278 FXUS65 KCYS 191141 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 541 AM MDT Sat Sep 19 2020 .SHORT TERM...(Today and Sunday) Issued at 310 AM MDT Sat Sep 19 2020 Current GOES WV Imagery shows an upper level disturbance over central OR and western ID that will continue to push east throughout the day. Surface winds will pickup ahead of the associated cold front that will push through southeast Wyoming later this afternoon. Expecting strong winds gusting 35 to 40 MPH west of the Laramie Range with 35 kt passing over at 700mb and deep mixing expected. Strong winds and low humidity will result in critical fire weather conditions and therefore a Red Flag Warning is in effect for much of southeast Wyoming Saturday. Along with the deep mixing, continued improvements in visibility and air quality are expected through the afternoon and after the frontal passage. However, critical fire weather conditions Saturday afternoon could result in flare ups with nearby wildfires including the recently identified Mullen Fire in the Snowy Range. An Air Quality Alert continues through midday Sunday for southeast Wyoming. Scattered showers associated with the widespread lift from the progressive upper level trough will develop Saturday evening with the cold frontal passage. This looks to be the best chance for measurable precipitation until Tuesday, however most models are depicting no more than a tenth of an inch of rainfall for most locations. Heading into Sunday, post-trough zonal flow will be present with gusty winds once again. Would not be surprised by a few brief 45 MPH gusts along the South Laramie Range and Bordeaux area Sunday morning. Will need to monitor RH values for possible fire weather headlines Sunday as current forecast keeps them around 20 percent. However, winds will most likely be around critical thresholds. .LONG TERM...(Monday through Friday) Issued at 249 AM MDT Sat Sep 19 2020 Summary: Near and then above normal temperatures will return next week and persist through at least next Saturday. Overall rain chances will be limited but Tuesday may have the best chance of at least some scattered showers and a few thunderstorms. However, overall precipitation amounts will be quite low and ongoing drought conditions will persist. At least elevated fire weather conditions will be likely through the week and Red Flag Warnings may also be needed. Details: After a Pacific frontal passage Saturday night into Sunday - overall synoptic pattern will feature a H5 ridge across the SE U.S., extending NW to the southern Rockies. WY/NE will be on the N/NW side of the H5 ridge in general W/E zonal flow with slight perturbations being resolved across multi-model output. These small influxes of localized enhanced dynamic lift combined with 0.4-0.7" PWATs, and 100-200 J/KG MLCAPE should aid in isolated to scattered diurnal showers and perhaps a rumble of thunder Mon-Wed afternoons. Greatest alignment of shower inducing parameters appears to be on Tuesday but coverage will be scattered at best with limited precipitation actually reaching the ground for much drought or warmth relief. Areas will be lucky if they receive over one quarter inch in the next week - with most receiving much less. Humidity percentile values will fall into the teens and 20s across the region and winds will be at least 10-20mph each afternoon. Will need to watch for tighter pressure gradients/deeper mixing if gusts can exceed 25mph for possible Red Flag Warnings day to day. Long range multi-model envelope does suggest a deeper trough and cooler conditions late next weekend into early next week but this, too, may be short-lived, with a return to warmer/drier conditions thereafter. Models still need to converge on better run-to-run consistency on this trough potential as overall confidence is low in exact evolution next Sun-Tues. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) Issued at 530 AM MDT Sat Sep 19 2020 Mid to high clouds scattered across the region this morning as an upper level disturbance moves through the Wyoming today. Haze and smoke will linger around SE WY terminals this morning with visibility down to 6 SM possible, but will clear out this afternoon. Winds will increase later this morning for SE WY terminals ahead of a frontal passage. Gusts around 30 kts are expected at KLAR and KRWL along with scattered showers in the afternoon. The front looks to pass through KCYS around 00z and NE Panhandle terminals around 02z-04z with gusty west winds. Otherwise, VFR conditions are expected through the forecast period. && .FIRE WEATHER... Issued at 249 AM MDT Sat Sep 19 2020 Critical fire weather conditions expected Saturday with low humidity and gusty winds to 40 MPH expected west of the Laramie Range. The threat for rapid fire growth is present and therefore a Red Flag Warning has been issued. Saturday late afternoon and into the early evening, a cold frontal passage is expected shifting winds from out of the southwest to a more westerly direction. Showers will accompany the frontal passage with no more than a tenth of an inch of rainfall expected with these storms. Windy conditions can be expected once again Sunday across Carbon and Albany Counties, however humidities are expected to remain above critical thresholds behind the frontal passage. A drier pattern looks to setup in the long term with near-critical fire weather conditions possible into next week. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Red Flag Warning from 10 AM this morning to 8 PM MDT this evening for WYZ301>310. NE...None. && $$ SHORT TERM...MB LONG TERM...JSA AVIATION...MB FIRE WEATHER...MB