####018003823#### FXUS62 KKEY 040321 AFDKEY Area Forecast Discussion National Weather Service Key West FL 1021 PM EST Wed Dec 3 2025 ...New DISCUSSION, MARINE, AVIATION... .KEY MESSAGES... -Nil rain chances are expected through the end of the week as dry air remains across the Keys. -North to northeast breezes overnight will shift to the northeast around daybreak on Thursday. Breezes further shift to the northeast to east during the day Thursday while remaining gentle to moderate. -The next opportunity for an unsettled pattern looks to occur sometime over the Sunday and Monday timeframe. && .DISCUSSION... Issued at 1020 PM EST Wed Dec 3 2025 A weak cool front has pushed through the Keys earlier this evening. However, this frontal passage was dry as KBYX radar has not detected any shower activity all evening across the Keys. The only noticeable items of interest are the increase in wind speeds across the Keys coastal waters, wind shift to the north to northeast, and slightly lower dew points. Temperatures along the Island Chain are in the lower to mid 70s and dew points are in the upper 60s to lower 70s compared to the lower to mid 70s earlier on in the day. Marine platforms surrounding the Island Chain are observing north to northeast of 10 to 15 knots west of the Seven Mile Bridge with 5 to 10 knots to the east and northeast of the Seven Mile Bridge. .SHORT TERM FORECAST... The 00z evening sounding shows a virtually dry atmospheric profile through the entire column. The wind profile shows slight backing with northerly winds around 1000 ft AGL and slightly northwest to north winds around 3000 ft AGL. This indicates ever so slight cold air advection occurring. Instability is virtually non-existent and the PWAT value measured was 1.43 inches which is a little below the 75th percentile for the date. GOES 19 Total Precipitable Water (TPW) products shows the higher PWATs observed earlier during the balloon launch are now to the south of the Island Chain. There was a narrow plume of increased moisture that pushed through with the front. This is now to the south of the Island Chain across the Straits. Therefore, GOES 19 Total Precipitable Water (TPW) now estimates PWAT values of 1.1 to 1.3 inches infiltrating the area. Therefore, no changes expected to the ongoing forecast as dry air will reign overnight. && .MARINE... Issued at 1020 PM EST Wed Dec 3 2025 There are currently no watches, warnings, or advisories in effect across the Florida Keys coastal waters. From synopsis, a cold frontal system will meander across the Florida Keys overnight. Breezes will veer northeasterly and freshen overnight and Thursday. High pressure building over the Ohio Valley will cause winds to veer southeasterly and slacken over the weekend. Another frontal passage is possible towards the beginning of next week. && .AVIATION... (00Z TAFS) Issued at 1020 PM EST Wed Dec 3 2025 VFR conditions are expected to persist through the TAF period. Near nil rain chances will also persist as dry air remains entrenched across the Keys. Near surface winds will remain north to northeast between 4 to 8 knots through the overnight before shifting to the northeast to east around daybreak. && .PRELIMINARY POINT TEMPS/POPS... Key West 80 70 81 73 / 0 0 0 10 Marathon 80 71 80 73 / 0 0 0 10 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...MJV Aviation/Nowcasts....MJV Data Acquisition.....DP Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest ####018007089#### FXUS65 KTFX 040322 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 822 PM MST Wed Dec 3 2025 .KEY MESSAGES... - Widespread snow expected Thursday evening through Saturday afternoon with the heaviest amounts in the mountains. - An active pattern continues through next week with warmer and windier conditions possible. && .UPDATE... Tonight, northwest flow aloft bringing down mini vorticity waves will bring light snow to the mountains. At lower elevations, patchy fog have developed along the Hi-line. With winds picking up overnight, I am not too concerned with much more development of fog. Any current fog will dissipate later in the night when breezy winds settle in. Gusty winds develop along the Rocky Mountain Front overnight and continue through the day Thursday. The first mini shortwave moves through Thursday morning, increasing chances for light snow across the region. -Wilson && .DISCUSSION... /Issued 426 PM MST Wed Dec 3 2025/ - Meteorological Overview: Calm conditions will continue through the rest of today with increasing cloud cover expected as the evening progresses. Thursday will start off dry before the first shortwave trough moves over the area in the afternoon kicking off the initial snowfall that will primarily focus on the mountains. On Friday, a second, stronger shortwave will move into the region bringing a chance for more widespread snow at lower elevations Friday night into Saturday afternoon. The combination of these two shortwaves over the two day period will allow for heavy snow in the mountains and lighter but still impactful snow at lower elevations across most of the region. Northwest flow aloft continues through the start of next week allowing for unsettled conditions to continue through at least last Wednesday. Additionally, there is growing confidence in stronger Chinook winds along the Rocky Mountain Front early next week which is expected to bring some warmer temperatures back to the lower elevations of north-central Montana. - Forecast Confidence & Scenarios: Lower Elevation Snow Thursday through Saturday: Light lower elevation snow is possible with the Thursday shortwave but the main event for lower elevations will be Friday afternoon through Saturday afternoon with the arrival of the second shortwave. With the second system, a widespread 1-2 inches is possible across a good portion of north-central Montana except the Golden Triangle which is set to miss most of the snowfall with this event. As of right now, there are a couple areas along the lower elevations which would be candidates for higher snowfall amounts, particularly along the Highway 200 corridor between Great Falls and Lewistown, the Smith River Valley, and the Gallatin Valley. Confidence was not high enough to add them to the initial Winter Storm Watch but these areas will need to be monitored with future updates as increases in snowfall amounts could justify adding these zones to the watch or eventual warning. But otherwise most of the lower elevation snowfall looks to be advisory level at this point with only minor impacts expected. Heavy Mountain Snow Thursday through Saturday: Confidence continues to increase in the potential for significant snowfall along the mountains of central and southwest Montana with the greatest impacts expected along the Continental Divide and ranges of central and southwest Montana. As such a Winter Storm Watch has been issued for Thursday evening through Saturday afternoon. Broadly speaking, 6 to 12 inches is possible with the ridgetops potentially seeing amounts greater than a foot. Travel Impacts Thursday through Saturday: By far, one of the biggest concerns with this system will be the timing and how it impacts the Thursday evening, Friday morning, and Friday evening commutes. With the initial snowfall on Thursday, depending on road temperatures, there will likely be some initial melting of the first few flakes. When this moisture refreezes as the night goes on the concern will be patches of ice forming and then receiving more snow as the event continues creating very slick roads. Additionally, some periods of moderate to heavy snowfall are possible particularly with the initial push on Thursday evening and again with the arrival of the second shortwave on Friday afternoon/evening. This could lead to periods of reduced visibility which will add to the potential for hazardous driving conditions. In particular, there is great concern regarding the impacts possible along I-90 from Belgrade to Bozeman Pass. Snowfall probabilities in Bozeman proper were not enough to warrant including Gallatin Valley in the Winter Storm Watch but minor to moderate impacts are still possible in the area due to slick roads and brief periods of moderate to heavy snowfall, particularly on the far eastern side of the Gallatin Valley heading towards the pass. Additional mountain passes and roads that might experience significant impacts include, but are not limited to, Marias Pass, Kings Hill Pass, Deep Creek Pass, and Highway 191 south of Bozeman to the Idaho border. If heading out, motorists need to be prepared for rapidly changing and deteriorating road and weather conditions and it is advised to carry chains as well as an emergency kit. -thor && .AVIATION... 04/00Z TAF Period VFR conditions will largely prevail through the 0400/0500 TAF period, but increasing mid-level cloudiness is expected across Southwest and into portions of Central Montana beyond 03z this evening and then across the remainder of Central Montana by Friday morning/afternoon. Snow will begin to increase in areal coverage Friday afternoon over and near the mountains, most notably near the KBZN, KEKS, KHLN, and KGTF terminals. Finally, some instances of low level wind shear can't be ruled out as low to mid-level flow increases, especially at the KLWT terminal beyond 06z Thursday. && .PRELIMINARY POINT TEMPS/POPS... GTF 23 38 24 35 / 0 30 30 50 CTB 21 35 20 30 / 0 20 10 40 HLN 21 36 26 38 / 10 40 40 60 BZN 14 33 23 36 / 10 50 50 50 WYS 9 24 15 30 / 30 80 80 80 DLN 18 36 23 40 / 0 20 30 40 HVR 10 35 18 30 / 10 20 20 40 LWT 18 36 21 34 / 0 30 40 40 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Storm Watch from late Thursday night through Saturday afternoon for East Glacier Park Region-Northwest Beaverhead County-Southern Rocky Mountain Front. Winter Storm Watch from Thursday afternoon through late Friday night for Big Belt, Bridger and Castle Mountains-Gallatin and Madison County Mountains and Centennial Mountains-Little Belt and Highwood Mountains. && $$ http://www.weather.gov/greatfalls