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Area Forecast Discussion
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
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563 FXUS65 KGJT 172048 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 248 PM MDT Wed Jul 17 2024 .KEY MESSAGES... - Temperatures are expected to remain a few degrees above normal with daily thunderstorm chances through the remainder of the week with a slight drying trend possible over the weekend. - Threats from thunderstorms will mainly be from gusty outflow winds though a few storms will be capable of producing smaller hail and moderate to heavy rainfall rates. Overall flooding threats remain low. - The combination of high based storms, gusty outflow winds and lightning will keep also keep a threat of new wildfire starts in the picture. && .SHORT TERM /THROUGH THURSDAY NIGHT/... Issued at 248 PM MDT Wed Jul 17 2024 The storm mode has changed this afternoon with less shear and slightly drier conditions in place. The best coverage remains over the San Juans where slow moving storm or training storms could lead to excess runoff through sunset but the probability of this is low. Similar conditions are expected Thursday though slightly higher PWAT will begin to creep into the 4 Corners region...westward moving Gulf of Mexico moisture in the wake of the lee side frontal passage and deep upslope flow. Storms should initialize on the higher terrain by mid-day as usual and migrate southeastward to adjacent valleys...with the southern valleys favored thanks to the better moisture profile. The HRRR attm is more bullish in keeping nocturnal convection into Thursday night which makes sense as we advect in additional moisture trapped under the main circulation aloft. This is an outlier solution attm so pops remain fairly light and will keep an eye on this trend. Temperatures will be fairly static with highs continuing to run several degrees above normal. && .LONG TERM /FRIDAY THROUGH TUESDAY/... Issued at 248 PM MDT Wed Jul 17 2024 Mostly a rinse and repeat forecast through the long term period as we just keep watching the area of high pressure waver back and forth across the Great Basin. On Friday the ridge will be centered over southern Arizona as an embedded shortwave associated with the parent trough dominating Hudson Bay brushes the Continental Divide. This will result in an uptick in shower and thunderstorm activity as PWATs continue to trend 110 to 140 percent of normal. Saturday will be more of the same, although storm coverage will gradually taper off across eastern Utah and more-so focus along the Divide into the evening hours. As we head into the weekend odds begin to favor a trend towards drier weather as the ridge of high pressure amplifies farther north into the Intermountain West. Certainly won`t lock in a dry and benign forecast by any means as unsettled weather continues just to our east as the trough stays trapped over the eastern CONUS. As this regime continues PWATs will gradually begin to trend down but aren`t anticipated to drop below normal until early next week. Regardless, pesky low level moisture paired with daytime heating and orographics will be sufficient to fuel at least scattered convection each afternoon into the new work week. But, as we transition a bit each day, the potential for heavy rain will become less likely as we shift more towards the threat of gusty outflow winds. As we head into Tuesday the ridge looks to slowly de-amplify as a trough of low pressure dives south from the Gulf of Alaska. Temperatures will remain largely stagnant through the period as we don`t see any notable shift in the synoptic pattern. This translates to continued hot temperatures with highs trending near to slightly above normal. Overnight lows each night will generally be mild for mid July. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1124 AM MDT Wed Jul 17 2024 Slightly drier conditions suggest a downturn in convective coverage today and early radar and satellite trend concur. Storms developing over ridges in the next few hours will take a slow drift southward...some surviving into the adjacent valleys. Confidence overall is low due to the lesser storm coverage but forecast for now favors KTEX KDRO and KASE for a passing storm with VCTS used elsewhere. Gusty winds continue to be the main threat from the storms today and could exceed 40 mph under the right conditions. Clearing tonight and VFR holds over the next 24 hours. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...15 LONG TERM...MMS AVIATION...TGJT