163 FXUS65 KRIW 231035 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 435 AM MDT Tue Apr 23 2024 .KEY MESSAGES... - Showers and a few thunderstorms across far southern Wyoming today. - Well above normal temperatures across the state today through Thursday. - Considerable increase in rain and snow across the state staring Thursday and continuing through the weekend. && .DISCUSSION... Issued at 208 AM MDT Tue Apr 23 2024 Ridging will begin to build back across the state today behind a trough that is sweeping across the Northern Plains. This ridge in not overly strong, so a few showers and thunderstorms may pass across Sweetwater County this afternoon. Probability of any accumulation above 0.10 inches remain very low. The main impacts from any showers would be gusty winds due to very dry near-sfc air. The remainder of western and central WY will be similar to yesterday, with generally high clouds and highs in the 60s. With the trough exiting across the northern US, pressure gradient today will be much lighter, so winds will be much less noticeable than on Monday. Wednesday will again be similar to today, with temperatures a step higher reaching the low 70s. Increased instability aloft will allow another round of isolated to widely scattered showers mainly for the southern half of the state during the afternoon. Precip amounts will again remain light, with very low probability of accumulation above 0.10". The next trough will be coming ashore along the southern California coast during the day Wednesday, and will induce broad troughing across the western US as moves to the east across the Four Corners region. This trough will bring along some deeper Pacific moisture and plenty of instability, so the probabilities remain high for considerable rainfall for lower elevations and snowfall at higher elevations. Current probabilities for receiving an inch of rainfall through Sunday remain 30 to 40 percent across the Wind River Basin, around 25% for Natrona and Johnson Counties, and around 10% for the Bighorn Basin. Ample snowfall can be expected for all higher mountain ranges, but will be tempered some by warming ground temperatures and faster sfc melting. && .AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/... Issued at 433 AM MDT Tue Apr 23 2024 VFR conditions will prevail through the period with wind remaining on the lighter side for most terminals. A weak shortwave within the westerly flow will bring some isolated showers to southwestern Wyoming Tuesday afternoon. This could bring brief lower ceilings to terminals as this activity moves to the northeast through Tuesday evening, but only enough confidence for VCSH at this time. Otherwise, broken high clouds will move in for the afternoon across the area. 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... None. && $$ DISCUSSION...Straub AVIATION...Hattings |