Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
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792 FXUS65 KCYS 070953 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 353 AM MDT Tue May 7 2024 .KEY MESSAGES... - Strong winds continue today and tonight for southeast Wyoming, but will be lighter compared to Monday. Wind-prone locations will still see wind gusts 60-70 mph. - Cool and unsettled weather continues for Wednesday and Thursday with a warming trend headed into the weekend. && .SHORT TERM /THROUGH WEDNESDAY/... Issued at 315 AM MDT Tue May 7 2024 Latest observations across southeast WY and western NE show winds gusting 40-50 mph across the high plains with gusts up to 65 mph over wind-prone areas near Arlington and Vedauwoo. This is considerably lower than the 75-85 mph wind gusts reported closer to midnight, but follows suit with the decreasing winds continuing into this morning noted in hi-res guidance. High Wind Warnings continue across much of southeast WY today, however high winds will likely not be as strong and widespread as Monday. Looking at wind gusts 45-55 mph for the high plains across southeast WY, while wind-prone locations will see gusts 55-65 mph. 700mb flow will be gradually weakening today with relaxing height gradients as the upper level low in northwest SD begins to retrograde westward, but still remaining above the climatological 99th percentile. A secondary vort max will move across the CO/WY border today increasing showers and storms today, mainly for south-central WY mountains with light accumulating snowfall. As this vort max passes through, expect winds to see another spike this evening and tonight with strong subsidence across wind-prone locations along the Laramie Range as much of the area moves underneath the left entrance of a 120 kt 250mb jet. This will persist until early Wednesday morning as mslp gradients begin to relax with the weakening occluded cyclone. In-house random forest guidance highlights this resurgence in winds after 00z Wednesday or at least an increase back up to near 70 mph for the Laramie Range and adjacent foothills. The retrograding upper level low will begin to slide south Wednesday increasing moisture across the CWA with snow showers along and west of the Laramie Range and rain farther east. Accumulating snowfall is likely in the mountains with sub- advisory amounts and overall precipitation rates being on the lower side. With the large scale troughing pattern remaining over much of the central CONUS, expecting below average temperatures to continue with highs in the 40s and 50s. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Issued at 315 AM MDT Tue May 7 2024 Minimal changes made from the previous forecast. We are still looking at a gradual warming trend as we transition into a ridging pattern toward the end of the week. While part of the low pressure system will continue eastward, models show a portion of the closed low retrograding southwest. This transition will expand the pressure gradient along the Rockies, weakening the winds across southeast Wyoming and western Nebraska (finally). Precipitation chances hang on through at least Wednesday night as the low continues to move eastward, but weak easterly, upslope flow remains across southeast Wyoming and western Nebraska. By Thursday afternoon, the ridge starts to creep into northern portions of the forecast area, increasing temperatures, and pretty quickly drying out the air. Due to the uncertainty of the timing of all the moving parts, the exact timing and impacts will need to be further refined as we get closer to Wednesday night. By Friday the low is further shifted southwestward and the ridge moves further east, long range models show southeast Wyoming and western Nebraska positioned on the eastern edge of the ridge until Sunday. Temperatures are forecast to be near- to just-above-normal. If the ridge shifts a bit further east, positioning the forecast area closer to the ridge axis, then we can expect much warmer temperatures. Sunday night into Monday, the ridge axis shifts further east, but is simultaneously squashed by a stronger shortwave and ejects out of the PACNW. The portion of the low that retrograded to the SW CONUS is also finally pushed eastward by the Subtropical Jet, and taps into moisture as it gets closer to the southern plains. This combination of dynamics from the upper-level shortwave to the north and the closed low to the south has the potential to cause more widespread precipitation headed into early next week. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1138 PM MDT Mon May 6 2024 Strong winds remain the primary concern across southeast Wyoming and western Nebraska. Strong winds are expected to remain overnight, but may decrease 5-10kts for a few hours before strengthing again. Showers will linger across southeast Wyoming and western Nebraska tomorrow afternoon, with showers ongoing at KCDR at this time. Ceilings at KCDR are above MVFR criteria, but ceilings could drop into the MVFR category as heavier rain showers move into this terminal. Additionally, low-level wind shear will be a threat overnight as surface winds decrease slightly, but strong winds remain aloft. Expect low-level wind shear at KCYS, KLAR, KBFF, KSNY, and KAIA overnight. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...High Wind Warning until 9 PM MDT this evening for WYZ103>105- 107>109-115-117>119. High Wind Warning until 6 PM MDT Wednesday for WYZ106-110-116. NE...High Wind Warning until 6 AM MDT early this morning for NEZ019- 020-054. && $$ SHORT TERM...MB LONG TERM...LEG AVIATION...AM