711 FXUS65 KCYS 312334 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 534 PM MDT Thu Jul 31 2025 .KEY MESSAGES... - Scattered to widespread thunderstorms continue through the beginning of the weekend with a daily risk of strong to severe weather possible. - Isolated to scattered showers and storms through the weekend, then decreasing precip potential through midweek. - Gradually increasing temperatures over the course of the period alongside an increasing risk of fire weather concerns. && .SHORT TERM /THROUGH SATURDAY/... Issued at 300 PM MDT Thu Jul 31 2025 Scattered showers and thunderstorms already increasing in coverage across the high terrain of Carbon and Albany Counties this afternoon and moving slowly eastwards into a more favorable environment for convective development. Current mesoanalysis indicates PWAT values of over an inch starting near the NE border and eastwards, alongside MLCAPE values of 1000-2500 J/kg in eastern WY, and 0-3km shear values maxing at 30-35 knots. All of this is contributing to supercell composite values of 8-12 for southeastern WY and the western extent of the NE Panhandle. High res guidance is honing in on some clusters of activity through this evening, and with a severe thunderstorm watch about to be issued it does look likely that we will see at least a couple to few warnings through the evening. Most likely culprits with this would be clustered storms with near to severe hail and some strong wind gusts, and with the high PWAT values for this time of year another round of flooding concerns can`t be ruled out as well. Moving into the overnight period, storms should start to weaken with the setting of the sun and the loss of daytime heating, though lingering showers could be possible through the evening and early nighttime hours. Southerly to southeasterly upslope flow should once again promote low clouds and possibly some fog, but with moisture moving slowly eastwards Cheyenne may be just west of this area. And on that note, another round of afternoon convection is then possible on Friday as the axis shifts just slightly eastwards. Much like today, storm initiation and strength will be dependent on cloud cover and and how it lingers as this could limit or inhibit development. But with a similar setup to today, more clusters of activity could bring hail and winds once again. Further west however, moisture will start to depart Carbon and Albany Counties. Teens to near single digit afternoon RH values are expected, and with breezy winds into the 20-30 mph range possible we may be encroaching onto critical fire weather concerns. For now have held off on a watch or warning, but don`t be surprised if we begin a series of red flag days that will extend into the long term forecast period. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Issued at 300 PM MDT Thu Jul 31 2025 The mid-/upper-level flow will be characterized by ridging over the High Plains and Intermountain West. PoPs will largely be governed by the placement of an expansive moisture axis extending from Texas to the Dakotas. PoPs look to transition from isolated/scattered coverage on Saturday and Sunday (mainly in the afternoons and evenings) to isolated at most (~10% chance) mainly across the eastern half or so of the County Warning Area (CWA) on Monday, Tuesday, and Wednesday. Subsequent forecast packages may shift PoPs slightly farther west or east, depending on how global models -- and hi-res models, once we are within their time windows -- position the moisture axis. The Storm Prediction Center (SPC) currently has the southern portion of our Nebraska Panhandle counties outlined in a Marginal Risk (level 1 out of 5) for severe thunderstorms on Saturday. Decent surface-to-500mb bulk shear embedded within the aforementioned ridge could aid in intensification/organization of diurnally-driven storms. PWATs associated with the moisture axis over the CWA are not progged to be anomalously high, so widespread flash flooding is unlikely. Additionally, speed maxima around 25-35 kts along the periphery of ridge (and over much of the CWA) should keep storms moving at a decent clip, again precluding flooding potential in any one area. Heat is expected to gradually build through the long term period given the aforementioned drying trend and ridging aloft. On Tuesday and Wednesday, high temperatures in the mid-90s to upper 90s are forecast across the Plains, with upper 80s to lower 90s across the higher terrain of Albany County and Carbon County. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 532 PM MDT Thu Jul 31 2025 Thunderstorms continue this evening across the region, moving into the Nebraska Panhandle. These terminals are the most likely to see activity, though some storms back into Carbon County could impact KRWL over the next couple of hours as well. Winds should lessen and CIGs should mostly rise overnight, though upslope flow is expected to once again bring low clouds to the Nebraska Panhandle during the morning hours. Storms expected again tomorrow during the early afternoon for our Wyoming sites, with the Nebraska Panhandle sites expected to see potential storms either right at or just after the end of the TAF period. Much like today, storms could be strong to possibly severe and will bring locally breezy and erratic winds. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...CG LONG TERM...WFOCYS AVIATION...CG