Flash Flood Warning 285, NWS Phoenix, AZ

818 
WGUS75 KPSR 212207
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
307 PM MST Wed Sep 21 2022

AZC013-021-220215-
/O.CON.KPSR.FF.W.0285.000000T0000Z-220922T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-Pinal AZ-
307 PM MST Wed Sep 21 2022

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 715 PM MST THIS 
EVENING FOR MARICOPA AND PINAL COUNTIES...

At 307 PM MST, Doppler radar and automated rain gauges indicated 
thunderstorms produced heavy rain in Vekol Wash. Between 1 and 2 
inches of rain had fallen over a large area of Vekol Wash basin. 
Flash flooding is already occurring.  Vekol Wash has risen several 
feet and its flow has exceeded 2000 cfs.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding.

SOURCE...Radar and automated gauges.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets and underpasses.

Some locations that will experience flash flooding include...
  Maricopa, Freeman and Ak-Chin Village.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3268 11229 3275 11237 3296 11227 3307 11207
      3305 11204 3295 11204

FLASH FLOOD...RADAR AND GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

MS

739 
WGUS55 KPSR 220135
FFWPSR
AZC013-021-220415-
/O.EXT.KPSR.FF.W.0285.000000T0000Z-220922T0415Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
635 PM MST Wed Sep 21 2022

The National Weather Service in Phoenix has extended the

* Flash Flood Warning for...
  Maricopa County in south central Arizona...
  Pinal County in southeastern Arizona...

* Until 915 PM MST.

* At 635 PM MST, local law enforcement reported ongoing flash 
  flooding along Vekol Wash with a swift water rescue near Warren 
  Road.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding.

  SOURCE...Law enforcement reported.

  IMPACT...Life threatening flash flooding of creeks and streams,
           urban areas, highways, streets and underpasses.

* Some locations that will experience flash flooding include...
  Maricopa, Freeman and Ak-Chin Village.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3268 11229 3275 11237 3296 11227 3307 11207
      3305 11204 3295 11204

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

MS

559 
WGUS75 KPSR 220405
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
905 PM MST Wed Sep 21 2022

AZC013-021-220415-
/O.CAN.KPSR.FF.W.0285.000000T0000Z-220922T0415Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-Pinal AZ-
905 PM MST Wed Sep 21 2022

...FLASH FLOOD WARNING FOR MARICOPA AND PINAL COUNTIES HAS BEEN 
REPLACED WITH A FLOOD WARNING...

LAT...LON 3268 11229 3275 11237 3296 11227 3307 11207
      3305 11204 3295 11204

$$

Hirsch

Area Forecast Discussion
National Weather Service Phoenix AZ
1050 AM MST Wed Sep 21 2022

.UPDATE...Updated 18Z Aviation Discussion.

&&

.SYNOPSIS...
Deep moisture is now in place resulting in heightened chances for
showers and thunderstorms. Rain chances peak the next two days
before gradually diminishing. Much of the activity will be focused
over Arizona with lesser chances in southeast California.
Expansive cloud cover will yield below normal temperatures the
next several days followed by readings warming back towards the
seasonal normal into the weekend.

&&

.DISCUSSION...
Scattered rain showers and a few thunderstorms have been moving
through the area the last couple of hours and are still ongoing at
this time. Due to quick storm motions rainfall accumulations have
not been that significant with most locations seeing less than a
tenth of an inch, but a few locations near Tonto Creek saw up to a
half inch. The thermodynamic environment remains favorable for
additional activity with locally up to 1000 J of MUCAPE per the
RAP analysis and 20-30 kts of effective bulk shear. Moisture
content is also elevated with PWAT near 1.5-1.8" for much of the
area. In terms of forcing, broad ascent continues due to
diffluence aloft. Most of the recent shower activity was focused
along a low level weakly frontogenetical boundary with enhanced
omega values along and ahead of it. As this feature moves north a
few showers may continue for the next few hours but coverage
should gradually diminish as subsidence increases. A secondary
band of light precipitation has also been ongoing along the
moisture gradient in western Maricopa County down through Yuma
County. This area of showers will also persist for a few more
hours and gradually move northwest with time.

Deep moisture advection will continue into the day today with
PWAT topping out near 2" by this afternoon, which is above the
99th percentile for this time of year, and dew points will climb
into the mid-60s across Southern AZ. A stalled north- south
oriented boundary/moisture gradient near the Lower Colorado River
will keep most of the deep moisture out of Southeast CA. This
bountiful moisture will support scattered shower and thunderstorm
development today. In terms of the convective evolution, HREF
guidance is in good agreement that after the current showers die
off, most of the morning hours should be pretty quiet. By late
morning or early afternoon additional activity will develop as the
lower atmosphere finally saturates and CAPE increases. MUCAPE may
approach 1000 J/Kg during this period. Further, mid level lapse
rates steepen slightly due to a glancing blow of a shortwave to
the northwest. In spite of these favorable factors, any lower
level forcing will be poorly defined which will ultimately limit
the ability for strong convection to develop where the moisture
content is maximized. Still, HREF guidance is quite confident (and
it conceptually makes sense too) that numerous showers and
thunderstorms will form during this afternoon. Many locations will
see rain totals of less than 1/4", but any location that sees
training storms develop could see much higher totals, perhaps as
high as 1- 2". A Flood Watch is in effect to account for this
risk. As a reminder, a Watch means conditions will be favorable
for flash flooding and does not mean you will experience it.

We are also watching a low, but non-zero, severe thunderstorm chance
today, mostly west of the Phoenix metro area. Surface to 6km
shear will be fairly high, upwards of 30-35 kts near the CO River
and decreasing eastward. The shear will support some organized
thunderstorm development and SBCAPE increasing through afternoon
heating Wednesday will support some strong updrafts. Strong wind
gusts and small hail will be the primary risk with precip loading.
Although the lower LCLs and associated lower DCAPE will limit the
overall wind potential. There may be an area from La Paz County
to western Maricopa County where conditions could come to together
to support an isolated supercell or two. Surface to 3 km SRH will
be decent for our area, up to 100-150 m2/s2, and the PBL lapse
rates will be fairly high, but the LCL heights will will likely
still limit any tornado threat over the lower deserts.

Shower and thunderstorm activity will continue into Thursday but
will become increasingly tied to the higher terrain where showers
or storms could still lead to localized flash flooding if training
develops. Convective coverage will continue to wain into the
weekend with any remaining activity ending by Sunday. Temperatures
will run well below normal through Thursday but will pop back up
to near normal Friday and onwards as upper level ridging returns
to the area and the boundary layer dries out significantly.

&&

.AVIATION...Updated 1750Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:

The main aviation impacts today will continue to be scattered
showers and thunderstorms, particularly during the mid afternoon to
early evening hours, with their associated lower CIGs and very brief
lower VSBYs. Current southeasterly winds are likely to become
southerly during the midday/early afternoon hours, then become
southwesterly during the late afternoon/evening hours.

There will likely be a few hour period this afternoon/early
evening where scattered thunderstorms will impact the area, with the
current thinking showing 20-00Z the period with the highest
likelihood of potentially impacting area terminals. Erratic wind
shifts with gusts to 20-25kts seem fairly likely with any storm
activity later today, but with wind directions likely favoring the
southwest. Current probabilities for winds above 30 kts peak late
afternoon/early evening at around 20%. Conditions to gradually
improve with winds becoming southeasterly during the mid/late-
evening hours. Thursday to be quieter as the main moisture axis
shifts off to the east and winds aloft become more westerly, keeping
t-storm activity mainly well off the the east of the Phoenix area.
Southeasterly winds in the morning to make their more typical switch
to westerly by late afternoon.

Southeast California/Southwest Arizona including KIPL and KBLH:

Little to no weather issues will exist through tonight. Winds will
continue to be fairly light, favoring the southeast at KIPL this
afternoon and the west starting this evening. Winds at KBLH will
continue to favor a southerly direction with some afternoon wind
gusts to around 20 kts possible. Midlevel moisture and CIGs of 10-
12K ft are expected through at least this afternoon at KBLH with a
chance (10-20%) of -SHRA impacting KBLH.

&&

.FIRE WEATHER...
A large moisture surge today through Thursday will result in a 30-
70% chance of rain for areas east of the Colorado River and 5-20%
chance west of the river. These factors along with elevated RH
values will lead to minimal fire weather concerns. A gradual
drying trend begins on Thursday afternoon but a few storms will
remain possible into Friday or Saturday. Min RH will fall to
15-25% by the weekend with mostly light diurnal winds and high
temperatures approaching 100 degrees once again in the lower
deserts.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Flood Watch through this evening for AZZ533-534-537>563.

CA...None.
&&

DISCUSSION...Hodges/Benedict
AVIATION...Percha/Kuhlman
FIRE WEATHER...Hodges

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
1041 AM MST WED SEP 21 2022

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

1005 AM     FLASH FLOOD      5 NW BEARDSLEY          33.73N 112.46W
09/21/2022                   MARICOPA           AZ   BROADCAST MEDIA

            MEDIA REPORTS FLASH FLOODING NEAR WITTMAN.
            WATER AND DEBRIS FLOWING OVER RAODWAY OFF OF
            GRAND AVE & JOMAX.

&&

BF

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
1146 AM MST WED SEP 21 2022

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

1124 AM     FLASH FLOOD      9 SSE PALO VERDE NGS    33.28N 112.80W
09/21/2022                   MARICOPA           AZ   MESONET

            CENTENNIAL WASH @ SPRR ID 24707 REACHED
            ACTION STAGE AT 9:54 AM MST. FLASH FLOOD
            IMPACTS DOWNSTREAM WHERE CENTENNIAL WASH
            CROSSES OLD U.S. 80 1.5 HOURS AFTER ACTION
            STAGE WAS REACHED.

&&

BF