Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
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563 FXUS65 KCYS 231159 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 559 AM MDT Mon Sep 23 2024 .KEY MESSAGES... - Patchy frost is possible early this morning in low-lying and wind sheltered areas. - Above average temperatures and dry conditions expected for the second half of the work week, with increased fire weather concerns Wednesday onward. && .SHORT TERM /THROUGH WEDNESDAY/... Issued at 255 AM MDT Mon Sep 23 2024 Latest GOES WV imagery shows a compact upper level shortwave progressing eastward along the KS/NE border that brought precipitation to much of northern CO last night. Cooler air from this system remains in the vicinity tonight with various sites dropping into the upper 30s at this hour, mainly in the valley locations around Laramie and Saratoga where the low- levels have become decoupled. Localized frost will be possible early this morning for locations that can avoid mixing from aloft, however latest RAP analysis shows a notable pressure gradient east of the lee trough with another approaching shortwave from the northwest. Additionally, westerly winds off the Laramie Range will keep portions o the I-25 corridor, including Cheyenne, slightly warmer through the night. This disturbance will be much less potent than the previous system in northern CO, but cannot rule out isolated shower development late this afternoon in the NE panhandle. Forecast soundings suggest dry low-levels with surface dew points only in the upper 20s. With generally weak forcing, any precipitation will likely evaporate before reaching the ground. Tuesday will be ~5F degrees cooler across the NE panhandle behind the weak frontal passage. Overall, most of the CWA will reach the 70s before the warmup into late this week begins. An upper level ridge will begin to develop over the central Rockies as 500mb height rises close to 588-590 dam. Latest NAEFS guidance shows this around the climatological 98th percentile for late September supporting afternoon highs 10-15F degrees above normal starting Wednesday. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Issued at 255 AM MDT Mon Sep 23 2024 The medium range to extended forecast remain unchanged as there is very little with regard to weather in the next several days. We will have above average temperatures and below normal chances for precipitation through early next week. A predominant upper level ridge pattern will become entrenched across the Intermountain West and Great Basin. This will become an omega block weather regime where weather disturbances propagate to our north and east as the next several days occur. Expect daytime highs in the 70s and 80s for the lower terrain, and slightly cooler in the mountain zones. By early next week, a potential shift in the upper level steering flow will cause a shortwave trough and associated cold front to move towards our cwa. Cooler temperatures are progged to then be prevalent for the time being. && .AVIATION /12Z TAFS THROUGH 12Z TUESDAY/... Issued at 534 AM MDT Mon Sep 23 2024 VFR expected for all terminals. Breezy to gusty winds of 20-30 knots by 18z to 0z this afternoon may create brief areas of LLWS and turbulence. Otherwise, expect wind gusts to be 12 knots or less Monday night. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...MB LONG TERM...BW AVIATION...BW