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Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
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991 FXUS65 KCYS 142003 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 203 PM MDT Wed Aug 14 2024 .KEY MESSAGES... - Scattered afternoon and evening showers and thunderstorms are expected today. Storms will have the potential to produce brief, heavy rainfall and strong gusty winds. - Seasonable temperatures will continue through the period. Showers and thunderstorms will be most likely on Sunday, Monday and Tuesday, with dry conditions for Saturday. - Fire weather concerns begin to increase Friday as well as Saturday with warmer temperatures and low afternoon humidity. && .SHORT TERM /THROUGH FRIDAY/... Issued at 200 PM MDT Wed Aug 14 2024 Isolated showers are beginning to pop up on radar early this afternoon. A few isolated lightning strikes are accompanying the weak thundershowers further west of our cwa. Wind gusts of 40-50mph have been observed with some of the weak rain showers further west near the UT/WY/CO state borders. With the modeled upper air soundings depicting an Inverted-V signature in the lower boundary layer, and skinny CAPE further aloft, this afternoon and evening is favored to see strong wind gusts with the rain showers and thunderstorms. In fact, the HRRR is the most aggressive with the deterministic output of wind gusts between 45-75mph along the I-80 corridor of southeast WY between 21Z and 1Z this afternoon/eve. With the modeled soundings depicting 30-40 knots from the surface to 500mb, the high-based rain shower and thunderstorm activity may not have those highest wind gusts realized in actuality. However, it is a possibility as DCAPE readings over 1000 J/kg are also modeled, which is a good rule of thumb for the higher potential of stronger wind gusts. The rain showers and thunderstorm activity should wind down by 6Z for most areas. Thursday will be another mild to warm day. Scattered cloud cover over the region will keeps temperatures slightly reduced near seasonal averages. Model soundings show another afternoon and early evening timeline of inverted-V signatures, so would expect there to be elevated to potentially strong wind gusts when rain showers and isolated thunderstorms occur. Similar timelines of the mid-afternoon to early evening looks good for the slight chance of showers and thunderstorms. PWATs will be slightly lower, so the potential for brief downpours is limited. An upper level ridge will amplify from the Four Corners region overnight Thursday into Friday. This will bring the next round of warmer temperatures to the area. A weak shortwave disturbance will be embedded within the H5 upper level flow on Friday. A slight chance of rain showers during the afternoon is progged, but the concerns for fire weather will begin to creep upwards. Daytime minimum humidity readings will range from 10-15% along and west of the Laramie Range. Breezy winds will also be present during the afternoon in this same area, so a possible fire headline may be prudent in the coming forecast updates. Overall a warm forecast remains on track, and the chances of rain showers reduce slightly in the short term period. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... Issued at 213 AM MDT Wed Aug 14 2024 Friday night/Saturday...West flow aloft will continue to dry out the airmass and thus we will see correspondingly warmer temperatures from the mid 80s to mid 90s. With precipitable water values lowering to 0.4 to 1 inch and warm temperatures aloft increasing the convective inhibition. it looks dry. Sunday...Despite ridging aloft developing, we will see an increase in atmospheric moisture content with precipitable water values increasing to 0.6 to 1.4 inches. Thus, we expect an increase in widely scattered to scattered late day showers and thunderstorms, most numerous from the Snowy Range to far southeast Wyoming. Monday/Tuesday...Atmospheric moisture content remains about the same as on Sunday, and thus we expect another round of scattered late day showers and thunderstorms each day, most numerous near the Colorado state line from the Snowy Range to far southeast Wyoming. With similar 700 mb temperatures, maximum temperatures should be about the same as those from Sunday. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1119 AM MDT Wed Aug 14 2024 Changes once again to the aviation forecast, with details becoming a bit more clear with the latest HiRes model guidance. Active weather expected once again today, with another progressive shortwave expected to dig across the Intermountain West through the evening hours. Less moisture has been observed throughout the morning, with dewpoints in the mid to high 40s for Southeast Wyoming, and into the mid 50s for the Nebraska Panhandle. At this time, not expecting much to change throughout the day, with the better moisture advection occurring in the central CONUS and just out of reach. Regardless, forecast soundings continue to indicate DCAPE around 1000 J/kg and the latest HiRes model guidance having convection spark off the shortwave digging through. Main concerns will be gusty to strong winds associated with the lines of storms expected to develop. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...BW LONG TERM...RUBIN AVIATION...MRD