textproduct: Grand Junction

KEY MESSAGES

- Winter Weather Advisories are in effect for much of our mountain zones through tomorrow evening.

- Freeze warning are in effect for northwest Colorado valleys tonight and most high to mid elevation valleys Wednesday night as low temperatures will drop into the 20s to near 30.

- High pressure will return temperatures back above normal late week.

DISCUSSION

Issued at 1054 PM MDT Tue May 5 2026

Complex Spring pattern in place with a dominant northern stream vortex centered near Hudson Bay absorbing a closed low over the Southwest. This is creating a phased positively tilted trough over over a large chunk of the CONUS with an amplified ridge nosing into the PacNW. The Col between the SW low and northern trough created a moisture barrier across southeast Utah into west- central Colorado with the KGJT RAOB showing PWAT of 0.15 and not far from the record min for the date. Several areas has single digit humidity this afternoon in this area. However up north in one moisture feed 1-2 inches of QPF has already fallen from the valleys to the top of the Park Range. Showers are also drifting into our far southern CWA on the fringe of the southern stream moisture tap. A leading cold front was hung up on the Tavaputs/Roan Plateaus today helping to produce the cool season precipitation up north and actually force some stronger convection closer to the boundary. Water vapor imagery is showing the main energy in the northern trough dropping through northern Wyoming this evening and this has given the front a push over the high plateaus moisture is returning to the desert valleys. This energy/trough axis will drop into the northern CWA in the predawn hours and swing out of the southern mountains by sunset. The better focus for precipitation will therefor shift similarly...across the north and central through mid morning then mainly in south through mid afternoon with cold air showers lingering over the high country through sunset. Then the cold air settles in under a much drier airmass filtering in on northerly flow and brings freezing temperatures again to mainly of the high to mid elevation valleys by Thursday morning. Winter has return to the high country looking at webcams but so far impacts have been limited to the mountain corridors. That likely changes overnight through much of the morning as this trough swings through and the cold air deepens. QPF from the blended solutions have trending downward with this run but impacts remain up high with the colder air increasing the snow to liquid ratios over the next 12 hours. They have been running less than 10:1 so the 2 inches of SWE up at Tower so far means snow amounts are closer to a foot. So no additions to the winter headlines and will upgrade the freeze watches as low drop into the mid 20s to low 30s Thursday morning. A weak and quick moving wave drops through the NW flow later on Thursday into early Friday and drops some light precipitation over the northern mountains but with minimal impact. Then the warm up is on under mainly dry conditions. The 6-10 day outlook from CPC says the whole picture...could we see 90s by early next week in some of the lower desert valleys. Stay tuned.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1128 PM MDT Tue May 5 2026

Widespread midlevel ceilings can be found across much of the forecast area and this will continue overnight and into tomorrow. In fact, clouds will lower as a front and upper level trough move through so MVFR conditions will occur from time to time with some IFR likely as well for all TAF sites. Showers and a few embedded thunderstorms will be possible as the front moves through. Conditions will start improving in the afternoon but then we can expect gusty winds to materialize.

GJT WATCHES/WARNINGS/ADVISORIES

CO...Freeze Warning until 9 AM MDT Wednesday for COZ001-002.

Freeze Warning from midnight Wednesday night to 9 AM MDT Thursday for COZ001-002-007-008-011-021>023.

Winter Weather Advisory until noon MDT Wednesday for COZ004- 010.

Winter Weather Advisory until 6 PM MDT Wednesday for COZ012- 018-019.

UT...None.