Alert archive / New Jersey / Mesoscale Discussions in 2021
Mesoscale Discussion 1312
The Storm Prediction Center issued this mesoscale discussion at Jul 17, 2021, 10:02 PM EDT for 5 states. It was in force for 58 min.
The area
The outline as issued.
The facts
- Issued
- Jul 17, 2021, 10:02 PM EDT (02:02 UTC)
- Expired
- Jul 17, 2021, 11:00 PM EDT
- In force
- 58 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 382
All 31 counties
Kent County, DE, New Castle County, DE, Caroline County, MD, Cecil County, MD, Kent County, MD, Queen Anne's County, MD, Atlantic County, NJ, Burlington County, NJ, Camden County, NJ, Cape May County, NJ, Cumberland County, NJ, Essex County, NJ, Gloucester County, NJ, Hudson County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Morris County, NJ, Ocean County, NJ, Salem County, NJ, Somerset County, NJ, Union County, NJ, Warren County, NJ, Kings County, NY, Richmond County, NY, Bucks County, PA, Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA
The radar
The Philadelphia radar (KDIX), 56 km from the middle of the area, began a volume at 02:02 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
Wallops Is Stn, VA (KWAL), launched 00:00Z, 2.0 hours before the alert went out and 207 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
- 1997 J/kg
- Mixed-layer CIN
- -29 J/kg
- Mixed-layer LCL
- 1118 m above ground
- 0-6 km bulk shear
- 18 kt
- 0-1 km storm-relative helicity
- 59 m²/s²
- 0-3 km storm-relative helicity
- 74 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
512
ACUS11 KWNS 180203
SWOMCD
SPC MCD 180202
NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-180300-
Mesoscale Discussion 1312
NWS Storm Prediction Center Norman OK
0902 PM CDT Sat Jul 17 2021
Areas affected...portions of far east Pennsylvania...northeast
Maryland...Delaware...New Jersey
Concerning...Severe Thunderstorm Watch 382...
Valid 180202Z - 180300Z
The severe weather threat for Severe Thunderstorm Watch 382
continues.
SUMMARY...A damaging gust or two remains possible over the next
couple of hours with the stronger storms. The best chance for a
damaging gust will be in a narrow corridor of central/southern New
Jersey in association with a cluster of storms moving through a
modestly unstable airmass.
DISCUSSION...The troposhere over much of the lower Hudson Valley has
been overturned by multiple rounds of strong to occasionally severe
thunderstorms over the past several hours. Though several storm
clusters remain in progress, an overall decline in intensity has
been noted, especially in terms of damaging gust production.
Nonetheless, an organized cluster of thunderstorms is currently
moving over the Philadelphia metroplex, and is progressing towards
an airmass that is relatively more buoyant/less overturned compared
to surrounding areas. These storms have the best chance at producing
a damaging gust over the next hour or so.
..Squitieri/Guyer.. 07/18/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OKX...PHI...AKQ...LWX...
LAT...LON 38907650 40127565 40937517 41077473 40957423 40687393
40147405 39647423 39257450 38967485 38757517 38657577
38907650Nearby
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.