Alert archive / Arizona / Mesoscale Discussions in 2021
Mesoscale Discussion 1522
The Storm Prediction Center issued this mesoscale discussion at Aug 14, 2021, 12:51 AM MST for Yuma County, Arizona. It was in force for 84 min.
The area
The outline as issued.
The facts
- Issued
- Aug 14, 2021, 12:51 AM MST (07:51 UTC)
- Expired
- Aug 14, 2021, 2:15 AM MST
- In force
- 84 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 439
County Yuma County, AZ
The radar
The Yuma radar (KYUX), 54 km from the middle of the area, began a volume at 07:54 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, 7.9 hours before the alert went out and 223 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
- 1603 J/kg
- Mixed-layer CIN
- -40 J/kg
- Mixed-layer LCL
- 2033 m above ground
- 0-6 km bulk shear
- 14 kt
- 0-1 km storm-relative helicity
- 6 m²/s²
- 0-3 km storm-relative helicity
- 78 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
699
ACUS11 KWNS 140752
SWOMCD
SPC MCD 140751
AZZ000-CAZ000-140915-
Mesoscale Discussion 1522
NWS Storm Prediction Center Norman OK
0251 AM CDT Sat Aug 14 2021
Areas affected...Parts of southwestern Arizona and adjacent portions
of southeastern California
Concerning...Severe Thunderstorm Watch 439...
Valid 140751Z - 140915Z
The severe weather threat for Severe Thunderstorm Watch 439
continues.
SUMMARY...Thunderstorm activity approaching Yuma may still pose a
risk for strong to severe wind gusts through 2-3 AM MST, before
crossing the international border and diminishing. The threat for
severe surface gusts appears to have mostly subsided elsewhere, and
a new severe weather watch appears unlikely.
DISCUSSION...Vigorous thunderstorm activity continues to develop
west-southwestward into and through the lower deserts to the west
and south of Phoenix. In general, downbursts appear to be
weakening, as conglomerate convective outflow continues to surge out
ahead of convection. However, to the southwest of an MCV (currently
northwest of Buckeye), lower/mid tropopspheric lapse rates remain
fairly steep with the boundary-layer remaining very warm and moist
(surface temps near 90F and dew points in the mid 70s), contributing
to moderately large CAPE. This could still support intensifying
thunderstorm development along the leading edge of the outflow as it
approaches the Yuma area through 09-10Z, accompanied by the
potential to produce strong downbursts, and locally strong to severe
wind gusts.
..Kerr.. 08/14/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PSR...
LAT...LON 32341479 33471494 33601422 33111368 32861332 32141403
32341479SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 13, 6:55 PM MST | Severe Thunderstorm Watch | SPC | Cochise, Gila, La Paz, Maricopa, Pima, Pinal and 3 more | 8 hr |
| Aug 13, 9:24 PM MST | Mesoscale Discussion | SPC | Gila, La Paz, Maricopa, Pinal, Yuma | 66 min |
| Aug 14, 4:34 PM MST | Mesoscale Discussion | SPC | Cochise, Gila, Graham, Greenlee, La Paz, Maricopa and 4 more | 116 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.