Severe Thunderstorm Warning 231, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
146 PM MST Sun Jul 28 2024

.SYNOPSIS...

Daily chances for showers and thunderstorms this
through the week. Main threats will be heavy rainfall with strong
gusty winds. Localized flash flooding and isolated severe winds
will be possible.

&&

.DISCUSSION...

While the axis of broad ridging sits to the east, mean
atmospheric flow over southeastern Arizona has become southerly.
Though not particularly fast, this will will aid in a slow
northward propagation of heavy raining convection today. As shown
by the morning upper air observation and GOES precipitable water
values, the atmosphere is certainly primed to produce very heavy
rainfall rates this afternoon and early evening. The combination
of instability and richest moisture generally favors thunderstorm
development from southern central Pima County through Santa Cruz
and Cochise counties, with isolated development further into
southern Pinal and Graham counties this afternoon. Though the
primary threat should be the very heavy rainfall rates, wet
microbursts may produce isolated strong to severe wind gusts as
well. Coverage should quickly diminish with sunset, however a few
late storms out of Sonora tonight can't be ruled out.

As the upper high drifts further east on Monday, flow aloft
becomes a bit stronger (around 10 to near 20 kts at 500mb). Under
otherwise similar atmospheric conditions to today, this may allow
for longer lived convection with potentially a bit of a higher
wind gust threat. That said, there is some uncertainty in severity
and favored location as models showing the potential for lingering
cloud cover in the morning which may inhibit full development of
instability. The 12Z HREF updraft helicity probability (a modeled
probability of potential thunderstorm organization and severity)
shows an uptick in probability tomorrow compared to today, however
more limited in spatial coverage towards the southern border.
Further analysis will need to be made tonight.

With the ridge sitting to the east, daily chances for
monsoon activity with a southerly component will continue. An
interesting added factor will be a low pressure circulation,
currently south of the Baja peninsula, which models currently
have moving north towards southern Arizona around mid-week. It's
much too early for details on this circulation's impact, however
it could cause some changes to the normal diurnal convective
timing cycle.

&&

.AVIATION...Valid through 30/00Z.

Scattered thunderstorms through 28/02Z near KOLS-KDUG and isolated
up north through KTUS and KSAD. Very heavy rainfall, brief MVFR
conditions, and isolated gusty outflow winds to 45 kts near any
thunderstorm today. Otherwise winds generally under 12kts this
afternoon and becoming light tonight. Chances for thunderstorms
expected again Monday afternoon. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...

Elevated moisture will continue with scattered afternoon and
evening showers and thunderstorms. Each day has the threat of
heavy rain, localized flash flooding and strong gusty outflow
winds. 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. As high pressure builds mid- week, high
temperatures should rise a bit and minimum relative humidities
should fall by a few percentage points.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Blowing Dust Advisory from 4 PM this afternoon to 8 PM MST this
evening for AZZ505.

&&

Public...Edwards
Aviation...Edwards
Fire Weather....Edwards

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Preliminary Local Storm Report
National Weather Service Tucson AZ
1248 PM MST Sun Jul 28 2024

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

1245 PM     Hail             10 SE Sierra Vista      31.48N 110.19W
07/28/2024  M0.70 Inch       Cochise            AZ   Trained Spotter

            Also reported about 0.5 inches of rain in 15
            minutes so far.

&&

AJE

Preliminary Local Storm Report
National Weather Service Tucson AZ
138 PM MST Sun Jul 28 2024

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

0115 PM     Tstm Wnd Gst     7 W Pirtleville         31.37N 109.69W
07/28/2024  M53 MPH          Cochise            AZ   Mesonet

            Mesonet station KP03 Cochise College
            Airport.

&&

AJE