Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
413 FXUS65 KTWC 152034 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 134 PM MST Mon Jul 15 2024 .SYNOPSIS...Temperatures slightly 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...Area radars indicate scattered shower/thunderstorm development mainly east/southeast of Tucson and in the White Mountains attm. Movement of the storms was west at 5-10 mph. The GOES-16 ECONUS Total Precipitable Water (PW) imagery continues to show values ranging from near 0.75 inches in the White Mountains, to around 1 inch in Cochise/Graham counties to over 1.50 inches in central/western Pima County. The U of A WRF and SPC HREF models both indicate the areas south/southeast of Tucson to be the most active today, shifting into central Pima County during the evening hours tonight. As for the Tucson metro area, both of these models have minimal convection occuring across Tucson today. However, both models do bring convection into far eastern/southeastern Pima County between 4-6 pm today, so if any organization of these storms takes place, or propagation along outflow boundaries occur, then convection will be a possibility in Tucson. Otherwise, a typical mid July monsoon pattern will continue through the rest of the work week. The mid/upper level high will meander between the Four Corners and west Texas, which keeps southeast Arizona in a favorable east/southeast moisture transport regime. The biggest uncertainty will be the day to day variability in shower and thunderstorm coverage, any big days versus down days, and the amount of debris clouds delaying convection initiation. Overall, each day this week will have the potential for mainly afternoon and evening showers and thunderstorms. By this weekend, an amplified ridge builds across the western United States and the mid/upper level high becomes centered to our north over the Great Basin. This is still a favorable position for monsoon activity across southeast Arizona, although as the mid level flow shifts to more of a northeasterly direction, thunderstorms may have a greater potential of moving off the rim into the lower deserts. High temperatures will be near normal today and then 2-4 degrees above normal through the weekend. The main concerns this week will continue to be the strong, gusty outflow winds and areas of heavy rainfall leading to localized flash flooding. && .AVIATION...Valid through 17/00Z. SCT-BKN clouds at 8k-12k ft AGL thru 16/04Z and again aft 16/18Z, with diminishing cloud cover between 16/04Z and 16/18Z. SCT TSRA/SHRA thru 16/04Z, mainly south/southeast of KTUS and in the White Mountains. SCT TSRA/SHRA developing areawide again aft 16/19Z. 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. The exception will be in the upper Gila River valley near KSAD where WLY/NWLY SFC wind will be 15-19 kts with gusts to 28 kts thru 16/04Z and again aft 16/18Z. 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 will primarily be southwest through northwest through most of the week. The exception will be in the upper Gila River valley around Safford, where afternoon/early evening winds will be west-northwest at 15-20 mph and gusts to 25-30 mph through Tuesday. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Zell Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson