245 FXUS65 KGJT 252350 AFDGJTArea Forecast Discussion National Weather Service Grand Junction CO 550 PM MDT Thu Sep 25 2025
.KEY MESSAGES...
- Chances for precipitation increase tomorrow through Monday, with Sunday being the most widespread coverage.
- Some storms may be capable of producing strong winds as well as heavy rainfall, which could impact the recent burn scars.
- With freezing levels around 11-13 kft this weekend there could be snowfall on the mountains with little if any impacts to the roadways.
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.SHORT TERM /THROUGH FRIDAY NIGHT/... Issued at 117 PM MDT Thu Sep 25 2025
Dry air has taken over with little clouds to speak of across the area. The next feature to watch is a closed low pressure over Southern California. Southwesterly flow out ahead of the low will advect steep lapse rates and moisture into the forecast area tonight that may be enough for high based showers and or virga. Very little rain is expected with these showers. Tomorrow the low pressure moves over the CA/AZ state line so do not expect much forcing from that system, but with the moisture advection it should result in some instability with peak heating. With the minimal forcing showers are expected to develop over and favor the high terrain in the afternoon. The western and southern portions of the area have the highest chances for showers. There is quite a bit of dry air to overcome once this moisture arrives to so it is uncertain what the rainfall rates will be, and if the showers will survive moving over the valleys. The stronger cells may be able to produce moderate to heavy rainfall, which could impact the recent burn scars. Temperatures today and tomorrow look to end up slightly above normal.
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.LONG TERM /SATURDAY THROUGH THURSDAY/... Issued at 117 PM MDT Thu Sep 25 2025
Models continue in good agreement with the cutoff low over SoCal Saturday starting to track northeastward becoming an open wave Sunday as it tracks across eastern Utah and Western Colorado, but discrepancies are creeping into the deterministic solutions on timing of the system moving across the region with the European model lagging the GFS by 18 hours and the Canadian in between. The ensembles show better agreement more in line with the European model. This is to be expected with cutoff lows as the models struggle to predict their ejection out of SoCal, especially in the transition season. There is also good agreement with a deep low descending out of the gulf of Alaska to shift the synoptic pattern a half wavelength east for the coming week with troughing over the Western States and ridging over the Plains States extending up into the Great Lakes by mid week. As this forecast is dependent on a cutoff low ejection across the region, there is not a lot of confidence in the model solutions, especially on timing, but the most likely outcome is subtropical moisture wrapping around the low to the southwest pushing clouds and showers with embedded scattered thunderstorms up into the southern and central mountains Saturday. Sunday looks to be the wettest day with widespread showers and scattered thunderstorms across the higher terrain with some storms moving off the terrain into the valleys. Of course, this will depend on the timing of the open wave tracking overhead. If it is delayed, then convection will stay mostly south of I-70 through the day with widely scattered showers and thunderstorms moving north more Sunday evening and overnight. We shall see; stay tuned. With the long wave trough over the Western States through the coming week allowing shortwaves to move through daily, the forecast is for unsettled weather daily through mid week amounting to isolated to scattered showers and thunderstorms mostly over the higher terrain with the shortwaves passing to the north mostly along and north of I-70.
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.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 540 PM MDT Thu Sep 25 2025
Clear skies and calm weather will continue through at least the next few hours. Moisture associated with an incoming system will begin to move in overnight from the southwest, increasing high and mid level cloud cover, and precipitation chances. As such, PROB30 has been included for KTEX tomorrow afternoon. Winds will generally be light, but gusty winds are possible near any showers or thunderstorms. VFR conditions are expected to prevail.
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.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None. UT...None.
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SHORT TERM...KJS LONG TERM...DB AVIATION...TGJT
NWS GJT Office Area Forecast Discussion