902 FXUS65 KGJT 071749 AFDGJTArea Forecast Discussion National Weather Service Grand Junction CO 1149 AM MDT Sun Sep 7 2025
.KEY MESSAGES...
- Showers and thunderstorms are expected mostly along and north of I-70 through this evening.
- Expect isolated to scattered afternoon showers and thunderstorms over the higher terrain daily through mid week.
- Thursday and Friday will see widespread showers and thunderstorms return with a passing system.
- Temperatures remain near normal today before a warming trend starts Monday.
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.SHORT TERM /THROUGH MONDAY/... Issued at 337 AM MDT Sun Sep 7 2025
Satellite imagery shows skies have cleared out under the subsidence of the ridge moving in from the west. There are a few light showers working their way across the northern area associated with a couple of weak mid-level disturbances moving through. One line approaching Hayden will move out of the region in the next few hours while another batch is just moving into the Uinta Basin and will pass across the northern area through the morning. Looking at observations, surface dewpoints remain in the upper 40`s and low 50`s across the region, and with the clear skies, should see strong diurnal heating this morning across much of the region south of the I-70 corridor. Guidance and the high-res CAMs have down played chances for convection to the south due to a cap forming below 500mb from the subsidence, but still cant rule it out completely. this will be something to watch today. Otherwise, expect scattered showers and thunderstorms along and north of the I-70 corridor this afternoon extending through the evening as another disturbance passes to the north. There is still a risk for heavier rain on the northern fire scars causing debris flows this afternoon and evening. Convection will be mostly isolated over the higher terrain along the Divide Monday as the atmosphere dries out. Temperatures today will be near normal and should warm a couple degrees tomorrow.
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.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Issued at 126 PM MDT Sat Sep 6 2025
PWAT`s continue to dry out significantly Monday following northwesterly flow and the stacked ridge amplifying overhead. Abundant southwesterly flow ahead of a PACNW storm will drive up heights and temperatures. Afternoon highs will top out a couple degrees above climatology, pushing 90 degrees in our desert valleys. This little warmup will be short lived, as the deepening low out west moves into the Great Basin Tuesday. Height falls and some prefrontal lift will produce scattered showers and convection by Tuesday afternoon, likely suppressing an otherwise hot day for much of the region. The low elevations will be on the warm side of climo, but the approaching storm is expected to take care of that by late week. Ridging over the Great Plains runs block for Wednesday and Thursday as the low drifts across the Intermountain West. This allows for some additional moisture to get picked up, as return flow on the high sends some late season monsoonal moisture back across the Four Corners. Moisture likely gets a helping hand from the low digging into Baja, sending additional Pacific moisture this way. PWAT values are into the 150 percent of climatology range Wednesday and Thursday. This should keep the area under afternoon showers and thunderstorms both days. Uncertainty creeps in Friday, as the low lifts northward and east. The monsoonal plume shifts east too. PWAT values remain high enough for additional shower and storm activity, but drier northwest flow behind the departing storm could dry things out for much of the CWA. This solution continues to dry things out Saturday. Concerns arise in the model`s handling of the decaying low, as well as the stubborn high pressure anchored over the Mississippi Valley. These features will have some control over the monsoon plume and its east/west breadth. There could easily be some additional showers Saturday on the southern mountains with a slight shift in the synoptic pattern. Temperatures Thursday, Friday, and Saturday look cool and fall-like in the wake of this storm.
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.AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 1142 AM MDT Sun Sep 7 2025
Isolated to scattered showers and thunderstorms are expected through 06Z, primarily north of I-70. Brief drops to MVFR conditions and ILS breakpoints are possible with the convective activity. Additionally, gusty outflow winds are a concern near showers and thunderstorms. Otherwise, VFR conditions are expected to prevail. Winds will become light and terrain driven tonight.
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.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None. UT...None.
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SHORT TERM...DB LONG TERM...LTB AVIATION...TGJT
NWS GJT Office Area Forecast Discussion