Severe Thunderstorm Warning 337, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
137 PM MST Tue Aug 20 2024

.SYNOPSIS...

A couple of active monsoon days with elevated heat risk today.
Thunderstorms today will be accompanied by the typical monsoon
threats of strong wind gusts, localized heavy rainfall and flash
flooding, and blowing dust. High temperatures will be several
degrees above average today before falling a few degrees mid to
late week. Wednesday looks to be active as well, with a higher
flash flood threat, mainly across Santa Cruz and Pima Counties.

&&

.DISCUSSION...

Today is shaping up to be another active monsoon day with a focus
of convective activity to the south and west of Tucson. PWATs are
around 1.2 to 1.4 inches over Tucson increasing gradually to 1.6
to 1.7 inches by Ajo. DCAPE values are around 1600 J/kg right now
and will be around 1600-1800 J/kg at the time of convection this
afternoon. Timing of storm development is around 1-2 PM MST along
the International Border moving generally to the northwest. There
is a chance for storms to impact the Tucson area around 4-6 PM
MST. The main concerns associated with storms today is strong
winds, there is a 10 percent chance for winds greater than 50
knots focused Tucson westward as denoted by the HREF, and locally
heavy rainfall. Flash flooding will be more of a concern for
slower moving storms and those that are west of Tucson, where
there is more moisture. High temperatures is also something to
keep in mind today. Most of southern AZ is at Moderate HeatRisk,
meaning that most individuals will be impacted by the heat,
especially those without proper cooling.

Tomorrow is shaping up to be another active monsoon day, with
flash flooding being the star of the show. Southerly flow aloft in
concert with strong model QPF values across the region will
generate strong thunderstorms. PWATs continue to impress with
values approaching almost 1.5 inches in Pima County. hence, we
will need to keep an eye on flash flood prone areas for productive
rainfall rates. In coordination with surrounding WFOs, WPC and
the Water Center, portions of Santa Cruz and Pima Counties will be
included in the updated Day 2 Excessive Rain Outlook.

After Wednesday, temperatures will normalize a bit, reducing the
HeatRisk. Scattered showers and thunderstorms are still possible
Thursday, but drying will limit widespread activity after that.

&&

.AVIATION...

MVFR conditions at all terminals near TSRA, with VSBY
restrictions, wind gusts to 45+ kts, heavy rain and mountain
obscurations. Outside of thunderstorm wind gusts, wind speeds will
be 12 kts or less, favoring a SELY direction this morning, then
SWLY thru NWLY direction this afternoon into evening. SFC wind
variable in direction at other times. Aviation discussion not
updated for TAF amendments. &&

.FIRE WEATHER...

Daily chances of mainly afternoon and evening showers and
thunderstorms can be expected across southeast Arizona through
Thursday, with a significant drying trend Friday through the
weekend. High temperatures will be 3 to 6 degrees above normal
today, lowering to 1 to 4 degrees above normal Wednesday into the
weekend. Min RH values will be in the 20-30 percent range in most
valleys locations this week (except lowering to near 15 percent in
eastern Cochise and the upper Gila River valley today). Min RH
values are expected to lower by late this weekend as the drier
overspreads the area. 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.

&&

Public...Malarkey/Singer
Aviation...Singer
Fire Weather....Singer

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