Alert archive / Pennsylvania / Mesoscale Discussions in 2021
Mesoscale Discussion 1203
The Storm Prediction Center issued this mesoscale discussion at Jul 8, 2021, 4:36 PM EDT for 13 counties in New Jersey; 11 counties in New York; 15 counties in Pennsylvania. It was in force for 114 min.
The area
The outline as issued.
The facts
- Issued
- Jul 8, 2021, 4:36 PM EDT (20:36 UTC)
- Expired
- Jul 8, 2021, 6:30 PM EDT
- In force
- 114 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 351
All 39 counties
Bergen County, NJ, Essex County, NJ, Hudson County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Morris County, NJ, Passaic County, NJ, Somerset County, NJ, Sussex County, NJ, Union County, NJ, Warren County, NJ, Bronx County, NY, Kings County, NY, Nassau County, NY, New York County, NY, Orange County, NY, Putnam County, NY, Queens County, NY, Richmond County, NY, Rockland County, NY, Suffolk County, NY, Westchester County, NY, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Dauphin County, PA, Delaware County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Monroe County, PA, Montgomery County, PA, Northampton County, PA, Philadelphia County, PA, Schuylkill County, PA, York County, PA
The radar
The Brookhaven radar (KOKX), 95 km from the middle of the area, began a volume at 20:39 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
Brookhaven, NY (KOKX), launched 12:00Z, 8.6 hours before the alert went out and 95 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
- 973 J/kg
- Mixed-layer CIN
- -77 J/kg
- Mixed-layer LCL
- 751 m above ground
- 0-6 km bulk shear
- 28 kt
- 0-1 km storm-relative helicity
- 60 m²/s²
- 0-3 km storm-relative helicity
- 93 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.3
The text
As transmitted.
961
ACUS11 KWNS 082037
SWOMCD
SPC MCD 082036
CTZ000-NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-082230-
Mesoscale Discussion 1203
NWS Storm Prediction Center Norman OK
0336 PM CDT Thu Jul 08 2021
Areas affected...eastern Pennsylvania northeastward into Connecticut
Concerning...Severe Thunderstorm Watch 351...
Valid 082036Z - 082230Z
The severe weather threat for Severe Thunderstorm Watch 351
continues.
SUMMARY...Isolated severe storms remain possible over parts of the
area, but the event has likely peaked. Locally damaging gusts or
marginal hail can be expected.
DISCUSSION...Storms continue to increase in coverage across
southeast PA in a zone of warm advection, and some of these may
contain marginal hail or strong wind gusts. Farther east, outflow
from an earlier, more robust cluster has reinforced a boundary which
is beginning to limit the warm sector over NJ. MLCAPE over 1500 J/kg
remains south of the outflow boundary, which may yet lead to a few
strong to severe cells, but shear is weaker with southward extent. A
continued increase in storm coverage and outflow production suggest
the greatest severe risk is in the short term.
..Jewell.. 07/08/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BOX...OKX...ALY...PHI...BGM...CTP...LWX...
LAT...LON 40767252 40487385 40297390 39967396 39717627 39847707
40267724 40907618 41407480 41787361 41857283 41707238
41387221 41047226 40907226 40767252SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 8, 12:00 AM EDT | Mesoscale Discussion | SPC | 60 min | |
| Jul 8, 1:44 PM EDT | Mesoscale Discussion | SPC | 3 hr | |
| Jul 8, 2:09 PM EDT | Severe Thunderstorm Watch | SPC | Greater Bridgeport Planning Region, Capitol Planning Region, Northwest Hills Planning Region, Lower Connecticut River Valley Planning Region, Naugatuck Valley Planning Region, Southeastern Connecticut Planning Region and 1 more | 7 hr |
| Jul 8, 1:31 PM EDT | Mesoscale Discussion | SPC | Cattaraugus, Chautauqua, Erie, Wyoming | 2 hr |
Nearby
Mesoscale Discussions in Pennsylvania, 2021Mesoscale Discussions in New Jersey, 2021Mesoscale Discussions in New York, 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.