Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
619 FXUS65 KTWC 041606 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 906 AM MST Thu Jul 4 2024 .SYNOPSIS...Chances of showers and thunderstorms will diminish into the weekend as drier air pushes down from the north. With high pressure building in from the northwest, daytime temperatures will be trending hotter into much of next week. Temperatures are expected to approach record levels in some locations. && .UPDATE...The moisture gradient is tightening as high pressure building in from the northwest brings a flow reversal and pushes the deeper moisture further south. Precipitable water values from around 1 to 1.2 inches north of Tucson and 1.3 to 1.5 inches from Tucson southward; ramping up to 1.7 inches just south of the border. Surface dewpoints will likely crash into the 30s or even lower this afternoon across portions of Graham, Greenlee and Pinal counties, with room for the Tucson area to again mix out into the 40s this afternoon. Any storms should be south and southeast of Tucson today as the mid level drying eats away our convective potential, with increasing chances as you near the international border. Minor updates to further reflect these trends and tweak temps up a little today. Please see the previous discussion below for additional details. && .PREV DISCUSSION... /issued 310 AM MST Thu Jul 4 2024/ Satellite imagery this morning showed plenty of convective debris clouds from Sonoran storms moving across the area. PW values on last evening Tucson sounding was down to just above 1" as drier air continues to push in from the N as high pressure aloft slowly builds in from the NW. Main forecast theme for the next 5 to 7 days will be a low grade monsoon pattern, with activity mainly S and E of Tucson, while temperatures heat up with near record highs tomorrow and Saturday, and possibly hotter the first half of next week with record to near record highs. Forecast highs next week are using the recommended initialization which may not be hot enough especially when compared to deterministic GFS/ECMWF/Canadian and GEFS/EPS/GEPS low-level thickness values. Thus left the current Excessive Heat (EH) Warning for tomorrow and Saturday with later shifts likely adding next week to the EH warning. There is a slight, less than 10%, chance that Tucson may tie the all-time July high temperature, which is 114 degrees, next Monday and/or Tuesday. && .AVIATION...Valid through 05/12Z. BKN-OVC high cirrus clouds AOA 20k ft AGL thru 04/15Z, then diminishing cloud cover. Between 04/18Z and 05/05Z, SCT-BKN clouds at 7k-10k ft AGL and ISOLD-SCT TSRA/SHRA. MVFR conditions near TSRA, with mountain obscurations, VSBY restrictions and gusts to 40+ kts. Aft 05/05Z, gradual clearing thru the remainder of the forecast period. Outside of TSRA outflows, SFC wind less than 10 kts and variable in direction thru 04/18Z and again aft 05/04Z. SFC wind between 04/18Z and 05/04Z WLY/NWLY at 8-15 kts and gusts to 15-25 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...There will be the daily chance for isolated to scattered showers and thunderstorms mainly from Tucson east and south into early next week. High pressure aloft will build to our northwest through the weekend into early next week, which will result in hot conditions. With the hotter temperatures and some of the deeper moisture getting pushed to the south and east of the region, min RH values will lower into the 10-18% range across the lower elevations and 15-30% in the higher elevations through early next week. Hot high temperature are expected into early next week, with highs 106-113 degrees from Tucson westward and in the Gila River Valley, and in the upper 90s to 105 degrees across Santa Cruz and Cochise counties. Excessive Heat will be an issue during this time frame. Outside of any thunderstorm outflow winds, 20-foot winds will generally be 15 mph or less each afternoon with occasional gusts to 20-25 mph through the weekend. Early next week there will be the potential for more elevated wind speeds in the 15-20 mph range, especially east of Tucson. && .CLIMATE... Record or near record high temperatures tomorrow and Saturday Date Jul 05 Jul 06 FCST RCD/YR FCST RCD/YR Tucson Intl Airport 110 111/2018 110 110/2023 Organ Pipe Cactus 111 115/1983 110 113/2018 Picacho Peak 112 113/2007 112 113/2005 Safford Ag Station 107 109/2007 106 109/2023 && .TWC WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning from 11 AM Friday to 8 PM MST Saturday for AZZ501-502-504-505. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson