248 FXUS65 KGJT 200951 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 351 AM MDT Sat Oct 20 2018 .SHORT TERM...(Today through Sunday) Issued at 351 AM MDT Sat Oct 20 2018 High pressure centered over the Central Rockies will bring more dry and warmer weather to Eastern Utah and Western Colorado today. Expect light winds and plenty of fall sun across the board with temperatures warming to near seasonal norms by this afternoon. The ridge axis will shift east tonight allowing high clouds to spread northeast through the Four Corners and across much of western Colorado by early Sunday morning. The increase in high cloud cover will help to moderate overnight lows in most areas to bring a break from the colder mornings of late. Moisture will steadily increase through the day on Sunday with an upper low strengthening off the central coast of California. This low will eventually drive eastward into the Great Basin to bring more unsettled weather into the area by early next week. Cannot rule out a few stray showers on Sunday across the higher terrain with focus across eastern Utah, but potential remains low at this time. Temperatures on Sunday will continue to nudge up, approaching 70 in the lower valleys. .LONG TERM...(Sunday night through Friday) Issued at 351 AM MDT Sat Oct 20 2018 On Sunday night the models are in fair agreement that a vorticity maximum will round the base of the main trough over the Great Basin. The forcing for ascent is not relatively strong, but steeper midlevel lapse rates above increasing low-level moisture from the Gulf should contribute to some instability. The main forcing appears to coincide with peak heating in the afternoon so showers and thunderstorms chances increase into the day Monday. Given the warm south-southwesterly flow snow levels should be above 10,000 ft although may lower to 8500 ft Monday night with the nocturnal cooling as well as within any convection. The more favored areas for precipitation on Monday seem to be southeast Utah, southwest and central Colorado. The models are also advertising another shortwave rounding the base of the main trough during the day Tuesday. Expect scattered to widespread precipitation with modest lift moving over the forecast area. Although there are some spatial-temporal difference with this wave so placement and timing could change. Given the current timing the amount instability could be limited by cloud cover and lapse rate contamination, but the moisture looks to be more robust. On Wednesday the favored upslope in the westerly flow should ring out the residual moisture in the form of isolated to scattered showers mainly in the higher elevations. The quick moving trough arrives Friday bringing another round of precipitation along the divide. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) Issued at 351 AM MDT Sat Oct 20 2018 VFR conditions expected at all sites through Sunday morning with light winds and mostly clear skies. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...JDC LONG TERM...KJS AVIATION...JDC |