930 FXUS65 KCYS 110541 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 1140 PM MDT Thu Jul 10 2025 .KEY MESSAGES... - A strong cold front will move south across the area Friday morning, with potential for strong storms and heavy rain Friday afternoon and evening near the higher terrain. - Temperatures will be warming Saturday through Monday, before a potent cold front brings cooler temperatures for Tuesday and Wednesday, with another warming trend for Thursday. Shower and thunderstorm chances will be greatest for Tuesday and Wednesday. && .SHORT TERM /THROUGH FRIDAY NIGHT/... Issued at 252 PM MDT Thu Jul 10 2025 Thunderstorms are becoming more widespread this afternoon as a shortwave moves east overhead and a sfc trough slides southward across the plains, backing westward into the higher terrain. Satellite-derived TPW percent of normal shows values roughly in the 120-150% range in advance of the shortwave with drier conditions in its wake. Near the sfc, SPC mesoanalysis shows sfc-based CAPE values in excess of 500 J/kg across most of the forecast area with a tongue of 1500-2000 J/kg in the immediate wake of the sfc trough and just to the lee of the Laramie Range. Much of this area has minimal CIN with the relatively steep low- and mid- level lapse rates. The exception is over Niobrara County eastward into the northern NE panhandle where convective inhibition is relatively strong. 0-6km bulk shear values are 30-40 kts east of the Laramie Range as well. Thus, will have to keep a close eye on strong to severe thunderstorm development over much of southeast WY and the southern NE panhandle, with large hail ~1.00 diameter and strong winds around 60 mph out of the strongest storms that develop. With the high TPW values, expect many of these storms to be efficient rain producers as well. Activity will diminish through the evening as the shortwave slides east. A strong cold front associated with an upper level trough over the northern US will push south across the forecast area Friday morning. The main focus for thunderstorms will be along the Laramie Range and near the CO border in the afternoon and evening where pooled moisture and strong surface forcing will support development. There is a marginal threat for strong winds and large hail out of storms that form in this area. In addition, NAM and GFS forecast soundings show a fairly moist profiles along and east of the Laramie Range, so expect moderate rain rates and rainfall totals with showers and storms in this area. WPC has the majority of the forecast area in a marginal risk for excessive rain. Maintained POP values of 60-70 percent in the vicinity of the southern Laramie Range to the WY/NE border with this possibility of heavy rain. Upslope stratus and fog will be the main concern for Friday night in the continued moist regime. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Issued at 252 PM MDT Thu Jul 10 2025 Saturday...Northwest flow aloft continues, and temperatures will slowly moderate as 700 mb temperatures rise to near 14 Celsius. Looks like enough moisture along a low level convergence axis near the Colorado state line to spark isolated to widely scattered afternoon showers and thunderstorms from Laramie to Cheyenne to Kimball. Sunday...Ridging aloft builds overhead with 500 mb heights nearing 5920 meters. Warm temperatures aloft should limit convective chances and produce a dry day. Decent warming trend with maximum temperatures in the mid 80s to mid 90s with 700 mb temperatures near 17 Celsius. Monday...Another hot day expected with 700 mb temperatures near 17 Celsius. Looks like enough low and mid level moisture for isolated to widely scattered afternoon and evening showers and thunderstorms. Tuesday...A progressive shortwave trough aloft moving across Montana and North Dakota will send a fairly strong cold front southward across our counties, dropping high temperatures into the mid 70s to mid 80s. With decent low level upslope winds and plenty of low and mid level moisture, we expect to see scattered afternoon and evening showers and thunderstorms. Wednesday...Another relatively cool day for mid July with low level upslope, plenty of cloud cover and high temperatures only in the mid 60s to mid 70s. Adequate moisture for scattered afternoon and evening showers and thunderstorms, most numerous near the Colorado state line where the moisture will be the deepest. Thursday...The atmosphere will slowly moderate with 700 mb temperatures returning to near 15 Celsius, yielding high temperatures in the upper 70s to mid 80s. Warm temperatures aloft will limit convection, though still should see isolated to scattered late day showers and thunderstorms. && .AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... Issued at 1140 PM MDT Thu Jul 10 2025 Upper level disturbance will continue to move southeast of the region tonight with diminishing chances of showers and thunderstorms. A strong cold front for this time of the year will move south into southeast Wyoming and western Nebraska late Friday morning through mid afternoon. HAZARDS/WEATHER TRENDS: VFR conditions through 20z Friday with clearing skies overnight. Surface cold front will begin to push into KCDR, KBFF region by 15z...and closer to 18z further south along Interstate 80. Showers and thunderstorms will develop along this front by mid to late afternoon...mainly impacting KLAR, KCYS, KSNY, and possibly KBFF and KAIA as well. Included prevailing MVFR and thunderstorms starting at 20z to 22z. Locally strong gusty winds are possible with some hail in and around these thunderstorms. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...WFOCYS LONG TERM...RUBIN AVIATION...TJT