Area Forecast Discussion
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
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529 FXUS65 KGJT 082121 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 321 PM MDT Mon Jul 8 2024 .KEY MESSAGES... - Rising temperatures bring the potential for heat related watches or advisories as early as Thursday. - Afternoon/evening showers and thunderstorms are possible each day for the San Juan Mountains and central Colorado mountains through early next week. && .SHORT TERM /THROUGH TUESDAY NIGHT/... Issued at 320 PM MDT Mon Jul 8 2024 High pressure will remain over the Great Basin and Desert Southwest in the near term. Dry northwest flow aloft will limit afternoon/evening shower and thunderstorm activity to areas along the central and southern Colorado portion of the Continental Divide. The moisture fueling this activity was working under the ridge from the east where deeper moisture resides. Sunny skies will drive temperatures 3 to 5 degrees above normal Tuesday. However, with few clouds and a dry airmass, overnight lows are expected to dip below seasonal norms both tonight and Tuesday night. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Issued at 320 PM MDT Mon Jul 8 2024 Circulation around the high pressure over the Great Basin Wednesday will pull limited moisture southeast along and east of the Divide, but enough for some cumulus development through the afternoon and even an isolated shower or thunderstorm. Probabilities are a bit higher to the south where the clockwise flow turns northeasterly to pull more moisture off the Front Range over the Divide into the San Juans. The high pressure will gradually slide east over the Rocky Mountains by Saturday where it will want to hang out going into next week. This opens the door to deep monsoonal moisture moving up off the Gulf of California into the Great Basin through the weekend and into Wyoming by Monday. Guidance indicated continued isolated showers and thunderstorms along the Divide favoring the southern mountains each afternoon through the week. Saturday and Sunday show an uptick in shower coverage with showers and thunderstorms becoming more scattered as they spread north and west over the higher terrain south of the I-70 corridor. Models don`t really show support for advection of moisture into the region, so the moisture source is likely evapotranspiration due to clear skies and intense warming under the high pressure. Early next week, model solutions diverge with some pushing the high east onto the Plains while the others keep it in place over the Rockies, its favored position. We`ll see which models are right. Also, with deep monsoonal moisture on three sides, models want to slip some moisture into the region under the high for widely scattered showers and thunderstorms across the higher terrain of eastern Utah and Western Colorado Monday. Again, I`ll believe that when I see it, not that it can`t happen, but the. models need to figure out what to do with the high, split it to the southwest over the Four Corners and east onto the plains, or shift it southeast over the panhandle of Texas to allow the moisture to move into the region. If the high remains anchored over the the Rocky Mountains, we`ll stay on the dry side with isolated showers and thunderstorms fed by evapotranspiration. Temperatures Wednesday will run five to eight degrees above normal through the lower elevations and near normal in the mountains. By the weekend as the high pressure moves in, temperatures will warm to five to ten degrees above normal with the mountains warming to almost five degrees above normal. These temperatures are assuming cloud buildups going into the weekend will limit diurnal heating, but if the clouds don`t form, the weekend temperatures will rise yet a few more degrees to near record highs and may warrant heat advisories especially in the lower valleys. Stay tune for more on these temperatures over the next few day, but know that we are moving into the warmest season of the year. Be sure to plan accordingly if you will be out in the heat and intense sunshine. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 1132 AM MDT Mon Jul 8 2024 Expect VFR conditions under mostly clear skies with generally light winds. The exceptions will be a few clouds along the southern divide with a possible shower and a few northwest gusts to near 20 kts mostly along and north of the I-70 corridor. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...NL LONG TERM...DB AVIATION...DB