Area Forecast Discussion
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
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326 FXUS65 KGJT 282031 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 231 PM MDT Tue May 28 2024 .KEY MESSAGES... - Conditions mainly dry and breezy, with chances for isolated to scattered showers and thunderstorms over the higher terrain each afternoon/evening throughout the week and into early next week. - Aside from a brief dip to near normal temperatures Thursday, expect above normal warmth this week. && .SHORT TERM /THROUGH WEDNESDAY NIGHT/... Issued at 152 PM MDT Tue May 28 2024 A modest bump in mid level moisture along with some limited instability (CAPE of 500 J/kg or less and steep lapse rates) is resulting in better coverage of showers and storms than seen in previous couple days. Storms are isolated to widely scattered in coverage and are favoring the high terrain. Very little shear and weak upper level winds is keeping the storms fairly anchored to the high terrain with weakening and quick dissipation as these storms drift into the valleys, more prevalent up north as the best moisture and instability remains here. So given the weak forcing and limited residence time of these showers/storms, expect storms to quickly dissipate with the loss of daytime heating today with valleys remaining mostly dry. High temperatures are much warmer today with 80s across many lower valleys and upper 80s to near 90 in the Grand Valley and lower desert valleys of east-central and southeast Utah. On Wednesday, the gradient tightens ahead of a cold front that is expected to move through Wednesday evening. This cold front is associated with an upper level shortwave trough that will pass to our north Wednesday night. So, as a result, it will be breezier Wednesday afternoon with gusts in the 20 to 30 mph range on average, with some gusts approaching 35 to 40 mph possible across the north. Not much moisture is associated with this system but enough instability and lift should result in isolated to scattered showers and thunderstorms Wednesday afternoon with better coverage across the north where some showers/storms could linger through the late evening hours Wednesday night. Gusty outflow winds seem to be the primary concern with these storms with limited moisture at the low levels. Given the flow is southwest and the front moves through Wednesday evening, highs on Wednesday should remain warm with highs 5 to 10 degrees above normal and a little higher than today. && .LONG TERM /THURSDAY THROUGH MONDAY/... Issued at 152 PM MDT Tue May 28 2024 In the wake of the dry cold front that is expected to move through Wednesday night, temperatures on Thursday will run 5-10 degrees cooler compared to the day previous. This will be most noticeable across northeast Utah and northwest Colorado, where temperatures are expected to top out around 5 degrees below normal. Along and south of the I-70 corridor, temperatures will be near to around 5 degrees above normal. These slightly cooler temperatures will only last a day, as warm air pushes back north in the wake of the departing upper level low. From Friday onward, blended guidance favors a gradual warming trend with temperatures of 5-10 degrees above normal across the board. While this first upper level low tracks by to our north, the combination of a weak westerly jet and the tightened pressure gradient aloft will lead to breezy conditions Thursday and Friday afternoon. Flow aloft then turns southwesterly by Saturday, continuing the gradual warming trend and bringing in some modest moisture. This moisture, along with the approaching upper level trough, will lead to a slight expansion of storm coverage over the higher terrain along the Divide during the afternoon and evening hours. This trough is expected to move overhead on Sunday, but models differ as to whether it remains robust or washes out as it meets the mountains. If it holds together, some more organized convection will be possible, mainly across the higher terrain of northeast Utah and northwest Colorado. If it washes out, look for status quo conditions on Sunday...warm, breezy, and mostly sunny. One more trough will brush by to our north early next week, although models disagree quite a bit on timing and how far south this trough will reach. What models do agree on, is that a piece of energy will break away from this northern storm track and drift southwest, setting up shop somewhere over SoCal as a cutoff low Monday or Tuesday. In response to this deepening area of low pressure, a highly amplified high pressure ridge will build north into the Great Basin. Should this forecast verify, eastern Utah and western Colorado are looking at a potentially prolonged period of unusually warm and dry conditions next week. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1123 AM MDT Tue May 28 2024 Skies will be mostly clear and winds light and terrain driven for the majority of the next 24 hours, with VFR conditions prevailing. Showers and storms are forming over the higher terrain and will drift over adjacent valleys as the day wears on, so have included VCTS in several TAFs to account for this. These showers will bring mainly lowered ceilings and gusty, erratic winds. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...MDA LONG TERM...BGB AVIATION...TGJT