Flash Flood Warning 2, NWS Tucson, AZ

370 
WGUS75 KTWC 180113
FFSTWC

Flash Flood Statement
National Weather Service Tucson AZ
613 PM MST Wed Jun 17 2026

AZC021-180123-
/O.EXP.KTWC.FF.W.0002.000000T0000Z-260618T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Pinal AZ-
613 PM MST Wed Jun 17 2026

...FLASH FLOOD WARNING WILL EXPIRE AT 615 PM MST THIS EVENING FOR
SOUTHWESTERN PINAL COUNTY...

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

&&

LAT...LON 3279 11180 3274 11177 3260 11179 3251 11183
      3251 11203 3257 11205 3272 11196 3277 11188
      3279 11188

$$

Area Forecast Discussion
National Weather Service Tucson AZ
1215 PM MST Wed Jun 17 2026

.SYNOPSIS...Increased moisture will result in potential afternoon
showers and thunderstorms from Tucson south and eastward today. Some
residual thunderstorm chances continue along the White Mountains
Thursday then dry conditions Friday through the weekend. Otherwise,
breezy afternoons with temperatures near normal through the weekend,
then warming above normal next week.

&&

.DISCUSSION...Still shaping up to be a bit more of an active
day for storms today across southeast Arizona with the main
concerns being strong to severe outflow winds resulting in
blowing dust. Isolated instances of heavy rainfall leading to
flash flooding cannot be ruled out. Best storm chances will be
across eastern Pima County eastward. Timing of storms across the
Tucson Metro look to be the start of the evening commute
through about 7-8 pm MST. People traveling during this period
should remain alert for possible sudden visibility changes and
avoid driving through flooded roads.

The pattern supporting the uptick in storms is a bit more nuanced
setup for the Monsoon. The subtropical high is centered to our south
near the Baja Spur putting southeast Arizona on the fringe of the
upper circulation with a weak upper low nudging into Arizona from
California. Between these features, the air will tend to spread out
and allow for rising motion supporting the potential for taller
storms. Without the high centered directly overhead, we see
temperatures only slightly above normal for this time of year. We
also have sufficient mid-level moisture in place for storms with
GOES West Total Precipitable Water product estimating values of
around 0.8 to 1.3 inches. With these numbers in mind and knowing we
are anticipating a bit of drier air intruding into the mid/upper
levels we will see a threat for both heavy rainfall and strong
outflow wind this afternoon and evening.

There are multiple avenues that would support convective initiation
this afternoon including both surface and terrain convergence. High
resolution guidance depicts storms first firing across higher
terrain areas in the White and Chiricahua Mountains around 1-2 PM.
Thereafter, storms start to develop in and around the Tucson Metro
both from surface and terrain convergence. Guidance also suggests
that outflows driven by these storms could be quite strong and
trigger additional storms persisting into the evening hours. Dry air
entrainment in the mid-levels of the storms could enhance their
downdrafts with DCAPE values in the 1500-2000 J/kg range suggestive
of a few gusts approaching or exceeding severe criteria (58 mph).
Winds this strong can cause damage to structures and loft widespread
areas of blowing dust. Therefore, we coordinated with the Storm
Prediction Center (SPC) to add southeast Arizona into a Marginal
Risk (level 1 of 5) for severe thunderstorms producing damaging
winds. There is also a marginal risk (level 1 of 5) for isolated
instances of flash flooding as locally heavy rainfall rates cannot
be ruled out with any slower moving storms.

The extended forecast continues to be on track as well with another
day of storms tomorrow but with fewer of the ingredients lining up
and for much less of the area. However, isolated showers and storms
will form over the White Mountains with the potential for gusty
winds again as the upper low continues to nudge east. By Friday, the
upper low will phase in with the Western US longwave trough and
eject northward. The result will be drier weather with broad
westerly flow. Look for temperatures to remain within degrees of
normal through the weekend, then trend warmer as high pressure
builds into the region next week.

&&

.PREV DISCUSSION... /issued 208 AM MST Wed Jun 17 2026/

The overall weather pattern over the Southwestern US continues to be
driven by a 500mb upper low centered off the Southern CA coast. A
few afternoon thunderstorms formed yesterday with the presence of
this upper low, but has since quieted down during the overnight
period. Blended Total Precipitable Water satellite data suggests PW
in the neighborhood of 1", good for 150-175% of normal for this time
of year.

Signs continue to point to a more active Wednesday afternoon
relative to Tuesday. This is due to the 500mb low drifting eastward
toward southeast CA. Supported by the left exit region of a passing
upper jet streak and an upper trough axis, high resolution models
are showing the most likely area of thunderstorm activity extending
from Tucson south and east Wednesday afternoon and evening. Another
area of activity looks to be over the White Mountains. Thermodynamic
profiles are impressive, with forecast CAPE above 1500 J/kg and
downdraft CAPE upwards of 2000 J/kg. With these indices in mind,
gusty outflow winds and resulting blowing dust appear to be the
greatest threats. Indeed, HREF and REFS ensembles show 10-25% chance
of wind gusts >50 kts in portions of far southeast AZ and eastward
Wednesday evening. We also can't rule out slow moving thunderstorms
causing isolated very heavy rainfall; WPC has issued a marginal risk
for flash flooding in our region.

Thursday may be the last day in this round of convective activity.
While the 500mb low remains close in proximity to the CA/AZ border,
the upper jet streak drifts northeastward in the next 24 hours, also
pushing the area of upper diffluence in the same direction. As such,
the best chance of thunderstorms on Thursday will remain over the
White Mountains. By Friday, the upper low will phase in with the
Western US longwave trough and eject northward. The result will be
drier weather with broad westerly flow. Look for temperatures to
remain within degrees of normal through the weekend, then trend
warmer as high pressure builds into the region next week.

&&

.AVIATION... /Valid 18Z Wednesday through 00Z Friday/
SCT-BKN clouds AOA 8-12k ft AGL through 18/05Z with decreasing
coverage from west to east thereafter. Isolated to scattered
TSRA/SHRA mainly from KTUS eastward with initial development
expected around 17/20Z lasting through about 18/04Z. SFC winds
generally WLY/NWLY at 11-18 kts with ocnl gusts to 20-30 kts.
Stronger SFC winds expected in the vicinity of KSAD and KALK.
Reductions in surface and slantwise visibility from BLDU and
TSRA. Gusty/erratic outflow winds possible near thunderstorms.
Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Winds will remain west/northwest through this week
with speeds of 10-20 mph and gusts 25-30 mph across much of the area
with stronger speeds of 15-25 mph and gusts to 35 mph in lower
elevations of Graham county. Moisture levels will remain slightly
elevated through Thursday, with minimum relative humidity 15-30
percent in lower elevations and 30-40 percent in the mountains. This
will bring bring chances (20-30 percent) for showers and
thunderstorms from Tucson south and eastward, along with the White
Mountains Wednesday. Precipitation chances remain in the White
Mountains Thursday but otherwise retreat to the Int'l border once
again. Dry conditions area-wide Friday and beyond with minimum
relative humidity lowering this weekend to 5 to 15 percent in the
valleys and 10 to 20 percent in the mountains. For Wednesday and
Thursday elevated to near critical fire weather conditions will be
possible in the Gila River Valley as winds increase and RH drops
below 15 percent.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...None.

&&

DVS

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