Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
148 FXUS65 KTWC 302023 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 123 PM MST Wed Sep 30 2026 .SYNOPSIS...The storm system responsible for heavy rain across Southeast Arizona the past couple days will exit the area this afternoon. A few light showers or rumbles of thunder cannot be ruled out mainly over the White Mountains and Chiricahua Mountains this afternoon. Otherwise, cooler and drier conditions will prevail for much of the area through the remainder of the week with breezy east to southeast winds picking up heading into the weekend. && .DISCUSSION...The final day of the official Monsoon Season has arrived! The main weather story today is gradual clearing as the storm system responsible for the recent heavy rainfall exits the area eventually ejecting into the southern and central plains. Still some residual moisture wrapping around the disturbance, so we can`t rule out a few light showers or rumbles of thunder over the White Mountains and/or Chiricahuas this afternon. However, with best forcing associated with the upper low now to our east and with a cooler, drier airmass moving in behind the disturbance the threat for heavy rainfall has ended. Thus, anything that develops would be light/showery in nature, associated with residual moisture, and would be forced from the terrain. Heading into the weekend we`ll see a drying trend take shape as a ridge of high pressure gradually builds across the Desert Southwest and into the Great Basin. Temperatures will remain below normal by 10-15 degrees for early October with an uptick in southeast breeziness over the weekend as a pressure gradient builds from higher pressure sliding down the front range of the Rockies. In fact, the latest NBM probability for sustained winds in excess of 25 mph across the valleys east of Tucson is generally 30 to 50 percent Friday into early next week, with the strongest probabilities Sunday and Monday. && .AVIATION...Valid thru 02/00Z. SCT-BKN 4-6k ft AGL BKN-OVC 9-12k ft AGL. Decreasing cloudiness expected gradually from west to east thru the afternoon. Can`t rule out a few stray -SHRA/-TSRA east/northeast of a KOLS to KE77 line, but confidence is low. SFC winds WLY/NWLY at 8-12 kts with gusts up to 22 kts thru 01/03Z becoming light and terrain driven thru 01/17Z. Tomorrow, SFC winds ELY/NELY at 8-12 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...The upper-level disturbance responsible for producing widespread heavy rainfall across Southeast Arizona Tuesday will exit the area today into New Mexico. There is enough residual moisture around for this system to produce a few light rain showers on its way out over the White Mountains and Chiricahuas, but confidence is low. Otherwise, a ridge of high pressure will take up residence across the region the second half of the week. Although this will provide dry conditions, it will also result in breezy east to southeast winds Friday into early next week. Afternoon high temperatures will be 10-15 degrees below normal again today, warming to only a few degrees below normal this weekend. Minimum RH values 35-55 percent in valley locations and 50-75 percent in the mountains today, generally lowering to 15-25 percent the second half of the week as drier air moves into the region. 20-foot winds will be less than 15 mph into Thursday, then gusty east to southeast winds Friday through early next week. && .HYDROLOGY...Still keeping a close eye on elevated flows observed on the Gila River near Duncan and Solomon as runoff continues from heavy rainfall over the last couple days. The Gila River near Duncan is forecast to remain near Action Stage through late this evening. Downstream near Solomon, the Gila River crested at 22.6 feet (Moderate Flood Stage) around 7 AM MST this morning but is forecast to remain above Flood Stage through 5 PM this afternoon. Downstream impacts could eventually reach Calva with a significant rise in the forecast potentially above Action Stage early tomorrow morning. But for now, we continue to collaborate with the Colorado Basin River Forecast Center (CBRFC) and local emergency management to closely monitor the situation and associated impacts. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ DVS Visit us on Facebook, X, YouTube...and at weather.gov/Tucson