Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
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510 FXUS65 KCYS 261737 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 1137 AM MDT Thu Sep 26 2024 .KEY MESSAGES... - Elevated to critical fire weather conditions are expected today. A Red Flag Warning remains in effect for parts of southeast Wyoming through 8pm MDT. - Above average temperatures and dry conditions expected for the forseeable future. && .SHORT TERM /THROUGH FRIDAY NIGHT/... Issued at 303 AM MDT Thu Sep 26 2024 Latest surface analysis depicts a cold front pushing from the Pacific Northwest and inching closer to the Intermountain West, with several shortwaves digging across the CWA kicking up some gusty winds across the wind prone areas. Outside of some increased wind speeds from 25 to 35 mph for both KBRX and KARL, observations have been relatively mild with temperatures in the low to mid 50s and clear overhead skies for both southeast Wyoming and the Nebraska Panhandle. Very little changes to the near term forecast, with the latest upper air analysis having the ridge axis centered across the High Plains, which is expected to shift slightly eastward as an upper level shortwave passes to the north and a developing blocking pattern shifts southward into the Four Corners. Under this setup, will see the southwesterly flow transition to warming downsloping westerly flow for much of our region. A significant warmup is still on track for today, with 700mb temperatures expected to climb upwards to around +16c and the resulting warm downsloping flow increasing surface temperatures into the high 80s to low 90s for southeast Wyoming and into the high 90s for the Nebraska Panhandle. Kept with the trends of blending in higher NBM percentiles into the short term forecast, with the NAEFS mean 700mb temperatures in the climatological 99th percentile for the majority of areas across southeast Wyoming and the Nebraska Panhandle. Main concerns in the forecast remained focus on the prolonged dry conditions, combined with the much warmer temperatures today, which will inevitably raise fire weather conditions as the minimum RH values drop to the mid to low-teens for much of southeast Wyoming and the Nebraska Panhandle. Wind speeds will remain the main uncertainty and if they are able to reach critical thresholds. Nevertheless, HREF probabilities of reaching critical fire weather conditions have continued to trend upwards for southeast Wyoming where current Red Flag Warnings are in effect through 8pm MDT tonight. Slight cooldown is expected Friday, with a weak surface front progged to dig southward through the area early Friday morning and dropping temperatures a good 10 degrees from today. Although, should be relatively short lived with the upper level ridge pushing more northward in the Dakotas by this weekend. As a result, another above average temperature day expected on Saturday, with NAEFS mean 700mb temperatures in the climatological max for portions of southeast Wyoming and the remaining areas in the 90th to 99th percentiles. Similar to today, continued mixing in higher NBM percentiles to the current blends to continue increasing daytime high for Saturday. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Issued at 303 AM MDT Thu Sep 26 2024 Dry weather will dominate the long-term forecast period. Not much change in overnight ensemble guidance with very high forecast confidence in no precipitation in southeast Wyoming and western Nebraska through this period. From a large-scale synoptic perspective, a broad ridge of high pressure will generally be in control through Sunday night. This upper-level ridge will become suppressed to the south by Monday as a broad trough moves through the far northern CONUS. At the surface however, things will be a bit more exciting as this broad trough will drive a surface cold front southward through the high plains on Monday. After several days of well-above to near record high temperatures, expect a return to near- normal temperatures on Monday for highs behind this cold front. Clear skies and a very dry, post-frontal airmass will result in a chilly fall night on Monday night into Tuesday with an outside chance of frost possible in places like Laramie, Rawlins, Cheyenne and even some of the typically colder locations in the high plains and western Nebraska. After another seasonable day on Tuesday, temperatures rebound by midweek as fast westerly flow enhances a broad downslope pattern by midweek. It looks very likely that the dry weather pattern will continue right through the end of next week and possibly even into the following weekend given robust ensemble pattern agreement showing zonal flow and PWAT values well below average. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1135 AM MDT Thu Sep 26 2024 VFR expected for all terminals through the forecast period. Breezy to gusty winds of 25-35 knots are anticipated for most terminals this afternoon, before dissipating after 0Z this evening. The NE Panhandle terminals will experience another short round of elevated winds between 6Z and 12Z where winds up to 25 knots are expected. For further details, please look at individual TAFs. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Red Flag Warning until 8 PM MDT this evening for WYZ417>422- 427-429-430-432. NE...None. && $$ SHORT TERM...MRD LONG TERM...MAC AVIATION...BW