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Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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309 FXUS65 KRIW 151058 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 458 AM MDT Thu Aug 15 2024 .KEY MESSAGES... - Warmer today with less coverage of showers and thunderstorms this afternoon. - Very warm and mainly dry Friday with elevated to possibly critical fire weather Friday afternoon. - Above normal temperatures expected from this weekend into next week with daily chances of afternoon and evening thunderstorms. && .DISCUSSION... Issued at 239 AM MDT Thu Aug 15 2024 All in all, it has been a fairly quiet night here at the humble Riverton weather abode. The main feature on the map tonight is a but if a mesolow that has rotated from eastern Wyoming into southwestern South Dakota. Just enough moisture wrapped around it to bring some showers and a occasional rumble of thunder to eastern Johnson County but this is moving away. Now will transition into a period of warmer and drier weather, But notice the modifier in the word, thank you all of my English teachers from many eons ago. Especially in the word drier. That will be the rule of thumb through the next few days. Ridging will build northward over the area today and bring warmer temperatures. There will still be above normal precipitable waters across the area though, especially East of the Divide and the north. The ridging should help keep the morning dry, leading to a mainly late show in the later afternoon and evening. Coverage will be less than previous days as well, maxing out at around 2 out of 5 in northwestern Wyoming. A few showers will linger into the overnight hours as well. Friday looks like the driest day of the period as the ridge bulges north and pushes the deepest moisture out of the area. The only chance for a shower or storm would be across the northern border but even here the chance is only 1 out of 5. Temperatures will continue as warm with highs in the 90s returning the warmer spots. The main concern here shifts to fire weather. We considered some watches for our southern and eastern counties with humidity falling to under 15 percent. We held off for now though. In Natrona County, wind is borderline. In Sweetwater County, there has been a fair amount of moisture the past several days. We will let the day shift take one more look at it for potential watches. We can upgrade them tomorrow night if needed. Elsewhere, wind will not reach criteria or humidity will be too high. Saturday looks like the warmest day with highs in the mid 90s for many of the lower elevations East of the Divide. The chance of thunderstorms will return to western Wyoming though as the ridge axis shifts eastward and allows so moisture to ride up the back side of it. Most of this should be restricted to west of the Divide, as southwest, downsloping flow should keep areas to east largely dry and hot. The increased humidity should also ease fire weather concerns across southern Wyoming as well. From Sunday into the middle of next week ridging will dominate the weather across the area and bring above normal temperatures. A few shortwaves will rotate through the flow and bring daily chances of afternoon and evening showers and thunderstorms. Sunday looks fairly active, especially across western Wyoming. For next week, there is more divergence in the models so timing the shortwaves and picking a more active day remains uncertain. && .AVIATION /12Z TAFS THROUGH 12Z FRIDAY/... Issued at 458 AM MDT Thu Aug 15 2024 Mainly VFR conditions expected to prevail across central and western Wyoming through the 12Z TAF period. Current guidance shows thunderstorms developing between 20Z and 22Z before moving eastward and potentially impacting terminals until 02Z to 08Z, tapering off from west to east. Gusty and erratic winds are possible, as well as frequent lightning, in thunderstorms. 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 239 AM MDT Thu Aug 15 2024 Fire weather concerns will below critical today with light to moderate wind and humidity remaining above critical levels. Increasing southwest wind and lower humidity will bring at least elevated fire weather to southern Wyoming and portions of central Wyoming with around a 25 percent chance of critical fire weather on Friday afternoon. && .RIW WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Hattings AVIATION...Gross/Hattings FIRE WEATHER...Hattings