Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
766 FXUS65 KTWC 020946 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 246 AM MST Wed Jul 2 2025 .SYNOPSIS...Monsoon moisture has arrived in Southeast Arizona. Scattered to numerous thunderstorm activity develops midday Wednesday and continues into the evening with a heavy rain and localized flash flood threat along with gusty outflow winds with areas of blowing dust. A drying trend is expected for the July 4th holiday and this weekend with storm coverage more isolated and focused on locales south of Tucson. Temperatures will drop to near normal levels today, then below normal to end the week before warming back up to above normal levels this weekend into early next week. && .DISCUSSION...An active Wednesday is shaping up for much of our forecast area. In the very near term, we still have some leftover convection early this morning generally across the T.O. Nation into Pinal County. These showers and embedded thunderstorms are producing locally heavy downpours. The CAMs have struggled to pickup on this activity that is being driven by a combination of residual outflows, mid level stretching deformation and upper level divergence ahead of a trough near the southern California coast. We anticipate this activity will gradually subside over the next few hours. Things are still on track for a busy monsoon day today. We`re continuing to see an increase in lower level moisture from Sonora and the Gulf of California with surface dewpoints generally in the mid 50s and PWATs ranging from about 1.1 to 1.4 inches. HREF and UofA WRF CAMs are in good agreement that we`ll see convective initiation around midday from the Tucson area southward into Santa Cruz County and then spreading outward from there off of outflows as individual storms tend to move slowly towards the west. The Flash Flood Watch previously issued continues to look good with 50-90% HREF 40-km 3 hour neighborhood probabilities of 1 inch or more from the Tucson area southward, and 10-20% neighborhood probabilities of 3 inches or more in Santa Cruz and south central Pima county. We also went ahead and hoisted a Blowing Dust Advisory from 1 PM to 7 PM for the Tucson Metro, T.O. Nation and south-central Pinal County as DCAPE values remain elevated at around 1000-1500 J/KG. These values are sufficient to create strong outflow winds to produce blowing dust out ahead of the heavier rain cores. While the bulk of the stronger storms will be during the afternoon into early evening, shower activity with some embedded thunderstorms could persist into the overnight hours tonight. While PoPs remain elevated on Thursday in the 30-60% range, if the activity today ends up being as widespread as expected, the atmosphere will be a bit worked over reducing the heavy rain threat compared to today. A more pronounced drying trend will commence on Friday as the combination of drier air aloft and high pressure centered to our south will result in much diminished shower and thunderstorm activity. Most locales will stay dry for July 4 celebrations with the highest PoPs around 15-30% from Tucson southward. For the weekend, a drying and warming trend with no mentionable PoPs by Sunday as high pressure aloft builds across the region bringing back hotter temperatures. Ensembles show the high nudging back northward next week which should reintroduce southeast AZ back into more favorable east to northeast flow to return some moisture. && .AVIATION...Valid through 03/12Z. SCT-BKN 7-12k ft AGL from KTUS westward thru 02/13Z, otherwise SCT-BKN 12-15k ft AGL early this morning, then SCT-BKN 5-10k ft AGL aft 02/18Z thru the end of the valid period. Scattered to numerous SHRA/TSRA will occur mainly 02/18Z-03/04Z with CIGS BKN 5-8k ft AGL. Storms that develop this afternoon and evening will also produce gusty outflow winds greater than 35 kts with reduced visibility due to localized BLDU. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Near to slightly below normal temperatures through Saturday as deeper atmospheric moisture moves into Southeast Arizona, then warming back up Sunday into early next week. Expect scattered to numerous showers and thunderstorms this afternoon into evening with locally heavy rainfall. Shower and thunderstorm chances persist Thursday, then some drying will tend to lower thunderstorm chances to around 15 to 30 percent Friday into the weekend with the highest chances along the Int`l border. Winds generally light and under 15 mph with the exception of gusty and erratic winds up to 35- 45 mph near any thunderstorms. && .TWC WATCHES/WARNINGS/ADVISORIES... Flood Watch from 11 AM MST this morning through this evening for AZZ502>504-507-513>515. Blowing Dust Advisory from 1 PM this afternoon to 7 PM MST this evening for AZZ502-504-505. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson