


Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
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441 FXUS65 KCYS 072259 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 459 PM MDT Mon Jul 7 2025 .KEY MESSAGES... - There is an Slight Risk (Level 2 of 5) for severe weather today across portions of western Nebraska. All modes of severe weather are possible today: large hail, damaging winds, and an isolated tornado. - Hot temperatures and dry conditions return Tuesday, limiting precipitation chances across the CWA. && .SHORT TERM /THROUGH TUESDAY NIGHT/... Issued at 1230 PM MDT Mon Jul 7 2025 Visible satellite imagery remains fairly clear late this morning, showing most of the cloud cover in South Dakota. There is a small cumulus field north of the Pine Ridge in Sioux and Niobrara Counties, which could be a potential area of development for storms later this afternoon. Although, based off the lack of cloud cover over the CWA now, storms could have a hard time developing this afternoon. Model soundings do show a capping inversion, but this looks to erode by early afternoon. However, there are several boundaries at play which could help storms initiate this afternoon. A weak shortwave moving across the area today as sent a front through the Interstate 25 corridor in Wyoming, switching winds out of the north. Dewpoints behind this front remain in the 50s which will be favorable for storms. A dryline along the Laramie Range could also be an area of initiation if clouds can develop. Lastly, more south and east flow in the Nebraska panhandle could lead to converging boundaries and areas of development. Hi-Res models show a bit of disagreement with each other, making it difficult to iron out a solution for today`s severe weather potential. The HRRR appears to be the least aggressive, showing only a few storms in the southern Nebraska panhandle. Other models like the NAMNest, RRFS, and MPAS show storm development in northeast Wyoming tracking southeastward into Niobrara County and the northern Nebraska panhandle. The environment in Converse and Niobrara Counties and the Nebraska panhandle are still favorable for severe weather if storms can develop. MUCAPE values range anywhere from 1200 to 2000 J/kg. Effective shear values are a bit weaker today compared to yesterday, however its still high enough to sustain stronger storms with rotating updrafts. DCAPE values remain over 1200 J/kg as well. These factors will lead to both a damaging wind and large hail threat for most areas east of the Laramie Range. Also cannot rule out the potential for an isolated tornado threat, mainly in the far eastern row of counties of the panhandle where MLCAPE values are over 1300 J/kg. Mid-level lapse rates are also very steep across the area which will help support deep convection if storms do get going. Storms will dissipate and/or move out of the area later this evening. Upper-level ridging will stregthen on Tuesday, allowing conditions to warm up and dry out. Temperatures will climb back up to above average with highs in the upper 80s to mid 90s. Precipitation concerns will be relatively low thanks to subsidence under the ridge and dry surface conditions. Hi-Res guidance does show the potential for a weak shower or thunderstorm to develop in the Interstate 80 corridor between Cheyenne and Sidney. Given the dry surface and inverted-v soundings, gusty winds will be possible. Any storms will dissipate by the evening hours, leading to a quiet overnight. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Issued at 205 PM MDT Mon Jul 7 2025 Water Vapor Imagery shows an active Pacific Ocean thats going to be responsible for the multitude of shortwaves traversing The Pacific Northwest and Intermountain West. Wednesday and Thursday will be our break as the ridge axis moves over the intermountain West to keep things dry over those two days. Temperatures look to soar into the 80`s and 90`s with a few isolated spots of 100 degrees. Friday starts the return of troughs as an upper level low flattens out our ridge to resurrect our storm chances. The 500mb and 700mb heights show this compression resulting in increased winds for Friday as those jets push through. The other result of these compressed heights will be the synoptic support to help increase the storms duration as well. Some cooler air will accompany this compression dropping temperatures back down into the 70`s before another ridge pushes through this weekend to turn the temperatures right back into the 80`s. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 455 PM MDT Mon Jul 7 2025 The storms didn`t pan out like expected. A robust boundary stalled right at the CO/WY border. However, KSNY did get storms and looks to be the only terminal today. Clear skies are expected tomorrow morning with light winds. Another round of storms will be possible tomorrow in the afternoon and evening. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...SF LONG TERM...MM AVIATION...MM