textproduct: Grand Junction

KEY MESSAGES

- Some high valleys will experience sub-freezing temperatures again tonight. - Showers and a few isolated thunderstorms are possible in the southern and central mountains on Monday and Tuesday afternoon. - Wind gusts of 40-55 mph will be common across the area on Wednesday afternoon ahead of the next storm system.

- Unsettled...cooler and wetter weather...will move in to end out the week.

DISCUSSION

Issued at 1030 PM MDT Sun Apr 19 2026

A closed low off the Pacific Coast has a weaker trough undercutting it and heading toward the DesertSW this evening. We remain under downstream ridging...amplified by a deep trough over much of eastern NOAM. GOES ALPW (advected layer PWAT) is verifying previous model solutions of a Gulf and SubTrop tap of moisture advecting northeast toward the 4 Corners. This moisture transport is return flow around a strong surface high over the S.Plains which is likely being enhanced by height falls to the West ahead of the approaching trough. This moisture will be well elevated by the time it progresses into our CWA early tomorrow. It should start out in the form of ACCAS which will blossom into showers and possibly a thunderstorm over the southern high terrain tomorrow afternoon. Lingering mositure along the divide will then lead to another round of isolated/widely scattered convection Tuesday afternoon...the hottest day of the forecast. Really not confident much will reach the ground as wetting rainfall as most will be virga or very light showers. The higher impact weather arrives on Wednesday in the form of strong winds. The upstream low will be moving into the Intermountain West leaving a strong southerly gradient downstream over our CWA. Expect those strong upper level winds to mix down to the surface making for periods of winds gusting 40 to 55 mph through most of the valleys across the region. The cold front arrives to our NW CWA late in the day on Wednesday. The well mixed atmosphere ahead of this will lead to high based showers enhancing the wind threat and some higher gusts will be possible. The northern half of the CWA will get the bulk of this storm system with more snow across the high peaks of the northern mountains. At this time impacts will be limited to brief winter driving conditions over the high passes.

PATTERN SHIFT LATE WEEK:

Moving forward, a cooler and wetter weather pattern will be ushered in the low pressure system out west. It will bring back temperatures slightly below normal and higher elevation snowfall for the northern and central mountains Thursday into Friday. Impacts for this late week event look to be more below freezing temperatures for the high valleys and temporary winter driving conditions over some of the mountain passes.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1141 PM MDT Sun Apr 19 2026

Weak moisture will continue to work beneath the ridge of high pressure parked over the region today. This will keep some scattered to broken mid and upper level clouds across most of the terminals, with less of an emphasis up north around KVEL and KHDN. Left PROB30 TSTM in KTEX Monday afternoon, as there appears to be enough moisture to work with during afternoon instability. Looks like KASE and KGUC will avoid showers, but non zero chances remain for any terrain against the Divide. Winds will gust a bit on the terrain too, but remain light in the valleys. A few gusty outflows could impact aviation around these mountain showers. However, VFR conditions will still prevail another day for the majority of eastern Utah and western Colorado.

GJT WATCHES/WARNINGS/ADVISORIES

CO...Freeze Warning until 9 AM MDT Monday for COZ002-008. UT...None.