Area Forecast Discussion
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
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017 FXUS65 KGJT 020925 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 325 AM MDT Tue Jul 2 2024 .KEY MESSAGES... - Much drier air infiltrates the area today leaving only isolated terrain based showers and thunderstorms along the Continental Divide and our southern mountains. - This drier regime brings the return of critical fire weather conditions...very localized today but becoming more widespread across northern portions of Colorado and Utah on Wednesday. - Dry and warm conditions persist through the Holiday weekend and likely into early next week. && .SHORT TERM /THROUGH WEDNESDAY/... Issued at 325 AM MDT Tue Jul 2 2024 It was a fairly exciting end to this monsoonal moisture push with a few robust storms likely dropping some hail and rainfall rates in excess of 1.5 inches/hour. With the arrival of the northern stream trough to the Rockies much drier air will be ushered into the CWA along with slightly cooler temperatures. Dew points have already dropped into the 30s behind the pseudo cool front...which has made it through northeast Utah and northwest Colorado as of 3 am. There are some high based showers developing in the upglide area behind the front but with the drier air infiltrating below haven`t seen any reports of this making it to the ground. Farther to the South with the moisture still in place some rainfall is still being reported but the rates have dropped significantly over the past several hours. A few showers linger this morning as the front`s progress stalls over the central CWA and the main trough axis swings through. Behind this there will likely be some very isolated mountain convection that forms with steep lapse rates aloft over lingering residual moisture. Temperatures will be noticeable cooler behind the front up north and in parts of the western CWA. Farther south the drier air and sunnier conditions look to bring warmer temperatures today than those from 24 hours ago...but most will be 4 to 8 degrees below normal for early July. With drier air and clearer skies in place low temperatures will be allowed to fall to more normal level and bring a welcome relief to the muggy overnights of the past few days. Temperatures on Wednesday will gain a few degrees under this drier atmospheric regime. Gone will be the threat of heavy rainfall...replaced by the return of fire weather concerns. Deep mixing means afternoon winds will on the increase and when combined with the lower humidity...critical fire weather conditions look to be possible over portions of the northern CWA where fuels could be ready to burn. More details below. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Issued at 325 AM MDT Tue Jul 2 2024 High pressure will dominate the long term period resulting in mostly dry weather. The ridge will remain situated off the West Coast on Wednesday night before slowly nudging inland on Thursday. Flow aloft will be out of the northwest across western Colorado and eastern Utah as we remain on the outer periphery of the ridge while the large trough pushing into the Northern Great Plains heads towards the Upper Midwest on Thursday. This synoptic shift will close off our tap to the monsoonal moisture with our precipitable water values gradually trending down a bit each day as the deeper moisture begins to erode in that drier northwest flow. It`s always a bit of a gamble to say there won`t be any chance for shower and thunderstorm activity through the end of the week given daytime heating, orographics, and residual moisture. But, for the most part, guidance knocks those PWATs down to well below normal area-wide as surface dewpoints drop back into the 20s and 30s. The ridge axis will continue to amplify on Friday but especially this weekend, though its center will remain over the West Coast. This will only further enhance the dry northwest flow overhead and see temperatures rebound back to normal. As troughing continues to impact the central CONUS some weak waves on the backside of the low may brush the Divide and bring some increased clouds to those areas. Otherwise, quiet weather prevails going into the new work week. One area to monitor will be potential fire weather concerns as mixing under the ridge brings breezy conditions most afternoons. We did just receive a bunch of rain over the last couple of weeks but there are some areas where fuels remain critical. Something to be mindful of regardless as humidities drop back into the teens. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1137 PM MDT Mon Jul 1 2024 Another busy overnight period as the last of the moisture and instability gets replaced by drier air for Tuesday. Gusty winds and MVFR producing showers could impact several of the southern and eastern TAF sites through sunrise. The drier air spreads in for tomorrow and storm coverage will be much more isolated and mainly limited to the higher terrain. So VFR should hold over the next 24 hours but will also be watching for some low clouds to form in the wake of heavy rainfall in some of the higher valleys. && .FIRE WEATHER... Issued at 325 AM MDT Tue Jul 2 2024 .A system moving across the Rockies today will sweep out the monsoonal moisture and replace it with much drier air. Localized areas of critical fire weather conditions are possible across the far northern fire zones today...but this becomes more widespread on Wednesday and a Fire Weather Watch has been issued as afternoon humidity and breezy conditions combine. Dry conditions look to persist into the near future as ridging anchored to our West keeps us in a northwest flow pattern...inhibiting the return of subtropical moisture. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...Fire Weather Watch from Wednesday afternoon through Wednesday evening for COZ200-202. UT...Fire Weather Watch from Wednesday afternoon through Wednesday evening for UTZ486-487. && $$ SHORT TERM...15 LONG TERM...MMS AVIATION...TGJT FIRE WEATHER...15