Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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050 FXUS65 KRIW 091736 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 1036 AM MST Tue Dec 9 2025 .KEY MESSAGES... - Moderate snowfall will continue across the NW higher elevations today and through Thursday. Total snow accumulation through Thursday will reach 2 to 3 feet. Warmer valley temperatures will inhibit most snowfall accumulations. - Very windy across much of the state today, with High Wind Warnings in effect for much of southern and central Wyoming. - Temperatures remain 10 to 20 degrees above normal && .DISCUSSION... Issued at 145 AM MST Tue Dec 9 2025 The next passing shortwave energy is beginning to impact the NW higher elevations this morning, and the overall flow the next several days continues to be favorable for continued snow accumulation. Between orographic lifting and the passing wave, accumulations of 2 to 3 feet are becoming more likely for the Tetons and Absarokas, with 6 to 12 inches for remaining higher mountain ranges and the greater YNP region. Current variety of winter warnings and advisories are well positioned, so no adjustments needed at this time. In a usual winter, temperatures would be cold enough to help get some of this precip into the lower valleys, but not this year. Temperatures today will be in the 40s for the western valleys, and in the low 50s for the lower elevations east of the Divide, so snowfall will be locked into the mountains for the remainder of the week. The core of the llvl jet streak will be passing by just to the north today, and with temperatures in the 50s, a large chunk of this wind energy will mix to the sfc during the afternoon. With H7 winds at 70kts as they pass by, peak sfc wind gusts of 50 to 60 mph are likely for southern WY stretching NE into the Casper vicinity. The only question is winds across northern Johnson County late this afternoon as the cold front barrels through. While winds sfc and aloft are aligned, models are not really bringing winds up until the system gets a little farther east. Will monitor this if High Wind Warnings are needed there. Beyond this, the H5 ridge along the Rockies doesn`t move much through the weekend, deflecting weather systems to the north and east, and keeping the unusually warm temperatures in place. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1034 AM MST Tue Dec 9 2025 VFR conditions across nearly all terminals through the period with the one exception being KJAC where a weather system will bring periods of rain/snow. Rain/snow showers will periodically move through KJAC for the start of the period. MVFR to possibly IFR conditions may be possible at times especially with any heavier showers. Precipitation will be possible at KJAC through the overnight with temperatures likely at or slightly above freezing leading to a mix of rain/snow or all rain. Showers should gradually dissipate by the late morning hours on Wednesday. The other terminals that may see an isolated brief shower or two are KCOD, KPNA, KCPR, and KWRL. Most of these terminals have low chances, less than 30% for a shower with possibly better chances at KCOD Wednesday morning. The other main concern will be strong gusty winds of 35 to 45 knots at KCOD, KCPR, and KRKS. These winds are expected to persist for another 2 or 3 hours after the start of the period before weakening. Winds will return to these terminals once again Wednesday morning with 30 to 40 knots possible through the end of the period. All other terminals are not forecast to see as strong of winds but gusty conditions will still be possible at times. Widespread gusts of 25 to 35 knots are possible at or shortly after the start of the period with these winds weakening after sunset with breezy conditions lingering. Mountain obscuration will likely persist through all of the TAF period with some improvement possible near the end of the period. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on smoke, icing, and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until 5 PM MST Wednesday for WYZ001-002- 012. Winter Weather Advisory until 5 PM MST Wednesday for WYZ008- 014-015-024. High Wind Warning until 2 PM MST this afternoon for WYZ016. High Wind Warning until 5 AM MST Thursday for WYZ019-020-022- 027>030. && $$ DISCUSSION...Straub AVIATION...Dziewaltowski