377 FXUS65 KGJT 281115 AFDGJTArea Forecast Discussion National Weather Service Grand Junction CO 515 AM MDT Sun Sep 28 2025
.KEY MESSAGES...
- Afternoon and evening convection continues again today in many areas but looks to favor the eastern mountain on Monday.
- Some storms may be capable of producing strong winds as well as heavy rainfall, which could impact the recent burn scars.
- Light snow can`t be ruled out for the highest elevations through Monday though little to no impacts are expected on mountain roadways.
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.SHORT TERM /THROUGH MONDAY/... Issued at 225 AM MDT Sun Sep 28 2025
Water vapor imagery shows the upper low still spinning over SoCal this morning. Models suggest this low will begin to be nudged to the northeast today as Low pressure digs farther into the EPac. The low makes into it to northern AZ by this evening then opens to a wave as it crosses the 4 Corners tonight and finally crosses the CWA on Monday as it continues to shear apart. Earlier convection continues to dissipate and throw out some gusty winds as it does so...but overall the radar quieting down early this morning and we should like start out with just isolated chances in most areas through most of the morning. There really isn`t a significant amount of forcing today with the lagging back to the West. QG ascent actually increases across the southeast CWA later tonight as the main lobe of energy rotates around the AZ low and head for the central Rockies by mid-day tomorrow. However with anomalous moisture in place expect instability to be released by weaker energy ejecting through the flow and orographic forcing...that most areas will have some threat of shower or thunderstorm activity today. CAPE values remain in the 500-800 j/kg in most area with the usually robust HIRES NAM showing 1000+ by peak heating today. Not confident all of this can be utilized but some more organized storms will be possible today with moderate to heavy rainfall rates the main threat...small hail and gusty winds both secondary threats. A lot of the activity should again taper off overnight with the exception over the southern valleys and mountains due to the above mentioned vorticity advection. The eastern mountains and valleys will be favored on Monday as this wave passes through with residual moisture and isolated convection possible farther West.
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.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Issued at 225 AM MDT Sun Sep 28 2025
The start of the work week will see unsettled weather continuing as the open wave remains overhead and the increased moisture gets worked on as the wave moves through. The best chances for any convection will be over the higher terrain as peak heating and the wave provide plenty of lift. Precip is expected to end late Tuesday night as the next shortwave approaches from the west. This shortwave will just clip extreme NW portions of the forecast area, if it does at all. Dry conditions then setup Wednesday through Thursday. After that, a longwave trough and surface cold front will be just on our doorstep though some timing and tracking differences have creeped into the various solutions. Time will tell. High temps will run a little warm, mostly, during the long term period as southwesterly flow advects in warmer temperatures from the south.
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.AVIATION /12Z TAFS THROUGH 12Z MONDAY/... Issued at 515 AM MDT Sun Sep 28 2025
Scattered showers and thunderstorms will be a constant threat to many of the TAF sites through the mid evening hours...with lesser coverage expected during the overnight hours. VFR remains in control and this remains in the forecast as well however ILS to low probability MVFR conditions will be possible when showers move over an airfield. Widespread high terrain obscuration is likely as this moisture and active weather moves through into early next week.
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.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None. UT...None.
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SHORT TERM...15 LONG TERM...TGR AVIATION...TGJT
NWS GJT Office Area Forecast Discussion