Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
808 FXUS65 KTWC 170950 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 250 AM MST Wed Jul 17 2024 .SYNOPSIS...Temperatures 4 to 7 degrees above normal through the rest of this week, with typical mid July moisture levels across the region. This will result in the daily chances for showers and thunderstorms. The main threats will continue to be strong gusty outflow winds and heavy rainfall leading to localized flash flooding. && .DISCUSSION...Residual showers and embedded thunderstorms continue early this morning to the west of Tucson. Much of this activity has formed on the outflow from a weakening MCS in far northern Sonora. It`s a bit difficult to discern at this juncture but it appears there is an MCV to the south of Nogales. CAMs have been struggling to pick up on this activity but regardless, expect it to trend downward through the early morning hours. The overall larger scale pattern remains quite persistent for our region as the mid/upper level high remains to our northeast, to the south of the Four Corners along the AZ/NM border. That continues to result in mid level easterly flow. Moisture levels are certainly adequate ranging from around 1 inch PWAT near the NM border to 1.5 inch over western Pima County. These levels are close to normal for this time of year. HREF/CAMs show scattered showers and thunderstorms developing mainly to the south and east of Tucson this afternoon, attempting to push west courtesy of outflows into the lower elevations/deserts this evening but confidence is low on how much storm activity there will be. There isn`t very much discernible in terms of disturbances/perturbations in the flow to hang our hat on today. Regardless, as we`ve seen over the past couple of days, there will continue to be a threat for gusty winds and localized flash flooding. Over the next few days and into the weekend there will be some minor changes to the flow pattern. The mid/upper level high to our north will begin to shift westward and slightly strengthen as it does so. Not much change to our easterly steering Thursday and perhaps Friday but by this weekend and into next week, northeasterly flow will dominate and that is a favorable direction for bringing storms off the Mogollon Rim/White Mtns into the lower elevations. Meanwhile, temperatures will nudge upward slightly, peaking Saturday about 5 to 8 degrees above normal. A few locales mainly to the north and west of Tucson will be teetering close to major Heat Risk levels so this is something we`ll be keeping an eye over the next couple of days. && .AVIATION...Valid through 18/12Z. BKN-OVC clouds 8-12k ft AGL south and west of KTUS will tend to diminish aft 17/12Z. Elsewhere, SKC-SCT clouds this morning. SCT-BKN clouds redevelop again aft 17/18Z, with diminishing cloud cover aft 18/05Z. SCT TSRA/SHRA thru 17/12Z west of KTUS. Otherwise, SCT TSRA/SHRA developing again for much of the area aft 17/19Z. MVFR conditions in TSRA, with mountain obscurations, vsby reductions and wind gusts to 40+ knots. Outside of TSRA, SFC wind at most locations 12 knots or less favoring a SWLY thru NWLY direction during the afternoon/early evening hours and variable in direction at other times. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Deeper moisture remains across southeast Arizona, with typical mid July moisture levels expected through at least the upcoming weekend. This will result in the daily cycle of mainly afternoon and evening showers and thunderstorms. The main threats will be strong, gusty and erratic outflow winds and heavy rainfall leading to localized flash flooding. Minimum relative humidity values will be 20-30 percent in most lower elevation locations and 25-40 percent in mountain areas. Away from thunderstorms, 20-foot winds will generally be 15 mph or less, with afternoon/early evening gusts to around 20 mph and light winds overnight. Wind direction during the afternoon will primarily be west to northwest into the weekend. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson