939 FXUS65 KGJT 132359 AFDGJTArea Forecast Discussion National Weather Service Grand Junction CO 559 PM MDT Sat Sep 13 2025
.KEY MESSAGES...
- This afternoon`s shower and thunderstorm activity should come to an end by sunset tonight, with the exception of some isolated showers in the northern half of the area.
- Conditions dry out tomorrow, so expect less active weather with below normal temperatures.
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.SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 259 PM MDT Sat Sep 13 2025
Showers and thunderstorms have been ongoing across the region this afternoon. Convection has been weakening from what we saw earlier in the day as CAPE decreases across the region, but scattered precipitation is expected to continue until sunset. After sunset chances of precipitation drop significantly for all but our northern mountains where a little bit of support from the trough passage remains. Even so, any precipitation overnight is expected to be more isolated, especially when compared to this afternoon. A pattern change as ridging builds aloft will allow for drier air to start pushing into the region. The most anomalously dry air looks to be south of I-70, where PoPs will be near zero through the day tomorrow. The weather should remain quiet into the start of the long term as support from the passing trough and jet moves east of our area. High temperatures remain below normal tomorrow afternoon, although still a few degrees warmer than today.
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.LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 259 PM MDT Sat Sep 13 2025
A trough will move inland into the Pacific Northwest overnight tonight, and will slowly pass over the Rockies through the first half of the week. Although moisture will be limited at this time (PWATs around 75-125% of normal), support from the trough passage may help increase PoPs. Elevated PoPs will primarily be along our northern border Monday night into Tuesday morning as this is where any PVA associated with the trough will be. However, the chances of precipitation transition to being along the higher terrain across the CWA on Tuesday and Wednesday afternoon. Ridging will build aloft on Thursday behind the trough passage, but as the ridge axis moves to our east, southwesterly flow may bring our next potential moisture push late in the week. Temperatures return to near normal on Monday, and will continue to oscillate above and below normal through the week.
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.AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 559 PM MDT Sat Sep 13 2025
Showers and thunderstorms are expected to diminish by early evening, with the exception of prolonged shower activity at HDN. VFR conditions should prevail, with a slight chance of MVFR during showers/storms and CIGS lowering to ILS breakpoint at times during convection for a few more hours. VFR is expected to return through the end of the TAF period after 06z for most locations although cannot rule out low stratus or fog developing given recent rainfall and cooler temperatures combined with partially clearing skies.
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.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Flood Watch until midnight MDT tonight for COZ003-006>014- 017>023. UT...Flood Watch until midnight MDT tonight for UTZ022-027>029.
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SHORT TERM...GF LONG TERM...GF AVIATION...SLC
NWS GJT Office Area Forecast Discussion