Area Forecast Discussion
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
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073 FXUS65 KGJT 061113 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 513 AM MDT Thu Jun 6 2024 .KEY MESSAGES... - The hottest temperatures of the season so far are expected today and tomorrow, with highs running 10-15 degrees above normal. - Increasing moisture will bring a return of mountain showers and thunderstorms starting Friday, with expanding coverage through the weekend. - Temperatures gradually cool back to near normal values by early next week. && .SHORT TERM /THROUGH FRIDAY/... Issued at 323 AM MDT Thu Jun 6 2024 The dome of high pressure centered over the Southwestern US remains firmly in control today, with clear skies and above normal temperatures being the rule. Areas along the Divide will likely see their warmest temperatures of the season this afternoon, as increasing moisture and cloud cover over the terrain tomorrow afternoon will keeps temperatures down. For the lower elevations, tomorrow still looks to be the peak of this period of unusual heat, with triple digits and near record highs expected for the desert valleys. Look for highs to run around 10 degrees above normal, with near 15 degrees above normal favored for lower elevations tomorrow. Overnight lows continue mild, also running around 10 degrees above normal. In the meantime, moisture across the region will be on the increase over the next several days as counterclockwise flow around a cutoff low lurking off the southern Baja peninsula combines will clockwise flow around the high pressure dome to pull some subtropical moisture northward. This afternoon, at best this will result in an increase in clouds over the higher terrain. By tomorrow afternoon, enough moisture will have advected into the Southwest to fuel some showers and storms over the terrain. Diurnal heating will be the main source of lift, although a weak trough riding around the high will also provide some broad, weak dynamic lift as a modest boost. All this to say, look for increasing storm coverage over the higher terrain Friday afternoon and evening, most favoring the Colorado Divide. Dry surface air will limit how much precipitation makes it to the ground, keeping main threats as gusty outflow winds and lightning. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Issued at 323 AM MDT Thu Jun 6 2024 The relocation of the SubTrop High from the Desert SW to the Southern Plains will be complete by early Saturday. Easterly flow around the southern periphery of this High will begin to transport Gulf of Mexico moisture back toward our southern CWA...which gets enhanced later in the day as a cold front dives along the lee of the Rockies into New Mexico and the upslope flow drives it through the gaps. Finally...a low pressure system will be drawn northward out of the Baja region on Sunday into Monday tapping into another moisture source with a Pacific origin. The bigger picture of this is PWAT is pushed up to near and above 3/4 of an inch for the weekend into early next week...which for early June is in the region of the 90th percentile. The moisture will help fire daily afternoon thunderstorms while also easing the temperatures back a bit each day back to just a single digits above normal instead of 10 to 15 degrees. With the higher then normal moisture in the profile there will be a threat of some of the organized storms producing moderate to maybe even heavy rainfall rates. However sounding profiles in the lower to mid elevations suggest gusty outflow winds will likely be more of a threat than wetting rainfall. Sunday afternoon looks to be the peak of the convective activity as the Baja low rotates south of the 4 Corners. As we get later into the week the SubTrop High looks to try and re-establish itself over the Desert SW with greater uncertainty on where the next cutoff low in the SoCal/Baja region will reside. Moisture will begin to wane by Tuesday with afternoon storms mainly becoming focused on the higher terrain. The decrease in moisture and storms will allow the temperature trend to increase with highs once again approaching the triple digits in the lower desert valleys by midweek. && .AVIATION /12Z TAFS THROUGH 12Z FRIDAY/... Issued at 512 AM MDT Thu Jun 6 2024 Clear skies and light, terrain driven winds will prevail today. Afternoon clouds will develop over the higher terrain, but are not expected to impact airport operations. Gusts up to 20 knots will be possible during the afternoon. VFR conditions will prevail for the next 24 hours. && .HYDROLOGY... Issued at 229 PM MDT Tue Jun 4 2024 High pressure building overhead through the end of the week will result in an unseasonably warm period across the Western Slope. Simultaneously, as those temperatures rise, so will the rate of snowmelt across our high terrain. Even though low to mid elevations have already melted out, there`s still an abnormally high amount of snow left over basins generally at and above 11,000 ft...and it`s melting...fast. As a result, creeks, streams and major tributaries along the Upper Colorado River Basin are on the rise. Seasonal peak flows are expected over the next 10 days, with the Upper Gunnison, Upper Yampa and Colorado Headwaters basins likely peaking for the season this weekend. Current guidance oscillates diurnal peaks cresting the Action Stage for portions of Gore Creek and Eagle River in Eagle County. No highlights needed, yet, for that area after discussion with local officials but we will keep an eye on things over the coming days. The Elk River near Milner in Routt County, on the other hand, is expected to exceed Minor Flood Stage each morning through Sunday. This increase in forecast stage/flow warranted an upgrade from Flood Advisory to a Flood Warning. Also, the East River near Almont is forecast to exceed Action Stage each morning through Sunday, with the potential for exceeding Flood Stage by Saturday. For now, a Flood Advisory is in effect for this stretch of river. However, stay tuned for the potential upgrade to a warning and/or extending the advisory downstream into the Gunnison at Gunnison. As scorching temperatures lure folks to the water, please remember the potential hazards associated with high flows during the snowmelt season. Fast flows are not just dangerous for those choosing to float the rivers. In addition, high diurnal swings may drastically change the depth and flow for normally small creeks and streams. Swift currents and cold water temperatures can catch you off guard, so please be vigilant with current conditions and look for forecast updates when recreating or working near the water`s edge. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...BGB LONG TERM...15 AVIATION...TGJT HYDROLOGY...ERW