Alert archive / Arizona / Mesoscale Discussions in 2021
Mesoscale Discussion 1521
The Storm Prediction Center issued this mesoscale discussion at Aug 13, 2021, 9:24 PM MST for 5 counties in Arizona. It was in force for 66 min.
The area
The outline as issued.
The facts
- Issued
- Aug 13, 2021, 9:24 PM MST (04:24 UTC)
- Expired
- Aug 13, 2021, 10:30 PM MST
- In force
- 66 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 439
Counties Gila County, AZ, La Paz County, AZ, Maricopa County, AZ, Pinal County, AZ, Yuma County, AZ
The radar
The Phoenix radar (KIWA), 51 km from the middle of the area, began a volume at 04:25 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 24 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.
243
ACUS11 KWNS 140425
SWOMCD
SPC MCD 140424
AZZ000-140530-
Mesoscale Discussion 1521
NWS Storm Prediction Center Norman OK
1124 PM CDT Fri Aug 13 2021
Areas affected...southern AZ
Concerning...Severe Thunderstorm Watch 439...
Valid 140424Z - 140530Z
The severe weather threat for Severe Thunderstorm Watch 439
continues.
SUMMARY...The threat for damaging winds continues across the Severe
Thunderstorm Watch area.
DISCUSSION...Latest regional radar data shows an impressive bowing
segment over Yavapai County, AZ, with a pronounced rear-inflow jet
and likely producing a concentrated swath of damaging winds.
Another cluster of storms was developing over eastern Gila County,
with more isolated strong/severe storms east/northeast of Phoenix.
In the presence of MLCAPE averaging 1000-1500 J/kg and 25 kts of
northeasterly mid-level flow, storms should continue to cluster and
move southwest across lower elevations through late evening and
early overnight hours with a risk for concentrated corridors of
damaging winds. This scenario is supported by the latest hi-res
guidance including the HRRR and 00z HREF.
..Bunting.. 08/14/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...TWC...FGZ...PSR...
LAT...LON 32781426 33871403 34601268 34571177 34051073 33741028
32621038 32251077 32261299 32781426SPC 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 14, 12:51 AM MST | Mesoscale Discussion | SPC | Yuma | 84 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.