####018011707#### FXUS65 KRIW 042300 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 400 PM MST Thu Dec 4 2025 .KEY MESSAGES... - Breezy to windy condition across parts of the state today with light snow increasing in coverage over western WY this evening. - The first significant snowfall for the mountains of western WY is on final approach. Periods of light to moderate snowfall will be possible tonight through Saturday afternoon across the lower elevations with moderate to heavy snow expected for the western mountains. - Widespread breezy to gusty winds are expected Friday afternoon through the overnight hours. Gusts of 25 to 35 mph will be common across the Wind Corridor with wind prone locations seeing gusts around 50 mph. - The upcoming week looks to see mild and dry conditions return to eastern WY with active weather possibly continuing across the west. && .UPDATE... Issued at 108 PM MST Thu Dec 4 2025 The overall forecast remains for the most part on track with only a few slight adjustments. Firstly, temperatures today will be near seasonable west of the Divide and on the warmer side of seasonable east of the Divide. Highs will range in the mid to upper 30s with some locations nearing 40 east of the Divide, temperatures west of the Divide will be cooler mainly around the upper 20s. Gusty winds have arrived at some locations this afternoon with gusts of 40 or more mph already occurring at Cody and Rock Springs. The upper Wind River Basin is also seeing some gusty winds currently with gusts of 30 to 40 mph. These winds are forecast to weaken slightly overnight but still remain windy through the overnight into Friday. As for the next few days the main focus continues to be the incoming system which will bring rounds of moderate to heavy snow across western WY. The previous discussion still does a good job of explaining the setup along with the timing of the system. Overall the forecast remains mostly unchanged with the only deviation being a slight shift in snowfall amounts. Western mountains are still expected to see anywhere from 10 to 20 inches with the higher elevations seeing 2 to 3 feet. As more hi-res models become available it seems there has been a slight increase in snowfall amounts across the Bighorns. Amounts look to have increased in coverage with much of the range north of Powder River Pass forecast to see 10 to 18 inches now. The other shift is over lower elevations of western WY this includes Jackson Hole, Star Valley, southern Lincoln County, and the upper Green River Basin. These locations have seen snowfall amounts drop slightly compared to overnight. A likely reasoning for this is the warmer temperatures that will be present Friday and Saturday. Forecasted temperatures at times may be flirting with the freezing mark with portions of Jackson Hole possible getting into the mid 30s. However, even with these slightly warmer temperatures, precipitation is still expected to fall as snow but accumulation may be hindered at times. Storm total amounts for these lower elevations look to range from 5 to 10 inches with lesser amounts of 1 to 4 inches nearby Pinedale and over southern Lincoln County. Winds increase during the afternoon/evening Friday across much of the state. This increase in winds combined with snowfall will likely make travel very difficult over portions of western WY Friday night through Saturday morning. Besides western WY, winds are forecast to increase east of the Divide with widespread gusts of 35 to 45 mph along the Wind Corridor from Casper to Rock Springs. An isolated snow shower or two may be possible Friday night through Saturday morning with most expected to remain dry. No additional winter highlights have been issued or changed. && .DISCUSSION... Issued at 343 AM MST Thu Dec 4 2025 10Z water vapor imagery shows strong north-northwest flow aloft with ridging over the Pacific and a broad trough to the east. An embedded weak disturbance is entering the northwest portions of the state. This will provide weak support for orographically-induced light snow chances (20%-40%) across higher elevations of Yellowstone National Park and the Teton Mountains through just after sunrise. Some breezy 20 to 30 mph winds will also be present from Rock Springs to Casper as the weak disturbance traverses the state through the morning. Seasonal temperatures are forecast today ahead of the incoming weather system. By the early afternoon, the first "wave" of this multi-day snow across the west and widespread gusty winds will approach. This first wave, currently (10Z) moving onshore over the Pacific Northwest, will mostly be a wind maker across the Absarokas (including the Cody area) , upper Wind River Basin, and across the Wind Corridor. This wind will be a result of a tightening pressure gradient ahead of the second "wave" and associated cold front later tonight. Gusty winds of 30 to 35 mph will be common across the aforementioned locations, with isolated gusts of 50 mph possible. Snow with this first wave will be confined to western Wyoming. Snow amounts this afternoon (from 11AM to 5PM) are forecast to be up to 0.5 inch across Jackson and Star Valleys and much of Yellowstone. The Tetons and high elevations of Yellowstone could see around 2 inches during this time frame. The second wave begins around sunset tonight as upper level divergence is enhanced over western Wyoming, thanks to being in the left exit region of a 125kt-150kt upper level jet. With abundant moisture filtering into the region and enhanced lift, due to orographics and upper level divergence, moderate to heavy snow is expected from sunset tonight through early Friday morning for the western mountains. During this time frame, snow amounts across the Teton, Gros Ventres, Salt River, and Wyoming Mountain Ranges and high elevations of Yellowstone range from 6 to 12 inches. As for the western valleys and low elevations of Yellowstone, snow amounts overnight tonight generally range from 1 to 3 inches. A lull in moderate to heavy snow is currently forecast between sunrise and midday Friday as the upper level jet shifts east over Wyoming. However, light snow will likely (90% chance) be falling during this time. Once the 125kt-150kt jet is overhead, the third wave begins early Friday afternoon and continues through Saturday morning. During this time, moderate to heavy snow is forecast across most of western Wyoming. Snow totals across the Teton, Gros Ventres, Salt River, and Wyoming Mountain Ranges range from 1 to 2 feet with the highest elevations seeing 3 feet. Thus, the Winter Storm Watch has been upgraded to a Winter Storm Warning beginning 5PM tonight and continuing through 2PM Saturday. Travel over Teton, Togwotee, and Salt River Passes could become very difficult, especially during both "waves". Winter Weather Advisories have also been issued for the Upper Green River Basin, the western Wind River Mountains, the Absarokas, Yellowstone, and Jackson and Star Valleys. Total snow amounts of at least 7 inches (80-90% chance) are forecast for Jackson and Star Valleys, Yellowstone, and the Upper Green River Basin. For these locations, the probabilities of at least 8 inches ranges from 40% to 80% over a 40+ hour period so opted only for Winter Weather Advisories at this time. Higher elevations of Yellowstone (Pitchstone Plateau) could see upwards of 2 feet, however, because these areas are largely untraveled, kept with the Advisory. Similar thinking swayed the thinking for the western Wind River MOuntains, the Absarokas, and the western Bighorns, with snow amounts between 8 and 12 inches. Locally higher amounts are possible (70%) across the highest elevations of these mountain ranges. It is important to note that gusty winds look to accompany the moderate to heavy snow, leading to reduced visibilities. With the strong upper level jet moving overhead Friday afternoon, winds begin to ramp up across the Wind Corridor and the Absarokas with frequent 25 mph to 35 mph gusts. This will likely (80-90% chance) translate to frequent gusts of at least 35 to 40 mph. Wind prone locations, such as South Pass and Muddy Gap, could potentially (50-80% chance) see gusts around 50 mph. Gusty 30 to 40 mph drainage winds across the upper Wind River Basin look to develop (90% chance) late Friday into Saturday as well. As the jet moves overhead, 700mb winds of 50kts to 60kts are forecast to develop over southern Wyoming, the Absarokas and the Upper Wind River Basin late Friday evening into the overnight hours. There is a 50% chance for wind gusts 60+ mph to occur in these areas as a result of the jet max moving overhead and mixing these stronger winds to the surface. Similar conditions look to develop through the rest of the Wind River Basin and northern Johnson County between 09Z and 12Z Saturday. These potentially high winds could last through Saturday morning, before gradually decreasing after 21Z Saturday. The upper-level jet begins to weaken and shift south during the day on Saturday, bringing an end to the impacts of the winter system. Ensemble guidance is in consensus that the northwest flow will persist Sunday into the early parts of next week, allowing for light snow to chances (30-80%) continue across the west. Elsewhere, dry conditions and a warm up to above normal temperatures is also looking more favorable. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 400 PM MST Thu Dec 4 2025 West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals. More persistent snow is beginning to move into western Wyoming late this afternoon. This has brought and will continue to bring IFR conditions at KJAC this evening through most of Friday morning. Confidence is lower on snow making it farther east, though there will be occasional MVFR ceilings at KPNA and potentially KBPI overnight. KRKS will continue to see a west wind through the period with gusts generally over 20 knots. Conditions are expected to improve at KJAC after 17Z Friday, though another push of snow is expected late in the period. Frequent mountain obscurations are expected through the period. East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals. Snow will have a more difficult time moving east of the Divide. The primary impact from this system will be strong wind at KCOD. Gusts will peak over 40 knots through this evening, dropping only slightly overnight. Otherwise, terminals will remain VFR through most of tonight. Cloud decks will lower around 12Z Friday, with MVFR ceilings expected at KCOD, KCPR, and KWRL through the end of the period. KCPR will have the best chance of light snow after sunrise Friday and have included a PROB30 group to account for this. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 2 PM MST Saturday for WYZ001-002- 008-013-014-023-025. Winter Storm Warning until 2 PM MST Saturday for WYZ012-024. && $$ UPDATE...Dziewaltowski DISCUSSION...Gerhardt AVIATION...Myers ####018004880#### FXUS63 KILX 042302 AFDILX Area Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 502 PM CST Thu Dec 4 2025 .KEY MESSAGES... - While another bitterly cold night is on tap for tonight, some relief is expected Friday through the weekend. Probabilities of temperatures below zero tonight are highest toward the I-72 corridor. - A series of disturbances will bring precipitation chances every few days through next week. The first one arrives Saturday night, bringing some light snow. There is about a 40-50% chance of more than an inch in areas north of Peoria. && .DISCUSSION... Issued at 205 PM CST Thu Dec 4 2025 The forecast over the next several days will be dominated by a series of upper disturbances moving southeast into the central U.S., bringing precipitation chances every few days, and brief respites from the unseasonably cold weather. The center of Arctic high pressure is drifting across southeast Iowa early this afternoon, gradually suppressing cloud cover in Illinois to areas south of I-70. Lots of temperatures in the mid- upper teens north of I-70, a good 25-30 degrees below normal for early December, but a bit shy of record cold-high temperatures due to today's high temperatures being recorded shortly after midnight. Where the snow cover is thinner south of I-70, low-mid 20s are currently prevailing. Low temperatures tonight are likely to be in the evening, as the high moves east of the state and winds start to turn more southerly. Latest HREF projects about a 35-40% chance of lows below zero from near Springfield east to Champaign. However, there is some concern that this is being driven too low by high-res models such as the HRRR and the ARW, which bring lows down to as much as 10 below zero. Will go closer to the NBM, which is mainly in the zero to 5 above range north of I-70 and fairly close to the earlier forecast. While a number of record lows will be out of reach, a few are closer to zero for today and Friday (see Climate section below). While wind chills get down to near 10 below near I-74, some slight improvement will be noted overnight as temperatures edge upward. Temperatures moderate somewhat on Friday and Saturday, with much of the forecast area reaching the freezing mark or higher. Several of the morning models continue to highlight a moist but very shallow layer at the surface beginning this evening. Will continue to highlight potential for freezing fog causing slick spots, especially east of I-55 and north of I-70. Morning model suite continues to highlight a fast moving storm system crossing the region later this weekend. NBM probabilities of more than an inch of snow are highest north of a Galesburg- Pontiac line (over 50%), ranging to about 20% near I-72/Danville. The GFS ensembles are about 12 hours slower than their European counterparts, and the forecast will continue to focus more on the midnight-noon Sunday period for accumulations. Additional clipper systems are projected to arrive Tuesday night, then again toward Thursday. The Tuesday night system currently looks to be a more northern track, which would favor more of a rain/snow mix in our area. With the latter system, the deterministic GFS and European models favor a southern track, though a non-trivial number of their ensemble members keep the snow chances more to the north. Plenty of time to watch that, though. Geelhart && .AVIATION... (For the 00z TAFs through 00z Friday Evening) Issued at 502 PM CST Thu Dec 4 2025 Main concern is potential for fog and stratus tonight. Short range guidance continues to key in on visibilities dropping over central IL tonight, down to IFR at times. However, there is poor agreement on location so this lends low confidence on the TAF for specific terminals. Kept lowest visibilities at KDEC-KCMI, but will need to watch trends as fog develops for potential amendments lower farther northwest. Fog should diminish by 14-15z, then VFR through afternoon. Calm winds will become light southeast tonight, then southwest around 10 kt by late morning. 25 && .CLIMATE... Issued at 205 PM CST Thu Dec 4 2025 Record low temperatures for today and Friday: Location Today Friday ======== ======== ========= Bloomington -7 (1893) -2 (1895) Champaign -6 (1893) 0 (1895) Decatur -6 (1893) 2 (1905) Jacksonville 2 (2006) -3 (1895) Lincoln 1 (1929) 3 (2005) Peoria -1 (1991) 0 (2005) Springfield 0 (2006) 4 (1895) Geelhart && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$ ####018002071#### FXUS65 KFGZ 042302 AFDFGZ Area Forecast Discussion National Weather Service Flagstaff AZ 402 PM MST Thu Dec 4 2025 .SYNOPSIS...Expect dry conditions and warming daytime temperatures well into next week. && .DISCUSSION...Well, the evolving pattern for at least the next 7 days looks an awful lot like a locked and loaded La Niña. We will be just east of a large eastern Pacific ridge through the period. This means nearly clear skies and warming temperatures, especially over higher terrain and south of the Mogollon Rim. Some areas north of the Mogollon Rim may be susceptible to low-level inversions for the next several days, potentially delaying the warming until next week as the ridge axis moves farther east. That's about it! Dry, light winds and a warming trend, enjoy! && .AVIATION...Friday 05/00Z through Saturday 06/00Z...VFR conditions expected through the TAF period, with increasing cloud cover expected overnight. Clear skies forecast to return by 18Z Friday. Light and variable winds anticipated through the period. OUTLOOK...Saturday 06/00Z through Monday 08/00Z...VFR conditions forecast through the weekend. Other than west through north winds 10-20 kts Saturday afternoon, light and variable winds should prevail. && .FIRE WEATHER...Friday and Saturday...Dry and warmer conditions are expected each day with little to no cloud cover. Winds will remain light, under 10 mph and predominantly from the north-northwest on Friday, followed by breezier west-northwest winds, 10 to 25 mph, on Saturday. Sunday through Tuesday...The dry and mild conditions persist with daytime temperatures 5 to 10 degrees above average by Tuesday. Afternoon winds will remain light and mainly from the north and northeast each day. && .FGZ WATCHES/WARNINGS/ADVISORIES...None. && $$ PUBLIC...Peterson AVIATION...Konieczny FIRE WEATHER...LaGuardia For Northern Arizona weather information visit weather.gov/flagstaff ####018009577#### FXUS66 KPQR 042304 AFDPQR Area Forecast Discussion National Weather Service Portland OR 303 PM PST Thu Dec 4 2025 .SYNOPSIS...A series of frontal systems will bring a period of wet weather Thursday through at least the middle of next week across southwest Washington and northwest Oregon. Ensemble guidance suggests a potentially impactful atmospheric river event next Monday into midweek, though uncertainty on exact impacts remains moderate to high. && .DISCUSSION...Thursday afternoon through Wednesday...Radar imagery Thursday afternoon depicts rain moving southeast across SW Washington and NW Oregon as the first of many frontal systems pushes into the PacNW. Observations indicate a front has remained stalled just west of the coast through the morning and early afternoon hours with rain mainly focused in a band north of Astoria through Clackamas County. The front is beginning to slowly move southeast, allowing rain to begin spreading farther south into the area, continuing through the night. Due to the northwest orientation of winds with this front, the central and southern Willamette valley as well as Lane County likely won't see much rain with this first round. Another frontal system will move through the region tomorrow, accompanied by an influx of additional moisture, with ensemble guidance indicating IVT values peaking around 500-600 kg/m/s. The upper level flow becomes more zonal with this system tomorrow, allowing for more rain in the Willamette Valley and Lane County than the first system. Total forecast rain amounts for this evening through Friday night top out around 0.3-0.6 inches for the interior lowlands and 1.5-3.0 inches for the coast, Coast Range, and Cascades, with locally up to 4.0 inches possible over the Cascades. Breezy southwest winds will also be possible with the frontal passage on Friday, with gusts most likely peaking around 20-30 mph. Showers are expected to linger through Saturday as zonal flow continues. Then, another frontal system moves through the area on Sunday. Ensembles indicate IVT values could peak around 300-500 kg/m/s with this frontal system, which would produce another round of widespread rainfall. Total rainfall amounts Saturday through Sunday are most likely to be around 0.4-1.0 inch for the interior lowlands, 0.75-2.0 inches at the coast and Coast Range, and 1.0-3.0 inches for the Cascades except for 0.4-0.8 inches over the Lane County Cascades. But, there remains a fair amount of uncertainty in both the low and high end potential. Impacts are not expected with rain amounts through Sunday, unless rain rates exceed 0.2-0.3 inches for multiple hours over certain watersheds leading to rivers that are prone to flooding quickly, such as the Grays at Rosburg and Willapa River. This will be something to monitor during heaviest periods of rain. The main period of concern continues to focus on Monday into late next week as ensemble guidance continues to indicate the potential for an impactful atmospheric river event. Over the past 48 hours, GEFS and Euro Ensemble guidance have consistently suggested two rounds of elevated IVT plumes pushing into the PacNW next week, one generally on Monday and another sometime Tuesday into Wednesday, with IVT values likely remaining above at least 250 kg/m/s in between, likely producing a continuous rain event with two rounds of increased precipitation. However, significant uncertainty still remains in the timing of elevated IVT values, location of the moisture plumes along the WA and OR coast, and exact peaks of IVT values. For the first peak, the 12z GEFS mean is around 650 kg/m/s with +1 standard deviation around 850 kg/m/s, and the 12z Euro EPS mean is around 800 kg/m/s with +1 standard deviation around 900 kg/m/s. The second round still has much more variability with both ensembles indicating the mean IVT values around 500-600 kg/m/s with +1 standard deviation around 750-800 kg/m/s. What does this mean? All of these factors have fluctuated between forecast runs over the past 24 hours and will likely continue to fluctuate until we get closer to the event, though ultimately, confidence is increasing slightly in this being a multi-day atmospheric river event leading to at least minor flooding impacts. The main period of concern for river flooding would be late Monday into Thursday as it takes time after rain begins for rivers to rise. HEFS guidance has introduced chances for a number of rivers to rise to Moderate flood stage (10-25%) and Major flood stage (8-15% chance) for rivers that drain from the Coast Range, Willapa Hills, and north Oregon and south Washington Cascades. The probabilities for specific river points can be found at the National Water Prediction Service website. Signals are also increasing for the potential of areal and small stream flood impacts for the Northern Willamette Valley north into the Washington lowlands (5-10% chance) as well as the Coast Range, Willapa Hills, and Cascades (30-50% chance), including the potential for landslides due to saturated soils. Additionally, there are signals for breezy winds with the frontal passage on Monday, although the ensemble spread remains very wide leading to low certainty in the peak wind forecast. If winds do end up even around 30-40 mph, saturated soils from nearly a week of rain could cause some downed trees, leading to impacts such as localized power outages. This is an event to keep your eye on, especially for those who live in flood prone regions. -03/DH && .AVIATION...Radar imagery and terminal observations as of early Thursday afternoon depicts a mix of LIFR/IFR/MVFR CIGs and VIS across all terminals as a warm front lifts over the region and brings rain and mist. High confidence (>90% chance) that IFR/MVFR CIGs and VIS continue through the evening as this system progresses inland. Another frontal system will move in early tomorrow morning after 12-15z Fri, maintaining these low CIGs as the low-level atmosphere remains saturated. Guidance suggests potentially heavier rain with this second system, so there could be brief VIS reductions to IFR or lower for any terminal Friday morning. Winds generally southerly to southwesterly, remaining under 10 kt through late tonight. Southerly winds increase to 10-15 kt Friday morning for most terminals with gusts up to 20-25 kt along the coast. KPDX AND APPROACHES...High confidence for IFR/MVFR CIGs and VIS through Friday morning as back-to-back frontal systems impact the area. East-southeasterly winds 4-6 kt increase and turn more southerly 8-10 kt after 12-15z Fri. -10 && .MARINE...Winds are forecast to gradually weaken to 10-15 kt and turn more westerly this afternoon and evening as the current front progresses inland. This lull will be short-lived as another frontal system will push across the waters tomorrow, returning southwesterly winds of 15-20 kt with gusts to 25-30 kt. Small Craft Advisories are in effect across all waters including the Columbia River Bar beginning 4 AM Friday, lasting through early Thursday morning. Seas of 4-5 ft this afternoon will build to around 7-9 ft at 10-11 sec as a northwesterly swell moves in with the next system. Will note that a very strong ebb may lead to higher seas of 10-11 ft in the Main Channel of the Columbia River Bar around 4-5 PM Friday. For the rest of the waters, seas likely (70-80% chance) build above 10 ft by Saturday morning. There is also a 30-50% chance that seas build above 13 ft, with the highest chances north of Cape Lookout and beyond 10 NM. The parade of fronts continue through the weekend and into early next week. Chances for widespread and frequent Gale force wind gusts of 34 kt or greater remain under 15% through early next week; however, chances for brief and isolated Gale force wind gusts are around 40-50% on Sunday and 50-70% on Monday. Seas briefly subside below 10 ft on Saturday night and Sunday, before building again on Monday with the next system. -10 && .BEACH HAZARDS...Coastal Flood Advisories remain in effect from for minor tidal overflow during high tide from 9 AM to 3 PM Friday and Saturday for the south Washington coast and Clatsop County coast in Oregon. Minor flooding up to 1 foot above ground level is possible during high tide in low lying areas near bays, sloughs, and the low reaches of the coastal rivers. Coastal residents in the warned area should remain alert for rising water and take appropriate action to protect life and property. -10 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...Coastal Flood Advisory from 9 AM to 3 PM PST Friday for ORZ101. Coastal Flood Advisory from 9 AM to 3 PM PST Saturday for ORZ101. WA...Coastal Flood Advisory from 9 AM to 3 PM PST Friday for WAZ201. Coastal Flood Advisory from 9 AM to 3 PM PST Saturday for WAZ201. PZ...Small Craft Advisory until 6 PM PST this evening for PZZ210. Small Craft Advisory from 4 AM Friday to 4 AM PST Saturday for PZZ210-251>253-271>273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland ####018008731#### FXUS65 KPIH 042304 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 404 PM MST Thu Dec 4 2025 .KEY MESSAGES... - Moderate to heavy mountain snow through Saturday morning, mainly across the eastern and southern highlands. Winter Storm Warning is in effect. - Light snow tonight for portions of the Snake River Plain, but warmer temperatures expected to change precipitation to rain or a rain/snow mix. - Windy late Friday through Saturday. Gusts could approach 40 mph at times. && .UPDATE... Issued at 401 PM MST Thu Dec 4 2025 We have gone ahead and issued a couple of Winter Weather Advisories to the mix for tonight through Friday night. For the Advisory for Ketchum to Stanley, it is mainly to capture impacts expected along Hwy 75 where closer to 7 to 10 inches is expected on Galena Summit. For the Advisory for the Idaho Falls zone, higher snow totals are expected to the northern and eastern portions of the zone. So, while Idaho Falls may only see 1 to 2 inches, areas north and east of Idaho Falls could see closer to 3 to 6 inches of snow. && .SHORT TERM /THROUGH SATURDAY NIGHT/... Issued at 212 PM MST Thu Dec 4 2025 Complicated forecast is unfolding for the next 48-72 hours. Satellite imagery shows wet northwest flow in place across the PacNW this afternoon. Shortwave features embedded in the flow on tap to bring a significant increase in precipitation to East Idaho starting late this afternoon through this evening, and continuing into the weekend. Confidence is high regarding precipitation becoming widespread over higher elevations overnight tonight, continuing through Friday night, and beginning to wane on Saturday. Shadowing is expected across portions of the Snake Plain, including the INL, where northwest flow would provide a downsloping effect. There is also high confidence that these systems will advect SOME warm air to the region, raising snow level elevations, but much lower confidence on how much warm air and where the snow level will actually end up. Models remain quite consistent in the amount of liquid precipitation expected, especially through Friday night. Looking at the HREF values, the mean supports 0.30-0.40" water along the I-15/US-20 and I-84/86 population corridors, dropping to 0.20-0.30" at the lower end but rising to 0.50-0.75" at the higher end. Some of this will fall as snow TONIGHT THROUGH EARLY FRIDAY, but this is where the incoming warmer air causes a problem. Areas from the Eastern Magic Valley northeast to about Blackfoot will see daytime highs Friday warm to above freezing, and thus we should see an introduction of rain/snow or a changeover to all rain during the day. Prior to the warm up, the areas between roughly American Falls and Rexburg may see 1-4" of snowfall (higher amounts north of Idaho Falls), which could impact the Friday morning commute. Snow levels rise with the incoming warmer air to between 6000 and 7000 ft, but the uncertainty on timing and amount keeps the rain/snow level much lower. Some of this will be due to precipitation and existing snow pack helping to keep lower elevations cooler than models (particularly the GFS and derivatives) want to warm it. Have nudged daytime highs slightly lower Friday with expectations of slightly slower warming. Once the changeover occurs, precipitation should stay rain or a rain/snow mix at lower elevations for the remainder of this event. For the eastern and southern highlands, model guidance has fluctuated slightly in liquid amounts, but the consensus remains similar: HREF indicates snowfall rates will approach 1"/hr at times tonight, and then again late Friday into Friday night. Liquid QPF means through Saturday generally exceed 0.50" but could range as low as 0.30" and could exceed 1.50" across the Bear River Range. This results in snow accumulations that exceed a foot in most higher elevation areas above 6000 ft. Ridge tops across the Big Holes and the Bear River Range could approach 2 ft accumulations by the time this event pushes through. Lower end snow amounts above about 6000 ft remain sufficient to support Winter Storm Warnings, and thus the watches have been converted over. Further northwest across the central mountains, most of the region should be shadowed by northwest flow. Amounts above 6500 ft could be enough to support heavier snowfall, but that leaves the only significant impact at Galena Summit with 6-10" (for now). Held off on issuing an Advisory for now, but wouldn't be surprised to see locally higher accumulations early enough to warrant an issuance. The last complication is winds, which increase Friday into Friday night with the onset of stronger winds aloft. At this stage, do not believe the winds will reach Advisory level across the Snake Plain, so will hold off on headlines for now. Gusts late Friday into Friday night could produce some blowing snow hazards in the warning area, so those gusts were mentioned in the Winter Storm Warning as well. Precipitation could continue into Saturday, again targeting higher elevations especially across the east and south highlands. This does look to be a relative "break" in the pattern so total amounts look weaker than the previous 36 hours. For now, will leave the ending of the current Winter Storm Warning in place. Mild temperatures do remain at lower elevations where precipitation looks to be much less, if at all. && .LONG TERM /SUNDAY THROUGH THURSDAY/... Issued at 212 PM MST Thu Dec 4 2025 Confidence is high in above normal temperatures for much of the extended period of the forecast. The greater forecast challenge lies with respect to placement and timing of precipitation as the overall pattern looks to remain messy with clouds and precipitation in place despite the warmer than normal temperatures. Valley temperatures on Sunday will be in the upper 30s to mid 40s but by Monday, should climb into the mid to upper 40s. This upward trend continues into Tuesday and towards the latter part of next week with upper 40s to lower 50s appearing very likely despite all the cloud cover in place. Mountain locations will also see above normal temperatures but the warmup wont be as significant keeping temps in the upper 30s to lower 40s for most days. This makes precip type challenging in the extended with a messy snow/mix/rain forecast each day across the higher elevations. As for precipitation, there is still large spread amongst model guidance and their associated ensembles as to where the heaviest precip will set up any given day with these occasional surges of Pacific moisture moving in through the upper level flow. Highest PoPs remain forecast across the higher terrain of the central mountains and eastern highlands but valley locations aren't immune from the precip potential either. The spreads are literally from no QPF to upwards of a quarter inch at times in the lower valleys so it's hard to have much confidence for any given day. In short, expect above normal temps to remain in the forecast with potentially wide variations from forecast to forecast on precip locations, amounts and timing until better continuity against within model guidance. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1100 AM MST Thu Dec 4 2025 BKN/OVC CIGs in the 1500-3500 ft range continue across eastern Idaho terminals with the exception of KSUN which continues to be on the far northern edge of some lower CIGs in the valley just south of the airport. Expecting the upcoming TAF period to be challenging with widespread low clouds and snow expected as our next weather system moves through the region. KBYI, KPIH and perhaps KSUN will likely see a transition from snow to a mix or even all rain at some point while some warmer air moves into the area from the south. Precip type confidence is lower than desired but confidence is much higher with regards to prolonged MVFR/IFR CIGs through much of the period. Winds will increase a bit too during the period with 15-25 kt gusts possible in the valley terminals. && .PIH WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 5 AM MST Saturday for IDZ053-072- 073. Winter Storm Warning until 5 AM MST Saturday for IDZ058>066. && $$ UPDATE...AMM SHORT TERM...DMH LONG TERM...McKaughan AVIATION...McKaughan