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Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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595 FXUS65 KRIW 180946 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 346 AM MDT Sun Aug 18 2024 .KEY MESSAGES... - Showers and thunderstorms will be a little more widespread today, though still most prevalent west of the Continental Divide. - Brief heavy rain and strong wind gusts of 35 to 45 mph will be possible with this activity. - Very similar conditions Monday before monsoonal moisture decreases Tuesday through midweek. && .DISCUSSION... Issued at 338 AM MDT Sun Aug 18 2024 Wyoming continues to be situated on the western edge of the persistent ridge, with the associated high now centered over the Texas/Oklahoma panhandles. Another shortwave will traverse the southwesterly mid/upper level flow this afternoon, accompanied by an associated monsoonal moisture surge. This will result in more widespread showers and thunderstorms today, though still most prevalent west of the Continental Divide where the best instability will set up (500-1000 J/kg CAPE). PWAT values will again approach an inch here, and any stronger or training storms could present a flash flooding threat. Otherwise, the primary concern will again be strong wind gusts, though we should not see the widespread strong to severe winds that were observed on Saturday. This activity will begin to decrease after sunset, coming to an end around midnight. Monday is shaping up to be very similar to today as the next wave moves in. Available moisture will slightly increase, bringing a better chance of convection along and east of the Divide. A low end flash flooding threat will continue across southwestern Wyoming. Further ahead, the general synoptic pattern will remain in place, though a decrease in available moisture will keep precipitation chances a little lower Tuesday through at least midweek. Temperatures will remain on the warmer side, generally around normal to five degrees above normal for this time of year. As we reach the weekend, ensemble cluster guidance is hinting at the potential for deeper troughing across the western US. This may bring a pattern change as it approaches Wyoming, but confidence on this solution is very low for now. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 1010 PM MDT Sat Aug 17 2024 Virga showers will continue to end through the first couple of hours of the TAF period. Winds have already subsided across much of the area, however winds of 15 to 20 kt will continue/develop at KCPR and KRIW through 12Z respectively. The winds at KRIW will subside by 16Z, while the winds at KCPR gradually decrease through 19Z and turn more north-northwest. Showers and thunderstorms will develop across areas west of the Divide and the Bighorn Basin between 19Z and 21Z, spreading toward the northeast through 00Z. Confidence is low on the timing of these storms, so have left PROB30 groups for impacted terminals for now. These storms are expected to cross into the Wind River Basin after 00Z, possibly impacting KLND/KRIW through 05Z. Any remaining showers/thunderstorms will be isolated toward the end of the TAF period, as gusty outflow winds continue across the forecast area. Gusts of 20 to 30 kt are expected with the storms Sunday, although isolated gusts of 40 to 45 kt cannot be ruled out. 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...Myers AVIATION...LaVoie