


Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
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070 FXUS65 KCYS 152357 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 557 PM MDT Tue Jul 15 2025 .KEY MESSAGES... - There is a Slight Risk (2 of 5) for severe thunderstorms Tuesday and Wednesday. - Temperatures should cool for Wednesday behind a cold front. - Warmer temperatures and isolated to scattered late day showers and thunderstorms will occur for Thursday through early next week. && .SHORT TERM /THROUGH WEDNESDAY/... Issued at 118 PM MDT Tue Jul 15 2025 As usual, convection and some thunderstorms have begun across the region. Expecting coverage of this to increase a bit this afternoon, with a chance for some thunderstorms including a marginal to slight risk of some stronger activity including hail and winds. The main show however occurs this evening as the upper level trough begins approaching and the jet kicks in, with wind shear rising as bulk shear values of 30-50 knots, locally nearing 60 knots, are expected. High resolution guidance has been consistent since early runs Monday showing a line of activity forming and moving across Wyoming and into our region later this evening and into the nighttime hours. While the overall intensity that models are showing has fluctuated, guidance is largely in agreement that these storms will move across Converse and Niobrara Counties and possibly the northern fringes of counties just to the south sometime between 10 PM and 1 AM. This system continues eastwards into the Nebraska Panhandle, but agreement on the strength of it as it moves in is much lower. Strong winds gusting in excess of 65-70 mph are expected with this line, but with our region you can never rule out some hail as well. CAMs indicate some scattered convection remains possible through the morning hours, but should largely wane. Then Wednesday during the day brings another round of thunderstorms, and looking better and better with each model run. Bountiful instability with MUCAPE values exceeding 2500 J/kg alongside bulk shear values into the 50-60 knot range will contribute to widespread thunderstorm development along the I-25 corridor during the afternoon. All severe hazards are possible with these storms with initial supercells then forming into clusters as they evolve eastwards later into the afternoon and evening, with hail and winds then becoming the much more predominant threat. And with activity both today and tomorrow training storms alongside potentially heavy QPF from PWAT values of 0.6-1.0 inch will bring a marginal risk of flooding. But behind the front we should see a cooler day on Wednesday with highs only into the 60`s and 70`s outside of our western zones which should remain a bit warmer with highs into the 80`s. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... Issued at 118 PM MDT Tue Jul 15 2025 Thursday...With temperatures warming aloft and a decrease in available moisture, we expect only isolated to scattered afternoon showers and thunderstorms near the Colorado state line from Laramie to Kimball. Will see a warming trend. Friday...The warming trend continues under zonal flow aloft. 700 mb temperatures near 16 Celsius will yield high temperatures from the mid 80s to mid 90s. Expect isolated to scattered late day showers and thunderstorms. Saturday...With an increase in low and mid level moisture, and a passing shortwave trough aloft, we should see an attendant increase in afternoon and evening shower and thunderstorm coverage. Slightly cooler with additional cloud cover and more precipitation coverage. Sunday...A low amplitude shortwave ridge aloft will move overhead, and with warmer temperatures aloft and drier air aloft, expect less coverage of late day showers and thunderstorms. 700 mb temperatures near 16 Celsius will yield maximum temperatures in the mid 80s to mid 90s. Monday...Hot temperatures continue with 700 mb temperatures near 18 Celsius, yielding highs in the mid 80s to mid 90s. Perhaps enough moisture for isolated late day showers and thunderstorms near the southern Laramie and Snowy Ranges, though warm temperatures aloft may produce enough convective inhibition to limit thunderstorm development, and keep it dry. Tuesday...Zonal flow aloft and limited low and mid level moisture will produce another mostly dry day, though cannot rule out isolated late day showers and thunderstorms if the convective inhibition can be overcome. 700 mb temperatures near 18 Celsius will yield maximum temperatures in the upper 80s to upper 90s. && .AVIATION /00Z TAFS THROUGH 00Z THURSDAY/... Issued at 544 PM MDT Tue Jul 15 2025 After a cold front passes the terminals tonight, a passing weather disturbance, moist atmosphere and upslope winds will help produce scattered to numerous showers and scattered thunderstorms late tonight and on Wednesday. Wyoming TAFS...For Rawlins and Laramie, scattered to broken clouds from 4000 to 12000 feet will prevail. Thunderstorms will be in the vicinity of Laramie after 19Z Wednesday. Winds will gust to 25 knots at both terminals until 03Z, and to 23 knots at Rawlins after 19Z Wednesday. For Cheyenne, scattered clouds near 10000 feet will prevail until 08Z, then fog will occur from 08Z to 15Z, lowering visibilities to 2 miles with ceilings near 1500 feet, then ceilings near 2500 feet will occur until 19Z, then ceilings will improve to 4000 feet after 19Z, with thunderstorms in the vicinity. Winds will gust to 20 knots after 19Z Wednesday. Nebraska TAFS...For Chadron and Alliance, ceilings will lower to 2500 feet after 03Z, then lower to 700 feet from 06Z to 15Z, with fog, reducing visibilities to 2 miles, then ceilings will improve to 2500 feet from 15Z to 19Z, before ceilings rise to 5000 feet after 19Z, with thunderstorms in the vicinity. Winds will gust to 28 knots until 03Z. For Scottsbluff and Sidney, ceilings will lower to 1500 feet after 05Z to 07Z, with fog reducing visibilities to 2 to 3 miles, then ceilings will improve to 2500 to 3500 feet from 15Z to 19Z, then rise to near 5000 feet after 19Z Wednesday, with thunderstorms in the vicinity. Winds will gust to 27 knots until 02Z to 05Z. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...CG LONG TERM...RUBIN AVIATION...RUBIN