Alert archive / New Jersey / Mesoscale Discussions in 2021
Mesoscale Discussion 1268
The Storm Prediction Center issued this mesoscale discussion at Jul 12, 2021, 7:25 PM EDT for 5 states. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 12, 2021, 7:25 PM EDT (23:25 UTC)
- Expired
- Jul 12, 2021, 9:30 PM EDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 374
All 34 counties
New Castle County, DE, Cecil County, MD, Harford County, MD, Kent County, MD, Bergen County, NJ, Burlington County, NJ, Camden County, NJ, Essex County, NJ, Gloucester County, NJ, Hudson County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Morris County, NJ, Passaic County, NJ, Salem County, NJ, Somerset County, NJ, Sussex County, NJ, Union County, NJ, Warren County, NJ, Richmond County, NY, Rockland County, NY, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Delaware County, PA, Lancaster County, PA, Lehigh County, PA, Monroe County, PA, Montgomery County, PA, Northampton County, PA, Philadelphia County, PA, Pike County, PA
The radar
The Philadelphia radar (KDIX), 87 km from the middle of the area, began a volume at 23:29 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, 11.4 hours before the alert went out and 219 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
- 857 J/kg
- Mixed-layer CIN
- -57 J/kg
- Mixed-layer LCL
- 697 m above ground
- 0-6 km bulk shear
- 25 kt
- 0-1 km storm-relative helicity
- 85 m²/s²
- 0-3 km storm-relative helicity
- 114 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 2.4
The text
As transmitted.
644
ACUS11 KWNS 122326
SWOMCD
SPC MCD 122325
NJZ000-NYZ000-PAZ000-DEZ000-MDZ000-130130-
Mesoscale Discussion 1268
NWS Storm Prediction Center Norman OK
0625 PM CDT Mon Jul 12 2021
Areas affected...Portions of nothern Mid-Atlantic
Concerning...Severe Thunderstorm Watch 374...
Valid 122325Z - 130130Z
The severe weather threat for Severe Thunderstorm Watch 374
continues.
SUMMARY...Damaging winds are likely to become more isolated with
time given airmass stabilization in WW 374. Locally greater buoyancy
is evident in northeast Maryland into northern Delaware. These ares
will see the greatest remaining risk for a strong wind gust.
DISCUSSION...Most of the airmass within eastern Pennsylvania into
New Jersey has been impacted by convection and cloud debris. This
has cooled temperatures into the mid/upper 70s F. A cluster of
storms near the northern Chesapeake Bay into the lower Delaware
River have temperatures to their immediate south near 90 F. This
region would have a relatively greater risk of a strong/damaging
wind gusts. Another cluster in northern New Jersey and far
southeastern New York has shown a weakening trend over the past 30
minutes. With nearby temperatures also dipping into the upper 70s F,
this trend is likely to continue.
..Wendt.. 07/12/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OKX...PHI...BGM...CTP...LWX...
LAT...LON 39337665 40887589 41407522 41437442 41167395 40377416
39357500 39207609 39337665SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 12, 1:32 PM EDT | Mesoscale Discussion | SPC | Kent, New Castle, Sussex | 88 min |
| Jul 12, 3:34 PM EDT | Severe Thunderstorm Watch | SPC | New Castle | 5 hr |
| Jul 11, 8:58 PM EDT | Mesoscale Discussion | SPC | Carroll, Washington | 62 min |
Nearby
Mesoscale Discussions in New Jersey, 2021Mesoscale Discussions in Pennsylvania, 2021Mesoscale Discussions in Maryland, 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.