Area Forecast Discussion
Issued by NWS Grand Junction, CO

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249 FXUS65 KGJT 121128 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 528 AM MDT Wed Jun 12 2024 .KEY MESSAGES... - Hot and dry conditions develop today and Thursday, with area temperatures 10-15 degrees above climatological averages. - A few showers and thunderstorms will develop on terrain this afternoon, capable of producing gusty outflows of 40-50 mph. - Another storm approaches the region Thursday night and will lead to widespread showers and a few thunderstorms. && .SHORT TERM /THROUGH THURSDAY/... Issued at 314 AM MDT Wed Jun 12 2024 Mid level water vapor satellite imagery, as well as the Grand Junction evening sounding show a shot of moisture working across the Great Basin and into the central portion of the CWA this morning. A few raindrops were observed here at the office, but mostly just mid clouds are popping on terrain features from Moab to Aspen. The low spinning off the SOCAL coast will continue to drive height rises up over the Four Corners, thus amplifying the ridge of high pressure overhead this afternoon. This will turn up the heat across the CWA with temperatures in the triple digits in our deserts and low valleys both today and Thursday. Elsewhere, temperatures are expected to remain 10-15 degrees above climatology today and tomorrow. Any moisture left overhead this morning will get pushed northward along the top of the ridge. There does appear to be enough fuel for some terrain based showers, favoring locales northward of I- 70 this afternoon. Isolated showers can`t be ruled out farther south along the Divide, but subsidence under the ridge and drier air will prove challenging for convection. While a few of these storms will take some of the edge off afternoon highs, the main concern will be gusty outflows and lightning. Shower activity will taper this evening and quiet conditions will return overnight under the ridge with overnight lows in the 50`s and 60`s across the region. Thursday will be a rinse and repeat of Wednesday. The ridge axis will shift east slightly, and temperatures will respond to a few more clouds and winds picking up ahead of the incoming low. Nonetheless, it will still be hot and dry Thursday afternoon. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Issued at 314 AM MDT Wed Jun 12 2024 The closed low that has been spinning off the California coast finally gets moving Thursday night and will weaken as it does so. Said low will track across northern Arizona overnight into Friday morning and will also bring an increase in moisture across our region. Forecast PWATs will be around 0.4 inches Thursday morning but reach near 0.8 inches for portions of the CWA by Friday morning. For this reason, models are picking up on some light precip to overspread eastern UT and extreme western CO for the early morning hours on Friday. As the low continues to weaken and become more of an open wave, precip is expected to expand across the area and by noon reach the I-70 corridor and areas south with the San Juans being favored for the most precip (about 0.25 inches). Might see some thunderstorms along with the showery precip but plenty of cloud cover and cooler temperatures will likely keep storms to a minimum. The main push of precip will shift to the Front Range Friday afternoon and evening but residual instability will be worked on by a mid to upper level trough as it moves overhead. Some spotty showers will continue as this occurs but QPF amounts are lackluster with 0.1 inches or less with this second push of precip. More good news along with the precip will be daytime highs dropping anywhere from 10 to 15 degrees on Friday as opposed to what we saw on Thursday. A welcome reprieve after the last few days. Saturday onwards, flow becomes southwesterly thanks to a low pressure system moving into the Pacific NW. Supporting this low will be an upper level jet that will approach our area through the weekend. The core of highest winds in the jet may just clip our CWA Monday. The reason this is important is because with limited cloud cover (over the higher terrain...par for the course), deeper mixing will allow some of these winds to reach the surface. In fact, we`ll start seeing some gusty winds Saturday for the northern valleys of around 20 to 30 mph. By Sunday, these winds will increase to 25 to 35 for the entire CWA and again on Monday...maybe a bit higher. Along with these winds, RH values will drop to single digits/low teens and with some fuels deemed critical (for some fire weather zones), Red Flag Warnings may be needed. Of course, we`re a ways out so this may change. Outside of the winds, dry conditions remain in place as highs start to warm up reaching about 10 degrees above more seasonal values for mid-June by Tuesday. && .AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
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Issued at 523 AM MDT Wed Jun 12 2024 VFR conditions will prevail at terminals today under a ridge of high pressure. A few clouds will sneak under the ridge today and lead to some scattered mid and upper clouds. A few showers are expected to form on terrain, favoring areas north of I-70. Along with showers will come the potential for a couple of 40-50 mph outflow gusts. Winds will prevail from the west, with a few gusts this afternoon, then settle at sunset back to terrain driven nocturnal winds.
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&& .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...LTB LONG TERM...TGR AVIATION...TGJT