Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
230 FXUS65 KTWC 211945 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 1245 PM MST Mon Jul 21 2025 .SYNOPSIS...Chance of showers and thunderstorms through Tuesday then drying out for most of southeast Arizona into next weekend. High temperatures generally below normal through Tuesday then heating up into the weekend. && .DISCUSSION...Showers and thunderstorms have had an early start today and latest KEMX radar imagery shows this activity continuing especially for locales south and east of Tucson. The storms today are certainly focused in the lower levels, below 20,000 ft and are efficient rainfall producers. This fits in well with the 18Z KTWC sounding which had more CAPE below 450mb with instability more marginal in the upper levels. Thus far, the storms have been relatively small in areal size but as daytime heating continues, thunderstorm coverage will tend to become a bit more numerous and expansive with a continued emphasis on locally heavy rain. Showers and thunderstorms should diminish this evening but as a weak 700- 500mb trough approaches tonight through Tuesday, we could see some lingering shower activity through the overnight. Meanwhile, Tuesday will be somewhat dependent on how much residual cloud cover remains. If there is adequate clearing, the focus will be on scattered showers and thunderstorms mainly from Sells eastward. If clouds or even light shower activity persists into Tuesday, that will put a damper on thunderstorm potential Tuesday afternoon. Drier air will then move in from the southwest Wednesday with any lingering thunderstorm chances mainly in the White Mountains with dry conditions elsewhere. This break in the monsoon with dry conditions and warming temperatures will continue into the weekend. Moderate HeatRisk will return with highs about 5 to 7 degrees above normal this weekend. Some modest moisture (and a return to some lower end PoPs) is expected to work its way back in as early as Sunday but more likely Monday. && .AVIATION...Valid through 23/00Z. SCT-BKN 8k-11k ft AGL thru the valid period. Expect SCT -SHRA/-TSRA thru 22/04Z with slight chances of -SHRA/-TSRA thereafter till 22/18Z before additional SCT -SHRA/-TSRA development thru end of valid period. Gusty and erratic winds up to 40 kts with any -TSRA. Otherwise, surface winds mainly under 12 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Below normal high temperatures through Tuesday then heating up into next weekend. Typical monsoon activity continues through Tuesday, then more pronounced drying and warming Wednesday into the weekend. Afternoon winds will remain southwesterly to westerly at 10-15 mph, with occasional gusts at or above 25 mph. Afternoon RH values in the valleys will be 20-40% through Tuesday and higher in the mountains before drying considerably with Min RH values of 10-20% in the valleys and 15-30% in the mountains. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson