Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
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931 FXUS65 KCYS 290440 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 1040 PM MDT Sun Apr 28 2024 .KEY MESSAGES... - A High Wind Watch has been issued for strong winds early Tuesday morning through Tuesday afternoon across the Laramie Range. - Active extended forecast period with multiple rounds of rain and snow showers with occasional thunder possible daily through the weekend. && .SHORT TERM /THROUGH MONDAY NIGHT/... Issued at 245 PM MDT Sun Apr 28 2024 As the low continues to remain nearly stationary along the NE/SD border, a shortwave embedded in the flow is kicking off some showers across areas along and west of the Laramie Range, these will likely fall as rain at lower elevations and snow at the highest peaks in the mountains. A rumble of thunder is possible, but strong or severe storms are not expected with little to no additional precipitation accumulation. After the showers have died off this evening, and skies begin to clear, temperatures are expected to drop with a low chance of areas of patchy fog and low clouds in the far eastern Nebraska panhandle. As a messy, weak, low amplitude ridge moves over southeast Wyoming and western Nebraska tomorrow, mostly dry conditions are expected with afternoon highs in the 60s to 70s. Monday late afternoon/evening though, a low passes to the north of the forecast area, but the trough dips just low enough to kick off more precipitation chances, and bring in cooler temperatures. Precipitation type this time will be mostly rain with snow in the mountains. However, areas of Carbon County and the Laramie Valley may briefly transition over to snow or at least a rain/snow mix early Tuesday morning. Precipitation accumulation is expected to be minimal with 2 to 5 inches of snow possible in the mountains and less than 0.02 to 0.25 inches of rain at lower elevations. In addition to increasing precipitation chances, winds will also begin to increase. Refer to the long term discussion for further details. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Issued at 245 PM MDT Sun Apr 28 2024 Tuesday will begin with an upper level low across the PacNW with multiple shortwaves passing in the flow through the middle of the week. The initial vort max passage with a surface low positioned neat the WY/MT/SD border will likely lead to gusty winds across the CWA with this bora wind event. Additionally, strong downward omega fields develop across the Laramie Range as the 110 kt jet exit shifts just to the north. Decided to go ahead with a High Wind Watch starting early Tuesday morning for much of the Laramie Range in southeast WY, including Interstate 25 between Cheyenne and Wheatland and Interstate 80 between Cheyenne and Laramie. Wind gusts around 60 mph will be possible, especially late Tuesday morning in the wake of the trough axis passage. However, this event will likely be short in duration. Local in-house guidance is hinting at the high wind potential, but probabilities are slightly lower than typical high wind events. Latest GFS has delayed the timing of the trough by 3-6 hours compared to 24 hours ago, which is also highlighted by in- house guidance. Will need to continue to monitor these trends as they will have significant impacts to the timing of this potential for high winds. With Tuesday mornings frontal passage, a few light showers will be possible. However, the next best chance for precipitation will come Wednesday afternoon into Thursday as the secondary vort max swings through our area associated with the same larger scale upper level low now over the north-central CONUS. Favorable isentropic lift with this system could lead to widespread showers, likely as rain east of I-25 and snow farther west. We could even see a few thunderstorms Wednesday afternoon with the surface low deepening across eastern CO. However, high uncertainty remains with timing of magnitude of colder air worked into our CWA. 60% of GEFS membership favors a colder solution, but still disagree on exact timing of the upper level trough passage. Most EC members are favoring a more progressive solution. An active pattern looks to continue into the weekend and early next week with multiple shortwave passages and possibly another Pacific wave approaching from the west. This will bring numerous chances for showers, but coverage will likely remain scattered. Should see a gradual warm up headed towards early next week with temperatures climbing 10-15F degrees above normal for early May. && .AVIATION /00Z TAFS THROUGH 00Z TUESDAY/... Issued at 1040 PM MDT Sun Apr 28 2024 Quiet overnight expected with only a few lingering showers around. These showers will likely not impact any terminals. VFR conditions are expected at all terminals. However, there is a 30 percent chance of MVFR CIGs at KCDR overnight, but confidence in this occurring is low at this time. Breezy conditions are likely throughout the day Monday at southeast Wyoming terminals. Increasing clouds and showers will also be possible at these terminals during the evening hours due to an incoming disturbance. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...High Wind Watch from Tuesday morning through Tuesday afternoon for WYZ106-107-116-117. High Wind Watch from late Monday night through Tuesday afternoon for WYZ110. NE...None. && $$ SHORT TERM...LEG LONG TERM...MB AVIATION...SF