Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
787 FXUS65 KTWC 271930 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 1230 PM MST Mon Jul 27 2026 .SYNOPSIS... Expect daily afternoon and evening showers and thunderstorms this week with day to day variability in coverage and strength. High temperatures will be 2-6 degrees above normal through the middle of this week then warm to 7-12 degrees above normal late this week into next weekend. && .DISCUSSION... Cumulus and towering cumulus are beginning to form along the terrain. Suitable moisture is in place with satellite derived PWATs around 1.0 to 1.75 inches, higher values Sells westward. High pressure overhead is centered over New Mexico and western TX today leading to southeast flow in the mid levels helping to pull moisture in from the Gulf of California. As surface heating continues today and low level drying occurs, an inverted V sounding will develop leading to DCAPE values around 1500 to 1700 J/kg. There will be a fair bit of mid-level shear as well, 25 to 35 kts, with decent updraft helicity thus there is the potential for strong, longer- lived storms to develop. Storms today will be focused to the Arizona/ Mexico international border and the Arizona/ New Mexico border. Stronger storms more likely be located along the Arizona/ Mexico international border. CAMs continue to have storms beginning to develop between 12 and 2 pm, initially on the higher terrain then moving west to northwest. Tomorrow, most of the ingredients seen today will be present. Mid level shear will remain elevated at 25 to 35 kts, DCAPE of 1500-1800 J/kg, and PWATs between 1.0 to 1.6 inches. Storms again will be focused to the Arizona/ Mexico international border and the the Arizona/ New Mexico border. Wednesday, chances for storms and showers begin to diminish as the high pressure center begins to move westward. By Thursday, high temperatures will be 7 to 12 degrees above normal leading to Major to Extreme HeatRisk. Therefore, an Extreme Heat Warning has been issued for most of southern Arizona (with the exception of the higher terrain) from Thursday morning through Sunday evening. At this level of HeatRisk, everyone should take proper precautions to prepare for the heat as anyone is at risk for heat related illnesses if not staying hydrated or cool. Friday and Saturday look to be the hottest days in the forecast during this stretch, with a 55% to 65% chance of 110 degrees for locales Tucson westward both days. Chances for storms and showers returns early next week as the center of high pressure oscillates eastward. && .AVIATION...Valid though 30/00Z FEW to SCT clouds AOA 10-12k ft AGL KTUS eastward becoming SCT to BKN 8-12k ft AGL aft 28/00Z. Isold to sct TSRA will be possible south and east of KTUS starting around 27/20Z through 28/04Z. KDUG and KOLS terminals will be most at risk of being impacted by TSRA. Any thunderstorm may produce wind gusts in excess of 40 kts. Outside of storms surface winds variable less than 8 kts this morning becoming NWLY 6-10 kts with occasional gusts this afternoon and evening. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER... High temperatures will remain above normal this week. Expect daily chances of afternoon and evening showers and thunderstorms with day-to-day variability on coverage of storms. Any thunderstorm will bring a threat of severe, erratic wind gusts as well as brief heavy rainfall and an isolated threat of flash flooding. Minimum relative humidity values will be 20-40 percent in the lower deserts through at least mid-week. Winds this weekend will mainly be light and under 12 mph outside of thunderstorms. && .TWC WATCHES/WARNINGS/ADVISORIES... Extreme Heat Warning from 8 PM Saturday to 8 PM MST Sunday for AZZ501>509. && $$ Malarkey Visit us on Facebook, X, YouTube, and at weather.gov/Tucson