mixed-phase

parcels, supporting weak convection into late morning. A few

lightning flashes are possible along the immediate coast, but the

overall thunder probability appears to be less than 10 percent.



As deep convection progresses east across the Gulf, it is expected

to wane with approach to southwest FL and the Keys early Wednesday

morning. This decaying phase should occur in response poor mid-level

lapse rates downstream of a positive-tilt trough and subsiding

large-scale ascent.



..Grams.. 01/20/2025



$$






                

                        

160

NWUS53 KAPX 202150

LSRAPX



Preliminary Local Storm Report

National Weather Service Gaylord MI

450 PM EST Mon Jan 20 2025



..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...

..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....

            ..REMARKS..



0800 AM     Snow             1 ESE Mancelona         44.90N 85.05W

01/20/2025  M9.0 Inch        Antrim             MI   Cocorahs



            Cocorahs station MI-AT-6 Mancelona 0.5 ESE.



0700 AM     Snow             3 S Cadillac            44.21N 85.41W

01/20/2025  M5.0 Inch        Wexford            MI   CO-OP Observer



            CO-OP Observer station CDLM4 Cadillac 9and10

            News.



0800 AM     Snow             3 N Wellston            44.26N 85.94W

01/20/2025  M4.0 Inch        Manistee           MI   CO-OP Observer



            CO-OP Observer station WELM4 Wellston Tippy

            Dam.



0800 AM     Snow             1 SSE Petoskey          45.36N 84.95W

01/20/2025  M3.6 Inch        Emmet              MI   CO-OP Observer



            CO-OP Observer station PTYM4 Petoskey NCMC.



1000 AM     Snow             1 NNW Wellston          44.23N 85.96W

01/20/2025  M3.6 Inch        Manistee           MI   Cocorahs



            Cocorahs station MI-MN-1 Wellston 0.8 N.



0800 AM     Snow             1 W Petoskey            45.37N 84.98W

01/20/2025  M3.5 Inch        Emmet              MI   CO-OP Observer



            CO-OP Observer station PETM4 Petoskey WWTP.



0700 AM     Snow             Lake Ann                44.72N 85.84W

01/20/2025  E3.0 Inch        Benzie             MI   Public



            Couple social media reports of about 3

            inches of snow in Lake Ann.



0800 AM     Snow             Charlevoix              45.32N 85.27W

01/20/2025  M3.0 Inch        Charlevoix         MI   CO-OP Observer



            CO-OP Observer station CHRM4 Charlevoix.





&&



$$












                

                        

637

FXUS63 KAPX 202352

AFDAPX



Area Forecast Discussion

National Weather Service Gaylord MI

652 PM EST Mon Jan 20 2025



.KEY MESSAGES...



- Bitterly cold with more lake snows



- Winds turn south Wednesday as temperatures warm back to near

  normal



- Widespread accumulating snow chances Wednesday and Thursday

  with breezy to gusty southwest winds



- Brief break of snow chances Friday, followed by a return of snow

  this weekend



&&



.SHORT TERM /THROUGH TUESDAY/...

Issued at 312 PM EST Mon Jan 20 2025



Pattern Synopsis/Pattern Forecast:



Deep troughing remains overhead, with attendant slug of bitterly

cold air working across the Great Lakes. Core of coldest temperature

anomalies (H8 temperatures below -30C) currently dropping southeast

into the northern Plains...with this core of coldest air set to

slide across our area later tonight into Tuesday morning. Great

Lakes remain largely open for business...with multi-bands of lake

generated snow impacting the favored snow belt locations. Complete

loss of dendritic growth zone is driving small flake formation,

limiting overall accumulations some but producing periods of near

whiteout conditions under the more intense bands. Temperatures have

recovered little, with most areas only in the lower to middle single

digits. While winds are not overly impressive, wind chill readings

are still several degrees below zero.



Little change expected as we head through tonight and Tuesday...with

dangerously cold temperatures and periods of impactful lake effect

snow.



Primary Forecast Concerns:



Temperature trends and lake snow evolution through Tuesday. Headline

management will also need to be addressed.



Details:



Number one issue remains the very cold temperatures, with top-down

temperature analysis showing lows tonight dipping at least a few

degrees below zero across most interior areas. Expect some of our

traditional colder interior locations to make a run into the

negative teens. Wind chill readings will be several degrees colder

yet, with many areas approaching/exceeding cold weather advisory

criteria (-20F eastern upper/-15F northern lower) later tonight into

Tuesday morning. Highs on Tuesday remaining in the single digits,

with wind chills remaining well below zero. As such...all inherited

cold weather advisories will remain.



Lake snows will continue, with most organized and heaviest snows

targeting northwest Chippewa County tonight...driven from what looks

to be strong meso-low driven low level convergence. Winds do back

southwest with time on Tuesday, eventually punting best snows north

into Ontario. More multi-band lake snows off northern Lake Michigan,

with slowly wavering winds generally targeting the traditional west

flow areas. Again...complete loss of dendritic growth layer will

keep a more "talcum powder" type snow, keeping overall snowfall

rates limited but producing areas of very low visibilities. Still,

through simple duration of snows, looking at several more inches of

snow in those favored areas by later Tuesday. Will extend inherited

advisories through Tuesday as needed.



&&



.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...

Issued at 312 PM EST Mon Jan 20 2025



Synoptic Pattern:



Modified Arctic surface high pressure center over IN/IL with long

wave upper troughing over the CONUS Tuesday evening/night. A

weakening lee side low near the Canadian rockies will drift to the

southeast and reach the northern midwest/western Great Lakes region

early Wednesday morning. Surface winds over northern MI will turn

southerly Tues night into Wed morning as well as mid to high level

clouds will move in from west to east. Early Wed morning low

temperatures will likely dip to below zero for most of the area,

with typical cold spots of NE lower and eastern upper seeing chances

of dropping to 10 to 15 below zero as skies will likely remain

clear.



Wednesday, a weakened surface low and upper shortwave will move

through the Great lakes. This will bring widespread snow chances to

northern MI with temperatures rebounding back to near normal. SLRs

can increase due to a favorable thermal profile, leading to chances

for accumulating snow Wed into Thursday.  North winds build back

into the area Thur into Fri with a possible break in snow chances

Friday. It will be a quick break however, with more snow chances

next weekend.



Forecast Details:



Overnight low temperatures Tues night into early Wed morning will

likely have the opportunity to drop, however a few things could halt

low temperatures falling. If the next system progresses down the

Canadian plains quicker than forecasted, clouds and surface winds

could keep overnight low temperatures right around zero or a few

degrees below vs 10 to 15 degrees below zero.



Widespread accumulating snow on Wed and Thurs is signaled in

deterministic global guidance, however it is still early and details

could change. The system is weakening as it moves over the CWA in

most guidance, however warmer temperatures and continental moisture

could generate a more productive environment for snowfall (a healthy

DGZ), which would increase SLRs compared to what we have been seeing

lately and allow snowfall to accumulate quicker. Its still uncertain

on the amount of continental moisture that will be available, so lake

enhancement might be needed for the highest snowfall amounts.



&&



.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...

Issued at 651 PM EST Mon Jan 20 2025



Lake effect snow bands expected to strengthen overnight, remaining

generally W flow over northern Lower MI (PLN, TVC, MBL) with less

certainty for CIU with a mesolow over Whitefish Bay. If this feature

tracks into CIU...which it seems like it might be...would expect

LIFR vsbys and winds even more variable than they are now. Influence

of the Mesolow could play a factor in PLN and perhaps even APN as it

could enhance ongoing W flow band near/just south of PLN. Do think

some subtle wind shifts are otherwise on the docket tonight,

generally within 20 degrees of W. Conditions largely MVFR into Tues

AM with IFR to LIFR at times under worst bands; improvements likely,

esp at APN, MBL, with increasing SW flow Tues afternoon.



&&



.APX WATCHES/WARNINGS/ADVISORIES...

MI...Cold Weather Advisory until noon EST Wednesday for MIZ016>018-

     020>036-041-042-086>088-095>099.

     Winter Weather Advisory until noon EST Tuesday for MIZ016-017-

     020>022-025-031-086-099.

MARINE...Small Craft Advisory until 5 AM EST Wednesday for LMZ342-

     344>346.



&&



$$



SHORT TERM...MSB

LONG TERM...ELD

AVIATION...FEF






                

                        

831

ACUS11 KWNS 210401

SWOMCD

SPC MCD 210400

TXZ000-210800-



Mesoscale Discussion 0043

NWS Storm Prediction Center Norman OK

1000 PM CST Mon Jan 20 2025



Areas affected...portions of south into southeast and eastern Texas



Concerning...Winter mixed precipitation



Valid 210400Z - 210800Z



SUMMARY...Wintry precipitation rates should increase through tonight

across southeastern portions of Texas, with sleet and freezing rain

accumulations likely to continue.



DISCUSSION...700 mb WAA continues to increase atop a sub-freezing

airmass over southeastern TX as a positively tilted mid-level trough

glances the region to the north. Meanwhile, the dry low-levels

support wet-bulb temperatures well below freezing given ample

evaporative cooling/sublimation potential. Over the next couple of

hours, continued cooling of the surface-850 mb layer, due to both

925 mb CAA and evaporative cooling, should support an increased

potential for wintry precipitation (as evident based on recent

reports of ice accretion and sleet accumulations).



The greatest near-term potential for freezing rain/ice accretion

will be along a zone roughly from Wilson to Tyler Counties, where

surface observations show surface temperatures already cooled below

32 F. Latest high-resolution guidance shows sleet/freezing rates

peaking sometime after 06Z, including over portions of deep-south

TX. With time, at least moderate snowfall rates may eventually be

observed closer to the southeast TX coastline.



..Squitieri.. 01/21/2025



...Please see www.spc.noaa.gov for graphic product...



ATTN...WFO...LCH...SHV...HGX...CRP...EWX...



LAT...LON   28789686 27639811 27479862 28629842 29729812 30359727

            30899592 31199473 31259398 30999377 30489386 29879437

            29819506 28789686