Area Forecast Discussion
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
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962 FXUS65 KGJT 210548 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 1148 PM MDT Mon May 20 2024 .KEY MESSAGES... - Showers and thunderstorms will spread south and eastward tonight as the cold front associated with a late season spring storm moves through the area tonight. - Colder air will cause snow to develop in the mountains with accumulation`s above 9,000 feet expected to range from 2 to 5 inches with locally higher amounts. - Cooler temperatures behind the front on Tuesday will bring markedly cooler temperatures with highs dipping by close to 15 degrees relative to today`s highs. && .SHORT TERM /THROUGH TUESDAY NIGHT/... Issued at 247 PM MDT Mon May 20 2024 Showers and isolated thunderstorms continued to fire along and northwest of the cold front associated with the late spring storm over the Great Basin. This activity has remained northwest of a line from KDWX to 30S KPUC and isn`t likely to shift much over the next few hours. Meanwhile, there is a marginal threat of severe wind gusts from stronger cells over the northwest through early evening. South and east of the line, strong gusty south to southwest winds were the rule, and while clouds have increased, no showers were apparent. The trough axis shifts eastward tonight while a vort lobe rotating through the base of the trough drives the cold front across the forecast area. Dynamic forcing along with convergence along the boundary will cause showers to move to the east and expand southward with showers becoming more likely as the night progresses. Infiltration of colder air will bring snow levels down to near 7000 feet over northeast Utah and northwest Colorado while hovering from 8500 to 9000 feet elsewhere. Mountain snow will largely be confined to areas above 8500 feet in the north and 9000 feet in the south with accumulations more notable above 9000 and 10000 feet, respectively. Not enough snow indicated to issue Winter Weather Advisories, but mountain passes are likely to see impacts, especially at Rabbit Ears and Vail Passes. Some of the trough`s energy shifts to the northern Plains on Tuesday, but the main trough is expected to pass over the area during the day. As a result, showers and thunderstorms remain likely over the mountains with the northern and central ranges favored and lesser chances over the lower elevations of eastern Utah and southwest Colorado. Total mountain snowfall from this event is expected to be around 3 to 6 inches in the higher elevations and locally up to 10 inches on favored peaks and ridges. Temperatures will be markedly cooler behind the front with highs running close to 10 degrees below seasonal norms. Drying and clearing is expected in the subsident region in the wake of the trough Tuesday night. As a result, we`ll see an end to shower activity while clearing and colder air brings unusually cool overnight lows with temperatures also dipping to near 10 degrees below normal, though it doesn`t appear a damaging freeze will occur in areas with sensitive vegetation. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Issued at 247 PM MDT Mon May 20 2024 Much drier weather is in store on Wednesday in the wake of our departing trough, but a few returning spotty showers can`t be ruled out across the Continental Divide mountains given lingering residual moisture and daytime heating. High temperatures will be roughly 4 to 8 degrees below normal for this time of year. By Thursday, mid-level flow becomes southwesterly again out ahead of another deep trough and cold front digging across the Intermountain West. In response, developing warm advection within the southwest flow ahead of the front will boost high temperatures by about 5 degrees compared to Wednesday... and more in line with seasonal norms. The cold front is progged to move across eastern Utah and western Colorado Thursday afternoon and evening, bringing another shot of cooler air in its wake. As for precipitation chances, moisture along and ahead of the front is modest at best, so despite decent forcing, slight chance to chance PoPs are mainly confined to the high terrain well to the north of the I-70 corridor, and QPF is mostly under a tenth of an inch. Behind the front, a cooler day is expected to round out the work week on Friday with highs once again several degrees below normal. A couple trailing waves have the potential to bring a few more rounds of unsettled weather Friday into the weekend, though significant differences still exist amongst the latest models. For now, will continue to lean on the blended solution, which favors northeast Utah, northwest Colorado, and the higher elevations along and north of I-70 for any additional precipitation. Given the potential for more clouds and precip, temperatures will continue to run a few to several degrees below normal. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1142 PM MDT Mon May 20 2024 Showers and a few thunderstorms will continue overnight as a frontal boundary slowly clears western CO and eastern UT. Winds will taper over the next few hours as the front passes. Showers and cloud cover will hang up on terrain closer to the Divide tonight and mountain terminals are likely to see intermittent periods of MVFR/IFR conditions with lower ceilings and showers. A few gusty winds from decaying showers are possible as well. Showers and thunderstorms will remain in the forecast for Tuesday afternoon as an upper level wave finishes working through the region. VFR conditions will likely finish the tail end of this TAF period, as the last of the shower activity pushes across the West Slope Tuesday evening. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...NL LONG TERM...MDM AVIATION...TGJT