Alert archive / Arizona / Mesoscale Discussions in 2021
Mesoscale Discussion 1267
The Storm Prediction Center issued this mesoscale discussion at Jul 12, 2021, 4:20 PM MST for 4 counties in Arizona. It was in force for 115 min.
The area
The outline as issued.
The facts
- Issued
- Jul 12, 2021, 4:20 PM MST (23:20 UTC)
- Expired
- Jul 12, 2021, 6:15 PM MST
- In force
- 115 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
Counties Gila County, AZ, Graham County, AZ, Greenlee County, AZ, Pinal County, AZ
The radar
The Phoenix radar (KIWA), 105 km from the middle of the area, began a volume at 23:23 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 12:00Z, 11.3 hours before the alert went out and 129 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.
- Mixed-layer CAPE
- 280 J/kg
- Mixed-layer CIN
- -525 J/kg
- Mixed-layer LCL
- 2475 m above ground
- 0-6 km bulk shear
- 26 kt
- 0-1 km storm-relative helicity
- 19 m²/s²
- 0-3 km storm-relative helicity
- 133 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.4
The text
As transmitted.
923
ACUS11 KWNS 122321
SWOMCD
SPC MCD 122320
NMZ000-AZZ000-130115-
Mesoscale Discussion 1267
NWS Storm Prediction Center Norman OK
0620 PM CDT Mon Jul 12 2021
Areas affected...East-Central/Southeast AZ...Far West-Central NM
Concerning...Severe potential...Watch possible
Valid 122320Z - 130115Z
Probability of Watch Issuance...40 percent
SUMMARY...Strong wind gusts are possible across east-central into
southeast AZ over the next few hours.
DISCUSSION...Recent regional radar and visible satellite imagery
shows increasingly clustered thunderstorms in and around the White
Mountains in east-central AZ/west-central NM. Additionally, the
storm cluster moving southwestward out of west-central NM has shown
more forward progression, suggesting a more cold pool dominated
storm structure. Combination of the increasing storm coverage and
the approaching cold pool may result in the evolution of a bigger,
modestly more organized convective line within the next hour or so.
Updrafts have generally be transient thus far, likely a result of
weak vertical shear and only modest instability, but new storm
development along the potential cold pool is still possible given
the weak convective inhibition in place. Downdrafts associated with
new development could then reinforce the cold pool, leading to the
potential for a few stronger gusts.
Overall convective evolution and the resultant development of a
strong cold pool is still uncertain, leading to lower watch
probability at this time. Even so, convective trends will be
monitored closely for signs that the threat is becoming high enough
to merit watch issuance.
..Mosier/Thompson.. 07/12/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...ABQ...EPZ...TWC...FGZ...PSR...
LAT...LON 34391188 34841110 34240944 33260861 32590891 32420974
32471092 33041154 33731181 34391188Nearby
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.