755 FXUS65 KGJT 191147 AFDGJTArea Forecast Discussion National Weather Service Grand Junction CO 547 AM MDT Fri Sep 19 2025
.KEY MESSAGES...
- Moisture is increasing today, and a few showers and storms are possible over the San Juans and southern valleys.
- Periodic shower and storm chances highlight the forecast this weekend with dry stretches in between rounds of precipitation.
- Unsettled weather continues into early next week before a return of drier conditions.
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.SHORT TERM /THROUGH SATURDAY/... Issued at 308 AM MDT Fri Sep 19 2025
Moisture is beginning to advect into the region, as shown by the increase in cloud cover on satellite imagery. Today the most anomalous increase in moisture will stay south of I-70. Terrain based convection is the primary precipitation forecast for the afternoon today, but a some passing weak waves of energy may support showers and thunderstorms outside of the higher terrain where moisture is most abundant. Considering the dry air that has been in place, virga may be possible with many of the showers and thunderstorms today. Some showers are possible overnight tonight into Saturday as weak disturbances continue to move across the region. During the afternoon on Saturday PoPs become more widespread, although still mostly over the higher terrain, as moisture advects northward through the CWA. The ECMWF Ens continues to favor more anomalous maximums in moisture, but overall it looks like the greatest PWAT anomalies will be around 150 to 200% of normal this weekend.
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.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Issued at 308 AM MDT Fri Sep 19 2025
PWAT anomalies of 150 to 200% of normal will remain across the forecast area at the start of the long term period. Despite high pressure to our south and some ridging over the CWA, pieces of energy will move through the mean flow, especially up north, and will allow showers and storms to form in the afternoon Sunday though coverage will be on the low side. On Monday, however, models are suggesting another plume of moisture moving up from the southwest while a separate trough approaches from the northwest. These two features, if the forecast holds, will both affect the area during peak heating Monday and may bring an active day with the San Juans and northern valleys looking to see most of the convection. Some precip will linger into Tuesday, favoring the Continental Divide and northern mountains. Drier air moves in from north to south Tuesday night into Wednesday but another shot of moisture is possible Wednesday evening and by Thursday morning, PWATS may reach near 200% of normal, if not a bit above. Discrepancies do appear between models as far as how much moisture moves in, and also when. If this moisture does move in, widespread convection will be possible Thursday but this far out, changes in the forecast are expected. High temperatures through much of the period will hover right around normal values for this time of year.
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.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 534 AM MDT Fri Sep 19 2025
High and mid level cloud cover will continue increasing today as moisture moves in. With the increased moisture comes increased chances of precipitation, mostly south of I-70. As such, PROB30 has been included for KMTJ, KTEX, and KDRO. Strong wind gusts are possible around any showers and thunderstorms. Brief drops to MVFR conditions may be possible with showers and storms, but otherwise VFR conditions are expected to prevail.
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.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None. UT...None.
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SHORT TERM...GF LONG TERM...TGR AVIATION...TGJT
NWS GJT Office Area Forecast Discussion