Flash Flood Warning 53, NWS Tucson, AZ

789 
WGUS75 KTWC 282254
FFSTWC

Flash Flood Statement
National Weather Service Tucson AZ
354 PM MST Sun Jul 28 2024

AZC003-282304-
/O.EXP.KTWC.FF.W.0053.000000T0000Z-240728T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Cochise AZ-
354 PM MST Sun Jul 28 2024

...FLASH FLOOD WARNING WILL EXPIRE AT 4 PM MST THIS AFTERNOON FOR 
SOUTHWESTERN COCHISE COUNTY...

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

&&

LAT...LON 3146 11034 3150 11030 3153 11024 3154 11013
      3149 11011 3141 11009 3134 11013 3134 11020
      3133 11030 3139 11030 3143 11034

$$

KJS

Area Forecast Discussion
National Weather Service Tucson AZ
955 AM MST Sun Jul 28 2024

.SYNOPSIS...Daily chances for showers and thunderstorms this
through the week. Main threats will be heavy rainfall with strong
gusty winds. Localized flash flooding and isolated severe winds
will be possible.

.UPDATE...Latest visible satellite imagery shows cloud cover
slow to dissipate this morning over the majority of Pinal, western
Pima, northern Cochise, southern Graham/Greenlee counties. Surface
dewpoints are in the 60s across most of the forecast area. The 12Z
TWC sounding reported 1.66 inches of precipitable water in the
atmospheric column this morning, which is just shy of the 90th
percentile for 12Z soundings on this date by about a tenth of an
inch, but well over the 75th percentile.

There is plenty of moisture in the atmospheric column again this
morning across southeast AZ with a deeper warm cloud layer depth of
around 11,100 ft (up from 7800 ft yesterday) and even weaker mean
flow aloft. There is just enough deep layer shear (around 20 kts) to
sustain storms that do develop today tapping into the 1300 J/kg of
most unstable CAPE, but with the mean flow being so weak, the
biggest concern today will be heavy rainfall leading to flash
flooding. Many areas that received heavy rainfall yesterday in Santa
Cruz and Cochise counties will likely receive additional rainfall
again today which amplifies the flash flood threat for those areas.
HREF is showing a broad area of 50-70 percent chance of receiving an
inch in a 3-hour period across Santa Cruz, Cochise, Graham, and
eastern Pima counties this afternoon with even a slight chance (10
percent) of receiving 3 inches in a 3-hour period over western Santa
Cruz county.

Wind threat overall appears to be on the lower end again today with
DCAPE from the 12Z TWC sounding coming in at ~960 J/kg, but cannot
rule out a few strong to severe winds out of the stronger storms.
Convective allowing models are highlighting a similar start time and
set up to yesterday (i.e., starting south and east of Tucson around
noon) but today will expect more coverage around the Tucson Metro
and T.O. Nation into the mid afternoon/early evening hours.

Overall, looking at another day of flash flooding concerns but with
increasing confidence of storms with heavy rainfall impacting the
Tucson Metro area to points west/northwest of Tucson this afternoon
and evening.

&&

.DISCUSSION...
Seasonable moisture in place with surface dewpoints in the 60s and
precipitable water values ranging from around 1.3 inches east to
1.6 inches west. A relative down day yesterday for the greater
Tucson area after being worked over by storms last night. Today
the flow should have recovered with a better chance of storms this
afternoon. Watch for a potential organized thunderstorm complex in
northern Sonora tonight that may push debris with embedded showers
into our area in the early morning hours.

Ensemble means have the high center reconsolidating to our east
the first half of the week, with a little stronger southerly flow
opening the door for a weak inverted trough to push into SE AZ
around mid week. Timing and trajectories uncertain, but it could
enhance an atypical diurnal trend with elevated chances of
overnight storms.

High center should reconsolidate near the four corners area to
start the new month for a very typical deep monsoon pattern for
continued thunderstorm chances. A strong H7 theta-e ridge should
extend further north through most of AZ and even northward as this
happens.

&&

.AVIATION...Valid through 29/12Z.
SCT-BKN clouds AOA 7-12k ft AGL. Scattered thunderstorms between
28/20Z and 29/04Z. Strong winds to 45 kts possible near TSRA with
MVFR conditions. Otherwise light winds this morning with winds
generally under 12kts this afternoon. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...
Elevated moisture will continue with scattered afternoon and
evening showers and thunderstorms. Each day has the threat of
heavy rain, localized flash flooding and strong gusty outflow
winds. Away from thunderstorms, 20-foot winds will generally be 15
mph or less, with afternoon/early evening gusts to 20-25 mph and
light winds overnight. As high pressure builds mid- week, high
temperatures should rise a bit and minimum relative humidities
should fall by a few percentage points.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Blowing Dust Advisory from 4 PM this afternoon to 8 PM MST this
evening for AZZ505.

&&

DVS

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