763 FXUS65 KGJT 210545 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 1145 PM MDT Fri Aug 20 2021 .SHORT TERM...(Tonight through Saturday night) Issued at 1240 PM MDT Fri Aug 20 2021 Many folks woke up to snow covered peaks this morning, so the first one is in the books. The closed low pressure that brought the active weather is lifting out over the northern plains today. High temperatures will run below normal since we are still under the influence of this system. Southwesterly flow will become established causing a warm up this weekend. Left over moisture has resulted in fair weather cumulus concentrated in northern Colorado otherwise skies are sunny. This system did drag in smoke from the western wildfires and the return of westerlies will keep it coming into the region. Lows tonight will be warmer than this morning and skies will be mostly clear. Tomorrow the next trough tracks over the Pacific Northwest and northern Great Basin. The southwest flow that develops tonight will try to tap into the monsoon moisture in AZ once again ahead of the approaching system. By tomorrow there may be enough moisture to support terrain-driven convection in the late morning and afternoon across most of the mountain ranges. Although the better chances reside across the northern third of the CWA closer to the lift associated with the trough passing to our north. The trough will clip us tomorrow night so the precipitation will generally be confined up north overnight. For the most part these showers and storms will be scattered and quick moving so flooding is not too much of a concern. .LONG TERM...(Sunday through Friday) Issued at 1240 PM MDT Fri Aug 20 2021 Westerly flow aloft will transition to the southwest by Sunday evening as an upper level trough elongates off the west coast. Meanwhile, a broad area of high pressure will extend from Baja towards the southeast CONUS. This will keep our forecast area under that drier southwest flow through Monday before monsoon moisture attempts to slowly trickle underneath the ridge for Tuesday and Wednesday. Generally this won't amount to much... mainly just an increase in mid and high-level clouds across the south and a slight uptick in convection over the San Juans. Elsewhere will see dry weather persist with temperatures climbing back to above normal with highs reaching the mid 90s for many of the lower valleys across southeast Utah and western Colorado. The previously mentioned Pacific trough will push farther inland at the midweek point but the high's presence to the southeast looks to deflect the better support to the Northern Rockies. This system will slowly trek east through the end of the week while the high's center drifts west. While the ridge will flatten slightly in response to the trough's progression, its base does not look to extend farther south than I-70. Therefore, continued mostly dry conditions are expected with diurnal showers and thunderstorms firing off the higher terrain each day through the end of the long term period. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1138 PM MDT Fri Aug 20 2021 Some midlevel clouds are expected tomorrow as a weak disturbance moves through. Scattered skies will be the rule with some cumulus development from about 18Z, give or take, onwards. A few showers and storms are possible in the afternoon but only included KTEX, KGUC, and KVEL with VCSH/VCTS. Even if convection does move over airfields, do not anticipate any drops below VFR. Some smoke will linger tomorrow but will not drop visibilities below 6 miles. Some gusty winds are also possible in the afternoon...nothing out of the ordinary...with gusts between 20 to 25kts possible. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...KJS LONG TERM...MMS AVIATION...TGR