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Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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989 FXUS65 KRIW 111716 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 1116 AM MDT Sun Aug 11 2024 .KEY MESSAGES... - Showers and storms will be more isolated today and largely confined to northern Wyoming. - More widespread showers and thunderstorms are likely from Monday through Wednesday. - Somewhat drier and warmer from Thursday into Friday. && .DISCUSSION... Issued at 325 AM MDT Sun Aug 11 2024 We are currently having another night of nocturnal convection as a shortwave moves across the area. Current radar shows a couple of storms capable of small hail, given the low wet bulb zero levels. But nothing severe is expected. And, with the fast movement of the storms, the chance of flooding remains very minimal. There should be somewhat of a lull in the activity today as shortwave ridging moves across the area and drier air moves in from the west. Most models how precipitable water values falling anywhere from 20 to 30 percent today from Saturday`s values. Satellite imagery shows drier air moving in now with convection ending to the west. As a result, most areas should end up with a rain free today today. Any showers and storms today should be confined to northern Wyoming, with the best coverage in Johnson County where moisture will remain somewhat deeper. But even here, the chance is only around 2 out of 5. One other thing today is some gusty breezes will develop across southern Wyoming. With humidity falling into the teens, elevated fire weather is possible. There has been some moisture lately, so we were on the fence about this though. So, we will issue a statement for elevated fire weather for Sweetwater and southern Lincoln Counties for this afternoon. The lull in the convection will be short, however. Some showers may move back into southwestern Wyoming later Sunday night, but most should hold off until Monday. For Monday, the deepest moisture will be found West of the Divide with a good coverage of showers and thunderstorms expected as precipitable water values surge back toward an inch in some locations. Chances taper further to the north and west as moisture will be slower to return to this area. Chances look more widespread across the area for Tuesday as deeper moisture spreads across the area. And by Wednesday, somewhat drier air the moves into the west, and this shifts the best chance of showers and storms to areas East of the Divide. Coverage of showers and storms should begin to decrease again Thursday and especially Friday and Saturday as ridging builds back over the area and most models show much drier air moving into the area, with precipitable water values falling to below normal levels. There will still be a few showers and storms around each day, but coverage will be limited to at most a 1 out of 3 chance and confined mainly to in and near the mountains. Temperatures should remain near to slightly below normal through Wednesday, then slowly climbing again starting Thursday as ridging builds northward. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 1115 AM MDT Sun Aug 11 2024 VFR conditions prevail through the TAF period. No showers or thunderstorms are expected to impact any terminals this afternoon. A few may develop over the mountains, but should be very isolated and remain away from any sites. The closest would be for KCOD, but chances remain under 20% through this evening. Afternoon mixing brings gusts 15 to 30 knots for some sites, which decrease after sunset this evening. Models are showing rain showers moving into Wyoming, from the west, after 09Z/Mon. There is model disagreement on exact timings and placements, so confidence remains low on the details. Have included PROB30 groups in many TAFs where these chances occur. Chances for showers and thunderstorms increases after the TAF period, for Monday afternoon. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on smoke, icing, and turbulence forecasts. && .FIRE WEATHER... Issued at 325 AM MDT Sun Aug 11 2024 A combination of humidity falling into the teens and a gusty westerly breeze will bring elevated fire weather to portions of Sweetwater and southern Lincoln Counties today. Elsewhere, although there will be a gusty breeze at times, relative humidity will remain above critical levels. Showers and thunderstorms will be more isolated today and confined mainly to northern Wyoming. Mixing and smoke dispersal will be generally good to excellent in the afternoon. More widespread showers and thunderstorms return to the west tomorrow and spread across most of the area for Tuesday. && .RIW WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Hattings AVIATION...Wittmann FIRE WEATHER...Hattings