023 FXUS65 KCYS 232340 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 540 PM MDT Fri Apr 23 2021 .SHORT TERM...(This evening through Saturday) Issued at 306 PM MDT Fri Apr 23 2021 Convective looking cumulus out across southeast Wyoming this afternoon, soon to spread east into the west Nebraska Panhandle - already spreading into Kimball County as we speak. Have noted 40 to 50 dBZ reflectivities on a few *very* short-lived cells, some lightning, and gusts 35 to 45 mph, but nothing more notable than that. Rain showers below 7kft, snow showers above 7kft and along the Pine Ridge. The front looks to be along the Laramie Range, and will reach the WY- NE border around 6 PM, exiting east by 9 PM. The peak of activity looks to be now, with heightened CAPE around 2-300 J/kg, and lapse rates around 8-9C, diminishing with every hour, especially around 6 PM. Some isolated shower activity will continue over night over the Panhandle; should end before sunrise. Saturday will be breezy with winds out of the south and southwest, mild and dry with highs in the 60s, and cloudy aloft as a few shortwaves pass overhead. This breezy and dry pattern will extend through Monday afternoon; have a few fire weather concerns for the southern Panhandle Monday afternoon. More in the fire weather section below. .LONG TERM...(Saturday through Thursday) Issued at 325 AM MDT Fri Apr 23 2021 Upper ridge over the Intermountain West will translate east and flatten over the Rockies and High Plains Saturday, resulting in a west-southwest flow aloft. A upper low off the WA/OR coast will weaken to an open wave as it moves inland Sunday. Flow aloft downstream of the trough will increase from the southwest. 700mb temperatures will moderate to 2 to 4C by Sunday. Expect dry conditions with surface temperatures warming into the 50s and 60s Saturday, and 60s to mid 70s Sunday. It will be breezy both days, especially Sunday with gusts of 30 to 40 kt west of the Laramie Range. Enjoy this weekend's weather as a pattern change is forecast beginning Monday with the approach of a deep upper trough and Pacific cold front. Moisture will advance into the CWA, with scattered showers developing west of the Laramie Range Monday morning and spreading to the I-25 corridor in the afternoon. It will remain warm ahead of the front over the eastern plains with highs from 65 to 75, cooling into the 50s behind the front. The GFS is the more progressive of the model solutions, with the ECMWF and CMC slower. A blend of the models would keep cool and showery weather in the forecast through Wednesday. Modest low/mid level lapse rates may result in SBCAPEs near 200 j/kg Tuesday afternoon, which may generate isolated thunderstorms. Following the departure of the upper trough Thursday, northwest flow aloft will bring a return to drier conditions, with temperatures moderating to near seasonal normals. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 534 PM MDT Fri Apr 23 2021 Wyoming TAFS...VFR at Rawlins. Wind gusts to 25 knots until 02Z, and to 30 knots after 15Z Saturday. VFR at Laramie and Cheyenne until 05Z or 06Z, with occasional MVFR, then MVFR until 12Z to 15Z, then VFR. Wind gusts to 20 knots at Cheyenne until 03Z, then to 25 knots at Laramie and Cheyenne after 15Z Saturday. Nebraska TAFS...VFR at Chadron and Alliance until 05Z or 06Z, with occasional MVFR at Alliance, then MVFR until 15Z, then VFR. Wind gusts to 20 knots until 06Z, then to 25 knots at Alliance after 15Z Saturday. VFR at Scottsbluff and Sidney until 06Z to 09Z, with occasional MVFR, then MVFR until 15Z Saturday, then VFR after 15Z Saturday. Wind gusts to 24 knots after 15Z Saturday. && .FIRE WEATHER... Issued at 306 PM MDT Fri Apr 23 2021 LAL2 thunderstorms today continuing through about 1800, maybe an hour or two longer over the west Panhandle. Dry and breezy this weekend, with min humidities creeping down each afternoon, in the 20s Saturday and in the teens Sunday and Monday. Winds look to pick up Monday with a strong cold frontal passage, though the fire concerns should remain low as precipitation begins in the afternoon from west to east. However, the southern Panhandle looks like it'll have a change at reaching criteria Monday afternoon ahead of the incoming precip. Will have to keep a close eye on the area as guidance becomes more accurate with timing. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...AB LONG TERM...MAJ AVIATION...RUBIN FIRE WEATHER...AB