917 FXUS65 KCYS 100538 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 1135 PM MDT Mon Jun 9 2025 .KEY MESSAGES... - Above average temperatures are expected Tuesday, and again Thursday through Sunday. - Showers and thunderstorms will return to the region Wednesday through Friday and possibly into the weekend, mainly in the afternoon and evening hours. && .SHORT TERM /THROUGH TUESDAY/... Issued at 345 PM MDT Mon Jun 9 2025 A dry, subsident airmass is settling in across the region this afternoon, supporting mainly clear skies today. The only exception is a few afternoon cumulus over Carbon county and in the higher terrain, but blue sky prevails elsewhere. Expect clear skies to continue through the night with the north to northwest breeze decoupling around sundown. The axis of the ridge will shift overhead on Tuesday, boosting 700- mb temperatures to around +12 to +15C across the area. Highs will push into the 80s to low 90s, roughly 10F above average for this time of year. Soundings show deep mixed layers setting up across the area during the day, but with less subsidence aloft, we should see a bit more afternoon cloud cover compared to today. We will likely see a few afternoon showers/storms, but this may be more virga than anything with very isolated coverage. Forcing will increase heading into Tuesday evening as a vort-max rides along a stalled frontal boundary just to our north. Overrunning lift will tap into some elevated instability and increase the coverage of scattered showers and thunderstorms Tuesday evening into early Wednesday morning. This will be focused along a modest frontal boundary that will push across the area from the northwest. The front and any showers/storms will have the potential to produce locally gusty winds. The post frontal environment on Wednesday will push a slightly cooler and more moist airmass southwest across the High Plains. There is some model disagreement regarding exactly where this boundary will set up, but lately, these back door frontal setups have been stronger than depicted by most models. As a result, nudged highs down slightly for Wednesday while keeping dewpoints fairly high. Increased low level moisture will be in place underneath stronger forcing as a more powerful upper level shortwave approaches from the west. Expect to see scattered thunderstorms developing in southeast Wyoming where the capping inversion is weaker. Steep lapse rates and marginal shear suggest the potential for a few strong to severe thunderstorms. While the cap over Nebraska will likely be eroding through the afternoon and evening hours, storms may struggle once they get to the state line. Therefore, PoPs are a little lower but still present Wednesday afternoon and evening for the Nebraska panhandle. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Issued at 345 PM MDT Mon Jun 9 2025 Thursday...A progressive shortwave trough aloft moves from northeast Wyoming in the morning, to the central Dakotas by evening. Looks like adequate low and mid level moisture for isolated to widely scattered showers and thunderstorms in the afternoon and evening, mainly east of I-25. 700 mb temperatures near 15 Celsius will yield high temperatures mainly in the 80s. Friday...A weak low amplitude ridge aloft prevails, though with a cold frontal boundary across our eastern counties, and adequate moisture, we should again see isolated to widely scattered showers and thunderstorms in the afternoon and evening, mainly east of I-25. Saturday-Sunday...Ridging aloft prevails and with 700 mb temperatures near 17-19 Celsius producing warm temperatures aloft and convective inhibition, only widely scattered evening showers and thunderstorms look possible east of a Lusk to Kimball line. High temperatures in the mid 80s to lower 90s. Monday...A weak cold frontal passage will drop maximum temperatures back into the lower to mid 80s. Adequate low and mid level moisture will help produce isolated to widely scattered late day showers and thunderstorms east of I-25. && .AVIATION /06Z TAFS THROUGH 12Z WEDNESDAY/... Issued at 1135 PM MDT Mon Jun 9 2025 Upper level ridge will continue to build over the area tonight and Tuesday, resulting in mostly clear skies and relatively light winds. A weak cool front will push south out of Canada later on Tuesday. HAZARDS/WEATHER TRENDS: VFR conditions are expected over the next 24 hours. Winds will gradually shift into the south or southeast Tuesday morning, but should remain light. 10% to 20% chance of showers and thunderstorms for KCDR Tuesday evening as the weak cool front moves south, but less than a 10% chance for thunder for all other terminals. Won`t include in TAFs for now due to low confidence. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...MN LONG TERM...RUBIN AVIATION...TJT