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Area Forecast Discussion
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
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073 FXUS65 KGJT 100547 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 1147 PM MDT Fri Aug 9 2024 .KEY MESSAGES... - Daily afternoon and evening thunderstorms with the threat of heavy rain rates, gusty outflow winds, frequent lightning, and small hail until further notice. - This uptick in available moisture will bring an enhanced threat of flash flooding and debris flows through the weekend and into early next week. - Temperatures will be cooling back toward normal with the increase in precipitation and cloud coverage through at least the middle of next week. && .SHORT TERM /THROUGH SATURDAY NIGHT/... Issued at 346 PM MDT Fri Aug 9 2024 There is high confidence in a wetter than normal forecast over the next few days...along with more temperate conditions thanks to the added moisture/clouds/precipitation. That is where the confidence end however with models struggling with convective feedback or their different schemes. Unfortunately the more broad-brushed approach to PoPs continue which may not always reflect reality on the radar. That said the latest CAMS have reset better and the general trend looks like the more active North shifts to the southern CWA through the evening and early morning hours. This will likely be driven by the energy moving across the NV/UT line attm where strong/severe storms have popped up on the gradient of the main moisture plume. The threat of heavy rainfall should taper off through the evening but fairly deep warm core storms should still be able to produce efficient rainers approaching an inch per hour in some areas. Another active day expected tomorrow with moisture settling in leading to CAPE values over 1500j/kg and around 35kts of shear. Again heavy rainfall will be the main threat but a few organized storms will likely be able to get some hail and stronger wind gusts to the ground. A strong moisture plume and passing jet to the North keeps a strong signal for nocturnal convection to continue well into early Sunday morning. Temperatures remain near to slightly cooler than normal until further notice. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Issued at 346 PM MDT Fri Aug 9 2024 The active weather pattern prevails through much of the long term period as a series of systems push across the area. These waves will act on the continued abundance of moisture as precipitable water values remain at least 150 to 180 percent of normal. As a result, look for scattered to numerous showers and thunderstorms each day. As has been the trend the last several days, gusty outflow winds, frequent lightning and small hail will be possible with storms. On days where shortwaves are present, locally stronger storms cannot be ruled out. With a continued juicy atmosphere the potential for excessive rainfall with thunderstorms will increase each day with flash flooding subsequently being a threat as well. This will especially be true over saturated soils, burn scars, and vulnerable steep terrain. Storms are expected to drift into the valleys each day, given surface dewpoints will remain in the 50s and 60s through at least Tuesday. Finally, with the presence of mild support aloft and plenty of moisture, nocturnal showers and storms are likely through early next week. So, plenty to monitor as we finish the weekend and head into the new work week. Late Tuesday and into Wednesday will see flow aloft across eastern Utah and western Colorado shift to the west as the subtropical high flattens to our south. This will cut off our direct tap to the monsoonal moisture and introduce some slightly drier air into the region. As has been mentioned numerous times this summer, models tend to be a bit aggressive with eroding deeper moisture in place in the wake of these monsoonal surges, so will tread with caution as guidance projects PWATs to drop back to 80 to 90 percent of normal. Either way, daily showers and storms are expected from mid week onwards as sufficient moisture will be in place to fire off at least isolated to scattered convection over the mountains each afternoon. Another trough of low pressure begins to elongate off the West Coast as we head into the latter part of the work week, which could open the door back to that subtropical moisture. Daytime highs through the long term period will remain below normal area-wide, thanks to the abundance of clouds and convection each day. Monday looks to be the coolest day of the period as a stronger wave passes through. Overnight lows each night will steadily remain a few degrees above normal for early August. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1142 PM MDT Fri Aug 9 2024 Isolated to scattered showers and thunderstorms will continue overnight, particularly across the southern portions of the area with VCTS at KTEX and KDRO. Elsewhere, showers will be hit or miss but expect periods of MVFR at times in rain with occasional breezy winds. Storms will redevelop Saturday afternoon with more widespread coverage late in the day and potential for some storms to linger overnight as a wave moves across the north. VFR should prevail for the most part with MVFR and locally IFR at times in any heavier showers/storms. && .HYDROLOGY... Issued at 346 PM MDT Fri Aug 9 2024 Storms with heavy rainfall have gone to the left and right of the Grizzly Creek burn scar today but so far the threat to Glenwood Canyon has been minimal. There are still some active storms upstream and will see how this plays out. The deeper monsoonal moisture remains over the area well into next week This will keep a persistent threat for flash flooding and debris flows across the majority of the area with potential rainfall rates in excess of 1-2" per hour. Be sure to stay weather aware over the coming days, especially if recreating outdoors and in locations prone to flash flooding and debris flows. Stay tuned for forecast updates, as well as any Watches, Warnings, and Advisories in the coming days. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...15 LONG TERM...MMS AVIATION...MDA HYDROLOGY...TGJT