Flash Flood Warning 37, NWS Phoenix, AZ

Area Forecast Discussion
National Weather Service Phoenix AZ
500 PM MST Wed Aug 12 2026

.UPDATE...00Z Aviation Discussion

&&

.KEY MESSAGES...

- Better moisture and more favorable conditions for showers and
  storms are expected by this evening, lasting into Thursday
  morning.

- A Flood Watch has been issued for the high terrain across
  central and portions of eastern Arizona from late afternoon
  through tonight. Locally heavy rainfall will also be possible
  into the south-central Arizona lower deserts.

- Near to below normal temperatures are forecast through Friday
  before warming back up over the weekend into early next week.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...
This afternoon and tonight continue to point towards being quite
busy, with the main forecast concern being the potential for
heavy rainfall stemming from a high likelihood of localized
rainfall rates of 1-2"/hr and training of storms in the higher
terrain areas, as depicted by CAMs. Due to this a Flood Watch has
been issued for all of Gila County as well as over far northern
Pinal and northeast Maricopa Counties from late this afternoon
through tonight.

The upper level pattern shows the Desert SW sandwiched between
the subtropical ridge, that has moved into Texas, and the upper
level trough along the California coast line. This set up has
promoted southerly flow aloft into our region and will be able to
tap into plenty of moisture from a decaying MCV from earlier this
morning over the Sonoran Desert. Current meso analysis along with
this morning's 12Z sounding have PWATs near 1.7" and closer to
1.8-1.9" in the western lower deserts. The morning sounding also
revealed a decent amount of MUCAPE, with most of the CIN near the
surface. The 12Z convective temperature was only 95F, and with an
afternoon high expected to to climb near to slightly above 100
degrees in the lower deserts, convection is likely to break
through any lingering surface level CIN. Model soundings are
forecasting MUCAPEs mainly between 750-1500 J/kg in the lower
deserts and will steadily diminish through the late evening hours,
into the overnight period, making late this afternoon and into the
evening hours the expected peak time for storms, similar to earlier
this week. However, CAMs still show storms likely continuing past
midnight, mostly in the higher terrain, while the lower deserts, to
include La Paz County, have the highest chance, 50-70%, of showers
during the evening hours, as mentioned previously. Additional
isolated showers and thunderstorms will again be possible Thursday
afternoon, but with the atmosphere drying out and forcing waining
there will be a significantly lower chance of localized heavy
rainfall.

Temperatures will be quite pleasant compared to what is normally
expected for mid August with afternoon highs mostly in the high
90s to low 100s, with many areas struggling to reach 100F. The
only exception will be areas in the western lower deserts where
temperatures will range in the low to mid 100s, keeping pockets of
Moderate HeatRisk in place. Otherwise, widespread Minor HeatRisk
is expected through the end of the week.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Dry air will continue to spread northeastward through Arizona on
Friday with low level mixing ratios dropping to around 8 g/kg over
the lower deserts to 9-10 g/kg over the eastern Arizona high
terrain. These moisture levels during the summer monsoon season
typically prohibit convection across the area with at most a
10-20% chance of isolated showers or weak storms across the far
eastern Arizona high terrain. However, even with the drying
conditions surface dew points well into the 50s will still keep
that slight muggy feeling in the air. The trough will continue to
influence the region through Friday keeping temperatures a few
degrees below normal under partly cloudy skies.

Saturday looks to be quite similar to Friday with periods of
higher clouds persisting, but temperatures will begin to tick
upward again as the subtropical high begins to nudge back into our
region. Guidance shows H5 heights gradually rising into a
592-595dm range by early next week, or back to around the 90th
percentile of climatology. Moisture levels look to stay fairly
steady for the rest of the weekend into early next week keeping at
most low grade monsoon storm chances in place. The increased
heights and somewhat dry conditions will help to push daytime
highs to above normal by Monday with readings right around 110
degrees for next Monday and Tuesday.

&&

.AVIATION...Updated at 0000Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Main aviation concern during the TAF period will be convective
activity around metro terminals this evening, and potentially once
again overnight. First SHRA/TSRA will occur between now and around
05Z-06Z, with the second, but less certain window, being between
07Z-12Z. Main impacts will be sub-VFR VIS and gusty and erratic
winds. How strong winds become remain uncertain, but there is
currently not a strong signal indicating gusts will exceed 30 kt.
Convective activity should begin to clear the area after 12Z at
the latest, but lingering SHRA for a few hours beyond that cannot
be completely ruled out. Outside of the variability and
uncertainty of the convective timeframe, winds are expected to
follow familiar diurnal trends.

Southeast California/Southwest Arizona including KIPL and KBLH:
Main aviation concern will be SHRA/TSRA this evening into early
tonight. Impacts associated with convective activity will be
reduced VIS and winds exceeding 30 kt at times. Activity at KIPL
will end within in the next few hours, but KBLH could see
lingering activity until around 06Z tonight, potentially
resulting in numerous strong outflows. Conditions through the
remainder of the night into Thursday morning should be much
calmer, with familiar diurnal wind trends and drier conditions
returning.

&&

.FIRE WEATHER...
Elevated humidity levels, cooler temperatures, and good chances
for wetting rains are anticipated through Thursday morning over
at least the eastern districts. The best rain chances will be
during the evening and overnight hours tonight with lingering
chances through Thursday afternoon. Afternoon MinRHs will range
between 25-35% across the lower deserts and 40-50% for the
eastern high terrain, while overnight recoveries will remain
excellent. Winds will predominately be out of the south southwest
much of the period with the exception of any modest outflows from
thunderstorm activity. Drying conditions will move into the
region Friday and through the weekend dropping MinRHs to between
15-25% while temperatures gradually rise back to above normal.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Flood Watch through late tonight for AZZ541-545-547-549-552-
     555>558-560>563.

CA...None.
&&

SHORT TERM...Ryan/Kuhlman
LONG TERM...Kuhlman
AVIATION...RW
FIRE WEATHER...Kuhlman

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Special Weather Statement
National Weather Service Phoenix AZ
513 PM MST Wed Aug 12 2026

AZZ540-544-559-130045-
Sonoran Desert Natl Monument AZ-Buckeye/Avondale AZ-
North Phoenix/Glendale AZ-
513 PM MST Wed Aug 12 2026

...A STRONG THUNDERSTORM WILL IMPACT MARICOPA AND PINAL COUNTIES
THROUGH 545 PM MST...

At 513 PM MST, Doppler radar was tracking a strong thunderstorm over
Estrella Mountain Park, or near Avondale, moving northeast at 5 mph.

HAZARD...Wind gusts up to 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Avondale, Goodyear, Tolleson, Cashion, Litchfield Park, Phoenix
International Raceway, Camelback Ranch, Estrella Mountain Park, and
Estrella Mountain Ranch.

This includes the following highways...
AZ Interstate 10 between mile markers 127 and 136.
AZ Route 101 between mile markers 2 and 3.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3337 11211 3335 11212 3322 11232 3334 11248
      3355 11234
TIME...MOT...LOC 0013Z 220DEG 5KT 3334 11235

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

SDB

Preliminary Local Storm Report
National Weather Service Phoenix AZ
515 PM MST Wed Aug 12 2026

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

0451 PM     Tstm Wnd Dmg     2 W Calexico            32.68N 115.53W
08/12/2026                   Imperial           CA   Dept of Highways

            Power lines down in the road.

&&

SB

Preliminary Local Storm Report
National Weather Service Phoenix AZ
531 PM MST Wed Aug 12 2026

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

0515 PM     Dust Storm       7 WSW Niland            33.20N 115.62W
08/12/2026                   Imperial           CA   Utility Company

            Webcam shows less than 1/4 mile in blowing
            dust. The cam showed a large wall of dust
            moving north just before being consumed.

&&

SB