949 FXUS65 KTWC 072034 AFDTWCArea Forecast Discussion National Weather Service Tucson AZ 134 PM MST Sun Sep 7 2025
.SYNOPSIS...Drying trend commences today with only slight chances of precipitation today and tomorrow focused on the higher terrain, with mostly dry conditions Tuesday. Breezy winds Wednesday and Thursday along with some increased moisture will result in slight chances for showers and thunderstorms Wednesday and Thursday, especially east of Tucson. Most of the week will have near normal temperatures.
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.KEY MESSAGES... - A drying trend leading to only slight chances (15-20%) of isolated showers and thunderstorms mainly along the higher terrain over the next few days. - Better moisture and forcing mid to late week will allow for some increased shower and thunderstorm chances (20-40%) and gusty afternoon winds (20-35 mph), strongest Wednesday-Thursday - Temperatures remain near normal throughout the week.
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.DISCUSSION...
Latest trends and models still indicating isolated showers and thunderstorms developing along the higher terrain today, mainly south and east of Tucson. Any storms that do develop will be moving slowly southeast and may be capable of producing locally heavy downpours. Not anticipating any significant impacts with any showers or storms that develop today though. Similar conditions tomorrow with what little chances (10-20%) we have remaining mostly confined to the higher terrain. Mostly dry conditions expected Tuesday.
Over the next few days we will transition from a more ridge dominate pattern to a more fall-like pattern. Currently we`re under weak northwesterly flow associated with a short amplitude ridge overhead. By late Tuesday-Wednesday we will begin to be influenced by a feature upstream, an upper low currently circulating near 40N, 135W off the Pacific Northwest coast. This upper low will dig into CA/NV over the next several days, leading to increased southwest flow across AZ. This will lead to noticeably breezy to gusty afternoon winds Wednesday-Thursday, with gusts to around 20-35 mph. In addition to increased winds, the added upper-level lift supplied by the upstream low and southerly flow will aid in enough moisture that our chances of precipitation increase a bit Wednesday-Thursday as well mainly from Tucson east. As the low continues to dig into AZ, drier southwesterly flow will dominate much of southeastern AZ by Friday, leaving us mostly dry again.
Unfortunately this fall-like pattern won`t influences our apparent temperatures too much, only slightly nudging temperatures down a couple of degrees. Overall temperatures will remain near seasonal normals through the next 7 days.
Looking beyond Friday, the upper low is progged to weaken as it lifts across the Rockies through the weekend, keeping mostly dry air in place with weak flow aloft.
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.AVIATION...Valid through 08/00Z.
Isolated showers and thunderstorms (-SHRA/-TSRA) mainly focused on the higher terrain today and tomorrow, will likely remain in the vicinity of KOLS, with low confidence impacting the terminal directly today. With any storms today expect variable and gusty winds to around 30-35 knots. Besides storm influences, winds should remain fairly light, generally less than 10-12 knots, favoring northwesterly directions through the afternoon and resuming typical overnight drainage patterns.
Aviation discussion not updated for TAF amendments. &&
.FIRE WEATHER...Minimum relative humidities 25 to 50 percent today, lowering to 15 to 30 percent much of next week. Drier air today in the valleys with just enough moisture for a slight chance of showers and thunderstorms focused in the higher terrain. Similar trends tomorrow with most locales staying dry Monday and Tuesday with slight chances of showers and thunderstorms mainly over the higher terrain. Thereafter, some moisture returns for a slight chance of showers and thunderstorms mainly east of Tucson mid to late week before drying resumes again Friday into next weekend. Expect gusty and erratic winds in or near any thunderstorms. Otherwise, surface winds will be mostly light through Tuesday, with breezy to gusty winds Wednesday- Thursday, bringing gusts to around 20-35 mph. High temperatures near normal for most of this week.
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.TWC WATCHES/WARNINGS/ADVISORIES... None. &&
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Discussion...Peters
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