Alert archive / New Jersey / Mesoscale Discussions in 2021
Mesoscale Discussion 2023
The Storm Prediction Center issued this mesoscale discussion at Dec 11, 2021, 7:29 PM EST for 5 states. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Dec 11, 2021, 7:29 PM EST (00:29 UTC)
- Expired
- Dec 11, 2021, 10:00 PM EST
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
All 56 counties
Kent County, DE, New Castle County, DE, Baltimore County, MD, Cecil County, MD, City of Baltimore, MD, Harford County, MD, Kent County, MD, Queen Anne's County, MD, 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, Salem County, NJ, Somerset County, NJ, Sussex County, NJ, Union County, NJ, Warren County, NJ, Bronx County, NY, Kings County, NY, New York County, NY, Orange County, NY, Queens County, NY, Richmond County, NY, Rockland County, NY, Sullivan County, NY, Westchester County, NY, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Delaware County, PA, Lackawanna County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne County, PA, Monroe County, PA, Montgomery County, PA, Northampton County, PA, Philadelphia County, PA, Pike County, PA, Schuylkill County, PA, Wayne County, PA, York County, PA
The radar
The Philadelphia radar (KDIX), 75 km from the middle of the area, began a volume at 00:33 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
Washington/Dulle, VA (KIAD), launched 00:00Z, 0.5 hours before the alert went out and 216 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1263 m above ground
- 0-6 km bulk shear
- 77 kt
- 0-1 km storm-relative helicity
- 187 m²/s²
- 0-3 km storm-relative helicity
- 12 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
046
ACUS11 KWNS 120030
SWOMCD
SPC MCD 120029
CTZ000-NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-120300-
Mesoscale Discussion 2023
NWS Storm Prediction Center Norman OK
0629 PM CST Sat Dec 11 2021
Areas affected...portions of eastern Pennsylvania...extreme
southeast New York...New Jersey...western Long Island...northeastern
Maryland...northern Delaware
Concerning...Severe potential...Watch unlikely
Valid 120029Z - 120300Z
Probability of Watch Issuance...20 percent
SUMMARY...A few strong to potentially damaging gusts may accompany a
narrow, low-topped squall line as it moves across portions of the
Mid Atlantic over the next few hours.
DISCUSSION...A narrow, low-topped squall line is beginning to take
shape along the surface lee-trough axis in central PA. This
convective line has been developing atop a marine-tropical surface
airmass, defined by mid 50s F surface temperatures/dewpoints.
However, from roughly York to Lehigh County, PA eastward, mid to
upper 60s F temperatures coincide with low 60s F dewpoints. Modified
22Z RAP forecast soundings for the 00Z period suggest scant
low-level buoyancy resides ahead of the developing low-topped
squall. Nonetheless, an impressive kinematic environment is in
place, with 50+ kts of effective bulk shear in place and a strong
LLJ contributing to 50+ kt flow 400 m AGL. As such, mechanical or
microphysically driven downward momentum transport may foster strong
to damaging wind gusts should the squall line intensify further, and
a severe gust or two cannot be ruled out.
..Squitieri/Grams.. 12/12/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OKX...ALY...PHI...BGM...CTP...LWX...
LAT...LON 38867514 38927586 39147643 39367679 39667702 39867707
40177679 41187604 41707552 41827476 41687418 41267359
40927360 40157398 39597418 39137456 38957475 38887507
38867514Nearby
Mesoscale Discussions in New Jersey, 2021Mesoscale Discussions in Pennsylvania, 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.