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Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
993 FXUS65 KTWC 181044 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 344 AM MST Thu Jul 18 2024 .SYNOPSIS...Temperatures will remain 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 thunderstorm activity across southern Cochise and Santa Cruz counties continue to linger at the time of this writing forming off outflows from evening convection in Sonora. CAMs have somewhat struggled on resolving this and similar activity over the past few nights, but anticipate it gradually diminishing as it pushes west into south central Pima county this morning. PWATS are currently running around normal for this time of year at around an inch near the NM state line to around 1.3 inches in the Tucson Metro to around 1.5 inches across western Pima county. The overall upper air pattern over the past couple of days has been characterized by a mid/upper level high drifting west over AZ/NM. The flow pattern resulting from the high is currently easterly/southeasterly, but as the high continues to meander northwest over the next few days we will see the flow pattern gradually becoming more easterly/northeasterly heading into the weekend. The northeasterly flow regime favors storms forming off the higher terrain/Mogollon Rim and then propagating into the lower deserts of Southeast Arizona through the late afternoon hours. Right now, Saturday and Sunday appear to be the best chances for convection of that nature. For today, HREF/CAMs are depicting scattered showers and thunderstorms primarily forming over Santa Cruz and southeastern Pima counties this afternoon as well as in the White Mountains and elevated terrain. The main concerns with these storms continues to be gusty outflow winds and locally heavy rainfall leading to the possibility for isolated occurrences of flash flooding. Temperatures will be a degree or two warmer across southeast Arizona today and tomorrow resulting in isolated areas of major HeatRisk. Decided to hold off on heat related products at this time as there is not enough widespread Major HeatRisk to warrant a headline. && .AVIATION...Valid through 19/12Z. SCT-BKN clouds at 8k-12k ft AGL gradually diminishing from east to west after 18/12Z and forming again after 18/19Z associated with SCT TSRA/SHRA development. MVFR conditions in TSRA, with mountain obscurations, vsby reductions, and wind gusts to 40+ kts. Outside of TSRA, SFC winds at most locations will remain under 12 kts favoring SWLY thru NWLY directions 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 20-25 mph and light winds overnight. Wind direction during the afternoon will primarily be southwest through northwest into the weekend. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ DVS Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson