Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
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415 FXUS65 KCYS 120504 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 1104 PM MDT Sat May 11 2024 .KEY MESSAGES... - Trending warmer through Monday, but remaining unsettled with daily chances for showers and storms. Severe weather is not expected. - A cold frontal passage is expected on Wednesday, with much of the region returning to below-normal temperatures and increased chances for rain and high-elevation snow. && .SHORT TERM /THROUGH MONDAY NIGHT/... Issued at 215 PM MDT Sat May 11 2024 A warming trend should persist across southeast WY & the western NE Panhandle as thermal profiles warm in response to weak upper- level ridging extending along the northern periphery of a closed low drifting eastward from the Four Corners into the central and southern plains over the next several days. Daytime highs should climb into the lower to middle 70s across much of the CWA Monday as 700-mb temperatures climb to near +8C by 00z Tuesday. Despite the warming trend, an unsettled pattern will likely persist with daily chances for showers & perhaps a few rumbles of thunder for some locales as multiple pieces of mid-level energy continuously pivot around the north side of the aforementioned low. Given the very modest moisture profiles & dry sub-cloud layer suggested by forecast soundings, potential rainfall amounts look to be fairly limited w/ most areas not seeing anything measurable, perhaps up to a few hundredths of an inch. Weak CAPEs under 500 J/kg, along with modest deep layer vertical shear will preclude any risk for strong to severe storms. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Issued at 215 PM MDT Sat May 11 2024 The long term forecast will start off active as numerous showers and thunderstorms look possible mid-week. The weather will quiet down towards the end of the week as a ridging pattern takes hold of western CONUS. A shortwave digging down from the Pacific Northwest on Tuesday will likely spark widely scattered showers and thunderstorms during the afternoon and into the overnight hours. A vorticity max over the CWA, as well as a weaker 250 mb 85 kt jet streak just north of the CWA will provide some of the ingredients needed to get thunderstorms. Location of the jet streak puts the CWA in the right entrance region, which is favorable for lift and the development of potentially stronger storms. GFS soundings from Tuesday afternoon into Tuesday evening do show areas of instability, with over 1000 J/kg of MUCAPE in parts of the CWA. There are even some impressive effective shear values over the northern tier of the CWA, with both Douglas and Chadron showing 35 kts EBWD. Because of this, cannot rule a few marginally severe to severe thunderstorms. Based on current sounding profiles, the main concern would likely be the potential for severe hail. This would mainly be in the northern tier of the CWA, as well as the Nebraska panhandle. Showers will likely become more numerous Tuesday night as the shortwave pushes into Wyoming, bringing with it more mid-level moisture. Showers will continue into the day Wednesday with the shortwave passing over the CWA. Cooler temperatures are expected with this shortwave which will lead to a more stable environment with less of a chance of thunderstorms developing. Could still hear a rumble of thunder or two, but it will predominately be rain showers across the area. With the shortwave pushing off to the east Wednesday night, expect a warmer and drier end to the week as an upper-level ridge builds over western CONUS. Temperatures will warm up above average across the CWA on Thursday and Friday, with minimal chances for precipitation both days. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 1103 PM MDT Sat May 11 2024 Mainly quiet conditions after midnight or so, although there is a slight chance for some fog or low CIGs at KSNY early Sunday morning. The probability is too low at this time, but worth keeping in mind. By mid-morning, expect northeast winds to take over at all terminals, followed by shower and thunderstorm activity in the early afternoon. These showers will have the potential to produce gusty and erratic winds. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...CLH LONG TERM...SF AVIATION...MN