Flash Flood Warning 160, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
220 PM MST Sat Aug 29 2026

.SYNOPSIS...Expect daily thunderstorms through at least Monday
with storms capable of strong to severe wind gusts and heavy
rainfall. After Monday storm chances begin to decrease. High
temperatures will remain above normal Sunday through much of
next week.

&&

.DISCUSSION...The upper air pattern across Arizona continues to
transition into a Monsoon Type IV pattern with the upper high
to our east and an upper level trof to the NW. This pattern
brings an increased threat of severe storms, flash flooding, and
nocturnal storms this weekend into Monday.

Storms have been forming over the higher terrain early this
afternoon with further development over the next 3 to 6 hours. Main
threat from storms today will be strong gusty outflow winds, some
which may be briefly severe, blowing dust and heavy rain. The strong
outflow winds may produce areas of blowing dust across Pima and
Pinal counties where a blowing dust advisory is in effect from 4 pm
to 8 pm. With potential rainfall rates with some of the stronger
cores being 1-2"/hr, flash flooding is a threat, especially across
Pinal, Pima and Santa Cruz county where a flash flood watch is in
effect. Not everyone will see heavy rain or rain at all in the flash
flood watch area. Tonight, across central Sonora MX near Hermosillo,
a decaying MCS may send a strong outflow north towards the area and
kick off some elevated storms across the central part of the
forecast, or mainly across Santa Cruz, eastern Pima and western
Cochise counties.

Sunday: after lingering morning convection ends, storms will be
developing over the higher terrain early afternoon and work their
way into the lower elevations. Another chance of localized severe
storms and flash flooding. Can't rule out storms continuing late
Sunday night into early Monday morning.

Monday: Likely a later start to convection with less areal coverage
of storms.

Tuesday and Wednesday: Low-grade monsoon days as the monsoon
calendar turns to September and possible tropical influences
during the month.

Speaking of the tropics, NHC is monitoring an area of disturbed
weather, associated with a tropical wave, well south of SW Mexico.
This may become the next named eastern Pacific tropical storm with
some model guidance indicating that the potential track will be
further east than where current Tropical storm Karina is at, and
closer to Baja by the end of next week. Confidence low this far out
but something to keep an eye on.

Temperature wise, today is the last day of the almost two-week long
Extreme Heat Warning. Highs will thus be cooler during the next 7
days but still running, except for Monday and Tuesday, above normal
for the most part.

&&

.AVIATION...Valid through 31/00Z.
SCT -SHRA/-TSRA thru 30/06z, bcmg ISOLD btwn 30/06z and 30/12z.
Chance of storms returning to the area aft 30/20z. Outflow SFC winds
nr TSRA 35-45 kts otrw SFC winds mostly less than 10 kts and terrain
driven. Clouds thru much of valid pd, SCT-BKN 8k-12k ft AGL.
Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Expect scattered afternoon and evening showers and
thunderstorms through Monday (30 to 70 percent daily thunderstorm
chances). Storms will be capable of strong to severe wind gusts and
heavy rainfall. After Monday storm chances and coverage decrease
with activity mainly from Tucson south and eastward. Temperatures
will remain above normal today with a cooling trend this weekend
into early next week. Minimum relative humidity values mainly 15 to
30 percent in the valleys and 20 to 40 percent in the mountains
today. Minimum RH values increase to 20 to 50 percent starting
Sunday into next week. Winds will generally remain less than 15 mph
and terrain driven through the week.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
 Extreme Heat Warning until 8 PM MST this evening for
  AZZ501>509.
 Flood Watch through late Sunday night for AZZ502>507-513>515.
 Blowing Dust Advisory until 8 PM MST this evening for AZZ501-
 502-504-505.

&&

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