Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
288 FXUS65 KTWC 060903 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 202 AM MST Sat Jul 6 2024 .SYNOPSIS...Excessive heat and hot temperatures through at least Tuesday, with high temperatures expected to approach record levels in some locations. Shower and thunderstorm chances will mainly be confined to south and east of Tucson through early next week as drier air overspreads Arizona from the north. && .DISCUSSION...Very little change in the forecast pattern and thinking versus 24 hours ago. A strong ridge of high pressure was currently centered over the northern California coast. This ridge will build slowly southeast through early next week, when it will be centered along the AZ/CA/NV borders. The models then show the high lifting northeast into Utah mid to late next week. This pattern will result in hot daytime temperatures and a low grade monsoon through early next week, with deeper moisture moving back into the region mid to late next week. The main story continues to be the EXCESSIVE HEAT and HOT daytime temperatures across southeast Arizona, with near record to record high temperatures. Have decided to extend the Excessive Heat (EH) Warning out through 8 pm MST Tuesday of next week. It may still need to go out even further depending upon how quickly moisture moves back into southern Arizona. At this time, the Excessive Heat Warning is in effect for all but Santa Cruz and Cochise counties and the mountain zones of southeast Arizona. During this time frame monsoon activity will be limited to mainly south/southeast of Tucson, across Santa Cruz and Cochise counties as the deeper moisture gets pushed south into northern Mexico and high pressure builds in from the northwest. GOES-16 Total Precipitable Water (PW) Imagery shows values currently around 0.67 inches in Tucson (0.81 inches on the KWTC 240706/00Z sounding), with 1.0-1.2 inches along the International Border and a very dry 0.20 inches in the White Mountains. The ensemble models indicate PW values will continue to lower through the weekend into early next week, when PW values will range from around 0.25 inches in the White Mountains to 0.5-0.7 inches across the rest of southeast Arizona and even much of northern Mexico. As the high shifts north and then northeast of the region mid to late next week, a more favorable moisture pattern returns to southeast Arizona and expect shower and thunderstorm chances to increase, as well as high temperatures to slowly decrease (but still remaining several degrees above normal levels). Model PW`s rebound to around 1" late next week. By next weekend, the models have the high centered over Colorado, with deep south/southeast flow across Arizona and PW`s increasing to 1.25-1.50" across southeast Arizona. && .AVIATION...Valid through 07/12Z. FEW-SCT clouds at 13k-15K ft AGL and BKN-OVC clouds AOA 20k ft AGL southeast of a Sells to KTUS to KSAD line thru 06/15Z, then diminishing cloud cover. Clear skies elsewhere. Between 06/18Z and 07/05Z, SCT-BKN clouds at 7k-10k ft AGL and ISOLD-SCT TSRA/SHRA mainly south and east of KTUS. MVFR conditions near TSRA, with mountain obscurations, VSBY restrictions and gusts to 40+ kts. Aft 07/05Z, gradual clearing thru the remainder of the forecast period. Outside of TSRA outflows, SFC wind 12 kts or less favoring a WLY/NWLY direction during the afternoon/early evening hours and variable in direction at other times. 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 south and east 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 10-17% range across the lower elevations and 14-25% in the higher elevations into the middle of next week. Hot high temperature are expected through at least Tuesday, 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. The exception will be in the upper Gila Rover valley near Safford on Sunday where northwest winds of 20-25 mph and higher gusts are expected. Early next week elevated wind speeds in the 15-20 mph range will be possible mainly to the east of Tucson. && .TWC WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning until 8 PM MST Tuesday for AZZ501-502-504>506- 509. && $$ Zell Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson