616 FXUS65 KRIW 100330 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 930 PM MDT Wed Jul 9 2025 .KEY MESSAGES... - Scattered rain showers and isolated thunderstorms continue into the overnight hours but becoming less in coverage. - Cooler temperatures arrive for Thursday with highs nearly 20 degrees cooler compared to Wednesday in some locations by Friday. - Dry and warming trend over the weekend and into early next week ahead of the next system to bring increased storm chances. && .UPDATE... Issued at 138 PM MDT Wed Jul 9 2025 The upcoming forecast remains on track with little to no changes from the overnight. Hot well above normal temperatures will prevail across the state today. Highs are expected to near the century mark in some locations east of the Divide with values in the upper 80s to low 90s west of the Divide. There is the potential for a few locations to see near or record high temperatures especially east of the Divide. A remnant low will move across southern ID tonight which will bring increased chances for showers and an isolated thunderstorm or two. The best chances look to be across southern WY with lesser chances elsewhere. The one thing to keep in mind will be the overall dryness of the atmosphere which will likely hinder precipitation from reaching the surface. So while it may look like there will be chances for showers much of these showers will be in the form of virga. Gusty outflow winds will be a concern as a result of this dryness. The SPC has recently upgraded the day 1 outlook to include a small area of marginal across far southern and northern WY. The main concern as mentioned earlier will be gusty outflow winds possibly ranging from 50 to 60 mph in isolated locations. Showers continue through the overnight into the morning hours on Thursday. Coverage will gradually spread east during this time with most, likely not seeing precipitation reach the surface. Thursday will see slightly cooler temperatures as a cold front begins to near the area. This front will create some chances for showers and thunderstorms during the afternoon and evening. Elevated fire weather conditions continue across the state for Thursday but are expected to gradually improve as moisture moves into the region behind the front. A brief break from the heat is expected for Friday as temperatures cool to below normal values. Highs are forecast to be nearly 15 to 20 degrees cooler than Wednesday. Temperatures east of the Divide will range in the mid to upper 70s with values in the upper 70s to low 80s west of the Divide. Shower and thunderstorms will be possible on Friday as the front passes with the best chances remaining across central and northern WY. Elevated PWAT values do look to possibly move into the region for Friday with well above normal amounts mainly east of the Divide. This may create some heavy downpours but these are expected to remain very isolated. The weekend sees warmer and drier conditions return to the area with highs returning to the upper 80s to low 90s. The next chance for precipitation does not look to arrive until the start of next week as a trough moves across the region. && .DISCUSSION... Issued at 157 AM MDT Wed Jul 9 2025 The anticipated hottest day of the week has finally arrived. The ridge that has been in place since Monday will continue its eastward shift eastward this morning over the Cowboy State. 700mb temperatures will be slightly higher today, ranging between 16C to 19C. 90 degree temperatures will be widespread once again, with portions of the Bighorn Basin approaching 100 degrees. Winds continue to look marginal for any fire weather highlights, however gusts over 25 mph will occur at times (between 21Z and 00Z) over areas with critical fuels. The atmosphere should be capped for most areas, however isolated virga showers will be possible again in the afternoon into the evening. Sweetwater County continues to look the most likely location at this time, due a lead shortwave that will move over the county from northern UT. Chances for these showers will begin to increase after 21Z and move out of the area through 06Z Thursday. Wind gusts of 55 to 60 mph will again be possible, due to the inverted-V sounding profiles in place. A remnant low will approach the area through the overnight hours Wednesday night, as it moves over southern ID. The aforementioned lead shortwave will be ahead of this system. Increasing chances for showers and isolated thunderstorms will become possible over western portions after 06Z. Lightning chances are low, due to a lack of moisture that is reflected in CAPE values of 100-200 J/kg. These chances for precip quickly spread east of the Divide by 09Z, heading to the east-northeast. Precipitation chances associated with this wave will exit Johnson County after 15Z, with additional showers possible over Johnson and Natrona counties through the afternoon. Little to no rain is expected from this activity today and Thursday, due to a lack of moisture. Temperatures will be about 10 degrees cooler across the CWA Thursday as a result of the passage of this remnant low lowering heights and suppressing the Four Corners high to the south (the high will retrograde over the Desert Southwest at the same time). Fire weather conditions will remain elevated as well, but critical RH values will be isolated and confined to Sweetwater County. As expected, the timing from the trough dropping south from Canada has slowed down and now looks to reach the MT/WY border Friday morning. Any precipitation looks to be confined to northern portions through the day Friday. Highs in the 70s east of the Divide is still in the forecast, while areas west of the Divide stay in the low to middle 80s. Dry conditions then return for the weekend, with seasonal temperatures on Saturday and highs in the 90s return for areas east of the Divide on Sunday. Showers and thunderstorms could be possible over far northern portions Monday afternoon, as another trough drops south from Canada/British Columbia. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 930 PM MDT Wed Jul 9 2025 VFR conditions expected throughout the period at all TAF sites. Some ongoing rain showers west of the Divide to include BPI/PNA/RKS through the morning at 13Z with no confidence of any other station at this time. Otherwise, light winds and increasing mid level clouds overnight into Thursday morning. Increasing winds up to 18kts at most locations, highest at PNA up to 25kts after 16-18Z through peak heating until sunset after 01-02Z with radiational cooling. Improving skies towards the end of the period for Thursday night into Friday with scattered to broken high clouds. No other significant weather elements at this time with the strong winds at LND no longer expected to start the period this evening. 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 138 PM MDT Wed Jul 9 2025 Elevated to near critical fire weather conditions are expected across much of the area today. Well above normal temperatures are forecast for the state with min RH values ranging in the single digits to low teens. Winds will be gusty at times this afternoon with periodic gusts of 20 to 30 mph. Stronger gusts will be possible with any nearby developing showers or thunderstorms. Isolated virga showers and an isolated dry thunderstorm cannot be ruled out this afternoon/evening especially across southern WY. && .RIW WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Dziewaltowski DISCUSSION...LaVoie AVIATION...Lowe FIRE WEATHER...Dziewaltowski