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Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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575 FXUS65 KRIW 131915 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 115 PM MDT Tue Aug 13 2024 .KEY MESSAGES... - Active weather continues today (Tuesday) and tomorrow (Wednesday) with showers and thunderstorms, most numerous West of the Divide. A few severe storms possible. - Trending warmer and drier from Thursday into next weekend, with Saturday looking like the warmest and driest day. && .DISCUSSION... Issued at 112 PM MDT Tue Aug 13 2024 Marginal Risk (Level 1 of 5) remains in place across Wyoming for the potential for severe thunderstorms this afternoon and evening. Thunderstorm ingredients are starting to come together with dewpoints in the upper 40s to 50s, SBCAPE values near 500 J/kg, and bulk shear values 30 to 40 knots. The best combination of these ingredients are along the western border and southwest corner of Wyoming, so that will be the area to watch for the strongest storms this afternoon. Elsewhere, the thunderstorms will likely be more "garden-variety" or strong with small hail and strong wind gusts. Cloud cover this morning has inhibited some storm development and could lead to the storms overaLl being weaker today, like yesterday. However, training storms, especially in areas that received a decent amount of rainfall yesterday, may lead to localized flash flooding in low-lying and poor drainage areas. Wednesday there is another Marginal Risk (Level 1 of 5) across central and southern Wyoming for the potential for storms to produce strong to severe wind gusts and hail. While the better moisture, instability, and shear will be outside of RIW`s forecast area, dewpoints are still expected to be in the mid-to upper-40s with SBCAPE 500-1000 J/kg and bulk shear values 30 to 40 knots. The combination of these ingredients in best along the southern half of the state, but a 30 to 50 percent chance of rain showers and thunderstorms extends across the whole state. Thursday brings drier and warmer conditions as a ridging pattern takes back over through the weekend. Weak disturbances embedded in the flow could kick off a few thunderstorms daily, but the confidence is low in any widespread impacts. Thunderstorm chances increase slightly Saturday night into Sunday as the ridge shifts eastward, placing central and western Wyoming on the western side, allowing some moisture to creep back in. Temperatures during this time are expected to be in the 70s to 80s west of the divide and 80s to low 90s east of the divide. Elevated fire weather concerns are expected especially Friday and Saturday as minimum relative humidity values approach critical across central and southern Wyoming with southwest wind gusts 20 to 25 mph. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1112 AM MDT Tue Aug 13 2024 Showers and thunderstorms this afternoon and evening. TAFs have TEMPO groups to indicate where the best chances fall. Overall, chances are 40% to 70% west of the Continental Divide, with around 40% chances or less east. Any storm could produce gusty outflow winds 30 to 40 knots, with the potential for higher gusts in the strongest storms. Brief drops to visibilities are possible too, if a storm directly passes over a terminal. Chances continue through about 06Z/Wed, mostly for locations east of the Divide. Winds decrease this evening, with lessening clouds. Wednesday has another chance of showers/storms near the end of the TAF period, but especially after, for Wednesday afternoon. 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... && $$ DISCUSSION...Gross AVIATION...Wittmann