Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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994 FXUS65 KRIW 060853 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 253 AM MDT Sat Jul 6 2024 .KEY MESSAGES... - Elevated to Critical fire weather conditions expected today across portions of central and southern Wyoming. The combination of low humidity and gusty west winds can be expected through this evening. - Showers and a few thunderstorms will move across northern Wyoming this afternoon and linger into the day Sunday. - Strong ridging brings a return to hot and dry weather next week. && .DISCUSSION... Issued at 209 AM MDT Sat Jul 6 2024 Northwesterly flow will continue to agitate the weather across northern and central Wyoming today and Sunday. With dewpoints still in the 30s and 40s east of the Divide, the next passing shortwave will be able to tap some of this moisture to spark showers and a a few thunderstorms this afternoon and evening. Main focus is across the Bighorn Basin and Natrona and Johnson Counties. Inverted-V profile indicates access to gusty winds aloft, so some storms could be accompanied by gusty winds. Shower activity will fade during the evening, but some lingering shower activity is possible for central WY overnight tonight, and will regenerate during the day Sunday. Wind field aloft on Sunday will be much weaker, so Showers will be more isolated, and confined to higher elevations, and downwind into Johnson/Natrona Counties. Any precip that does fall will be light. On the other side of the Divide, moisture is much more lacking, both sfc and aloft, so shower activity will not be a threat. Instead, gusty winds translating to the sfc during the afternoon will combine with the dry sfc atmosphere to bring an elevated to critical fire weather threat. See Fire weather section below for details. Beyond Sunday, the H5 ridge centered over California will begin to shift east, setting up across Utah by midweek. This will push the storms track into Canada, allowing increased daily heating across Wyoming. Temperatures will be well into the 90s by Wednesday, and several triple-digit readings are likely by the end of the week. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 940 PM MDT Fri Jul 5 2024 Showers over northern portions of the forecast area will end by 08Z. Winds will be light, with SKC skies for most of the area. Wind gusts of 20 to 30 kt will return, starting at KBPI/KPNA around 16Z/17Z, and increasing at the other terminals after 18Z. Gusts around 35 kt will occur at KRKS. Showers and isolated thunderstorms will develop over northern portions after 21Z, proceeding to the southeast through the rest of the afternoon into the evening. KCOD, KWRL and KCPR will be the likely impacted terminals. Some of these showers could still be moving over KCPR by the end of the TAF period. Conditions should remain VFR, even as showers pass over these terminals and at other terminals where skies will remain mostly clear. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... Issued at 209 AM MDT Sat Jul 6 2024 Warm temperatures today across central and southern WY will bring very dry conditions this afternoon. Humidity levels will be 10 to 15 percent generally south of a line from Riverton to Casper, with the driest conditions across Sweetwater County. A passing weather system will bring along gusty winds aloft, which will mix down to the sfc during the afternoon. Expect frequent gusts above 30 mph for this region during the afternoon, decreasing around 8 PM this evening. Winds aloft turn more from the north overnight, pulling increased moisture in from the north. This will bring improved humidity readings for Sunday, so fire weather threat will be decreased. && .RIW WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 2 PM this afternoon to 8 PM MDT this evening for WYZ280-283. && $$ DISCUSSION...Straub AVIATION...LaVoie FIRE WEATHER...Straub