Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
852 FXUS65 KTWC 161648 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 948 AM MST Wed Jul 16 2025 .SYNOPSIS... Another active monsoon day is expected once again today, with the primary threat of flash flooding. && .KEY MESSAGES... - Prior monsoon conditions, including persistent cloud cover, are likely to limit solar heating today. This should suppress convective potential to some extent, leading to more isolated and weaker thunderstorms that will be slower to initiate. Any precipitation will generally favor higher terrain areas, with localized downpours still capable of posing a flash flooding threat. - A low to moderate HeatRisk remains in place for the week, and the WPC has placed the region in a Marginal Risk for excessive rainfall today. && .DISCUSSION... Residual rainfall over much of Pima County, including the TO Nation, associated with an MCV continues this morning. Cloud cover and precipitation activity may act to inhibit widespread convection this afternoon and evening, but isolated thunderstorms are likely, especially in Northern parts of Graham and Greenlee counties and south of Tucson. Localized flooding remains the main threat with any storms that form. At the current time, we have a flood warning out for the Catalina Foothills area including Finger Rock and a Flood Advisory for areas including Oro Valley and Picture Rocks. Temps will struggle to make it out of the mid-90s at most locales today due to the cooling effect the widespread precipitation. Otherwise, the thing to focus on is safety when traveling across the region, especially in and around the Tucson Metro area. Several road closures have been reported at low water crossings and the like. Have a plan in place if you encounter any of these. Turn around don`t drown! && .PREV DISCUSSION... /issued 237 AM MST Wed Jul 16 2025/ .SYNOPSIS... An active monsoon pattern will continue today, with the potential for severe thunderstorms being more limited than yesterday due to recent active weather, but a primary threat of flash flooding still exists. && .KEY MESSAGES... - Prior monsoon conditions, including persistent cloud cover, are likely to limit solar heating today. This should suppress convective potential to some extent, leading to more isolated and weaker thunderstorms that will be slower to initiate. Any precipitation will generally favor higher terrain areas, with localized downpours still capable of posing a flash flooding threat. - A low to moderate HeatRisk remains in place for the week, and the WPC has placed the region in a Marginal Risk for excessive rainfall today. && .DISCUSSION... While severe thunderstorm activity initially began in the early afternoon yesterday, storm intensity did not ramp up until well into the evening hours. With the high pressure associated with these storms moving east into the four corners region, widespread but light precipitation currently persists and will into the early morning hours of Wednesday. CAPE values reaching up to 500 J/kg in localized areas are expected, sufficient for some convective development, yet significantly lower than yesterday`s values. The highest probabilities for severe weather are concentrated near the New Mexico border. Enhanced wind fields are also focused along this corridor, though guidance suggests a limited threat. That said, 24-hr precipitation totals highlight isolated yet notable potential, with ensemble probabilities indicating a 10-20% chance of exceeding 2 inches of rainfall produced by the strongest storms in select locations. These include the Tucson metro and areas south and east. The primary threat today will be heavy rainfall and the potential for flash flooding if the residual cloud cover from the current MCS does not inhibit convection. Have a plan when it comes to encountering flash flooding. Turn around, don`t drown. Looking ahead to Thursday and Friday, CAPE values will gradually increase, but lower precipitable water content on Thursday will limit day two thunderstorm activity. 24 hour precipitation greater than one inch is limited to a 10% probability late Thursday/early Friday for southern Pima County. There will be some day to day variability in high temperatures over the next week, but generally expect them to be within a few degrees of normal for this time of year. HeatRisk will remain low to moderate for the rest of the week. A drier period is likely to set in at some point in the next week, but it is highly uncertain when this will be. This is because there is low predictability in the evolution of a closed upper low off the Baja coast over the next several days. && .AVIATION...Valid through 17/12Z. SCT-BKN 6-12k ft AGL through the period. Isolated to scattered TSRA/SHRA are expected after 16/20Z for portions of southeast Arizona. Wind gusts of 40-50 kts are possible with the thunderstorms today, especially near KSAD. Otherwise, SFC winds mainly less than 12 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER... A more active monsoon pattern continues the next couple of days. Deeper atmospheric moisture moving into the region will bring the potential for locally heavy rainfall and flash flooding today. Temperatures will be slightly cooler than normal today and Thursday, then near normal late this week. Winds will remain westerly from 10-15 mph, with occasional gusts at or above 25 mph. Afternoon RH values in the low lying areas will be 20-30% through the remainder of the week. && && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Public...Singer/Dang Aviation...Singer/Dang Fire Weather....Singer/Dang Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson