Damaging Wind in Arizona, July 23, 2024

Area Forecast Discussion
National Weather Service Tucson AZ
227 PM MST Tue Jul 23 2024

.SYNOPSIS...Daily chances for showers and thunderstorms are
expected through this week into this weekend with the main
threats being strong gusty winds and heavy rainfall.

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.DISCUSSION...Latest Visible/WV satellite imagery shows partly
cloudy skies across southeast Arizona with the mid/upper level high
centered to our northwest over southern Nevada. KEMX radar has
started to pick up on a few showers/T'storms over the T.O.
Nation/western Pima County and in the higher terrain of far northern
Graham and Greenlee Counties. The focus today will tend to be on
areas to the south and west of Tucson where the deepest moisture
lies and this is where the HREF/CAMs are depicting the best coverage
of showers and thunderstorms this afternoon into early evening. Main
concerns will be gusty outflow winds and locally heavy downpours.
Meanwhile, as scattered storms develop and move off the White
Mountains they will tend to struggle pushing into the lower
elevations given the drier air (PWAT at or just under 1 inch) across
Graham/Greenlee/Cochise. With that said, for most locales, this will
tend to be more of a down day in coverage.

Wednesday is now shaping up to be an active day for most of our
forecast area as a classic rim to valley setup looks to be taking
shape. Some additional Gulf of California moisture will push in
tonight, especially from Tucson westward with a slight increase in
moisture for eastern areas and up on the Mogollon Rim/White
Mountains. HREF/CAMs are in very good agreement on developing
thunderstorms over the higher terrain, which then push to the south
to southwest during the afternoon. Additionally, some localized
convection will develop near and adjacent to the Sky Islands from
Tucson eastward in the afternoon. As the storms from the White
Mtns/Mogollon Rim move into a more favorable thermodynamic
environment, expect upscale growth into the deserts where steep
lapse rates and deeper moisture will be in place. HREF late
Wednesday afternoon into early evening is showing a 30 percent
chance of winds greater than 50 mph within 25 miles of a point in
locales just west of Tucson into the T.O. Nation aided by DCAPE
values of around 1500 J/KG. The strong gusty winds will have the
potential to produce areas of blowing dust. As storms clusters
organize and merge, that will also be conducive for heavy rain and
areas of flash flooding, generally from Tucson westward. For locales
to the north and east of Tucson, strong gusty winds with locally
heavy rain will be the primary threats. Thunderstorm activity could
continue well into the evening across the western deserts.

While not much in the flow pattern changes on Thursday compared to
Wednesday, if our area gets hit hard Wednesday, that will typically
result in a more down day Thursday. Thereafter, abundant moisture
remains in place heading into the weekend with daily chances for
showers and thunderstorms. The high will briefly wobble a bit closer
to us on Saturday which may lower convective chances a bit to the
west of Tucson. However, that would be short lived as the ensembles
show the high reorienting a bit more to our north and east Sunday
into early next week as an inverted trough approaches from the
southeast. This would result in an active monsoon period.

Temperatures will generally be about 3 to 6 degrees above normal
through the weekend.

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.AVIATION...Valid through 25/00Z.
SCT-BKN clouds 8k-12k ft AGL will continue into this evening,
diminishing aft 24/05Z, then SCT-BKN clouds 8-12k ft AGL develop
again aft 24/18Z. ISOLD to SCTD -SHRA/TSRA mainly west of KTUS into
this evening with ISOLD -SHRA/TSRA north of KSAD. Another round of
scattered to numerous SHRA/TSRA expected to develop aft 24/20Z and
impact much of SE AZ Wednesday afternoon into evening. Strong winds
to 45 kts near TSRA. Outside of TSRA, SFC winds ELy/SELY. Aviation
discussion not updated for TAF amendments.

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.FIRE WEATHER...Scattered afternoon and evening showers and
thunderstorms with day to day variability on which areas will see
the best chance of rainfall. Wednesday is looking particularly
active at this time. Each day into early next week will have the
threat of heavy rain, localized flash flooding and strong gusty
winds. Minimum relative humidities will be 20 to 30 percent in most
lower elevation locations and 25 to 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.

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.TWC WATCHES/WARNINGS/ADVISORIES...None.

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