806 FXUS65 KTWC 032256 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 356 PM MST Thu Jul 3 2025 .SYNOPSIS...Ample Monsoon moisture remains across Southeast Arizona today resulting in scattered showers and thunderstorm across Southeast Arizona, especially from the Tucson Metro Area to the Southeast in to Cochise county. The primary threat from storms into this evening will be heavy rainfall producing localized flash flooding. A drying trend is expected for Independence Day and this weekend with storm coverage more isolated and focused on locales south of Tucson. Temperatures will remain below normal through Friday before warming back up to above normal levels by Sunday and continuing through much of next week. && .DISCUSSION...The one thing to know about the nature of Monsoon season, in general...the day after an active thunderstorm day is usually followed by a down day as the atmosphere has a difficult time recovering. Things were starting off that way until the mid-afternoon, then strong to severe storms developed near the Tucson Metro Area producing flash flooding to the west, south and northern portions of Tucson. There was plenty of atmospheric moisture across Southeast Arizona today. The latest GOES PWAT imagery indicates PWAT values around 1 inch east and southeast of Tucson and an area around 1.45 inches to the northwest. This matches up with the 03/18Z KTWC sounding that reported a PWAT of 1.40 inches. The sounding also indicated plenty of CAPE for deep convection (MU CAPE 1129 k/kg), but the problem initially was that there was strong shear between the middle and upper portions of the storms that caused the storm updrafts to tilt toward the northeast. It wasn't until we saw enough surface heating the the valleys this afternoon to get sustained and deep updrafts. The upper pattern is defined by an upper trough across Nevada, with high pressure over Texas/northeast Mexico. The upper trough continues to lift NE today, with the southern periphery of the 500 mb trough axis swinging through our neck of the woods. This trough passage was able to provide a lifting mechanism, eroding the warm layer seen on the sounding around 500 mb. The coverage of the storms this afternoon will continue to be scattered in nature, but they will be capable of producing heavy rainfall rates resulting in flash flooding. I would still expect additional scattered thunderstorms develop this afternoon into the early evening, especially along an axis from Tucson to Douglas (which will align itself with the best deformation aloft from the trough passage). We can expect a downturn in thunderstorm activity for Independence Day and into the weekend as high pressure builds into the area from the south, extending across Southeast Arizona and Sonora Mexico. The unfortunate side effect from this is that we will begin to warm up to above normal readings Sunday into early next week. The high then is progged to shift north toward the Four Corners by the middle of next week. Although this should be a more favorable location for thunderstorm activity, the 300 mb high stacking on top of will somewhat limit deep convection. With direr air setting up across the eastern CWA, and a surge of moisture moving up the Gulf early next week, the main threat from thunderstorms will be strong and gusty outflow winds east of Tucson, with the potential for heavy rainfall from Tucson west. && .AVIATION...Valid through 05/00Z. SCT-BKN 7-12k ft AGL from KTUS eastward thru 04/05Z, becoming SCT 12-15k ft AGL overnight. SCT- BKN 7-12k ft AGL will redevelop aft 04/19Z. Scattered SHRA/TSRA are expected through 04/04Z with CIGS BKN 5-8k ft AGL and gusty outflow winds up to 40 kts. Surface winds generally WLY 8-13 kts, becoming SLY less than 10 kts overnight. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Slightly below normal temperatures Friday, then warming back this weekend into next week. Expect scattered showers and thunderstorms this afternoon into this evening with locally heavy rainfall/flash flooding the primary threat. A decrease in thunderstorm activity is expected Friday through the weekend as the area transitions into a low grade monsoon pattern. An eventual uptick in monsoon activity is expected next week but will be dependent on how quick the high pressure aloft shifts north. Winds generally light and under 15 mph with the exception of gusty and erratic winds up to 35-45 mph near any thunderstorms. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson |