285 FXUS65 KCYS 212037 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 237 PM MDT Sat Aug 21 2021 .SHORT TERM...(Tonight - Sunday Night) Issued at 208 PM MDT Sat Aug 21 2021 A few showers & thunderstorms will be possible across southeast WY and the western NE Panhandle this afternoon & evening as upper-lvl difluence overspreads the region ahead of a short wave tracking to the east across the Great Basin & Intermountain West. Best chances for convection will be along & west of the Laramie Range where the overall moisture profiles should favor greater coverage of showers and storms. Still, very dry boundary layer conditions should limit precipitation amounts. Deep inverted-v profiles, along with strong unidirectional flow aloft suggests potential for strong/gusty wind with some of this activity. Showers should diminish overnight with subsidence increasing behind the aforementioned wave. Winds should increase overnight as downward omega strengthens & 700-800 mb flow increases with the passage of the trough axis. H7 & H85 CAG to CPR gradients climb to near 50 meters with 50+ knot flow around 650 mb or so, suggesting potential for strong winds especially in the 12z to 18z time frame as a stable layer develops aloft. Vertical X-Sec analysis across the Arlington gap suggests a strong inversion near the surface which is expected to keep winds just under 58 MPH, and our local experimental GFS-based model guidance is also suggesting peak gusts in the 45-57 MPH range. Have issued an SPS to highlight this threat for now, but this will definitely be something to keep an eye on overnight into early Sunday. Warming temperatures Sunday w/ deep subsidence and resulting sunny skies. Downsloping wind may further aid in significant drying aloft, suggesting consensus dew- points are at least 5 degrees too high. GFS dew points are looking fairly realistic for the scenario, bringing minimum RHs down to 10 percent for much of the plains along with gusty winds. See Fire Wx discussion. .LONG TERM...(Monday - Saturday) Issued at 208 PM MDT Sat Aug 21 2021 A generally warm & dry forecast period expected as ridging remains in control aloft for much of the central and eastern US. It should remain breezy at times w/ strong southwesterly flow aloft, but the potential for precipitation will remain low given a rather limited supply of moisture. Highs will be in the 80s and 90s, warmest east of I-25. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 1140 AM MDT Sat Aug 21 2021 The main concern with this forecast is the timing of a disturbance moving through the area late tonight through Sunday morning. Ahead of this disturbance it will be quite breezy overnight especially over the Nebraska panhandle in response to the low level jet. After the disturbance moves through, the wind is expected to shift to the southwest at speeds of 25 to 35 mph with some higher gusts up to 45 mph possible in the gap areas and higher elevations above 8000ft MSL. Precipitation chances will be limited to the higher terrain where one cannot rule out some virga showers along with gusty winds up to 50 mph. && .FIRE WEATHER... Issued at 208 PM MDT Sat Aug 21 2021 A change toward considerably warmer & drier conditions will likely yield critical fire weather conditions for areas along and east of I-25 on Sunday. A Fire Weather Watch is in effect from 10 AM until 8 PM MDT on Sunday for FWZ 301-310-311-312-313. RHs may fall to 10 percent along w/ wind gusts 35 to 40 MPH. Fire conditions may stay elevated through early next week for portions of southeast Wyoming mainly west of the Laramie Range. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Fire Weather Watch from Sunday morning through Sunday evening for WYZ301-310. NE...Fire Weather Watch from Sunday morning through Sunday evening for NEZ311>313. && $$ SHORT TERM...CLH LONG TERM...CLH AVIATION...REC FIRE WEATHER...CLH