Alert archive / New Jersey / Mesoscale Discussions in 2021
Mesoscale Discussion 1783
The Storm Prediction Center issued this mesoscale discussion at Sep 23, 2021, 1:29 PM EDT for 20 counties in New Jersey; 8 counties in New York; Bucks County, Northampton County, Philadelphia County, Pennsylvania. It was in force for 61 min.
The area
The outline as issued.
The facts
- Issued
- Sep 23, 2021, 1:29 PM EDT (17:29 UTC)
- Expired
- Sep 23, 2021, 2:30 PM EDT
- In force
- 61 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
All 31 counties
Atlantic County, NJ, Bergen 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, 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, Queens County, NY, Richmond County, NY, Rockland County, NY, Westchester County, NY, Bucks County, PA, Northampton County, PA, Philadelphia County, PA
The radar
The Philadelphia radar (KDIX), 33 km from the middle of the area, began a volume at 17:30 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, 5.5 hours before the alert went out and 144 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
- 103 J/kg
- Mixed-layer CIN
- -11 J/kg
- Mixed-layer LCL
- 687 m above ground
- 0-6 km bulk shear
- 42 kt
- 0-1 km storm-relative helicity
- 249 m²/s²
- 0-3 km storm-relative helicity
- 201 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 1.1
The text
As transmitted.
777
ACUS11 KWNS 231730
SWOMCD
SPC MCD 231729
NYZ000-CTZ000-NJZ000-PAZ000-231830-
Mesoscale Discussion 1783
NWS Storm Prediction Center Norman OK
1229 PM CDT Thu Sep 23 2021
Areas affected...Portions of New Jersey...far eastern
Pennsylvania...and far southeast New York.
Concerning...Severe potential...Watch unlikely
Valid 231729Z - 231830Z
Probability of Watch Issuance...5 percent
SUMMARY...Isolated damaging wind gusts are possible through the
afternoon.
DISCUSSION...A line of storms has developed across southern New
Jersey/eastern Pennsylvania in a narrow axis of instability ahead of
a cold front. Occasional damaging wind reports have been received
from this activity, but most measured wind gusts along the line are
in the 30 to 40 mph range. Do not expect winds to be much stronger
given the downstream environment with weak lapse rates and limited
instability with cloud cover likely keeping it that way. Therefore,
isolated damaging wind gusts may continue through the afternoon, but
a more organized threat which may necessitate a severe thunderstorm
watch does not appear necessary.
..Bentley/Bunting.. 09/23/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OKX...PHI...BGM...
LAT...LON 40827532 41417473 41387366 41037325 40777327 40567352
40377395 39647404 39197444 38987473 38977513 39247534
40827532SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 23, 10:30 AM EDT | Mesoscale Discussion | SPC | Camden, Cumberland, Gloucester, Salem | 2 hr |
| Sep 23, 3:13 AM EDT | Mesoscale Discussion | SPC | Adams, Berks, Chester, Cumberland, Dauphin, Lancaster and 3 more | 5 hr |
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.