Alert archive / Arizona / Mesoscale Discussions in 2021
Mesoscale Discussion 1530
The Storm Prediction Center issued this mesoscale discussion at Aug 15, 2021, 8:50 PM MST for Pinal County, Arizona. It was in force for 55 min.
The area
The outline as issued.
The facts
- Issued
- Aug 15, 2021, 8:50 PM MST (03:50 UTC)
- Expired
- Aug 15, 2021, 9:45 PM MST
- In force
- 55 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
County Pinal County, AZ
The radar
The Phoenix radar (KIWA), 8 km from the middle of the area, began a volume at 03:51 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, 3.8 hours before the alert went out and 35 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
- 1548 J/kg
- Mixed-layer CIN
- -94 J/kg
- Mixed-layer LCL
- 2123 m above ground
- 0-6 km bulk shear
- 25 kt
- 0-1 km storm-relative helicity
- -22 m²/s²
- 0-3 km storm-relative helicity
- 56 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.3
The text
As transmitted.
150 ACUS11 KWNS 160350 SWOMCD SPC MCD 160350 AZZ000-160445- Mesoscale Discussion 1530 NWS Storm Prediction Center Norman OK 1050 PM CDT Sun Aug 15 2021 Areas affected...south-central AZ Concerning...Severe potential...Watch unlikely Valid 160350Z - 160445Z Probability of Watch Issuance...5 percent SUMMARY...The risk for severe gusts may continue as a thunderstorm cluster moves to the west-southwest from eastern AZ and approaches the greater Phoenix metro over the next few hours. DISCUSSION...Radar imagery from KPHX shows a cluster of intense thunderstorms in a relatively optimized balance for renewed thunderstorm development on surging outflow. The 00z Phoenix raob showed relatively steep low to mid-level lapse rates. Surface cooling has been tempered this evening due to rich low-level moisture (14 g/kg lowest 100 mb mean mixing ratio)---limiting the lessening of low-level lapse rates. Furthermore, the 25-kt flow in the 3-6 km layer per the raob will support storm movement to the west-southwest and perhaps augment wind potential with evaporative cooling. As a result, it is plausible severe gusts move into the eastern part of the Phoenix metro during the next 1-2 hours as this activity continues west-southwestward before eventually weakening. ..Smith/Bunting.. 08/16/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TWC...FGZ...PSR... LAT...LON 33681227 33951101 33111037 32681146 32941226 33681227
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 16, 3:01 PM MST | Mesoscale Discussion | SPC | Gila, Graham, Maricopa, Pinal, Yavapai | 59 min |
| Aug 16, 3:54 PM MST | Severe Thunderstorm Watch | SPC | Cochise, Gila, Graham, Maricopa, Pima, Pinal and 2 more | 10 hr |
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.