Alert archive / New Jersey / Mesoscale Discussions in 2021
Mesoscale Discussion 1674
The Storm Prediction Center issued this mesoscale discussion at Sep 1, 2021, 6:34 PM EDT for 9 counties in New Jersey; 4 counties in New York; Philadelphia County, Pennsylvania. It was in force for 56 min.
The area
The outline as issued.
The facts
- Issued
- Sep 1, 2021, 6:34 PM EDT (22:34 UTC)
- Expired
- Sep 1, 2021, 7:30 PM EDT
- In force
- 56 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 483
Counties Burlington County, NJ, Camden County, NJ, Gloucester County, NJ, Hudson County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Somerset County, NJ, Union County, NJ, Kings County, NY, New York County, NY, Queens County, NY, Richmond County, NY, Philadelphia County, PA
The radar
The Philadelphia radar (KDIX), 31 km from the middle of the area, began a volume at 22:32 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, 10.6 hours before the alert went out and 168 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
- 51 J/kg
- Mixed-layer CIN
- -80 J/kg
- Mixed-layer LCL
- 1274 m above ground
- 0-6 km bulk shear
- 22 kt
- 0-1 km storm-relative helicity
- 31 m²/s²
- 0-3 km storm-relative helicity
- 201 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.2
The text
As transmitted.
124
ACUS11 KWNS 012234
SWOMCD
SPC MCD 012234
NYZ000-NJZ000-PAZ000-012330-
Mesoscale Discussion 1674
NWS Storm Prediction Center Norman OK
0534 PM CDT Wed Sep 01 2021
Areas affected...Far eastern Pennsylvania and New Jersey
Concerning...Tornado Watch 483...
Valid 012234Z - 012330Z
The severe weather threat for Tornado Watch 483 continues.
SUMMARY...Confirmed tornadoes have occurred both north and south of
Philadelphia. The environment will continue to support tornadic
potential, particularly for areas in southern/central New Jersey.
DISCUSSION...Supercells moving northeast along the slowly northward
advancing warm front have recently produced tornadoes as confirmed
by TDS signatures from KDIX. The northern storm is now moving
Somerset County, NJ, with the southern storm moving through
Camden/Burlington Counties (NJ). Given objectively analyzed 0-1 km
effective SRH over 200 m2/s2 (confirmed by KDIX VWP), supercells
that can maintain strength are expected to continue posing a threat
for tornadoes. At present, the Camden/Burlington storm is moving
within an airmass unaffected by much precipitation and should have
the greatest tornado potential for the next 1-2 hours.
..Wendt.. 09/01/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OKX...PHI...
LAT...LON 40337510 40597488 40837382 40557342 39987385 39797453
39677505 39717529 39937532 40337510SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 1, 11:03 AM EDT | Mesoscale Discussion | SPC | Cape May, Cumberland, Salem | 2 hr |
| Sep 1, 12:40 PM EDT | Tornado Watch | SPC | Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester and 9 more | 9 hr |
| Sep 1, 3:09 PM EDT | Mesoscale Discussion | SPC | Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester and 5 more | 3 hr |
| Sep 1, 4:28 PM EDT | Mesoscale Discussion | SPC | Burlington, Camden, Gloucester, Hudson, Mercer, Middlesex and 5 more | 2 hr |
| Sep 1, 6:22 PM EDT | Tornado Watch | SPC | Bergen, Essex, Hudson, Passaic, Union | 7 hr |
| Sep 1, 4:01 AM EDT | Mesoscale Discussion | SPC | Chester, Delaware, Lancaster, York | 119 min |
Nearby
Mesoscale Discussions in New Jersey, 2021Mesoscale Discussions in New York, 2021Mesoscale Discussions in Pennsylvania, 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.