Area Forecast Discussion
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
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131 FXUS65 KGJT 231139 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 539 AM MDT Sun Jun 23 2024 .KEY MESSAGES... - Another round of isolated to scattered showers and thunderstorms will initiate around noon, build through the afternoon and diminish through the evening. A few stronger to severe storms may still form on the terrain across the north. - High pressure moves in today, warming the region to about five degrees above normal. - Expect afternoon convection to form daily over the higher terrain as trapped moisture is recycled. && .SHORT TERM /THROUGH MONDAY/... Issued at 318 AM MDT Sun Jun 23 2024 The weather pattern struggles to let go of the more Spring-like pattern of deep troughs descending into the Pacific Northwest and transiting east across the northern states with cool boundaries reaching south to brush the northern areas of the region, and grabbing onto the more Summer-like pattern of high pressure to the south over Texas and New Mexico drawing subtropical moisture from the Gulf of Mexico, northern Mexico and the Gulf of California into the Desert Southwest and north into the eastern Utah and Western Colorado. Tonight there is finally some activity over Sonora looking somewhat MCS-ish that is typically seen much earlier in May, but this is only one. It has been an interesting transition this year. Currently dominated by high pressure across the south from the Desert Southwest to the Lower Mississippi Valley, eastern Utah and Western Colorado will see temperatures generally warm about five degrees above yesterday as high pressure builds north over the region. Moisture continues to be trapped under the high to get recycled into showers and thunderstorms each afternoon with the diurnal heating. Such is the forecast again today with again a slight down-tick in convection over what we saw yesterday. With afternoon CAPE running 200-500 J/kg and shear at 20-25 kts, isolated stronger thunderstorms are still possible over the higher terrain with strong gusty winds and small hail being more the norm for these storms. Expect convection to initiate around noon following the diurnal heating cycle, and increase through the afternoon before dropping off going into the evening. We`ll see scattered showers and thunderstorms over the higher terrain with denser activity over the San Juans to the south becoming more isolated as you go north. Skies will clear out overnight under the subsidence, readying the atmosphere for another round of heating Monday and similar convective activity with temperatures about the same as today. Guidance continues to try to dry out the region, but without a significant system to sweep the moisture out of the area, the pattern of afternoon showers will continue. Additionally, as the high to the south wobbles slightly east, more over Texas Sunday night as an inverted trough rotates around the west flank, the circulation will allow some supplemental moisture to slip north into the Desert Southwest and into the region to further strengthen the diurnal cycle. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Issued at 318 AM MDT Sun Jun 23 2024 The broad east-west oriented mid-level high across the southern tier of the U.S. begins to consolidate over New Mexico Monday night into Tuesday as a low pressure system approaches the Pacific Northwest. As the trough approaches the West Coast Wednesday, it impinges on the the western flanks of the ridge causing moisture from the Mexican Plateau that had been kept west of the region to begin drifting northward over the forecast area. As a result, afternoon/evening showers and thunderstorms will increase from isolated coverage on Tuesday to scattered Wednesday. By Thursday, moisture levels peak with precipitable water levels near an inch for much of the forecast area and as a result, moist convection becomes widespread and the potential for heavy rain increases. As the trough moves across the Pacific Northwest to the northern Rockies on Thursday night then to the northern High Plains on Friday, the moisture tap from the south is shunted to the east allowing drier air to infiltrate in the west flow behind the trough. Consequently, the area should see a downturn in moist convection on Friday with even less shower/thunderstorm activity Saturday as drying continues. Temperatures are expected to remain 5 to 10 degrees above normal Tuesday and Wednesday with readings in the low 100`s forecast for the Grand Valley and the lower elevations of southeast Utah. However, increased clouds and shower coverage is expected to bring temperatures to near normal levels Thursday with a slow rise coinciding with drying Friday and Saturday. && .AVIATION /12Z TAFS THROUGH 12Z MONDAY/... Issued at 524 AM MDT Sun Jun 23 2024 Expect mostly VFR conditions and light winds through the TAF period. The exception will be convection starting around 18Z over the higher terrain, drifting into adjacent valleys and winding down after 00Z. Look for scattered showers and storms over the southern mountains with more isolated coverage as you go north. Included VCTS in KTEX and KDRO, but not enough certainty to include it in any other TAF`s, though most mountain sites have some minimal risk through the afternoon. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...DB LONG TERM...NL AVIATION...DB