Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
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346 FXUS65 KCYS 081124 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 524 AM MDT Mon Jul 8 2024 .KEY MESSAGES... - Confidence is growing for a potentially significant heat wave to impact the region late in the week into the first half of the weekend. && .SHORT TERM /THROUGH TUESDAY NIGHT/... Issued at 359 AM MDT Mon Jul 8 2024 With an exiting trough to the east and a building ridge to the west, the CWA will enter into a period of quiet weather, with warming and drying conditions expected. The upper-level trough axis will slowly push into the center of the country today, keeping some lingering cooler 700 mb air across the CWA. However, combined with abundant sunshine expected from the dry air aloft, temperatures will begin to rebound from Sunday`s below average temperatures. Highs for most locations this afternoon will still be slightly below average in the mid 70s to mid 80s. Looking at another increase in high temperatures on Tuesday as the ridge over the West Coast strengthens and begins to gradually shift eastward. 700 mb temperatures will climb to +12C to +16C, which will put high temperatures right around average for this time of year. Could also see an isolated shower or thunderstorm develop over the high terrain as a weak disturbance passes overhead. Any capping inversions will quickly be eliminated by rapid low-level warming, but the lack of decent moisture will likely lead to only a slight chance for any storms over the high terrain. Even Hi-Res guidance isn`t too keen on anything developing in the CWA. Rather, it keeps storm chances further south where there is a tad more moisture and forcing. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Issued at 359 AM MDT Mon Jul 8 2024 The latest models and ensembles show no change to the medium to long range forecast as a significant heat wave looks likely late this week and through next weekend. Wednesday will likely be our last "average" day for a while in terms of temperatures. Models show the upper level high, responsible for the record heat across the west coast, drifting eastward into the eastern Great Basin region and the Intermountain west. 700mb temperatures will climb to near 20c for western and central Wyoming and Colorado on Wednesday with highs near 90 degrees across Carbon county. Further east, mid 80s to low 90s are expected with light east to northeast winds for the high plains. Again, can`t rule out a quick shower or thunderstorm in and near the mountains Wednesday afternoon due to a weak disturbance on the eastern periphery of the upper level high, but most locations will remain dry and likely stay that way through the weekend. For Thursday through the weekend, all models and ensembles are in excellent agreement...showing the center of the 598-600dm upper level high drifting northeast into Utah and eventually near the Utah/Wyoming/Colorado border as we head into Saturday. The associated ridge axis will extend northward into Montana during this time with increasing subsidence aloft across eastern Wyoming and western Nebraska/Dakotas. Ensembles continue to show very little, if any, spread with solutions regarding POP and max and min temperatures. Continued to use a blend of the NBM 75th percentile for max temperatures. This will result in afternoon high temperatures solidly into the mid to upper 90s across most of the forecast area with readings of 100-106 degrees for areas below 5000 feet, such as Torrington, Scottsbluff, Alliance, and Chadron. The best chance to see daily high temperature records appears to be this weekend with daily records a few degrees lower on July 13th and 14th compared to the previous days. All time highs (monthly and yearly) are on the table as well since current forecast highs are within a few degrees of these records. At this time, it looks like Saturday will be the hottest day of the week for southeast Wyoming, with Sunday likely the hottest day for western Nebraska as afternoon temperatures approach 110 for portions of the northern and central panhandle. By late in the weekend and into early next week, models continue to be in great agreement show slight weakening of the strong upper level high pressure, which is forecast to drift south into Colorado and the four corners region. Some monsoon moisture begins to make its way north, with PWATs climbing back to 0.75 to 1.00 inch next Monday. Continued to increase POP late Sunday through next Monday as thunderstorms may return to the forecast area. However, this is still 7-8 days away so kept POP below 35 percent for now. && .AVIATION /12Z TAFS THROUGH 12Z TUESDAY/... Issued at 524 AM MDT Mon Jul 8 2024 High pressure aloft will begin to build across western Wyoming today with northwesterly flow continuing for eastern Wyoming and western Nebraska. Impacts to Aviation will be minimal early this week with light winds and little or no precipitation. HAZARDS/WEATHER TRENDS: VFR conditions will prevail today and tonight. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...SF LONG TERM...TJT AVIATION...TJT