textproduct: Grand Junction

KEY MESSAGES

- Valley rain and mountain snow returns to the forecast this weekend favoring the southern mountains and adjacent foothills.

- Quiet conditions return briefly Sunday afternoon and Monday before another round of precipitation arrives during the middle of next week.

- Unsettled and cool conditions are favored to persist into the late week period as well.

DISCUSSION

Issued at 1050 PM MST Fri Nov 13 2026

The H500 hand analysis map this evening is playing out as expected with an Omega-like pattern in place. A strong downstream blocking trough over eastern NOAM is forcing the upstream trough to negatively tilt as it moves farther inland. In between the highly amplified ridge remains but has shifted onto the Plains from 24 hours ago. Showers have developed in the western CWA and with a strong PV lobe rotating across the 4 Corners overnight...a few strikes of lightning will be possible. Weaker echos on the radar suggest moisture is increasing on the southerly flow into the southern mountains but so far webcams and snotels are relatively quiet. This will be changing in the next few hours with the heaviest precipitation still expected during the early to mid morning hours on Saturday as the surface front and large scale coincide with moisture in place. Snow levels still look to hover in the 8-9kft level for the bulk of this event...lowering to mountain bases by sunset tomorrow as the system is exiting. The southern mountains...especially the crescent of the southern San Juans remain favored to catch the best moisture and produce the highest snow amounts. 4 to 8 inches should cover most of the advisory area though hi-res guidance is picking out some of the favored high peaks and snotels for the higher amounts closer to a foot. Otherwise 1 to 4 inches should cover the remaining mountain forecasts though colder northwest flow often throws some bonus inches. QPF amounts in the southern basins are still in the 1/3 to 2/3 inch range for liquid precipitation with again some isolated higher amounts possible due to the convection. Hydrographs are still only showing some minor rises on the smaller tributaries to the San Juan with the main steam holding steady. Temperatures will be much cooler tomorrow in the post frontal environment but overall end up near to above normal in the drier northern CWA and 5 to 10 degrees cooler in the wetter southern areas. By sunrise on Sunday the trough and PV stream will be east of the divide and ridging will be translate across the Great Basin to the Great Plains through Monday afternoon as the next deep trough arrives to the West. Models still show a moderate AR with this system which again survives the upstream terrain and brings more widespread precipitation to the area in the mid week time frame. The QG forcing has been trending a bit farther North which will bring better chances for precipitation to our northern CWA which as been missing out lately. This system is a tad cooler and this should translate to better a snowfall forecast for most of the higher terrain...but will need to continue to watch trends in speed and track as we get nearer. Temperatures will moderate to near normal Monday into Tuesday before a colder end to the week. Models spread still significant and changing daily on how the pattern in the late week period evolves but the overall flavor is for a large trough in the West keeping unsettled conditions on the radar.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1050 PM MST Fri Nov 13 2026

Moisture is beginning to increase with scattered showers developing and lowering cigs over eastern Utah and southern Colorado. Expect precipitation coverage to increase with light rain showers in valley terminals with light snow showers mixing in for mountain sites. The precipitation and lowering cigs could lead to ILS breakpoints being reached after 06z. Precipitation is expected to decrease in coverage Saturday afternoon.

GJT WATCHES/WARNINGS/ADVISORIES

CO...Winter Weather Advisory until 9 PM MST Saturday for COZ019. UT...None.