154 FXUS65 KGJT 071800 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 1200 PM MDT Fri Oct 7 2022 .UPDATE... Issued at 901 AM MDT Fri Oct 7 2022 Temperatures across the Steamboat Springs area have risen above freezing so the Freeze Warning has been allowed to expire. Over the last few days, temperatures across the Steamboat Springs area have dropped to, or just below freezing, and with the average freeze and hard freeze dates being in late August and mid September, respectively, no more Freeze Warnings are expected to be needed for that area. Thus, the Freeze Watch has been cancelled. && .SHORT TERM...(Today through Saturday) Issued at 320 AM MDT Fri Oct 7 2022 GOES nighttime microphysics beautifully illustrates the clash between the two different air masses encompassing the CWA. A closed low remains anchored over the Desert Southwest, which continues to infiltrate tropical moisture into the Four Corners region. The southerly winds will continue to transport moisture northward and PWATs across southeast Utah and southwest Colorado will remain in the 150 to 200 percentile (of normal) range through the short term. As a result, diurnally driven showers and storms will feed off available moisture and blossom atop the San Juan's this afternoon. Moisture content gradually decreases over northern ranges, at which air mass number two comes into play. Dry northwesterly winds dominating the direction of flow aloft two- thirds of the region will return tranquil Fall-like weather. Isolated storms are possibly over higher terrain, though, PoP grids reflect the reducing likelihood of wetting rain the further north you travel. Clearing conditions overnight will allow for temperatures to dip rapidly after sunset. Areas along the Yampa River Basin fall within sub-freezing criteria and risk for another frigid night are at bay. Have included a Freeze Watch for the Upper Yampa Basin, where areal coverage of freezing temperatures exceeds 50 percent of the forecast zone. Though, anticipate cold temps to trickle along the Hwy 40 corridor from Steamboat through Maybell. Looking south, cities along the Hwy 160 corridor will be insulated by cloud coverage and overnight lows look to stay about 5 to 10 degrees above normal. In addition, the southern flank of the southwest San Juan's lie under an area of convergence between dry northerly winds and moist air mass to the south. Hi-Res guidance maintains nocturnal showers/storms across this region well into the night. By Saturday, a shortwave wrapping around the closed Desert Southwest low may support another round of early afternoon storms and showers across the Four Corners region. Sliver of instability from bufkit soundings, and lift via dynamics and/or orographics suggests an environment for stronger storms to be capable of producing small hail and gusty outflow winds. Meanwhile, another wave swooping down from the north will also trigger isolated convective over higher terrain across the central and northern zones. Areas north of the San Juan's will have less moisture to work with, therefore, impacts will be more wind driven. Storms wane overnight across much of the CWA Saturday, however, the collision of the northern wave with southerly winds over the CO/NM border may suggest another round of nocturnal storms thriving throughout the night. .LONG TERM...(Saturday night through Thursday) Issued at 320 AM MDT Fri Oct 7 2022 The Rex Block shows no signs of breaking down in the long term period with the latest model runs. Sunday will see the upper level ridge firmly planted over the western CONUS while a broad trough dominates the eastern states. The pesky circulation over the Desert Southwest, having transitioned to an open wave, will continue to reside over southern Arizona / New Mexico throughout the day. As the synoptic pattern remains unchanged, we can expect another round of showers and thunderstorms Sunday afternoon and early evening, focused across southwest Colorado where PWATs remain slightly above normal. Elsewhere, quiet, mostly sunny weather will prevail under the influence of dry northerly flow. On Monday the southwest shortwave will lift northeast into the Southern Plains while another embedded disturbance cuts into SoCal. The high's center will be shifted further west over the Pacific in response leaving eastern Utah and western Colorado in a messy mix of flow aloft. Overall, dry weather will prevail but residual moisture paired with orographic support will fuel scattered convection over mostly the San Juans during the day. Another upper level trough will drop in from central Canada on Tuesday before quickly elongating over the Northern Great Plains by the evening hours. By Wednesday morning, this will result in a nearly identical pattern to what we're currently experiencing - ridge to the west, pronounced trough to the east, with a weak midlevel circulation over the Baja / southern Arizona / southern New Mexico region. The same can be said for Thursday with both the West Coast ridge and the eastern trough amplifying even more. There is some hope for some shortwaves to drop into the region on the backside of the trough, which would bring some better storm chances to our area, or at least expand it further north. We'll just have to wait and see how this pattern evolves. A mix of slightly below and slightly above normal temperatures can be expected each afternoon through the long term period. The northern zones will trend on the mild side due to mostly sunny skies while areas further south will be cooler in response to daily chances for showers and storms. Overnight lows each night will trend 4 to 8 degrees above normal for early to mid October. && .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) Issued at 1140 AM MDT Fri Oct 7 2022 VFR conditions will prevail for the majority of TAF sites over the next 24 hours with terrain driven winds and occasional breezy conditions at high elevation sites. Isolated to scattered storms look to build over the southern high terrain, with San Juans favored for better chances and coverage. KTEX and KDRO will have the better chance at seeing VCTS with gusty outflow winds and brief light to moderate rain the primary concerns. Skies should clear this evening with exception of southwest Colorado where clouds and showers could linger into the overnight. Confidence wasn't high enough to keep mention in the TAF for the overnight period though. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ UPDATE...TGR SHORT TERM...ERW LONG TERM...MMS AVIATION...MDA