Alert archive / Arizona / Special Weather Statements in 2021

Special Weather Statement, NWS Phoenix, AZ

August 18, 2021

NWS Phoenix, AZ issued this special weather statement at Aug 18, 2021, 12:45 PM MST. It was in force for 45 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 18, 2021, 12:45 PM MST (19:45 UTC)
Expired
Aug 18, 2021, 1:30 PM MST
In force
45 min
Issued by
NWS Phoenix, AZ
Hail
0.25 in
Wind
40

The radar

The Phoenix radar (KIWA), 77 km from the middle of the area, began a volume at 19:45 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.

The nearest sounding before it

Phoenix, AZ (KPSR), launched 12:00Z, 7.8 hours before the alert went out and 56 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-pSkew-T log-p diagram, Phoenix, AZ at 12:00Z on 2021-08-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1239 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Phoenix, AZ at 12:00Z on 2021-08-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 52 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
1239 J/kg
Mixed-layer CIN
-34 J/kg
Mixed-layer LCL
1144 m above ground
0-6 km bulk shear
13 kt
0-1 km storm-relative helicity
52 m²/s²
0-3 km storm-relative helicity
40 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement 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 special weather statement went out at Aug 18, 11:44 AM MST, 1 hour 1 minute earlier.

Area forecast discussion, Aug 18, 11:44 AM MST, 1 hour 1 minute before
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In the hours before

Local storm report, Aug 18, 11:51 AM MST, 54 minutes before
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Local storm report, Aug 18, 12:13 PM MST, 32 minutes before
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Special weather statement, Aug 18, 12:26 PM MST, 19 minutes before
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Special weather statement, Aug 18, 12:29 PM MST, 16 minutes before
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Special weather statement, Aug 18, 12:38 PM MST, 7 minutes before
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Special weather statement, Aug 18, 12:45 PM MST, 0 minutes before
Special Weather Statement
National Weather Service Phoenix AZ
1245 PM MST Wed Aug 18 2021

AZZ541-545-182030-
New River Mesa AZ-Cave Creek/New River AZ-
1245 PM MST Wed Aug 18 2021

...A strong thunderstorm will impact portions of Maricopa County
through 130 PM MST...

At 1244 PM MST, Doppler radar was tracking a strong thunderstorm 7
miles east of New River, moving northeast at 15 mph.

HAZARD...Winds in excess of 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
New River, Cave Creek, Carefree, Camp Creek, Seven Springs and
Anthem.

This includes AZ Interstate 17 between mile markers 229 and 241.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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 3401 11181 3394 11178 3389 11181 3378 11200
      3378 11209 3396 11222 3397 11219 3405 11215
TIME...MOT...LOC 1944Z 224DEG 11KT 3395 11200

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

AD

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 17, 5:16 PM MSTFlash Flood Warning Considerable damage threatPSRGila6 hr
Aug 17, 6:05 PM MSTFlash Flood Warning Considerable damage threatPSRGila6 hr
Aug 17, 9:08 PM MSTFlash Flood WatchPSRGila, Maricopa, Pinal23 hr
Aug 18, 7:55 AM MSTFlash Flood Warning Considerable damage threatPSRGila4 hr
Aug 18, 8:48 AM MSTFlash Flood Warning Considerable damage threatPSRGila, Maricopa, Pinal6 hr
Aug 18, 9:26 AM MSTFlash Flood Warning Considerable damage threatPSRGila, Pinal5 hr
Aug 18, 9:39 AM MSTFlash Flood Warning Considerable damage threatPSRGila4 hr
Aug 18, 10:16 AM MSTFlash Flood Warning Considerable damage threatPSRGila4 hr
Aug 18, 11:16 AM MSTFlash Flood Warning EmergencyCatastrophic damage threatPSRGila3 hr
Aug 18, 11:37 AM MSTFlash Flood Warning Considerable damage threatPSRGila5 hr
Aug 18, 11:46 AM MSTSevere Thunderstorm WarningPSRMaricopa29 min
Aug 18, 11:59 AM MSTFlash Flood Warning Considerable damage threatPSRMaricopa5 hr
Aug 18, 12:16 PM MSTSevere Thunderstorm WarningPSRMaricopa29 min
Aug 18, 12:26 PM MSTSpecial Weather StatementPSRMaricopa49 min
Aug 18, 12:28 PM MSTFlash Flood Warning Considerable damage threatPSRGila, Maricopa5 hr
Aug 18, 12:28 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa4 hr
Aug 18, 12:29 PM MSTSpecial Weather StatementPSR46 min
Aug 18, 12:38 PM MSTSpecial Weather StatementPSR52 min
Aug 18, 12:52 PM MSTSevere Thunderstorm WarningPSRMaricopa53 min
Aug 18, 1:00 PM MSTSevere Thunderstorm WarningPSRMaricopa45 min
Aug 18, 1:06 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa5 hr
Aug 18, 1:11 PM MSTSevere Thunderstorm WarningPSRMaricopa35 min
Aug 18, 1:19 PM MSTSpecial Weather StatementPSRGila41 min
Aug 18, 1:23 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa4 hr
Aug 18, 1:39 PM MSTSpecial Weather StatementPSRMaricopa51 min
Aug 18, 1:40 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa6 hr
Aug 18, 1:46 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa4 hr
Aug 18, 1:47 PM MSTSpecial Weather StatementPSR43 min
Aug 18, 2:09 PM MSTSpecial Weather StatementPSR51 min
Aug 18, 2:13 PM MSTSpecial Weather StatementPSRMaricopa47 min
Aug 18, 2:15 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa6 hr
Aug 18, 2:29 PM MSTSevere Thunderstorm WarningPSRGila, Maricopa46 min
Aug 18, 2:32 PM MSTSpecial Weather StatementPSR43 min
Aug 18, 2:34 PM MSTSpecial Weather StatementPSRGila41 min
Aug 18, 2:45 PM MSTFlash Flood Warning Considerable damage threatPSRGila, Maricopa6 hr
Aug 18, 3:02 PM MSTSpecial Weather StatementPSR43 min
Aug 18, 3:03 PM MSTSpecial Weather StatementPSRPinal42 min
Aug 18, 3:11 PM MSTFlash Flood Warning Considerable damage threatPSRGila, Maricopa5 hr
Aug 18, 3:19 PM MSTSpecial Weather StatementPSR41 min
Aug 18, 3:33 PM MSTFlash Flood Warning Considerable damage threatPSRGila, Maricopa4 hr
Aug 18, 3:41 PM MSTSpecial Weather StatementPSRGila64 min
Aug 18, 3:46 PM MSTFlash Flood Warning Considerable damage threatPSRGila5 hr
Aug 18, 4:13 PM MSTSpecial Weather StatementPSRMaricopa47 min
Aug 18, 4:39 PM MSTSpecial Weather StatementPSRMaricopa51 min
Aug 18, 4:58 PM MSTSevere Thunderstorm WarningPSRMaricopa32 min

Nearby

Special Weather Statements in Arizona, 2021Every special weather statement in 2021

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.