Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
008 FXUS65 KTWC 241038 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 338 AM MST Tue Jun 24 2025 .SYNOPSIS... Increasing moisture today will bring chances for showers and thunderstorms this afternoon and evening. Highest chances will be in Cochise county into Graham and Greenlee counties with just slight chances as far west as Tucson to Nogales. Additional shower and thunderstorm chances are possible each afternoon through this week mainly closer to the New Mexico border. && .DISCUSSION... Southwest flow remains in place over southeastern Arizona today between a trough base sitting over southern California and a broad upper ridge centered over the mid-Atlantic. This southwesterly flow has drawn rich moisture up from Mexico through New Mexico into the central plains, creating a moderate risk of excessive rainfall in New Mexico today from WPC. While the majority of this moisture feed will remain to the east, low to mid level flow becoming increasingly southerly over northern Mexico this morning will bring increasing precipitable water values into southeastern Arizona, especially over far eastern and southern areas. Current (10Z) GOES derived precipitable water observations depict 1-1.3 inch values from the southern Cochise county border south through northern Sonora Mexico. By mid-day today models indicate this moisture should be well into southeastern Arizona, generally near and east of a Dudleyville-Tucson-Nogales line. A few light isolated showers may develop this morning along the push of moisture into southeastern Arizona as depicted by recent HRRR runs, though more likely the morning result of this moisture will remain ACCAS and virga. With increasing instability by early this afternoon, isolated to scattered showers and thunderstorms should develop in the aforementioned area of moisture and push north. Tucson to Nogales will be on the western periphery of this moisture field, therefore see the lower end of shower and thunderstorm probabilities today as well as potential rainfall rates. Further east through Cochsie and into Graham and Greenlee counties MUCAPE values increase to 500-850 J/kg and subsequently the 00Z HREF LPMM (local probability matched mean) includes pockets of moderate rainfall rates. Though overall flooding threats are low, southeastern Cochise county will likely be under the overlap of richer moisture and corridor for multiple rounds of rain as convection should move in from Sonora in the evening, which may pose a modest flooding risk in low and flood prone areas. Gusty outflow winds may also accompany any stronger storms, however severe winds are unlikely. A similar pattern aloft remains over the coming days, with some variance in moisture quality and therefore precipitation chances. Guidance pushes moisture east on Wednesday with any convective chances kept to Cochise, Graham, and Greenlee counties. A similar precipitation outlook returns on Thursday as recent model runs have trimmed back the western edge of the moisture field away from Pinal through eastern Pima and Santa Cruz counties. By the end of the week the upper level pattern will become a more diffuse after the previous trough lifts away from the region, reducing confidence in day to day chances as moisture quality will depend on outflows and previous days activities. Drier conditions are likely this weekend with the loss of the previous upper level pattern. As mid-level heights rise with the exiting of the upper trough, temperatures will rise to above normal again by the weekend. With the ridging process the upper high should become oriented over the southwest CONUS next week, potentially centered over the Four Corners. While this would be a favored location to usher in good monsoon moisture, there are still some differences in global model ensemble members on the orientation of this ridge, which adds some uncertainty at this time regarding exact timing of moisture arrival. && .AVIATION... FEW-SCT ceilings at 9k-13k through the period with decreasing coverage after 25/03Z. Scattered showers and thunderstorms near and east of a KSAD-KFHU line after 24/18Z with isolated showers and thunderstorms near KOLS-KTUS. Activity diminishing near KTUS- KOLS after 25/00Z, lingering through the evening in eastern terminals including near KSAD-KDUG. Brief periods of MVFR visibility and gusts to 40 kts possible under showers and thunderstorms. Winds today otherwise generally light and southwesterly up to 12 kts with a few afternoon gusts to 20 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER... Increasing moisture today in eastern zones, especially across Cochise, Graham, and Greenlee county will keep minimum relative humidities above 20 percent. Minimum values 10-20 percent west of this area. This moisture will bring chances for showers and thunderstorms this afternoon and evening, with a slight chance as far west as Tucson to Nogales. Winds turn southwest and remain generally light and under 15 mph, though brief gusty and erratic winds possible with any thunderstorm. Chances for showers and thunderstorms return daily this week but mainly for far eastern areas closer to the New Mexico border. Conditions likely dry this by this weekend as temperatures rise above normal. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Public...Edwards Aviation...Edwards Fire Weather....Edwards Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson