Alert archive / Arizona / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 9, NWS Phoenix, AZ

July 9, 2018Maricopa County, Pinal County, Arizona

NWS Phoenix, AZ issued this severe thunderstorm warning at Jul 9, 2018, 3:59 PM MST for Maricopa County, Pinal County, Arizona. It was in force for 31 min. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Jul 9, 2018, 3:59 PM MST (22:59 UTC)
Expired: Jul 9, 2018, 4:30 PM MST
In force: 31 min
Issued by: NWS Phoenix, AZ
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Maricopa County, AZ, Pinal County, AZ

The radar

The Phoenix radar (KIWA), 28 km from the middle of the area, began a volume at 22:59 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.

What was reported inside it

Time	Report	Where	Remark
Jul 9, 4:14 PM MST	TSTM WND GST 80	6 N Florence, AZ	DELAYED REPORT. MEASURED BY AZ ALERT STATION.
Jul 9, 4:14 PM MST	TSTM WND GST 80	6 N Florence, AZ

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

Did it verify

Verified. The Iowa Environmental Mesonet's Cow matched 2 storm reports to this severe thunderstorm warning; the first came 15 minutes after it went out.

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, 11.0 hours before the alert went out and 57 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.

313 
WUUS55 KPSR 092259
SVRPSR
AZC013-021-092330-
/O.NEW.KPSR.SV.W.0009.180709T2259Z-180709T2330Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Phoenix AZ
359 PM MST MON JUL 9 2018

The National Weather Service in Phoenix has issued a

* Severe Thunderstorm Warning for...
  Maricopa County in south central Arizona...
  Pinal County in southeastern Arizona...

* Until 430 PM MST.

* At 359 PM MST, a severe thunderstorm was located over Blackwater,
  or near Coolidge, moving west at 10 mph.

  HAZARD...60 mph wind gusts and penny size hail.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* Locations impacted include...
  Casa Grande, Florence, Coolidge, Queen Creek, Blackwater, San Tan
  Mountain Park, Magma, San Tan Valley, Randolph, Valley Farms,
  Sacaton and Cactus Forest.

* This includes the following highways...
  AZ Interstate 10 between mile markers 184 and 195.
  AZ Route 87 between mile markers 129 and 153.
  AZ Route 79 between mile markers 129 and 140.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3322 11176 3311 11130 3300 11129 3295 11137
      3284 11179
TIME...MOT...LOC 2259Z 105DEG 8KT 3302 11157 

HAIL...0.75IN
WIND...60MPH
 
$$

Hernandez

1 follow-up statement

491 
WWUS55 KPSR 092318
SVSPSR

Severe Weather Statement
National Weather Service Phoenix AZ
418 PM MST MON JUL 9 2018

AZC013-021-092330-
/O.CON.KPSR.SV.W.0009.000000T0000Z-180709T2330Z/
Maricopa AZ-Pinal AZ-
418 PM MST MON JUL 9 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 430 PM MST
FOR MARICOPA AND PINAL COUNTIES...

At 418 PM MST, a severe thunderstorm was located over Blackwater, or
near Coolidge, moving west at 10 mph.

HAZARD...60 mph wind gusts and penny size hail.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees.

Locations impacted include...
Casa Grande, Florence, Coolidge, Queen Creek, Blackwater, San Tan
Mountain Park, Magma, San Tan Valley, Randolph, Valley Farms and
Sacaton.

This includes the following highways...
AZ Interstate 10 between mile markers 184 and 195.
AZ Route 87 between mile markers 129 and 153.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3314 11141 3305 11140 3295 11138 3284 11179
      3322 11176
TIME...MOT...LOC 2318Z 105DEG 8KT 3303 11162 

HAIL...0.75IN
WIND...60MPH
 
$$

Hernandez

What forecasters said that day

The local office's own words before this severe thunderstorm 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 severe thunderstorm warning went out at Jul 9, 3:05 PM MST, 54 minutes earlier.

Area forecast discussion, Jul 9, 3:05 PM MST, 54 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, 3:45 PM MST, 14 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, 11 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

Local storm report, Jul 9, 3:52 PM MST, 7 minutes before

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

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

0339 PM     HAIL             3 ESE EAST MESA         33.39N 111.64W
07/09/2018  E0.75 INCH       MARICOPA           AZ   TRAINED SPOTTER

            DIME TO PENNY SIZED HAIL REPORTED NEAR
            ELLSWORTH AND HIGHWAY 60.

&&

Local storm report, Jul 9, 3:53 PM MST, 6 minutes before

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

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

0348 PM     HEAVY RAIN       2 WSW APACHE JUNCTION   33.40N 111.58W
07/09/2018  E1.25 INCH       MARICOPA           AZ   TRAINED SPOTTER

            RAINFALL OF 1.25 INCHES NEAR MERIDIAN AND
            PUEBLO WHICH OCCURRED IN 25 MINUTES.

&&

Local storm report, Jul 9, 3:57 PM MST, 2 minutes before

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

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

0350 PM     HAIL             1 E EAST MESA           33.42N 111.67W
07/09/2018  E0.25 INCH       MARICOPA           AZ   TRAINED SPOTTER

            PEA SIZED HAIL AT SOSSAMAN AND MAIN.

&&

Local storm report, Jul 9, 3:59 PM MST, 0 minutes before

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

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

0357 PM     FLASH FLOOD      5 WNW FLORENCE          33.06N 111.46W
07/09/2018                   PINAL              AZ   TRAINED SPOTTER

            STREET FLOODING WITH WATER OVER THE CURBS IN
            THE MERRILL RANCH DEVELOPMENT OF FLORENCE.

&&

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, 3:51 PM MST	Flash Flood Warning	PSR	Maricopa	3 hr
Jul 9, 3:57 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	33 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

Severe Thunderstorm Warnings in Arizona, 2018 Every severe thunderstorm 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.