Flash Flood Warning 142, NWS Tucson, AZ

240 
WGUS75 KTWC 200159 RRA
FFSTWC

Flash Flood Statement
National Weather Service Tucson AZ
659 PM MST Wed Aug 19 2026

AZC019-200345-
/O.CON.KTWC.FF.W.0142.000000T0000Z-260820T0345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Pima AZ-
659 PM MST Wed Aug 19 2026

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 845 PM MST THIS
EVENING FOR EAST CENTRAL PIMA COUNTY...

At 659 PM MST, Doppler radar indicated thunderstorms producing heavy
rain across the warned area. Between 1 and 1.5 inches of rain have
fallen. Flash flooding is ongoing or expected to begin shortly.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Radar indicated.

IMPACT...Flash flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Mainly rural areas of East Central Pima County.

This includes Route 83 between mile markers 37 and 40...and between
mile markers 49 and 51.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3191 11068 3173 11070 3173 11055 3182 11056
      3195 11051

FLASH FLOOD...RADAR INDICATED

$$

DVS

254 
WGUS75 KTWC 200335
FFSTWC

Flash Flood Statement
National Weather Service Tucson AZ
835 PM MST Wed Aug 19 2026

AZC019-200345-
/O.EXP.KTWC.FF.W.0142.000000T0000Z-260820T0345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Pima AZ-
835 PM MST Wed Aug 19 2026

...FLASH FLOOD WARNING WILL EXPIRE AT 845 PM MST THIS EVENING FOR
EAST CENTRAL PIMA COUNTY...

Flood waters are receding. The heavy rain has ended. Flooding is no
longer expected to pose a threat. Please continue to heed remaining
road closures.

&&

LAT...LON 3191 11068 3173 11070 3173 11055 3182 11056
      3195 11051

$$

JRM

Area Forecast Discussion
National Weather Service Tucson AZ
116 PM MST Wed Aug 19 2026

.SYNOPSIS...An uptick in afternoon showers and storms returns to
Southeast Arizona this afternoon and evening with the strongest
storms capable of producing isolated strong to severe wind gusts,
blowing dust, and heavy rainfall. Blowing dust could impact travel
along and near Interstate 10 and Interstate 19. Moderate to major
HeatRisk continues with forecast high temperatures 5 to 7 degrees
above normal.

&&

.DISCUSSION...So far this afternoon storms were forming in the White
Mountains with cumulus fields developing over the higher terrain
elsewhere. We will see the storms continue to form and gradually
push to the west and south during the afternoon and eventually into
central Pima County in the evening hours. The latest WRF guidance is
not in agreement on the timeline for when storms would potentially
impact the Tucson Metro with the WRF-GFS trending on the later side
and the WRF-HRRR more on the earlier side. To describe how this
difference is manifesting, it looks like the WRF-GFS is picking up
on storm development in Cochise County off the Galiuro, Whetstone,
Dragoon, Rincon, and Catalina Mountains around 3 pm to 5 pm MST
which would send outflows and additional storm development into the
Tucson Metro earlier than the WRF-HRRR that does not have this
development and instead relies on outflows from the south of Tucson
and from storms currently pushing off the White Mountains.
Essentially, we're looking at a two hour time difference depending
on how storm development trends.

The environment is ripe with instability according to the latest SPC
mesoanalysis. As of this writing there is 1500-2500 J/kg of MLCAPE
and around 20-30 kts of effective bulk layer shear as well as DCAPE
of 1400-1600 J/kg. Given this environment and the trends of the
convective allowing models, I think clustering of storms is on the
table along with potentially a few stronger discrete quasi
supercellular storms.

Tomorrow looks a bit similar to today but turning down the intensity
of all of the ingredients a little bit and with storms centered more
over the northern portions of our area including Graham, Greenlee,
and Pinal counties. There will still be showers and storms over the
rest of the southeast Arizona, but that's where I am initially
seeing the best ingredients for stronger outflows setting up.

Otherwise, we look to remain in an active weather pattern into the
weekend as the upper high center moves toward the Four Corners
Thursday into Friday, then into the Rockies by Saturday afternoon.
The Extreme Heat Warning remains in effect through Friday evening,
and we will be monitoring for continuing heat concerns heading into
the weekend.

&&

.PREV DISCUSSION... /issued 1000 AM MST Wed Aug 19 2026/

High resolution guidance as of this writing depict
increasing confidence for storms capable of producing strong, gusty,
and erratic outflow winds, blowing dust, and locally heavy rainfall
this afternoon and evening.

The 19/12Z run of the HREF depicts a high chance (70-90%) for gusty
outflow winds exceeding 35 mph, with a slight chance (10-20%) for
gusts to exceed 55 mph. The Storm Prediction Center (SPC) has
upgraded most of southeast Arizona into a slight risk for
thunderstorms today capable of producing isolated severe wind gusts
which is consistent with the aforementioned wind exceedance
probabilities. Scattered showers and storms forming around Noon MST
will become more widespread and perhaps more organized later in the
afternoon as they propagate west and south toward the Tucson Metro
(most likely around 5 pm to 7 pm MST) and continuing out over Tohono
O'ohdam Nation. Storms will be supported by modest deep layer (0-6
km) shear of around 20-25 kts with mean storm motions of around 10-
15 mph. As always, blowing dust becomes an increasing concern with
gusty outflow winds from organized thunderstorm clusters. But with
the increasing probabilities for gusty winds, my confidence in
organized thunderstorm outflows and potential haboob formation for
today are notably higher than they were at this point yesterday. The
night shift did coordinate with the Phoenix WFO to hoist a Blowing
Dust Advisory for portions of Pima and Santa Cruz counties extending
into Pinal and Maricopa counties. That will be in effect from 3 pm
to 10 pm today. Motorists should use caution driving along the
Interstate 10 and 19 corridors.

Secondarily, we've seen a notable surge of moisture over the past 24
hours. The Weather Prediction Center has upgraded areas from Tucson
metro west from a marginal risk into a slight risk for excessive
rainfall with isolated instances of flash flooding. Surface
dewpoints across the area have surged into the mid/upper 60s over
the past 24 hours. Satellite estimated precipitable water ranges
from about 0.9 inches in the White Mountains and along the
international border in Cochise County to 1.4 inches in western Pima
and southeast Pinal counties with even higher amounts south of the
international border. HREF depicts likely chances (70-90%) for
precipitable water to exceed 1.5 inches this afternoon and evening
as even richer and deeper moisture moves into the area. The deeper
moisture has been a rapidly evolving situation over the last few
days, and in my opinion the guidance is looking a bit more
impressive than yesterday with a slight chance (10-20%) for hourly
rainfall rates to exceed an inch per hour.

&&

.AVIATION...Valid through 21/00Z.
SCT-BKN 7-11k ft AGL BKN-OVC 12-15k ft AGL with scattered to
numerous -SHRA/-TSRA through 20/05Z. Gusty and erratic outflow winds
possible near TSRA with gusts to 40-50 kts. Organized outflows may
produce VSBY less than 1/2 SM in BLDU, especially from KTUS
west and northwest. Winds outside of thunderstorms mainly light
and terrain driven. Tomorrow, scattered -SHRA/-TSRA return after
20/19Z. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Strong thunderstorms will return to Southeast
Arizona this afternoon. The primary concern with storms this
afternoon is that they will be capable of producing organized storm
outflow winds 45-55 mph, potentially producing localized dense
blowing dust. Deep moisture moving into the region from the Gulf of
California will bring about a secondary concern of heavy rainfall
capable of producing isolated flash flooding, especially across
central and eastern Pima county. Otherwise, an uptick in storm
strength and coverage into the upcoming weekend. Hot conditions will
persist this week with an Extreme Heat Warning in effect today
through Friday for portions of the Southeast Arizona. Winds mainly
light and terrain driven. Strong, gusty and erratic winds will
accompany thunderstorms. Minimum relative humidities 15-25 percent
in lower elevations with 25-35 percent in the higher terrain.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...

Extreme Heat Warning until 8 PM MST Friday for AZZ501-502-504>506-509.

Blowing Dust Advisory from 3 PM this afternoon to 10 PM MST
this evening for AZZ501>506.

&&

DVS

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Preliminary Local Storm Report
National Weather Service Tucson AZ
410 PM MST Wed Aug 19 2026

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

0210 PM     Hail             1 W Rio Rico            31.48N 111.00W
08/19/2026  M1.00 Inch       Santa Cruz         AZ   Trained Spotter

            1 inch sized hail.

&&

MJS