Flash Flooding in Arizona, November 29, 2019

Name: Flash Flooding in Arizona, November 29, 2019
Start: 2019-11-29T00:30
End: 2019-11-29T08:15
Location: Arizona

November 29, 2019 · NWS PSR · 4 events in 1 county or zone

Where it happened

Every event with a place to put it. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: $1,000
Crop damage: None recorded
Events: 4

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS PSR wrote it up.

A powerful Pacific low pressure system moving slowly through the desert southwest interacted with deep moisture to produce widespread heavy rain across the central deserts during the morning hours on November 29th. Aided by frontal lift, isolated thunderstorms developed which further enhanced rain totals. The heavy rain resulted in several instances of flash flooding across the western portions of Maricopa County that occurred near or before sunrise. Most of the flash flooding took the form of flowing washes or roads becoming washed out or impassable. In some cases, data from Maricopa County Flood Control District gages was used to infer the presence of flash flooding. Fortunately, there were no reports of accidents or injuries due to the flash flooding.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Phoenix, AZ wrote its last area forecast discussion before the first event at Nov 28, 11:27 PM MST, 1 hour 3 minutes earlier.

Area forecast discussion, Nov 28, 11:27 PM MST, 1 hour 3 minutes before

Area Forecast Discussion
National Weather Service Phoenix AZ
1127 PM MST Thu Nov 28 2019

.UPDATE...
Updated 06Z aviation discussion.

&&

.SYNOPSIS...
Rainfall will increase in coverage tonight as a strong low pressure
system moves into the Desert Southwest. There will also be very windy
conditions at times along with a slight chance of thunderstorms.
Snow levels will drop rapidly across Gila County Friday morning
and it will be cold enough for accumulating snow, generally above
4500 feet. Warmer and drier conditions are expected during weekend as
high pressure builds across the Rockies. Another low pressure system
will bring a chance of rain to the region midweek.

&&

.DISCUSSION...
The heaviest precipitation associated with the well-advertised
Pacific low pressure system has moved inland along the southern
California coast while further east across Arizona, showers early
this morning across Maricopa County didn't amount to much.

Latest visible satellite shows some breaks in the clouds across
western Arizona, which reveal thickening stratocu marching due
northward, embedded with an anomalously strong 40 kt low-level jet.
The HREF suggests the increasing instability across western Arizona
coupled with vorticity-forced ascent will result in a developing area
of shower activity late this afternoon and this evening, likely
stretching from Maricopa and La Paz Counties back into Yuma County.

Latest CAMs and global models depict the main batch of precipitation
stretching along a north-south line near the Colorado River Valley
late this afternoon and this evening. Given the 60-80 kt deep-layer
shear and modest instability, there is some potential for organized
convection, most likely in the form of a squall line. However, a
supercell cannot be ruled out as well. The strongest storms will be
capable of producing heavy rain, hail, and even severe wind gusts.
A brief tornado is also possible within any sustained supercells or
embedded circulations, particularly across Imperial and Yuma
counties.

The NAEFS 850 mb wind percentiles near 55 kt will approach
all-time records this evening across southwestern Arizona. With
widespread shower activity moving steadily across Arizona, it won't
be difficult to mix down gusts as high as 40-55 mph to the surface.
ECMWF-E and GEFS plumes have generally captured the potential for
stronger wind gusts and this is reflected in the latest forecast.
Heaviest rain across south-central Arizona will likely occur between
10 pm and 7 am. Little change was made to forecast QPF. Ensembles
continue to suggest rain totals will range from 1 to 1.5 inches
across the Phoenix area, with higher amounts to the north and east.

The heaviest precipitation will translate eastward into Gila County
Friday morning. A Winter Storm Warning remains in effect for
significant snow accumulations, generally above 4500 feet. Rainfall
will taper off quickly during the morning across the Phoenix area,
with clearing likely in the lower deserts during the afternoon.

In the wake of the low pressure system, a ridge will migrate
eastward across the Desert Southwest Saturday and amplify across the
Rockies Sunday. GEFS indicates mid-level heights will remain above
average through early next week, which will translate into above
normal temperatures Monday and Tuesday. There is increasing
likelihood another trough will impact the region during the midweek
period. Both the GEFS and ECMWF-E suggest the potential for
another 0.5-1.0 inch of rain. However, thicknesses point to a warm
system with above normal snow levels.

&&

.AVIATION...Updated at 0627Z.

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

Strong southerly winds with gusts up to 35 knots are expected
through 10Z as showers gradually increase in coverage and SCT-BKN
ceilings lower to around 4-5 kft. Isolated stronger gusts are
possible ahead of and along the front, particularly with any
convection that is able to mix down higher momentum air aloft
associated with a 50 knot low-level jet. Deeper convection is
generally not expected until the front arrives at the terminals
closer to 10-11Z, along which there should be enough instability
and frontal forcing to produce isolated thunderstorms within a
line of convection. A brief period of IFR-MVFR visibilities and
ceilings are expected with this convective line, with widespread
rain showers behind it through 16-17Z. Southerly wind gusts in
excess of 35 knots will be possible along and ahead of the front,
with westerly wind gusts up to 25 knots expected behind the front.
Ceilings should improve tomorrow with a slight chance of showers
and possibly an elevated thunderstorm or two in the afternoon, but
confidence is too low to include them in the TAF at this time.

Southeast California/Southwest Arizona including KIPL and KBLH:

Light to moderate rain showers will continue through 08-09Z at
KBLH and 12Z at KIPL behind the front with BKN-OVC ceilings
generally staying above 5-6 kft. Further east over eastern Yuma
and La Paz Counties, scattered showers and a few thunderstorms
are expected to develop ahead of a frontal line of convection over
the next few hours before moving into south central Arizona.
Frequent southerly 30-40 knot wind gusts with isolated stronger
gusts are expected ahead of and along the front, particularly with
any convection that is able to mix down higher momentum air aloft
associated with a 50 knot low-level jet. Shower activity will end
from W-NW to E-SE on Friday morning as skies gradually clear with
westerly wind gusts up to 35 knots during the afternoon.

&&

.FIRE WEATHER...
Saturday through Wednesday:
Below normal temperatures Saturday will warm to near normal by
Monday under slow drying conditions and light winds. Moisture
levels should remain fairly elevated through early next week with
minimum RH values mostly above 35 percent. The next low pressure
system then looks to approach from the west late Tuesday into
Wednesday bringing increased moisture, rain chances, and breezy
conditions later Wednesday

&&

.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Flash Flood Watch through Friday afternoon for AZZ534-537>563.

     Wind Advisory until 4 AM MST Friday for AZZ534-537>544-546-
     548>551-553>555-559.

     Wind Advisory until 9 AM MST Friday for AZZ545-547-552-556>558-
     560>563.

     Winter Storm Warning until midnight MST Friday night for AZZ557-
     558-563.

     Flash Flood Watch until 5 AM MST Friday for AZZ530>533-535-536.

     Wind Advisory until midnight MST tonight for AZZ530>533-535-536.

CA...Flash Flood Watch until 4 AM PST Friday for CAZ569.

     Wind Advisory until 11 PM PST this evening for CAZ562-564-565-
     569-570.

     Winter Storm Warning until 4 AM PST Friday for CAZ560.

     Wind Advisory from 2 AM to 3 PM PST Friday for CAZ560.

&&

DISCUSSION...Hirsch
AVIATION...Hopper
FIRE WEATHER...Kuhlman

In the hours before

Local storm report, Nov 28, 7:51 PM MST, 4 hours 39 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
751 PM MST THU NOV 28 2019

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

0727 PM     FLASH FLOOD      4 N EAST BLYTHE         33.66N 114.57W
11/28/2019                   RIVERSIDE          CA   FIRE DEPT/RESCUE

            CAR FLOODED AND FLOATING AT 6TH AVE & US95,
            RESCUED THROUGH ROOF.

&&

KW

Local storm report, Nov 28, 9:53 PM MST, 2 hours 37 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
953 PM MST THU NOV 28 2019

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

0834 PM     FLASH FLOOD      4 WNW FELICITY          32.76N 114.84W
11/28/2019                   IMPERIAL           CA   DEPT OF HIGHWAYS

            OGILBY ROAD CLOSED FROM I-8 TO CALIFORNIA
            STATE ROUTE 78 DUE TO FLOODING PER
            CALIFORNIA HIGHWAY PATROL.

&&

LJH

Local storm report, Nov 28, 10:09 PM MST, 2 hours 21 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
1009 PM MST THU NOV 28 2019

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

0822 PM     FLASH FLOOD      5 S QUARTZSITE          33.60N 114.22W
11/28/2019                   LA PAZ             AZ   LAW ENFORCEMENT

            ALL WASHES FLOODED OUT ALONG HIGHWAY 95 FROM
            MILE POST 90 NORTH TO QUARTZSITE PER LA PAZ
            COUNTY SHERIFFS OFFICE; POINT OF REPORT AT
            FRENCH CREEK IN THE MIDDLE OF THE FLOODED
            AREA.

&&

LJH

The radar

The Phoenix radar (KIWA), 149 km away, was scanning. The volume nearest the first event began at 07:31 UTC.

Open the radar archive at this moment

Event by event

4 flash flood. Local standard time, as filed.

Flash Flood, Maricopa

When: November 29, 12:30 AM MST to 5:00 AM MST
Where: Maricopa County, 13.98 mi SSE of Gladden to 6.19 mi S of Gladden
Cause: Heavy Rain
Reported by: County Official
Coordinates: 33.718, -113.193

A powerful Pacific low pressure system moving slowly east across Arizona interacted with deep moisture to produce widespread moderate to heavy rain across the western portion of Maricopa County during the morning hours on November 29th. Aided by frontal lift, isolated thunderstorms developed which enhanced rain totals. The heavy rain resulted in an episode of flash flooding over mostly open country, north of Interstate 10 and just east of the county line. According to a report at 0626MST from a county official, Eagle Eye road was closed from milepost 6 to milepost 13 due to flash flooding. The time of the actual flash flooding was about 0232MST and was based off of data from a Maricopa County Flood Control stream gage. The gage crested at 7.22 feet at 0208MST and the expected travel time of the flood wave was used to determine the time of flash flooding at Eagle Eye road. The location of the flooding was about 10 miles southeast of the town of Gladden. There were no reports of any accidents due to the flash flooding.

Flash Flood, Maricopa

When: November 29, 1:30 AM MST to 7:30 AM MST
Where: Maricopa County, 4.84 mi WNW of Harqua to 8.67 mi W of Harqua
Cause: Heavy Rain
Reported by: Public
Coordinates: 33.274, -113.079

A powerful Pacific low pressure system moving slowly east across Arizona interacted with deep moisture to produce widespread moderate to heavy rain across western portions of Maricopa County during the morning hours on November 29th. Aided by frontal lift, isolated thunderstorms developed and enhanced rain totals. The heavy rain led to an episode of flash flooding over far west central Maricopa County near the Eagle Tail Mountains. According to a delayed report from the public, flash flooding resulted in Agua Caliente road becoming flooded and impassable where it crosses the Fourth of July Wash. The actual flash flooding occurred about 0207MST and was based off of data from a Maricopa County Flood Control District streamgage which showed the wash cresting at 2.2 feet; estimated travel time of the flood wave resulted in the time of the actual flash flooding. There were no reports of accidents due to the flash flooding.

Flash Flood, Maricopa

When: November 29, 1:30 AM MST to 8:00 AM MST
Where: Maricopa County, 1.48 mi W of Wickenburg to 1.55 mi SE of Wickenburg Muni Arpt
Cause: Heavy Rain
Reported by: Fire Department/Rescue
Coordinates: 33.968, -112.756

A powerful Pacific low pressure system moving slowly east across Arizona interacted with deep moisture to produce widespread moderate to heavy rain across western portions of Maricopa County during the morning hours on November 29th. Aided by frontal lift, isolated thunderstorms developed within the bands of rain, locally enhancing rain totals. The heavy rain led to an episode of flash flooding in the community of Wickenburg during the early morning hours. According to the Wickenburg fire and rescue department, flash flooding caused the vulture mine road to become closed at Sols Wash, about 3 miles to the northwest of Wickenburg. The actual time of the flooding was estimated to be 0351MST, based on data from a Maricopa County Flood Control District streamgage; the gage crested at 1.79 feet and travel time of the flood wave was used in estimating the exact time of flash flooding. There were no reports of accidents due to the flash flooding.

Flash Flood, Maricopa

When: November 29, 3:00 AM MST to 8:15 AM MST
Where: Maricopa County, 2.45 mi SSE of Bosque to 2.02 mi ESE of Gila Bend
Cause: Heavy Rain
Property damage: $1,000
Reported by: County Official
Coordinates: 32.937, -112.535

A powerful Pacific low pressure system moving slowly east across Arizona interacted with deep moisture to produce widespread moderate to heavy rain over western portions of Maricopa County, including the community of Gila Bend, during the morning hours on November 29th. Isolated thunderstorms were present and they further increased rain totals. The heavy rain led to some flash flooding east of Gila Bend and along Highway 238. According to the Maricopa County Sheriff's Office and the department of transportation, flash flooding caused state route 238 to be closed from milepost 24 to Gila Bend. There were no reports of accidents due to the flash flooding.

What these are

Flash Flood: Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Arizona in 2019 Every state in 2019 This day in weather history Warnings in Arizona, November 2019

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 860200, 860201, 860222, 860223.