Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
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016 FXUS65 KCYS 310454 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 1054 PM MDT Thu May 30 2024 .KEY MESSAGES... - Potential for a late night severe thunderstorm event in the Nebraska Panhandle late this evening into the early morning hours Friday. - Daily chances for precipitation continue into the weekend before turning drier early next week with above average temperatures. - After a weather disturbance produces a slight chance for showers and thunderstorms on Sunday, dry and warm weather will prevail for Monday through Thursday. && .UPDATE... Issued at 735 PM MDT Thu May 30 2024 Current forecast for tonight and early Friday morning appears on track, with late night convection picking up between 10 PM and 1 AM. A few of these thunderstorms may become strong to severe overnight through early Friday morning with large hail the primary threat. Added fog to the forecast for the I-25/I-80 Junction and areas east of I-25 towards the southwest Nebraska Panhandle. Expect outflow winds from thunderstorms and additional moisture advection along the Laramie Range and Cheyenne Ridge. High resolution models continue to indicate a possibility of dense fog around sunrise Friday. Added patchy fog with areas of fog for the southern Laramie Range. If thunderstorms become too numerous, fog may have a hard time developing...so left out the mention of dense fog for now. && .SHORT TERM /THROUGH SATURDAY NIGHT/... Issued at 200 PM MDT Thu May 30 2024 Beautiful day ongoing this afternoon with only some upper level clouds being observed across the CWA. Most of Wyoming under the influence of surface high pressure...in between a departing cold front across central Nebraska and an approaching cold front to the northwest. Surface trough extends from north central Colorado...north into the west slopes of the Laramie Range and then northwest into northern Carbon County. Latest mesoscale guidance continuing to forecast a late show tonight for convection...focusing on thunderstorms developing after 06Z. HRRR most aggressive with development and coverage over Cheyenne and Kimball Counties...possibly into the eastern half of Laramie County. MUCAPE values near 1000 to 1500 J/KG over these areas this evening. Did add severe wording into the southern Panhandle for late this evening into early Friday for thunderstorms. Upper shortwave tracks across eastern Montana/northeastern Wyoming Friday afternoon for another rounds of scattered afternoon and evening showers/thunderstorms. Saturday may perhaps be our best chance for severe convection as a dryline develops across southeast Wyoming and pushes eastward into western Nebraska. Depending on the timing of this dryline push...could see supercells developing across the Panhandle Saturday afternoon. Storm Prediction Center already has a Slight Risk area identified for the Panhandle Saturday afternoon. && .LONG TERM /SUNDAY THROUGH THURSDAY/... Issued at 200 PM MDT Thu May 30 2024 Sunday...A progressive and low amplitude shortwave trough aloft is progged to move across the forecast area around peak heating. Although low and mid level moisture looks rather scant, there should be enough moisture for isolated to widely scattered afternoon showers and thunderstorms, mainly east of Interstate 25. A bit warmer than Saturday with 700 mb temperatures near 11 Celsius, yielding maximum temperatures in the upper 70s west of I-25, with 80s east of I-25. Monday...Looks like the warmest day of the week with 700 mb temperatures near 15 Celsius, yielding high temperatures from the mid 80s to mid 90s. Warm temperatures aloft and limited low and mid level moisture will likely keep this day dry. Tuesday...A progressive shortwave trough aloft moves across the northern Rockies, sending a dry cold front across our counties, and dropping high temperatures some 5 to 10 degrees. Wednesday-Thursday...Ridging aloft builds across our forecast area, producing mostly clear conditions and warm temperatures with 700 mb temperatures near 14 Celsius on Wednesday and 17 Celsius on Thursday. Warm temperatures aloft will likely inhibit convective development. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 1050 PM MDT Thu May 30 2024 A complex forecast has become more complex over the past few hours. Primary aviation concern will be thunderstorms east of the Laramie Range, but KRWL and KLAR will likely not see any storms overnight. KCYS, KBFF, KCDR, KSNY, and KAIA will likely see isolated to scattered thunderstorms beginning within the next 1-2 hours and likely coming to an end between 11 and 13Z. One the backside of the storms, KCYS will likely see fog moving in, dropping the terminal to IFR to LIFR in the densest fog. KCYS should be the only terminal that sees fog overnight, but cannot completely rule out KSNY at this time. Winds will be calm overnight before increasing into the afternoon hours tomorrow. Expect gusty and erratic winds near any thunderstorms that develop. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ UPDATE...TJT SHORT TERM...GCC LONG TERM...RUBIN AVIATION...AM