Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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213 FXUS65 KRIW 191730 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 1130 AM MDT Wed Jun 19 2024 .KEY MESSAGES... - A very seasonal day today, with near average temperatures and dry conditions. - Rain shower and thunderstorm chances (25% to 60%) Friday. - Hot and dry starting this weekend. Current long-range models continue this trend through next week. && .DISCUSSION... Issued at 142 AM MDT Wed Jun 19 2024 Temperatures begin to rebound today, with highs 10 to 15 degrees warmer than yesterday. These values are slightly below average for mid-June. Dry southwest flow is also in place, keeping the area dry. A couple models depict a few convective cells this afternoon over Johnson and northern Natrona Counties. This would be about a 10% to 15% chance. Casper Mountain also has this chance. Winds are also less today as the previous weather system moves further away. A light breeze occurs today for Natrona and Johnson Counties; gusts to around 30 mph are possible if any convection does occur. This overall tame weather continues into Thursday. Temperatures continue to climb, with highs in the upper 70s to middle 80s, or a little above average. Most places look to remain dry, but a little afternoon and evening convection is possible along the Continental Divide due to the enhanced lift, and towards Johnson and Natrona Counties due to some incoming moisture ahead of the next system. Precipitation chances increase across the area late Thursday and especially for Friday. A tropical system moving westward into Mexico from the Gulf of Mexico brings ample gulf moisture. With the combination of a high over the eastern U.S. and an incoming trough over the western U.S., moisture will be funneled northward from Mexico towards Wyoming. Recent model runs have lessened the moisture reaching Wyoming compared to yesterday. There are widespread chances across the area, but are currently looking to be more of the scattered variety, with chances generally 25% to 60%, higher for the mountain locations. In other words, everywhere will have a shot of rain, but not everywhere will get rain. We are still a couple days out however, and as mentioned, there are really three synoptic features in play here, so if any of them change, the forecast can change. With the projected weakening of the tropical system, and a strengthening high over the southern U.S., this moisture will not remain over the state long. Rain chances come to an end Saturday, with models actually showing less than 15% chances across the entire area by Saturday afternoon. As this high pressure builds in, so do increasing temperatures through the weekend. A hot Sunday and Monday are on tap, with hot conditions looking to continue through next week. Highs Sunday and Monday are still forecasted to be in the 90s for much of the area. Hot places, like Greybull, realistically could hit 100. Fire weather-wise, fuels are still indicated to be green. Friday will be the only real shot for rain in the next week. With the hot and dry conditions through next week, minimum relative humidities (RH) each day fall below 15%. As the week continues, nighttime RH recovery worsens, though remains fair to good depending on location. Breezy to windy afternoons are possible a few days next week. The next chance for any rain, past this Friday system, could maybe be next Friday (6/28). This far out, though, there is very low confidence. The Climate Prediction Center (CPC) has warmer than normal and drier than normal conditions favored in the current 6-10 and 8-14 day outlooks. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1130 AM MDT Wed Jun 19 2024 VFR conditions are expected through the next 24-30 hours over western and central Wyoming. High clouds continue to stream from SW to NE over much of the area today, with some mid-level cumulus starting to form during the late morning over southern WY as well as the northwest WY mountains. Some moderate cumulus with light showers is expected to develop late this afternoon over Casper Mountain and the northern Absarokas, potentially pushing some gusty winds into KCPR and KCOD, respectively. Winds will remain light to breezy through the afternoon, though some sites may see gusts to 20 kts. Winds decrease overnight with continued mid- and high-level clouds mainly over the central and eastern parts of the state, and some sites like KRKS and KCPR should see some east winds. Clouds increase Thursday over the area as shower possibilities slightly increase over the central and northern WY mountains during the mid to late afternoon. Afternoon SW winds should be gusty at KRKS with east winds increasing from KCPR to KRIW/KLND. Please see the Aviation Weather Center and/or CWSUs ZDV and ZLC for the latest information on smoke, icing, and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES...None. && $$ DISCUSSION...Wittmann AVIATION...McDonald