


Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
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957 FXUS65 KCYS 011051 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 451 AM MDT Tue Jul 1 2025 .KEY MESSAGES... - There is a Marginal Risk of strong to severe Thunderstorms this afternoon for portions of western Nebraska and far eastern Wyoming. - Warm temperatures and daily chances for PM showers and thunderstorms will continue late this week and into next weekend. && .SHORT TERM /THROUGH THURSDAY/... Issued at 440 AM MDT Tue Jul 1 2025 Clear skies and quiet conditions early this morning as an upper level ridge axis remains over the region today. Warmer temperatures are expected this afternoon with highs in the 80s to low 90s, warmest below 4500 feet. Although it should be pretty nice day across the area, model analysis shows a weak upper level shortwave/vorticity max near the Wyoming and Montana border. This vort feature is expected to drift southeast through this afternoon. Current surface observations show ample low level moisture with dewpoints in the 50s along and east of the Laramie Range. Combined with some forcing near the upper level shortwave and weak surface convergence due to lee-side troughing...showers and thunderstorms are expected to develop around or shortly after noon. There is a marginal risk for strong to severe thunderstorms east of the I-25 corridor. 0-6km shear values are generally around 25 knots and slowly increase towards 30 knots by the end of the day. This should be enough shear to justify a few strong thunderstorms, but coverage will be limited as the upper level ridge axis and associated midlevel subsidence will remain over the area. Kept POP and Prob of thunder between 15 to 30 percent into this evening. Primary concerns will be hail up to quarter sized and gusty winds. A developing low level jet may enhance this thunderstorm activity in the evening hours, but most of the activity may be moving into central Nebraska by then. For Wednesday and Thursday, a pretty typical summer weather pattern sets up across the region as a slow moving upper level ridge moves east of the area. High temperatures will remain in the 80s west of I-25, and upper 80s to mid 90s east of I-25. Secondary 590 dm ridge axis will push into the area Wednesday. With increasing midlevel subsidence and the lack of any notable forcing, kept mention of precipitation west of the Laramie Range. Showers and thunderstorms will return to most of the region on Thursday as a broad eastern Pacific trough moves into the Great Basin Region and finally into the Intermountain West Thursday afternoon. This feature is expected to bring some subtropical moisture to the area as PWATs increase between 1.00 to 1.50 inches. Continued to increase POP across southeast Wyoming with some heavy rainfall possible. High temperatures will be slightly cooler Thursday afternoon due to cloud cover, but still near or slightly above average for this time of the year. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Issued at 455 AM MDT Tue Jul 1 2025 Models show the pacific upper level trough continuing to lift northeast across the area Friday with another round of showers and thunderstorms. Thunderstorm coverage is forecast to lower this weekend due to the lack of forcing as weak zonal flow develops across the Intermountain west and across the Rocky Mountain Region. Temperatures remain in the upper 70`s to the mid 80`s across the forecast area. 700mb temperatures stay around 16 celsius which translate surface temperatures into the low to mid 80`s for the lower elevations and upper 70`s to low 80`s for our more mountainous regions. As we head into next week, models show another slow warming trend as a 595 to 600dm upper level high develops near the four corners region. The position of this high is a bit far south, so any shortwave activity digging south of of Canada will be enough to trigger showers and thunderstorms each afternoon. Kept thunderstorms in the forecast Monday and Tuesday as all models do not show this upper level high drifting northward until the middle of next week. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1145 PM MDT Mon Jun 30 2025 Upper level ridge axis will remain over the region this morning through Tuesday. Widely scattered thunderstorms are possible across most terminals after 19z as a weak disturbance aloft slowly drifts southeast across the high plains. HAZARDS/WEATHER TRENDS: VFR conditions will prevail over the next 24 hours with brief MVFR VIS possible in thunderstorm and shower activity this afternoon. Kept some LLWS over the western Nebraska terminals from 08z to 12z this morning. These winds may occasionally mix down to the surface but winds below 15kt should prevail. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...TJT LONG TERM...TJT/MM AVIATION...TJT