Area Forecast Discussion
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
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704 FXUS65 KGJT 061803 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 1203 PM MDT Mon May 6 2024 .KEY MESSAGES... - A strong spring storm will continue to bring widespread precipitation this morning with significant mountain snow expected across the northern Colorado ranges. Light snow accumulations are possible for the higher valleys as well as most other mountain ranges. - Another disturbance will bring more snow showers across the north on Tuesday. This system will also drag another strong cold front through the region, setting up the potential for widespread freezing temperatures Tuesday night. - Much cooler and unsettled weather will be the rule for the rest of the week ahead as several disturbances keep mountain showers in the forecast most afternoons. && .UPDATE... Issued at 1201 PM MDT Mon May 6 2024 Winds gusting over 40 mph in the southern Uinta Basin so added a wind advisory through this evening for that area. Will continue to monitor the Upper Colorado/Eagle Valleys from Rifle to Eagle for the same and possibly the Gunnison Basin. These same areas and more will continue to see some stronger winds on Tuesday as well. && .SHORT TERM /THROUGH TUESDAY/... Issued at 355 AM MDT Mon May 6 2024 As expected, a strong cold front came blasting across eastern Utah and western Colorado overnight, leaving us with much colder temperatures in its wake. Temperatures are some 20 to 30 degrees colder than just 24 hours ago, which has allowed rain along and behind the front to change to snow in many of the higher elevations above 5000 feet early this morning. Even places like Meeker, Rifle, and Montrose have changed to snow, with some minor grassy accumulations possible there. Widespread precipitation, some heavy at times, will continue through the early daylight hours before drier air and subsidence builds in behind the departing shortwave trough. Thus, am expecting a gradual downtrend in shower activity in most places by late morning or early afternoon. The exceptions will be across the central and northern Colorado mountains and their adjacent high valleys as moisture, instability, and favorable orographics will keep snow showers going deep into the afternoon. Several more inches of accumulation are likely in those areas, with the Flat Tops, Elkheads, and Park Range favored the most. Given the time of year, roads should mostly just stay wet or quickly melt back; however, any heavier rates of 1 inch per hour or more can lead to roads becoming snow-covered and slick. This will especially be the case for the high mountain passes such as Rabbit Ears Pass and Vail Pass. Overall, think we have the potential impacts well covered with the ongoing Winter Weather Advisories, so no changes were made with this forecast package. Despite precipitation ending for most and clouds likely breaking for some sun this afternoon, high temperatures will be a good 10 to 20 degrees below normal, which is quite a stark contrast from yesterday. Overnight lows will be much chillier too, especially up north where snow showers are likely to linger before tapering off late. On Tuesday, another shortwave rounding along the southern periphery of a closed low spinning across the northern High Plains will dig across the northern Four Corners. This wave, which will act on residual moisture and daytime instability, will spark a fresh round of showers across the eastern Uintas, portions of northwest Colorado, and the northern Colorado mountains. Snow levels will continue to hover between 5000 and 6000 feet, so most of the showers will fall as snow (perhaps mixed with a little rain closer to 5000 feet) in those areas. With that being said, the largest accumulations will be found across the the highest elevations of the Park Range, which is where the most favorable orographics, moisture, and instability reside. Latest 00Z model guidance shows accumulations of 3 to 6 inches in the Park Range, with isolated amounts up to 7 or 8 inches. Given that this is only expected to impact a fairly small portion of COZ004, have opted not to issue any additional winter highlights at this time. Use caution if you`ll be traveling over Rabbit Ears Pass, however. Accumulations outside of the Park Range will generally amount to 3 inches or less. Outside of those northern mountains and high valleys, mainly dry weather is in store, but it will be another cool day with temperatures well below seasonal normals once again. It will also be another breezy to borderline windy day as the shortwave pressing in from the north will be accompanied by a strong mid and upper level jet which will help to tighten the pressure gradient across eastern Utah and western Colorado. Wind gusts of 35 to 45 mph will be common Tuesday afternoon, with some spots (particularly in the higher elevations) seeing gusts closer to 55 or 60 mph. Still a bit too early for wind highlights yet, but something that will certainly be considered with the next couple of forecast packages. If you`re a fan of the cool spring weather, you`re in luck. The passing shortwave will throw another cold front through the forecast air later Tuesday afternoon and evening, with an even colder blast of air rushing in behind it. That will set up a very chilly period from Tuesday night into Wednesday. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Issued at 355 AM MDT Mon May 6 2024 A mid-level short wave trough in the southwest quadrant of the storm over the Dakotas sweeps southeastward over the northern most zones Tuesday night. This will keep scattered showers going over the northern and central Colorado mountains and adjacent valleys through Wednesday morning. Additional snow accumulations will be light. During the remainder of the week an interesting pattern develops where a piece of the polar jet wraps back around the Dakotas low flowing westward across the northern Rockies. This causes a broad east-west oriented mid-level low to form over the forecast area which is expected to persist for the remainder of the week and into the weekend. General instability and lingering moisture trapped within the weak cyclonic flow under the low suggests less organized shower activity over the area with an uptick in activity each afternoon in response to daytime warming. There is less certainty by Sunday however, as the GFS/Canadian solutions diverge from the ECMWF`s. The latter showed the low lingering overhead during the weekend while the others suggested the low will finally breakdown and become absorbed into the main northwesterly flow over the central Plains. This would bring drier conditions Sunday while the ECMWF solution suggested more of the same. Since blends get significant input from the EC, the current forecast remains showery, but do expect that will change over the next few days. Expect temperatures to run 10 to 15 degrees below normal on Wednesday with morning lows near or below freezing for the Grand Valley and southeast Utah where some vegetation is susceptible to damage. However, temperatures are expected to moderate during the remainder of the long range period, reaching near normal levels Friday, then rising to around 5 degrees above normal this weekend. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 1138 AM MDT Mon May 6 2024 Winds will continue to be an issue region-wide over the next 24 hour with gusts of 25 to 45 mph again possible through sunset...followed by areas of LLWS as the valleys decouple...then gusts reform by mid morning on Tuesday. Cold air aloft will continue to force showers over much of northern Colorado and the Continental Divide through early evening. A thunderstorm or two is also possible with gusty winds and possibly some small hail possible. Another system rolls through by the early morning hours and snow will again spread over much of northern Colorado with terrain obscuration likely through the day. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...Winter Weather Advisory until 6 PM MDT this evening for COZ004- 010-013. UT...Wind Advisory until 9 PM MDT this evening for UTZ024. && $$ UPDATE...15 SHORT TERM...MDM LONG TERM...NL AVIATION...TGJT