Alert archive / Arizona / Mesoscale Discussions in 2017
Mesoscale Discussion 1313
The Storm Prediction Center issued this mesoscale discussion at Jul 14, 2017, 2:55 PM MST for 9 counties in Arizona. It was in force for 65 min.
The area
The outline as issued.
The facts
- Issued
- Jul 14, 2017, 2:55 PM MST (21:55 UTC)
- Expired
- Jul 14, 2017, 4:00 PM MST
- In force
- 65 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 60%
Counties Cochise County, AZ, Gila County, AZ, Graham County, AZ, Greenlee County, AZ, Maricopa County, AZ, Pima County, AZ, Pinal County, AZ, Santa Cruz County, AZ, Yavapai County, AZ
The radar
The Phoenix radar (KIWA), 6 km from the middle of the area, began a volume at 21:55 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Phoenix, AZ (KPSR), launched 12:00Z, 9.9 hours before the alert went out and 37 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
- 391 J/kg
- Mixed-layer CIN
- -287 J/kg
- Mixed-layer LCL
- 1843 m above ground
- 0-6 km bulk shear
- 15 kt
- 0-1 km storm-relative helicity
- 48 m²/s²
- 0-3 km storm-relative helicity
- 150 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.3
The text
As transmitted.
522
ACUS11 KWNS 142156
SWOMCD
SPC MCD 142155
AZZ000-142300-
Mesoscale Discussion 1313
NWS Storm Prediction Center Norman OK
0455 PM CDT Fri Jul 14 2017
Areas affected...Central/southern Arizona
Concerning...Severe potential...Watch possible
Valid 142155Z - 142300Z
Probability of Watch Issuance...60 percent
SUMMARY...A severe thunderstorm watch may be needed for the
discussion area within the next hour or so.
DISCUSSION...Scattered, relatively high-based thunderstorms have
developed along the higher terrain of the Mogollon Rim over the past
couple of hours. These storms are in a relatively weakly sheared
environment, with deeply mixed boundary layer profiles supporting
outflow-dominant activity. Northeasterly mid-level flow (around
20-25 knots) is supporting south/southwestward propagation of this
activity into lower elevations. Given the outflow-dominant nature
of these storms, it appears likely that cold pools will merge and
support some propagation of convective activity through the
discussion area through at least 02-03Z, with some risk for damaging
wind gusts affecting the Tucson and Phoenix areas in the next few
hours.
Given the expected convective evolution and appreciable damaging
wind threat over the next several hours, a severe thunderstorm watch
is currently being considered.
..Cook/Edwards.. 07/14/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...TWC...FGZ...PSR...VEF...
LAT...LON 32181353 32761389 33571403 34201392 34891336 35001284
34791180 34421050 33900944 33370915 32640905 32020914
31400940 31341102 32181353SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 13, 6:39 PM MST | Mesoscale Discussion | SPC | Santa Cruz | 96 min |
| Jul 14, 4:35 PM MST | Severe Thunderstorm Watch | SPC | Maricopa, Pima, Pinal | 4 hr |
Nearby
Mesoscale Discussions in Arizona, 2017Every mesoscale discussion in 2017
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.