Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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985 FXUS65 KRIW 140857 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 257 AM MDT Tue May 14 2024 .KEY MESSAGES... - Showers and thunderstorms will develop across the state today. Stronger thunderstorms will produce locally gusty winds. - Another round of showers will develop on Wednesday, but will be more isolated in nature. - Drier for the latter half of the week, but showers will still be possible across the northern Wyoming mountain ranges each afternoon. && .DISCUSSION... Issued at 205 AM MDT Tue May 14 2024 More active day in store across most of Wyoming today, with showers and thunderstorms. The first in a series of shortwaves is currently racing east across northern WY, and is bringing increasing showers and a few thunderstorms. Radar and satellite trends have shown an increasing trend both in number and intensity of showers across the Bighorn Basin, which correlates well with convective models. Expect this activity to continue east this morning, with shower and thunderstorms generally north of a Pinedale to Riverton to Casper line. A trailing wave hot on the heels of the first wave will sweep into northern WY early this afternoon. The second wave will catch up with the first wave, bringing even more shower and thunderstorm enhancement. CAM models do have most of the activity with this second wave across northern WY this afternoon and evening, but isolated activity will sweep across southern WY right around sunset. Latest soundings show continued inverted-V profile, common for Wyoming, which indicates any storms would produce locally gusty winds. With a jet streak wrapping around the southern end of the trough, best downburst threat would be across southern WY with any isolated thunderstorms. Most activity will fade quickly near sunset with loss of daytime heating, but some shower activity may continue across Natrona County through around 06Z/15. As the trough slowly moves east on Wednesday, broad northwest flow returns in its wake. With modest moisture and trailing instability, some shower activity should develop along the higher elevations of the Absarokas/Winds/Bighorns during peak daytime heating. Northwesterly flow will then take those showers southeastward, keeping a 30-50% possibility for showers reaching into greater Fremont, Natrona, and Johnson Counties. This pattern continues again on Thursday, with showers focusing again on the Bighorns and Absarokas again, but having a bit more trouble detaching from the higher elevations. Lower confidence currently on forecast into the weekend, as one model shows larger trough sweeping in Friday with more showers, while other model has weaker trough passage mainly to the north over the weekend. Cluster analysis of ensembles leans well toward the latter, with continued light shower development on northern mountains, while the trough mainly moves to the north over the weekend. In either scenario, considerable lower level drying is noted, with low humidity Thursday through the weekend. With systems approaching Friday and/or Saturday, gusty southwest winds will ramp up again, especially for southern WY. This would lead to elevated fire weather concerns especially for the weekend. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1055 PM MDT Mon May 13 2024 A couple of shortwaves will keep an active TAF period across the area. In the short term, there will be some isolated convection through the overnight hours moving from west to east. Western and then northern terminals will have the best chance at brief impacts through the morning. Conditions are expected to remain predominantly VFR, though brief periods of MVFR ceilings are possible with any storm that moves over terminals. The next wave arrives by late morning and will set off another round of showers and thunderstorms for Tuesday afternoon. All terminals other than KRKS have at least brief mention of convection for the afternoon. The main concern with this activity will be brief MVFR ceilings and strong wind. There is some guidance hinting at bringing this farther south to KRKS around 00Z Wednesday, but confidence is not high enough to include this for now. 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... None. && $$ DISCUSSION...Straub AVIATION...Myers