Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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272 FXUS65 KRIW 060342 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 942 PM MDT Fri Jul 5 2024 .KEY MESSAGES... - Fire Weather Watch in effect Saturday from 2 PM MT to 8 PM MT for low relative humidity and strong gusty winds across portions of Fremont and Natrona counties. - Isolated to scattered showers and thunderstorms possible this evening. Increased coverage of showers and thunderstorms expected tomorrow (Saturday) late afternoon and overnight. - Long period of well above-normal temperatures and dry conditions expected through the upcoming week. && .DISCUSSION... Issued at 201 PM MDT Fri Jul 5 2024 Satellite imagery shows a disturbance moving south along the lee side of the northern Rockies this afternoon with a decent cu field developing across central and eastern Wyoming. While a brief shower or thunderstorm is possible this afternoon and early evening, confidence is low in any major impacts except for gusty winds and lightning in storms. Confidence increases in rain showers and thunderstorms tomorrow afternoon and overnight, especially across north-central Wyoming, as another disturbance ejects southward along the lee side of the northern Rockies. Primary concerns with these showers and thunderstorms would be gusty winds and lightning. In addition, ahead of the frontal passage tomorrow, there is a 60-80% chance of critical fire weather conditions where fuels are cured across portions of Fremont and Natrona counties. Due to this, a Fire Weather Watch is in effect. Wyoming remains on the eastern edge of the ridge across the western CONUS through the weekend, keeping conditions warm, mostly dry, and breezy. Tuesday into Wednesday the ridge begins to shift more eastward, increasing temperatures, and continuing the mostly dry pattern. Wednesday through the weekend, temperatures are forecast to be well above-normal, potentially record breaking a few afternoons. NAEFS percentiles has 700 mb temperatures near 90-99th percentile Wednesday through at least the weekend. While overnight temperatures will still drop into the low 50s, this prolonged period of above- normal heat does create some concern for heat, especially for sensitive and vulnerable populations. Forecast high temperatures are in the 80s to 90s across much of central and western Wyoming, reaching potentially 100+ degrees in portions of the Bighorn Basin starting Thursday. && .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 224 PM MDT Thu Jul 4 2024 Fire Weather Watch in effect for portions of Natrona and Fremont counties Saturday afternoon for low relative humidity values and strong gusty winds ahead of a frontal passage. Additional long period of elevated to near-critical fire weather conditions expected through next week with well above-normal temperatures and dry conditions. Weaker winds will be the main limiting factor in critical fire weather conditions. && .RIW WATCHES/WARNINGS/ADVISORIES... Fire Weather Watch from Saturday afternoon through Saturday evening for WYZ280-283. && $$ DISCUSSION...Gross AVIATION...LaVoie FIRE WEATHER...Gross