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Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
709 FXUS65 KTWC 021502 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 802 AM MST Tue Jul 2 2024 .SYNOPSIS...Chances of showers and thunderstorms today through Wednesday, then gradually diminishing during the rest of the week. Some storms will generate strong winds and locally heavy rainfall. With high pressure building in from the northwest, daytime temperatures will be trending hotter Thursday into at least early next week. && .UPDATE...The morning KTWC sounding still pointing at a busy day for much of SE AZ. Precipitable water hanging in with 1.6 inches to go with surface dewpoints in the 60s. Modest convective inhibition that should be easily overcome with solid insolation through the morning hours. Good convective potential for valleys after an early start in the mountains, with initial development over higher terrain by late morning hours. We put out a minor update tweaking initial mountain convection a little earlier with broader valley support in the afternoon. Some of the storms will likely get frisky but we don`t have the shear to support more widespread organized convection. Possible convective complex in Sonora this evening. Please see the previous discussion below for additional details. && .PREV DISCUSSION... /issued 235 AM MST Tue Jul 2 2024/ Clear to scattered mainly high level clouds was over the area this morning under S/SW flow aloft per latest GOES-18 IR imagery. PW values this morning ranged from 1.3" east to 1.6" west with higher values over northern Sonora MX. For today, with more sun around versus previous days, expect most of the area seeing scattered showers and thunderstorms this afternoon/evening with main threats once again being strong gusty winds and brief heavy rain. Some CAMs are indicating Santa Cruz and Cochise counties could be the focus of more areal coverage of storms later today. There is some indication that outflows from storms in northern Sonora MX this evening will push north into the area later tonight developing some isolated elevated storms. Highs today at or a few degrees above normal. Wednesday will see reduced areal coverage of storms due to decreasing moisture values as high pressure aloft, building over California, turns flow aloft out of the N/NE. Still could see a minor rim shot mainly east of Tucson Wednesday evening. Highs similar to today. Thursday into early next week...Strong high pressure aloft building over CA/NV/AZ will be the driving force in drying out and heating the area up. Expect minimal thunderstorm activity each day with high temperatures heating up resulting in moderate to major heat risk criteria being met. The initialized NBM temperatures for Thu-Mon, in my opinion, are not hot enough. Looking at in house low-level thickness study, I went with the top end of the temperature spread, or the NBMs 95th percentile, for high temperatures, and they still may not be hot enough. Daily record highs will be approached starting Fri and continuing into early next week. Held off on hoisting an Excessive Heat Watch in this forecast package, but this is something for later shifts to consider. Looking out to 10 days, or next Thursday, Excessive Heat will continue. && .AVIATION...Valid through 03/12Z. FEW-SCT clouds at 9k-12k ft AGL and SCT-BKN clouds AOA 20k ft AGL thru 02/17Z, then SCT-BKN clouds at 7k-10k ft AGL thru the remainder of the forecast period. ISOLD-SCT TSRA/SHRA between 02/18Z and 03/05Z. MVFR conditions near TSRA, with mountain obscurations, VSBY restrictions and gusts to 40+ knots. Otherwise, outside of TSRA outflows SFC wind generally 10 kts or less, favoring a WLY/NWLY direction during the afternoon/early evening 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 east and south through the end of the week, with a slight chance of showers and thunderstorms along the International Border this weekend into early next week. High pressure aloft will build to our northwest late this week into early next week, which will result in drier and hot conditions. The deeper moisture will get pushed south and east of the region late this week into early next week, with Min RH values lowering into the 10-18% range across the lower elevations and 15-30% in the higher elevations. High temperature will warm considerably late this week through the weekend, 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 likely 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 the occasional gust of 20-25 mph. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson