Severe Thunderstorm Warning 270, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
152 PM MST Tue Aug 6 2024

.SYNOPSIS...A disturbance aloft will result in an active monsoon
pattern today with numerous showers and thunderstorms, mainly from
Tucson westward. Otherwise, expect scattered showers and
thunderstorms each day through this week, with potential for heavy
rainfall and strong wind gusts. Temperatures cool to near normal
levels today through Thursday, then warm up to above normal
levels Friday through the weekend.

&&

.DISCUSSION...Current water vapor shows the upper level low
centered over northern Sonora slowly moving northwestward.
Isolated storms have already formed in Cochise County and Santa
Cruz County. Expect this activity to continue with development
over the next couple of hours between Tucson and Nogales, then
westward progression along outflows late in the afternoon into the
evening. All the ingredients are in place for strong to severe
storms mainly from Tucson south and westward this afternoon and
evening. PWAT values range from 1.4"-1.75" from Benson westward.
The AZ/NM border area is around 1" which will put a damper on
storms in that area. MLCAPE is between 1000-1500 J/kg with 30-40
kts of 0-6 km shear thanks to the enhanced flow from the upper
level low. DCAPE is around 1500 J/kg and there is also a bit of
dry air in the mid-levels evident on water vapor imagery, which
can help enhance downdrafts. Storms will be capable of strong to
severe wind gusts, which could also lead to blowing dust. Isolated
severe hail in the strongest storms also can't be ruled out.
Heavy rainfall will also be a threat with these storms. HREF 3
hour probability matched mean QPF is highlighting Santa Cruz
County as well as southern Tohono O'odham Nation with 50-70
percent chance for an inch or greater and 10 percent chance for
three inches this afternoon and evening.

Wednesday the upper level low will be centered over western Sonora
and southwest Arizona. Moisture will increase east of Tucson with
the AZ/NM border seeing PWAT values around 1.4". Storm chances
will shift to encompass areas from Tucson eastward. Western Pima
County will be in the subsidence region of the upper level low
leading to decreased storm coverage. Upper level dynamics won't
be as good as today, but storms will still be capable of strong
wind gusts and localized heavy rainfall.

Thursday into Friday the upper level low drifts southwestward over
Baja California. High pressure becomes centered over New Mexico
putting the CWA in southeast mid-level flow. Moisture stays around
climatological normals Thursday, then Friday eastern areas begin
to dry out. Each day enough moisture will be in place for
continued isolated to scattered thunderstorms with normal threats
of strong winds and locally heavy rainfall. Saturday the dry air
pushes further east with PWAT values below normal from Tucson
eastward. This could lead to a down day, but will hinge on how
much moisture southeast Arizona loses Friday into Saturday.

Temperatures will be around normal today through Thursday then
warm up Friday into the weekend as heights increase with the high
centered just to the east. Saturday looks to be the warmest day
with highs 6-9 degrees above normal.

&&

.AVIATION...Valid through 08/00Z.
SCT-BKN clouds at 6k-9K ft AGL and BKN-OVC clouds at 10k-14k ft
AGL thru this evening then a slight reduction in coverage
overnight. Expect scattered TSRA this afternoon and evening first
forming from KOLS to KTUS then moving westward along outflows.
Best timing for storms impacting KOLS will be 06/21Z-07/01 and
KTUS will be 06/22-07/01. MVFR conditions expected near TSRA,
with VSBY restrictions, wind gusts to 45+ kts, and heavy rain.
Outside of thunderstorm wind gusts, wind speeds will be less than
12 kts, favoring an SWLY in the afternoon and ELY through SLY
direction. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Scattered to numerous showers and thunderstorms
are expected today, with isolated to scattered mainly afternoon and
evening showers and thunderstorms Wednesday through the upcoming
weekend. Min RH values will be in the 25-40 percent range in the
valleys through Thursday (and higher in the mountains), decreasing
to 20-30 percent Friday through the weekend. Outside of thunderstorm
outflow winds, 20-foot winds will generally be 15 mph or less, with
afternoon/early evening gusts to 20-25 mph and light winds
overnight.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Blowing Dust Advisory from 4 PM this afternoon to 8 PM MST this
evening for AZZ501-502-505.

&&

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Preliminary Local Storm Report
National Weather Service Tucson AZ
157 PM MST Tue Aug 6 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0150 PM     Tstm Wnd Gst     6 NE Nogales            31.42N 110.85W
08/06/2024  M67 MPH          Santa Cruz         AZ   ASOS

            ASOS station KOLS Nogales International
            Airport gusted to 67 mph.

&&

JVT

Preliminary Local Storm Report
National Weather Service Tucson AZ
200 PM MST Tue Aug 6 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0154 PM     Tstm Wnd Gst     6 NE Nogales            31.42N 110.85W
08/06/2024  M75 MPH          Santa Cruz         AZ   ASOS

            ASOS station KOLS Nogales International
            Airport gusted tp 75 mph.

&&

JVT