textproduct: Grand Junction

KEY MESSAGES

- Critical fire weather conditions continue through tomorrow, with afternoon gusts of 35-45mph and low relative humidities.

- Red Flag Warnings are in effect for much of eastern Utah and portions of southwest Colorado from 1PM to 8PM Friday.

- A pattern shift this weekend will bring cooler temps, increased cloud cover, and a chance of showers.

DISCUSSION

Issued at 1044 PM MDT Thu May 28 2026

The 18Z run of the models are in good agreement with satellite imagery as the deep vertically stacked low spins over the Central California Valley. Late this afternoon going into the evening hours, a shortwave rotating around the deep low spawned a few stronger thunderstorms across the northern Colorado Mountains that produced outflow winds over 40 mph and up to half inch hail. The eastern slope with better moisture and energy saw strong thunderstorms with large one inch hail reported. As expected with sunset, these storms have diminished. Models are forecasting the low pressure system to finally start to eject to the east into Utah Friday as it opens into a trough system before turning more to north moving into Wyoming Saturday and Montana Sunday. Friday will see similar conditions as today with isolated afternoon showers and thunderstorms developing mostly along the central and northern Divide. With the approaching trough, coverage will become more widely scattered across the northern areas in the late afternoon and going into the evening generally along and north of the I-70 corridor favoring the southern and western faces of the higher terrain. There isn't much moisture with these storms, thus little accumulation is forecast, maybe a few tenths inch in the mountains. The main threats from these storms will be lightning, possible dry lightning, and strong outflow winds gusting 50 mph. Though thunderstorms normally diminish overnight into Saturday, cold air aloft advection and upper level dynamics of the left exit region of the jet overhead will keep thunder in the forecast through the night. Look for isolated to scattered thunderstorms to pick up again across northern Utah and Colorado Saturday afternoon with diurnal heating and as the trough moves overhead. These storms will continue mostly the north of I-70, but expect a few extending south into the central Colorado mountains. Again, with the dry lower atmosphere, most of the rain with these storms will evaporate before reaching the ground resulting in gusty outflow winds and possible dry lightning. Sunday will see another round of isolated thunderstorms across the northern areas as a shortwave rotates around the low that will be to our north. The primary threat will be dry lightning as little if any precip will come from these storms.

Temperatures Friday will run near normal to five degrees above normal across eastern Utah and Western Colorado. The winds increase Friday with the approaching low from the west and conditions remain dry across the western and southern areas. A Red Flag Warning is in place for eastern Utah and southwestern Colorado from 1 to 8 PM Friday for dry conditions, extremely low relative humidity and winds gusting over 25 mph. Temperatures Saturday will cool ten degrees across the southern areas and 15 degrees across the north with the trough passage. This will bring an end to the Red Flag Warnings for a while, but be aware that localized areas of critical fire weather conditions will continue, especially in the Four Corners area. Look for temperatures to warm back to about five degrees above normal by mid next week with isolated afternoon showers and thunderstorms developing along the Divide daily.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 513 AM MDT Fri May 29 2026

Mid and high level moisture will eventually lead to shower activity by this afternoon with showers increasing in coverage across the North overnight. Gusty winds in excess of 45 mph will be threats from the showers and storms through the late evening. Gusty winds associated with a cold front will also bring some gusty winds in the 30 to 40 mph range over the South this evening.

FIRE WEATHER

Issued at 1154 AM MDT Thu May 28 2026

A deep closed low stalled over the Great Basin begins to shift east into Utah Friday. The pressure gradient remains tight, leading to gusty surface winds again tomorrow. Dry southwesterly flow continues to dominate causing relative humidity to drop below 15%, particularly in eastern Utah and portions of southwestern Colorado. Hence, a Fire Weather Watches for Friday have been upgraded to Red Flag Warning is active for eastern Utah and southwestern Colorado from 1 PM to 8 PM Friday. A pattern shift this weekend brings lighter winds, increased moisture, and cooler temperatures, thus bringing an end to the period of elevated fire weather concerns.

GJT WATCHES/WARNINGS/ADVISORIES

CO...Red Flag Warning from 1 PM this afternoon to 8 PM MDT this evening for COZ207-290-292. UT...Red Flag Warning from 1 PM this afternoon to 8 PM MDT this evening for UTZ486-487-490-491.