Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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632 FXUS65 KRIW 160000 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 600 PM MDT Sat Jun 15 2024 .KEY MESSAGES... - Warm and windy weather continues into Saturday evening across most of the region with an elevated fire weather risk for central basins. - Isolated showers and thunderstorms will be possible over parts of Natrona, Johnson, and eastern Sweetwater Counties this afternoon/early evening. - Unsettled and cooler weather to start next week. Temperatures 5-15 degrees below normal, with the chance for light snow in the higher elevations of northern Wyoming. && .DISCUSSION... Issued at 131 PM MDT Sat Jun 15 2024 The morning started off unsettled, especially across parts of the Wind River Basin, where showers created outflow gusts of 50+ mph in places such as Lander. Fortunately, the unsettled weather has passed for much of the CWA, with the sun breaking through the clouds and temperatures continuing to warm. A shortwave is currently making its way across western Montana this afternoon and will gradually move into Canada by Sunday. This will leave much of the CWA dry, with most of the precipitation remaining to the north. However, there is a small chance (10-20%) of an isolated shower or thunderstorm developing in parts of Natrona and Johnson County this afternoon/evening. The main impacts on our CWA from this shortwave look to be increasing wind. The pressure gradient has tightened and SW/W winds have gradual increased. Sustained winds of 15-25 knots will be widespread today with gusts of 30-40 knots at times. These winds combined with dry RH values of 10-15% will create elevated fire weather conditions during the afternoon and evening today. However, fuels are still non-critical, so overall fire concerns are expected to remain minimal for now. Winds decrease after sunset becoming light and variable through late Sunday morning. After a stretch of above normal warmth, cooler weather will make its return for the start of next week. This change in weather is largely due to a potent upper-level low moving into the PACNW on Sunday. Quiet weather and seasonable temperatures remain over the CWA for Sunday, with breezy winds being the only thing of note. As the system nears the region on Monday, winds increase and chances for showers develop mainly across the northern CWA. This system ushers in some very unseasonably cool temperatures, with 700 mb temperatures ranging from -2 to -6 Celsius on Monday and Tuesday. Believe it or not, this creates the possibility for light snow in the higher elevations of the Tetons, Absarokas, Bighorns and YNP. However, snow impacts are looking very limited with only light accumulations possible in the highest elevations. Temperatures will likely have a greater impact than any light snow that may fall Monday and Tuesday. Models show a (40-80%) chance of seeing lows 32 degrees or cooler for many western basins and even a small chance of (10-30%) in western Sweetwater County. Overall, low temperatures on Tuesday and Wednesday morning are looking chilly. The current forecast is showing lows to be 10-15 degrees below normal for much of the CWA, with a good chance of the western valleys and basins seeing below freezing values. Quiet and warmer weather returns for the second half of next week as an area of ridging tries building back into the region. Confidence remains low at this time as some models are hinting at a few disturbances trying to interrupt this flow. However, a return to seasonable to above normal temperatures is looking likely at this point. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 559 PM MDT Sat Jun 15 2024 VFR conditions prevail at all terminals through 00Z/Monday. Gusty west to southwest surface wind of 15-35kts remains the primary aviation hazard through sunset (02Z-03Z/Sunday). West to northwest 10-15kt wind lingers for many areas until 06Z-09Z/Sunday. A shortwave earlier today has exited the forecast area with little to no convection anticipated through midday Sunday. There is a patch of mid-level moisture that will lower mid-cloud decks overnight with a hint of embedded light showers from west-central to north-central Wyoming. Again, no impacts with any weak convection that may develop. KCPR has the best chance for late day convection Sunday, but have opted to not include VCSH at this range. Westerly wind 8- 14kts will be common Sunday 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... None. && $$ DISCUSSION...Dziewaltowski AVIATION...Jones