Severe Thunderstorm Warning 362, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
954 AM MST Fri Aug 23 2024

.SYNOPSIS...Daily chances for thunderstorms continue. Heavy rain,
strong wind gusts, and small hail will be possible with any
thunderstorm. Thunderstorm chances shift eastward this weekend,
to near and east of Tucson. High temperatures near to slightly
above normal through the forecast period.

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.UPDATE...

Under south to southwest flow aloft, scattered convection is
expected to develop this afternoon mainly Tucson-Nogales eastward,
though a cell or two is possible into central Pima and Pinal
counties. Dry mid-level air has moved into southeastern Arizona,
as indicated by the 08Z NUCAPS pass, which should bring a threat
of strong to severe wind gusts today. Additionally, effective
bulk shear is forecast to be in the 25-35 knot range, especially
east of Tucson- Nogales. Combined with precipitable water to
around 1.25", heavy rainfall rates and small hail are expected,
with an isolated potential for severe hail of around one inch in
diameter. Convection this morning was observed from Douglas
through Rodeo, NM, which may delay or hamper convective chances
in southeastern Cochise county, but potential elsewhere still
looks on track as discussed.

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.PREV DISCUSSION... /issued 305 AM MST Fri Aug 23 2024/

.DISCUSSION...The sky across SE AZ this morning was mostly clear
with some thin high clouds passing through. Last nights upper air
plot had the area under S/SW flow aloft between mid-level high
over west TX and upper low off the PacNW. Water vapor imagery this
morning showed an upper level trof, mainly in the 400-300 mb
area, over western Sonora MX. This feature will be a player in our
forecast today. PW values across the area this morning ranged
from 1" to 1.25".

Today: As the above mentioned upper level trof over western
Sonora MX weakens today as it lifts north it will develop an area
of upper level divergence over the eastern half of the forecast
area this afternoon with Tucson on the western edge. Combined
with an increase in mid- level wind shear, scattered showers and
thunderstorms will develop with a few storms producing strong to
severe wind gusts, small hail. SPC has our area under marginal
threat for severe storms. On the wet side, flash flooding threat
is limited a bit due to storms moving to the N/NE around 15 mph.
Tucson likely will need outflow interactions to get storms going
across the metro area. Although not in the forecast can't rule
out some blowing dust being generated from outflows.

Saturday: A little bit of drying from the west under SW flow aloft
with the PacNW upper low moving inland and the upper high centered
over Oklahoma. Also the area may be worked over after what occurs
today. Still looking at scattered afternoon/evening storms.

Sunday through Thursday: Daily chances of afternoon and evening
storms, mainly across the eastern half of the forecast area, for
the last full week of August.

High temperatures for the next 7 days will run at or a few degrees
above normal.

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.AVIATION...Valid through 24/12Z.
Isolated to scattered SHRA/TSRA mainly east of a TUS-OLS line after
23/18Z. Visibility reductions, wind gusts up to 45 kts, heavy rain,
and mountain obscurations possible with any thunderstorm. Outside of
thunderstorm wind gusts, winds generally 15 kts or less with a
southwest to northwesterly direction. Scattered thunderstorms again
Saturday afternoon primarily east of KTUS-KOLS. Aviation discussion
not updated for TAF amendments.

&&

.FIRE WEATHER...Scattered thunderstorms are likely this afternoon
and evening, mainly near and east of Tucson to Nogales as drier air
nudges in from the west. High temperatures will be near to slightly
above normal through the forecast period. This drier air will act in
lowering minimum relative humidities to around 18-28 percent Friday
through the weekend. Outside of any 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...
None.
&&

Update...Edwards

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