Alert archive / Arizona / Flash Flood Warnings in 2018

Flash Flood Warning 7, NWS Phoenix, AZ

July 9, 2018Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Jul 9, 2018, 3:51 PM MST for Maricopa County, Arizona. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jul 9, 2018, 3:51 PM MST (22:51 UTC)
Expired: Jul 9, 2018, 6:22 PM MST
In force: 3 hr
Issued by: NWS Phoenix, AZ
Area: Storm-based polygon
Flood severity: None

County Maricopa County, AZ

The radar

The Phoenix radar (KIWA), 73 km from the middle of the area, began a volume at 22:54 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this flash flood warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The nearest sounding before it

Phoenix, AZ (KPSR), launched 12:00Z, 10.9 hours before the alert went out and 55 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 482 J/kg
Mixed-layer CIN: -272 J/kg
Mixed-layer LCL: 1601 m above ground
0-6 km bulk shear: 10 kt
0-1 km storm-relative helicity: 19 m²/s²
0-3 km storm-relative helicity: 22 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

006 
WGUS55 KPSR 092251
FFWPSR
AZC013-100145-
/O.NEW.KPSR.FF.W.0007.180709T2251Z-180710T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
351 PM MST MON JUL 9 2018

The National Weather Service in Phoenix has issued a

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

* Until 645 PM MST.

* At 350 PM MST, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area. Flash flooding is expected to
  begin shortly.

* Some locations that will experience flooding include...
  New River, Cave Creek, Carefree, Desert Mountain, Camp Creek and 
  Seven Springs.

LAT...LON 3400 11176 3379 11185 3379 11205 3393 11199
      3402 11192

$$

MS

1 follow-up statement

031 
WGUS75 KPSR 100122
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
622 PM MST MON JUL 9 2018

AZC013-100132-
/O.CAN.KPSR.FF.W.0007.000000T0000Z-180710T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
622 PM MST MON JUL 9 2018

...THE FLASH FLOOD WARNING FOR MARICOPA COUNTY IS CANCELLED...

The heavy rain has ended and no reports of flooding have been 
received. Flooding is no longer expected to pose a threat. Please 
continue to heed any remaining road closures.

LAT...LON 3400 11176 3379 11185 3379 11205 3393 11199
      3402 11192

$$

MS

What forecasters said that day

The local office's own words before this flash flood warning went out, 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 this flash flood warning went out at Jul 9, 3:05 PM MST, 46 minutes earlier.

Area forecast discussion, Jul 9, 3:05 PM MST, 46 minutes before

Area Forecast Discussion
National Weather Service Phoenix AZ
305 PM MST Mon Jul 9 2018

.SYNOPSIS...
Monsoon moisture levels will continue to remain high enough this
week to bring daily thunderstorm chances to most of the region.
An upper level trough moving through today and early Tuesday should
enhance monsoon activity creating better chances for more widespread
storms than a typical monsoon day. Temperatures will continue to
trend downward through the middle of the week and then level off a
few degrees below normals.

&&

.DISCUSSION...
Current radar shows showers and thunderstorms that have developed
southeast and east of the Phoenix from Pinal cty. to S. Gila county
with more extensive storm development taking place in south central
and northern Arizona. The very strong Monsoon high pressure system
remains in place over the central Rockies. It is in an excellent
position to continue to provide moist easterly flow from the Gulf of
Mexico and Mexico into the Desert Southwest via it's attendant south
stream easterly jet. A pronounced upper level low and inverted
trough seen in water vapor imagery over east AZ with a dry slot
wrapping into is progged to move over our region this afternoon and
evening  where it will expand and dramatically decelerate.

The strong easterly wave will have plenty of moisture to work with
as it moves into a well conditioned Monsoon environment. Boundary
layer dewpoint temperatures remain very high with 60s and 70s F
being reported at the surface and 12-20C being reported through 925
and 850mb. Amidst significant mid level moisture advection from the
southeast, strong sounding and model CAPE of up to 1500-2000 j/kg.,
and sfc-6km shear of 30-35kt expect a good chance of a mixed bag of
Monsoon threats from this afternoon through tonight. This includes
the threat of severe thunderstorm winds, flash flooding and dense
blowing dust. The strongest storms will be capable of producing
gusts near 60mph and peak rainfall rates over 4in./hr as well as the
potential for hail. High-res models indicate the prime threat areas
to be from Phoenix westward to the California border. Expect a
series of strong easterly outflows to span our forecast area from
north to south and sweep from Maricopa and Pinal counties all the
way to southeast CA.

Tuesday looks to be a bit drier and more of a down day, however
Tuesday night and Wednesday morning are shaping up to be another
fairly active Monsoon period.

&&

.AVIATION...
South-Central Arizona including KPHX, KIWA, and KSDL:
Storm activity over Pinal, Gila, and Yavapai Counties will
converge over Maricopa County - including metro Phoenix - between
22Z- 00Z. Storms then track westward. Expect large swaths of
strong surface winds from thunderstorm outflow. The winds will
also cause areas of reduced visibility in blowing dust. The
stronger storms will produce brief heavy rain and small hail.
Anticipate much quieter conditions over metro Phoenix beginning by
03Z. However, renewed shower development is anticipated overnight
but not with very strong storms.

Southeast California/Southwest Arizona including KIPL and KBLH:

Strong storms are expected to move out of Yavapai and Maricopa
Counties and into southwest Arizona beginning by about 23Z. Storms
are anticipated to track westward and weaken as they move west of
the Lower Colorado River Valley. However, large swaths of strong
winds and blowing dust are possible throughout the area.

Aviation Discussion not updated for amended TAFs.

&&

.FIRE WEATHER...
Thursday through Monday:
An active Monsoon pattern continues the rest of the week into
early next week. As usual, south-central AZ will have better
chances than areas west of there. Minimum humidities will remain
above 15% with good overnight recovery. Apart from thunderstorm
activity, winds will generally be light.

&&

.SPOTTER INFORMATION STATEMENT...
Spotters may be needed late this afternoon and evening.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

DISCUSSION...Sawtelle
AVIATION...AJ
FIRE WEATHER...AJ

In the hours before

Local storm report, Jul 9, 3:31 PM MST, 20 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
331 PM MST MON JUL 9 2018

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

0329 PM     HAIL             2 WSW APACHE JUNCTION   33.40N 111.58W
07/09/2018  E0.25 INCH       MARICOPA           AZ   TRAINED SPOTTER

            PEA SIZED HAIL NEAR MERIDAN RD AND SOUTHERN
            AVE.

&&

Local storm report, Jul 9, 3:37 PM MST, 14 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
337 PM MST MON JUL 9 2018

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

0320 PM     DUST STORM       PHOENIX MESA GATEWAY AI 33.31N 111.66W
07/09/2018                   MARICOPA           AZ   AWOS

            VISIBILITY DOWN TO ONE QUARTER MILE.

&&

Special weather statement, Jul 9, 3:37 PM MST, 14 minutes before

Special Weather Statement
National Weather Service Phoenix AZ
337 PM MST MON JUL 9 2018

AZZ547-549-557-558-092315-
Fountain Hills/East Mesa AZ-Mazatzal Mountains AZ-
Rio Verde/Salt River AZ-Pinal/Superstition Mountains AZ-
337 PM MST MON JUL 9 2018

...SIGNIFICANT WEATHER ADVISORY FOR MARICOPA AND PINAL COUNTIES UNTIL
415 PM MST...

At 336 PM MST, Doppler radar was tracking a strong thunderstorm near
Canyon Lake, or 9 miles southeast of Sugarloaf Mountain, moving west
at 20 mph.

Half inch hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Sugarloaf Mountain, Saguaro Lake, Canyon Lake, Goldfield Ranch, Fort
McDowell and Tortilla Flat.

This includes AZ Route 87 between mile markers 195 and 209.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3365 11129 3344 11134 3362 11169 3381 11160
TIME...MOT...LOC 2236Z 084DEG 16KT 3359 11142

Hernandez

Local storm report, Jul 9, 3:42 PM MST, 9 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
342 PM MST MON JUL 9 2018

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

0333 PM     TSTM WND GST     4 ESE EAST MESA         33.40N 111.62W
07/09/2018  E50 MPH          MARICOPA           AZ   TRAINED SPOTTER

            50 MPH WIND GUSTS NEAR ELLSWORTH AND
            SOUTHERN. IN ADDITION, PEA SIZED HAIL AND
            RAINFALL OF 0.33 INCHES IN 5 MINUTES.

&&

Local storm report, Jul 9, 3:45 PM MST, 6 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
345 PM MST MON JUL 9 2018

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

0344 PM     HAIL             3 W APACHE JUNCTION     33.41N 111.60W
07/09/2018  E0.75 INCH       MARICOPA           AZ   TRAINED SPOTTER

            DIME TO PENNY SIZED HAIL REPORTED NEAR
            BROADWAY AND SIGNAL BUTTE. POWER OUTAGE AS
            WELL.

&&

Special weather statement, Jul 9, 3:48 PM MST, 3 minutes before

Special Weather Statement
National Weather Service Phoenix AZ
348 PM MST MON JUL 9 2018

AZZ541-545-092330-
New River Mesa AZ-Cave Creek/New River AZ-
348 PM MST MON JUL 9 2018

...SIGNIFICANT WEATHER ADVISORY FOR MARICOPA COUNTY UNTIL 430 PM
MST...

At 348 PM MST, Doppler radar was tracking a strong thunderstorm over
Camp Creek, or 15 miles north of Scottsdale, moving southwest at 15
mph.

Dime size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Scottsdale, New River, Cave Creek, Carefree, Desert Mountain, Camp
Creek and Seven Springs.

LAT...LON 3393 11173 3392 11172 3370 11184 3385 11211
      3402 11187
TIME...MOT...LOC 2248Z 033DEG 14KT 3391 11186

Hernandez

The office that day

Everything else NWS Phoenix, AZ issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 8, 5:12 PM MST	Dust Storm Advisory	PSR	La Paz, Maricopa	48 min
Jul 8, 5:48 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	27 min
Jul 8, 5:52 PM MST	Flash Flood Warning	PSR	Maricopa	113 min
Jul 8, 6:21 PM MST	Special Weather Statement	PSR		39 min
Jul 8, 8:02 PM MST	Blowing Dust Advisory	PSR	Maricopa, Pinal	118 min
Jul 8, 8:05 PM MST	Special Weather Statement	PSR	Pinal	55 min
Jul 8, 8:48 PM MST	Dust Storm Warning	PSR	Pinal	42 min
Jul 8, 8:50 PM MST	Dust Storm Advisory	PSR	Maricopa, Pinal	25 min
Jul 8, 9:04 PM MST	Dust Storm Warning	PSR	Maricopa, Pinal	56 min
Jul 8, 9:15 PM MST	Special Weather Statement	PSR	Maricopa	60 min
Jul 8, 9:35 PM MST	Special Weather Statement	PSR	La Paz	40 min
Jul 8, 9:41 PM MST	Dust Storm Warning	PSR	Maricopa, Pinal	64 min
Jul 8, 9:43 PM MST	Dust Storm Warning	PSR	Maricopa	62 min
Jul 8, 9:47 PM MST	Dust Storm Advisory	PSR	Maricopa, Pinal	58 min
Jul 8, 9:50 PM MST	Special Weather Statement	PSR		55 min
Jul 8, 10:09 PM MST	Flash Flood Warning	PSR	Maricopa	6 hr
Jul 8, 10:44 PM MST	Dust Storm Warning	PSR	Maricopa, Yuma	61 min
Jul 8, 11:12 PM MST	Dust Storm Warning	PSR	Yuma	63 min
Jul 9, 12:03 AM MST	Dust Storm Advisory	PSR	La Paz, Yuma	57 min
Jul 9, 12:50 AM MST	Dust Storm Advisory	PSR	La Paz, Yuma	55 min
Jul 9, 3:38 AM MST	Special Weather Statement	PSR		52 min
Jul 9, 2:21 PM MST	Severe Thunderstorm Warning	PSR	Pinal	24 min
Jul 9, 2:45 PM MST	Flash Flood Warning	PSR	Pinal	3 hr
Jul 9, 2:46 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	44 min
Jul 9, 2:49 PM MST	Dust Storm Advisory	PSR	Pinal	56 min
Jul 9, 2:56 PM MST	Special Weather Statement	PSR	Pinal	34 min
Jul 9, 3:01 PM MST	Severe Thunderstorm Warning	PSR	Pinal	29 min
Jul 9, 3:04 PM MST	Special Weather Statement	PSR		26 min
Jul 9, 3:15 PM MST	Special Weather Statement	PSR		30 min
Jul 9, 3:17 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	28 min
Jul 9, 3:19 PM MST	Dust Storm Warning	PSR	Maricopa, Pinal	26 min
Jul 9, 3:23 PM MST	Flash Flood Warning	PSR	Maricopa, Pinal	103 min
Jul 9, 3:29 PM MST	Severe Thunderstorm Warning	PSR	Pinal	31 min
Jul 9, 3:34 PM MST	Flash Flood Warning	PSR	Pinal	3 hr
Jul 9, 3:37 PM MST	Special Weather Statement	PSR		38 min
Jul 9, 3:40 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	35 min
Jul 9, 3:45 PM MST	Dust Storm Warning	PSR	Maricopa, Pinal	30 min
Jul 9, 3:48 PM MST	Special Weather Statement	PSR		42 min
Jul 9, 3:57 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	33 min
Jul 9, 3:59 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	31 min
Jul 9, 4:11 PM MST	Dust Storm Advisory	PSR	Maricopa	34 min
Jul 9, 4:13 PM MST	Dust Storm Warning	PSR	Maricopa, Pinal	62 min
Jul 9, 4:15 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	30 min
Jul 9, 4:28 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	32 min
Jul 9, 4:31 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	29 min
Jul 9, 4:33 PM MST	Severe Thunderstorm Warning	PSR	Pinal	25 min
Jul 9, 4:44 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	31 min
Jul 9, 4:47 PM MST	Areal Flood Advisory	PSR	Maricopa	118 min
Jul 9, 4:50 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	25 min
Jul 9, 4:55 PM MST	Dust Storm Advisory	PSR	Maricopa	65 min

Nearby

Flash Flood Warnings in Arizona, 2018 Every flash flood warning in 2018

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.