


Area Forecast Discussion
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
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290 FXUS65 KGJT 041812 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 1212 PM MDT Sat Oct 4 2025 .KEY MESSAGES... - Breezy southwesterly winds with gusts of 30-40 mph continue today, with locally stronger winds possible particularly around the Four Corners. - Showers and storms associated with the approaching low pressure continue through this evening. Light snow is possible above 9k feet. - Temperatures drop below normal today and tomorrow, then rebound to near normal values Monday as warmer and more seasonable conditions return. && .SHORT TERM /THROUGH SUNDAY/... Issued at 306 AM MDT Sat Oct 4 2025 The center of the approaching low is currently centered around the Nevada/Arizona/Utah border. Diffluent flow aloft out ahead of this low, along with some enhanced jet dynamics, continues to provide ample lift to keep showers and thunderstorms going across the region. Activity has, for the time being, tapered off for areas north of I-70, but has filled in across southeast Utah and southwest Colorado, where the best lift and most ample moisture is currently located. Yesterday evening`s 00z GJT sounding had a PWAT of 0.64, which is well above normal for this time of year, and does fall within the forecasted 150-200% of normal PWAT values associated with this storm. And this moisture will continue to increase through midday as we remain under moist, strong southwesterly flow. While the moisture is definitely there, and these storms have produced wetting rains across the region already, their quick speed will put a damper on totals. Areas that see training storms, and terrain features that favor southwesterly upslope flow, will see the best precipitation accumulation with this storm. The vast majority of eastern Utah and western Colorado will see this precipitation fall as rain, but as cooler air moves in aloft today, the highest elevations could see some snow...at best an inch or two of snow accumulation is possible. In addition to the increasing moisture, we`re seeing increasingly strong and gusty southwesterly winds ahead of the low. Some of this is due to deep mixing still tapping into the 90-100 knot jet aloft and mixing down the stronger winds, and some is due solely to the surface pressure gradient continuing to tighten. Widespread gusts of 30-40 mph are expected into this afternoon, with pockets of stronger gusts above 45 mph. Some of the lower valleys in the Four Corners region are particularly favored to see these higher end winds, and a Wind Advisory remains in effect for these areas from 10 AM MDT to 5 PM MDT today. Winds will finally start to taper off this evening thanks to the surface cold front and upper level trough axis swinging through during the afternoon. Flow aloft switches to westerly to northwesterly and finally relaxes. Temperatures are very mild tonight, thanks to the presence of increased moisture, clouds and showers, and those elevated winds. The clouds and precipitation this morning will slow daytime warming considerably, and then the surface cold front will push through this afternoon, ushering in a much cooler airmass. All in all, today`s highs will run a solid 10-15 degrees below what we saw yesterday, and run 3-5 degrees below early October norms. With much drier air sweeping in behind the low tonight, clear skies and quieter winds, along with that cooler airmass, will join to promote radiational cooling. Guidance at this point only has limited areas of below freezing temperatures tonight, but that is something to keep an eye on, particularly for some of the higher elevation valleys. This pattern of clear skies, lighter winds, and below normal temperatures will follow into tomorrow, where a beautiful fall day is in the works for most areas. The one exception will be for areas of northeast Utah and northwest Colorado, particularly close to the Wyoming border. Enough moisture sticks around there to keep some clouds in place, and a few weak waves swinging through could trigger a few light rain showers. This will also keep temperatures even cooler, with highs expected to be 5-10 degrees below normal. Elsewhere, highs will remain 3-5 degrees below normal, and most locations will see abundant sunshine. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Issued at 306 AM MDT Sat Oct 4 2025 The long term period will start out with a long wave trough draped across much of the Intermountain West. The best support will remain over Wyoming, Idaho and Montana so while there will be a slim chance for a few isolated showers over the northern mountains, quiet conditions will be the rule. Upper level support will then shift to the Plains which will cause the trough to remain in place. Eventually, a closed low will form in the base of the trough, Monday into Tuesday. By Wednesday, the system will start tracking eastward causing flow to become more southwesterly. Some available moisture to the south will be entrained by this flow, bringing increasing chances for precipitation, especially over the San Juans up into the central mountains. By late in the week, a new closed low develops off the Pacific Northwest Coast. This will build some ridging into the Four Corners and Southern Rockies. At this point, PWATs, which have been at or below normal, will start to climb once more as flow aloft draws moisture up from the south. So chances of mountain showers or thunderstorms, particularly over the southern ranges, remains through the end of the week. Temperatures are expected to gradually warm through the long term period. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1158 AM MDT Sat Oct 4 2025 A period of showers and thunderstorms continue to lift northward across Colorado and eastern Utah through the afternoon, as an upper level system slowly advances eastward. The main impacts into this evening with any storm will be lightning, gusty winds and locally heavy rain. Gusty winds to 25-35 knots are expected through this evening, before diminishing for most zones by early Sunday morning. Mainly expect VFR cigs, except MVFR/IFR at times in heaviest rain. Mainly MVFR VSBY in areas of precipitation. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...Wind Advisory until 5 PM MDT this afternoon for COZ020-021. UT...None. && $$ SHORT TERM...BGB LONG TERM...TGR/TGJT AVIATION...TGJT