Alert archive / Arizona / Mesoscale Discussions in 2021

Mesoscale Discussion 1274

July 13, 20214 counties in Arizona

The Storm Prediction Center issued this mesoscale discussion at Jul 13, 2021, 3:56 PM MST for 4 counties in Arizona. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jul 13, 2021, 3:56 PM MST (22:56 UTC)
Expired: Jul 13, 2021, 6:00 PM MST
In force: 2 hr
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 5%

Counties Gila County, AZ, Graham County, AZ, Greenlee County, AZ, Santa Cruz County, AZ

The radar

The Phoenix radar (KIWA), 93 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.

The nearest sounding before it

Phoenix, AZ (KPSR), launched 12:00Z, 10.9 hours before the alert went out and 115 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: 338 J/kg
Mixed-layer CIN: -375 J/kg
Mixed-layer LCL: 1936 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: -1 m²/s²
0-3 km storm-relative helicity: 11 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

744 
ACUS11 KWNS 132256
SWOMCD
SPC MCD 132256 
NMZ000-AZZ000-140100-

Mesoscale Discussion 1274
NWS Storm Prediction Center Norman OK
0556 PM CDT Tue Jul 13 2021

Areas affected...Central/East-Central/Southeast AZ...Far
West-Central NM

Concerning...Severe potential...Watch unlikely 

Valid 132256Z - 140100Z

Probability of Watch Issuance...5 percent

SUMMARY...Isolated hail and damaging downbursts are possible over
the next few hours.

DISCUSSION...Scattered thunderstorms continue to develop within the
warm and modestly moist air mass across the Southwest. Storm motion
has been predominantly westward, with the exception of the storms
near PRC, which moved eastward. This varying motion is evidence of
the weakly sheared environment void of strong steering flow.
Additionally, this weak vertical shear is also resulting in short
updraft duration. New development will likely continue to occur on
storm outflow, but the overall severe threat appears limited due to
the weak vertical shear and relatively modest instability. Even so,
a few strong updrafts are still possible, mostly as a result of
storm mergers, with the potential to produce isolated hail and
damaging downburst winds.

..Mosier/Thompson.. 07/13/2021

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

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

LAT...LON   35191224 35431180 35271098 34460875 33430861 33160923
            32840968 32150994 31411048 31591155 32841112 33581144
            34421250 35191224

Nearby

Mesoscale Discussions in Arizona, 2021 Every 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.