Alert archive / Arizona / Mesoscale Discussions in 2021

Mesoscale Discussion 1540

August 16, 2021Pinal County, Arizona

The Storm Prediction Center issued this mesoscale discussion at Aug 16, 2021, 9:23 PM MST for Pinal County, Arizona. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued
Aug 16, 2021, 9:23 PM MST (04:23 UTC)
Expired
Aug 16, 2021, 11:00 PM MST
In force
97 min
Issued by
the Storm Prediction Center
Concerning
Severe thunderstorm watch 442

County Pinal County, AZ

The radar

The Phoenix radar (KIWA), 39 km from the middle of the area, began a volume at 04:23 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 00:00Z, 4.4 hours before the alert went out and 60 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 00:00Z on 2021-08-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2667 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 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 00:00Z on 2021-08-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 24 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
2667 J/kg
Mixed-layer CIN
-7 J/kg
Mixed-layer LCL
1942 m above ground
0-6 km bulk shear
18 kt
0-1 km storm-relative helicity
24 m²/s²
0-3 km storm-relative helicity
44 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

086 
ACUS11 KWNS 170424
SWOMCD
SPC MCD 170423 
AZZ000-170600-

Mesoscale Discussion 1540
NWS Storm Prediction Center Norman OK
1123 PM CDT Mon Aug 16 2021

Areas affected...Arizona

Concerning...Severe Thunderstorm Watch 442...

Valid 170423Z - 170600Z

The severe weather threat for Severe Thunderstorm Watch 442
continues.

SUMMARY...Gusty winds are expected with a squall line as it
propagates off the higher terrain.

DISCUSSION...Weak mid-level vort is rotating south across
northwestern NM late this evening. This feature may be partly
responsible for loose organization of convection that has evolved
from southern Coconino-Gila-northern Graham County over the higher
terrain. Forward propagation is expected to continue in a
southwesterly direction at roughly 25kt and if this movement
continues would affect the eastern PHX metro perhaps as early as
0630-07z. Gusty winds are the primary threat with this squall line.

..Darrow.. 08/17/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...TWC...FGZ...PSR...

LAT...LON   34351169 33111046 32681099 32961181 34351169

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 16, 6:21 PM MSTMesoscale DiscussionSPCCochise, Gila, Graham, Greenlee, Maricopa, Pima and 2 more84 min
Aug 16, 11:39 PM MSTMesoscale DiscussionSPCMaricopa96 min

Nearby

Mesoscale Discussions in Arizona, 2021Every mesoscale discussion 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.