Area Forecast Discussion
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
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060 FXUS65 KGJT 210531 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 1131 PM MDT Sat Jul 20 2024 .KEY MESSAGES... - Daily showers and thunderstorms can be expected, though storm coverage will gradually decrease each day and begin to favor the mountains. - Gusty outflow winds, lightning, and brief moderate to heavy rain will be possible with storms. Localized flash flooding is possible down south. - Wildfire starts from lightning remain possible into the new week as storms remain high based. && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 208 PM MDT Sat Jul 20 2024 Drier weather has prevailed across the north as expected today, thanks to the advection of drier air from the northwest. Down south has been a different story as we`ve seen convection re- develop over the higher terrain. The atmosphere remains juicy as moisture stays pooled across southwest Colorado in particular, leading to some drift of showers and storms into the adjacent valleys. Not much wind with storms thus far but the potential for gusty outflows remains possible in addition to periods of moderate to heavy rain. Similar to the last several days, the threat for localized flash flooding prevails as storms continue to train, so something to monitor over the coming hours. With the loss of daytime heating this evening, convection will begin to taper off from north to south. However, a weak shortwave will brush southwest Colorado tonight, seeing showers linger near the Four Corners into Sunday. The ridge amplifies farther north on Sunday, advecting additional dry air into the region, with PWATs projected to drop back to slightly below normal. Even so, there will be plenty of pockets of moisture lingering down south and along the Divide, so look for another round of showers and thunderstorms to develop by midday Sunday. Once again, storms will be capable of producing gusty outflow winds and we can`t rule out brief heavy rain. Outside of storms, look for dry weather with passing clouds. Temperatures will continue to trend slightly above normal through the period. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 208 PM MDT Sat Jul 20 2024 The area of high pressure that has influenced our weather for many days now will continue to do so through much of the long term period. This high pressure will remain to our west which will keep generally northerly flow across the region. This will keep the deeper moisture to our south so while we will still see afternoon and evening convection, heavy rainers will be less of a concern. Even so, in this type of environment even brief, heavy rain could cause some concerns in those particularly flashy areas. As far as actual moisture, PWATs Monday through Wednesday will be around 0.4 inches while Thursday and Friday we`ll see a bump into the 0.8 to 1.0 inch range. The reason for the increased moisture towards the end of the week is an approaching trough from the PacNW that is forecast to flatten the high pressure. Both the GFS and EC are indicating this occurring while ensemble clusters are also forecasting this trough moving through. As the high begins to break down, flow will become more south through southwesterly allowing monsoonal moisture to return. Thus, an increase in PoPs and convective coverage which the NBM looks to be handling quite well. All that being said, we`ll see convection firing off the terrain Monday through Wednesday with the usual gusty outflow winds, small hail, and brief, heavy rain possible. Thursday will see a small increase in coverage but the bigger push of moisture won`t occur until Friday. For Friday then, we`ll see an uptick in coverage and also QPF. Of course, the usual caveat applies and that being this far out, some changes can be expected especially for Thursday and Friday. As far as temps are concerned, we`ll see generally seasonal highs Monday with a warmup midweek before dropping back down to more normal highs heading into the weekend. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 1127 PM MDT Sat Jul 20 2024 An outflow boundary has been gradually working its way from north to south across the area, bringing a period of strong, gusty northerly to northeasterly winds as it passes by. This boundary is through KGJT but is expected to briefly impact KMTJ at the least. Confidence is low that it will hold together over the San Juans to reach KTEX and KDRO. Otherwise, remnant clouds from this afternoon`s convection are slowly dissipating, with SKC expected within the next 3-6 hours. Winds will be generally terrain driven, outside of impacts from outflow boundaries. Showers and storms will be focused across the San Juans and along the Divide tomorrow, otherwise winds will continue to follow typical terrain driven patterns, with gusts up to around 20 knots possible in the afternoon. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...MMS LONG TERM...TGR AVIATION...TGJT