Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
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505 FXUS65 KCYS 161817 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 1217 PM MDT Tue Jul 16 2024 .KEY MESSAGES... - Widely scattered storms possible Tuesday afternoon. Increasing moisture Wednesday will support strong to possibly severe thunderstorms Wednesday afternoon. Daily chances for precipitation continue through the rest of the week. - Warm mid-week before cooling trend begins for the weekend. && .SHORT TERM /THROUGH WEDNESDAY NIGHT/... Issued at 335 AM MDT Tue Jul 16 2024 Latest GOES WV imagery shows a convective complex across central KS/NE ongoing early this morning from earlier convection originating in eastern CO/WY associated with a shortwave passing overtop the southwest CONUS upper level high. Remnant outflow boundaries with these systems will likely keep the focus of higher low-level moisture and best storm coverage east of the CWA late this afternoon. However, widely scattered storms may still develop along the higher terrain early this afternoon and spreading across adjacent plains through early this evening. Overall, instability profiles will be quite limited across much of the CWA, but do improve late this afternoon across the northern NE panhandle that could support sustaining a stronger cell moving southeast out of the Black Hills as some CAMs suggest. Temperatures will be a few degrees cooler than Monday with 700mb temps slightly dropping to ~12-14C behind Monday evneing`s frontal passage, but still looking at afternoon temperatures in the mid-80s to low-90s. Storm chances and coverage increase headed into Wednesday as southeasterly flow will return higher dew points along and east of the Laramie Range. The surface high near the Canadian border will begin to slide south into the north-central CONUS with an upslope setup across our area as another shortwave rounds the top of the upper level ridge across the western CONUS. Steeper mid-level lapse rates with improving low-level moisture will support MLCAPE values between 700-1400 J/kg based on the latest HREF IQR. Flow is fairly unidirectional above the low-level southeasterly flow, but bulk shear values would support a few strong storms to develop off the Laramie Range and immediate foothills. SPC has highlighted most of the Front Range with a Day 2 Marginal Risk for severe thunderstorms. && .LONG TERM /THURSDAY THROUGH MONDAY/... Issued at 335 AM MDT Tue Jul 16 2024 Upper-level ridging will develop once again over the western CONUS Thursday through most of the long term forecast. This ridge is progged to bring warmer temperatures to southeast Wyoming and western Nebraska once again, but should be cooler than this previous weekend. 700mb temperatures will only increase to the 15C mark under the ridge on Thursday leading to surface temperatures in the mid-80s to mid-90s. This ridge will remain overhead for Friday as well, with a 500mb high centered over the Four Corners region and advecting in monsoonal moisture. Precipitable water will surge well over an inch for portions of the Panhandle with closer to an inch over southeast Wyoming. With several vorticity maxima traversing through the ridge, precipitation looks likely both Thursday and Friday evening, with Friday having the better chance for wider-spread precipitation. As a result of the additional precipitation and cloud cover expected for Friday, temperatures will be cooler in the low-80s to low-90s across the region. Saturday and Sunday both look cooler as the upper-level ridge retrogrades slightly back to the west and colder air floods down from Canada. Northerly to northwesterly flow aloft will remain for both days, leading to the potential for precipitation chances in the afternoons. A large fetch of northerly winds will be present from southern Canada to northern Arizona, further promoting the cooler temperatures. Temperatures on Saturday are expected to be in the low- to upper-80s, with upper-70s to mid-80s expected Sunday. Kept PoPs fairly low for these two days, between 20 and 30%, as afternoon showers and storms will be difficult to track down at this time. The cooler temperatures look to remain through the early week as the strong northerly flow aloft remains. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1210 PM MDT Tue Jul 16 2024 In general, VFR prevails. Expect increasing clouds w/ SCT to BKN coverage around 10k feet AGL along with the threat for isolated/ widely scattered showers and thunderstorms. Confidence is rather low that a thunderstorm will impact any given terminal, but such activity may result in a brief period of MVFR conditions through the afternoon. Greatest convective coverage should stay confined to the higher terrain of southeast Wyoming. The main hazard will likely be gusty/erratic surface winds in excess of 40 knots. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...MB LONG TERM...AM AVIATION...CLH