Area Forecast Discussion
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
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333 FXUS65 KGJT 302327 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 527 PM MDT Tue Apr 30 2024 .KEY MESSAGES... - The next in a series of disturbances will bring another round of rain and snow showers along with isolated thunderstorms to the region from late tonight through Wednesday night. - Impacts favor northwest Colorado and the northern and central Colorado mountains where accumulations are expected to range from 3 to 6 inches. - Cold front associated with this system brings cooler temperatures on Wednesday, mainly across the north, along with strong gusty winds across the entire region. - Next system arrives over the area on Friday with the north continuing to be favored in this pattern. && .SHORT TERM /THROUGH WEDNESDAY NIGHT/... Issued at 304 PM MDT Tue Apr 30 2024 Showers ended across the northern and central mountains this morning in response to subsidence/drying on the back side of the exiting mid-level trough. However, this break appears to be short-lived as the next trough moves to the Great Basin tonight. Models indicated overrunning precipitation will develop after midnight as the flow aloft shifts to the southwest. Combined with divergence in the right entrance region of the polar jet over central Wyoming this activity will be confined to areas north of the I-70 corridor with a slight chance for showers over the central Colorado mountains. Showers increase in coverage and intensity, spreading into the southern mountains Wednesday and Wednesday night as the trough passes over the area. During this period, mid and jet level upward forcing will be maximized so mountain snow begins in earnest, mainly for areas above 8500 feet. The northern and central mountains can expect 3 to 6 inch accumulations will locally higher amounts with only 1 to 3 inches expected for the northwest San Juan Mountains. Looking farther south, the lower elevations of southeast Utah and southwest Colorado shouldn`t see any moisture from this system. Meanwhile, passage of the cold front associated with this system will bring 3 to 5 degrees of cooling for all but the Four Corners area where the late arrival of the front will be too late to impact highs much. Showers decrease late Wednesday night, but scattered showers are likely to persist over the central Colorado mountains and the northwest San Juans into the early morning hours. Overnight lows will be markedly colder in the wake of the from Thursday morning with lows around 10 to 15 degrees cooler for the northern and central zones, but only marginally colder for the Four Corners region. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Issued at 304 PM MDT Tue Apr 30 2024 The synoptic pattern open Thursday with ridging off the Pacific Coast and over the Great Lakes, and a longwave trough in between over the Western CONUS with a low pressure system anchored over southern Saskatchewan holding the pattern in place. With the most recent shortwave that pushed a cold front south through the region overnight having moved east of the Rockies and out onto the Plains, the next shortwave system will be dropping into the Pacific Northwest bringing more unsettled weather to the northern and central mountains of eastern Utah and Western Colorado Friday. A deeper, much stronger system drops out of the Gulf of Alaska into the Pacific Northwest Friday night pushing the ridge that had been off the Pacific Coast inland, disrupting the synoptic pattern that has been in place for the past week shifting the longwave trough and Canadian low to the east. From her on the models tend to diverge on the track and timing of this next low pressure system with the European models digging not quite so deep and tracking it farther north over Wyoming and Montana, while the GFS and GEFS models dig the low deeper onto California and the southern Great Basin before ejecting it to the northeast over Utah and northwestern Colorado into Wyoming Monday into Tuesday. Confidence in the track and timing of this next major system is low at this point, but models are indicating a significant atmospheric river (AR) associated with this system with IVT of 150 to 300 kg/m/s moving up into the region early next week. Current guidance hasn`t picked up on this moisture as of yet, so we`ll have to be patient another few days to realize what this system may have in store for the region. With that being said, the front that pushes south through the region Wednesday night look to get hung up in the San Juan Mountains Thursday. Temperatures will run five to ten degrees below normal to the north and near normal in the southern areas through the day. Lingering orographic showers will continue through the day mostly in the northern and central mountains with little accumulation. Friday will see another round of showers in the northern and central mountains as the next shortwave passes to the north with snow levels dropping below 8000 feet, but little if any accumulation. Convection shuts down Friday evening and skies clear as the trough moves east and the ridge slides in from the west. Saturday will be clear, warm and dry with temperatures reaching five to ten degrees above normal. Sunday into early next week will see temperatures fall as the major system approaches. Look for showers and possible thunderstorms between Sunday afternoon and Tuesday depending on the track and timing of this storm. Look for significant precip from this system, but the details are up in the air at this point. Stay tuned for updates on this next system. && .AVIATION /00Z TAFS THROUGH 00Z THURSDAY/... Issued at 522 PM MDT Tue Apr 30 2024 Mostly clear skies and gusty westerly winds will continue through the next 3 hours before winds relax and begin to follow typical drainage patterns. High level clouds, and eventually mid level clouds, will be on the increase from north to south through the night as a cold front approaches the area. Precipitation associated with this front will reach KVEL and KHDN late tomorrow morning, with remaining TAF sites seeing impacts through the afternoon hours. VFR conditions are expected to prevail until that point. The frontal band may bring reduce visibility and lower ceilings, leading to possible MVFR to IFR conditions after 18z tomorrow. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...NL LONG TERM...DB AVIATION...TGJT