Forecast Discussion
377 FXUS65 KTWC 092016 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 116 PM MST Sun Aug 9 2026 .SYNOPSIS...Expect daily chances of showers and thunderstorms much of this week. While there will be day to day variability, Monday and Wednesday look to be the most active days. Storm coverage will Friday through next weekend. High temperatures this afternoon will run 5 to 8 degrees above normal, lowering to near normal Monday and Tuesday with additional lowering to around 3 to 6 degrees below normal Wednesday and Thursday before temperatures warm again. && .DISCUSSION...Visible satellite imagery shows cumulus cloud development this afternoon across the higher terrain of southeast Arizona. The area is under easterly flow aloft with mid/upper level high near the Four Corners. Still plenty of moisture for much of southeast Arizona with PWAT around 1 to 1.5 inches, highest values west. Cochise County PWAT is a bit lower in the 0.7 to 0.9 inch range and that area will struggle most with convection this afternoon into evening. CAMs are showing two primary areas of storms developing this afternoon, the first being south to southwest of Tucson close to the Int`l border and another area moving off the White Mountains with storm movement today towards the west. Given the ample surface heating, elevated DCAPE values will support gusty winds in excess of 50 mph with the strongest storms. In fact, the HREF has an area of 10% 40-km neighborhood probability of 50 kts from Tucson westward with a smaller area of 30 percent over central and western Pima County. These strong winds will also result in areas of blowing dust due to strong outflows. In addition to the gusty winds, a few storms may cluster west of Tucson resulting in isolated flash flooding potential into the evening hours. Monday is shaping up to be a bit more active than today as easterly flow aloft continues with PWAT values ticking up slightly compared to today and modest mid/upper level support for storms. This will result in another round of showers and thunderstorms for most of southeast Arizona, with the highest chances from Tucson westward. WPC has highlighted the area in a SLGT risk of excessive rainfall and that looks good. HREF has a widespread area of greater than 50% 40-km neighborhood probability of 3-hr QPF of 1 inch or greater. While there is still some uncertainty on storm mode for Monday, and whether storms stay more discrete or become more clustered resulting in heavier rain potential especially into the evening, felt it was prudent to highlight the potential for heavy rain by hoisting a Flash Flood Watch from Tucson area westward from 2 PM to 10 PM. In addition to the flash flood threat, severe winds will also be a threat with considerable DCAPE and even around 20-30 kts of 0-6km bulk shear brining the potential for small hail as well. Given the wind potential, added in areas of blowing dust north and west of Tucson into the forecast. The active pattern will persist Tuesday and Wednesday with Wednesday still looking like a more active day as a disturbance in northern Sonora may help aid storm development then. Thereafter, as southwest flow moves in starting Thursday, that will shift storm chances from about the Tucson area eastward Thursday, then generally near the NM border Friday through next weekend with most of SE Arizona remaining dry those days. Temperatures will lower to near normal levels Monday and Tuesday, then to about 3 to 6 degrees below normal Wednesday and Thursday, with warming thereafter to above normal values for next weekend. && .AVIATION...Valid thru 11/00Z. ISOLD-WDLY SCTD -SHRA/-TSRA with clouds 8-12k ft AGL, mainly west of a KSAD-KOLS line into this evening and then again Monday afternoon for much of SE Arizona. Gusty erratic winds of 35-45 kts possible with any thunderstorm. Outside of storms SFC winds WLY/NWLY at 8-12 kts with occasional afternoon gusts to 20 kts this afternoon and evening. SFC winds light and terrain driven after 10/06Z thru 10/18Z with WLY/NWLY winds resuming thereafter. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect daily afternoon and evening showers and thunderstorms through Thursday with less coverage Friday into n ext weekend. Minimum relative humidity will be 20-40 percent Monday through Thursday lowering to around 15-30 percent thereafter. Temperatures will be near normal through Tuesday, dropping to below normal Wednesday and Thursday, then warming again next weekend. Outside of thunderstorms, winds terrain driven to around 10 mph with occasional afternoon gusts to 20 mph. && .TWC WATCHES/WARNINGS/ADVISORIES... Flood Watch from Monday afternoon through Monday evening for AZZ501>506-514-515. && $$ Visit us on Facebook, X, YouTube, and at weather.gov/Tucson
NWS TWC Office Area Forecast Discussion