Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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668 FXUS65 KRIW 231841 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 1241 PM MDT Sun Jun 23 2024 .KEY MESSAGES... - Hot and dry will be the main story through mid-week. - Slight chances (30%) of mostly virga showers across southern portions today and tomorrow. Gusty outflow winds would be the main concern. - Better chances for showers and thunderstorms looks to come Wednesday and especially Thursday thanks to a shortwave drawing up Gulf moisture into the region. This should also provide a brief reprieve from the heat. && .DISCUSSION... Issued at 1236 PM MDT Sun Jun 23 2024 Today will be one of those days when you step outside into the dry, hot, wind and feel like you stepped into a blast furnace. Get used to that feeling because you`ll be feeling it through much of the week. Today will be the warmest day of the week, but don`t take that to mean that the rest of the week will be cooler, because it certainly won`t feel that way. Temperatures today will be in the upper 90s to near 100 across east of the Divide basins. Best chances to reach 100 will be across the upper Bighorn Basin near Greybull and Powell (60% chance) and across the central Wind River Basin between Riverton and Shoshoni (20 to 30% chance). Chances of reaching tomorrow for those same locations are 25% and 10% respectively. High temps will remain in the upper 90s across basins east of the Divide and lows only dropping to near 60 overnight through Wednesday. We should finally get some short- lived relief late in the week, but more on that later. Similarly to yesterday, convection has begun to fire off of the Uintas and across southern Sweetwater County as of 1230. Not expecting much, if any, precipitation out of these popcorn showers as dewpoint depressions are around 50 degrees. Given the aforementioned large dewpoint depressions, gusty winds will be a concern, even from seemingly weak virga showers. Convection should spread a bit farther north than it did yesterday. Hi-res models continue to prog weak convective activity across much of eastern Sweetwater County, into eastern Fremont and Natrona counties this afternoon. Again, not many of these showers to even reach the ground. Tomorrow will see much of the same, spreading across the same areas by mid-afternoon. There is a better chance of showers reaching the ground from stronger cells tomorrow, but precip continues to be limited and wetting rain (>0.1") chances will remain nil. By Wednesday and especially by Thursday, those wetting rain chances will increase though, and we should start to see some relief from the heat by Thursday. A low begins to slide into the PACNW Wednesday afternoon and will help to draw some Gulf moisture into the ridge. This will increase PoPs across the south and higher terrain on Wednesday. As the shortwave moves east into northern WA/ID Thursday, PoPs will become more widespread and wetting rain chances significantly increase. This will be a similar set- up to what we saw last Friday, so certainly monitoring the potential for strong storms as well as the heavy rain threat. WPC is already pushing a D5 Marginal ERO for Thursday across southern WY, with forecast PWATs above normal across much of the area and close to 1" across southern WY. For comparison, "normal" PWATs are around 0.4". This trough not only has a chance to bring some much needed moisture, but also some cooler air. Not cold air, but GFS and ECMWF both indicate 700mb temps in the +2 to +5 range, which certainly would provide some relief. Unfortunately, this looks to be short-lived, with the ridge rebuilding quickly behind it for next weekend, but we will enjoy any relief we can get! && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 1032 AM MDT Sun Jun 23 2024 VFR conditions are expected through the period as high pressure persists across the area. Wind will become breezy this afternoon with gusts of 20 to 25 knots at most terminals. While a few isolated showers are possible during this time, mainly east of KRKS, little to no precipitation is expected. The main concern with this activity will be gusty outflow winds gusting over 40 mph. Wind and any showers will subside after sunset, leaving clear skies through Monday morning. 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...Hensley AVIATION...Myers/Hensley