Alert archive / Pennsylvania / Mesoscale Discussions in 2021
Mesoscale Discussion 1164
The Storm Prediction Center issued this mesoscale discussion at Jul 6, 2021, 4:23 PM EDT for 7 states. It was in force for 97 min.
The area
The outline as issued.
The facts
- Issued
- Jul 6, 2021, 4:23 PM EDT (20:23 UTC)
- Expired
- Jul 6, 2021, 6:00 PM EDT
- In force
- 97 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 335...336
All 75 counties
New Castle County, DE, Berkshire County, MA, Bristol County, MA, Franklin County, MA, Hampden County, MA, Hampshire County, MA, Middlesex County, MA, Norfolk County, MA, Plymouth County, MA, Suffolk County, MA, Worcester County, MA, Cecil County, MD, Harford County, MD, Atlantic County, NJ, Bergen County, NJ, Burlington County, NJ, Camden 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, Albany County, NY, Bronx County, NY, Columbia County, NY, Delaware County, NY, Dutchess County, NY, Greene County, NY, New York County, NY, Orange County, NY, Putnam County, NY, Rensselaer County, NY, Richmond County, NY, Rockland County, NY, Sullivan County, NY, Ulster County, NY, Westchester County, NY, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Columbia County, PA, Dauphin 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, Susquehanna County, PA, Wayne County, PA, Wyoming County, PA, York County, PA, Bristol County, RI, Kent County, RI, Newport County, RI, Providence County, RI, Washington County, RI
The radar
The Brookhaven radar (KOKX), 105 km from the middle of the area, began a volume at 20:24 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, 8.4 hours before the alert went out and 105 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
- 230 J/kg
- Mixed-layer CIN
- -195 J/kg
- Mixed-layer LCL
- 1202 m above ground
- 0-6 km bulk shear
- 19 kt
- 0-1 km storm-relative helicity
- 139 m²/s²
- 0-3 km storm-relative helicity
- 184 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
467
ACUS11 KWNS 062023
SWOMCD
SPC MCD 062023
MAZ000-NHZ000-RIZ000-CTZ000-NYZ000-VTZ000-NJZ000-PAZ000-DEZ000-MDZ000-062200-
Mesoscale Discussion 1164
NWS Storm Prediction Center Norman OK
0323 PM CDT Tue Jul 06 2021
Areas affected...RI...MA...CT...NJ...southeast NY...eastern
PA...northern DE...far northeast MD...southern VT/NH
Concerning...Severe Thunderstorm Watch 335...336...
Valid 062023Z - 062200Z
The severe weather threat for Severe Thunderstorm Watch 335, 336
continues.
SUMMARY...The threat for damaging winds continues across the
remaining valid portions of Severe Thunderstorm Watches 335 and 336.
DISCUSSION...Several clusters of severe storms were in progress at
2015z from western MA southwest into northeast PA, with reports of
measured severe gusts and wind damage. The downstream environment
will remain favorable for a continued severe risk with
moderate/strong MLCAPE and 30-35 kts of westerly flow in the 850-700
mb layer. Damaging downburst winds remain the primary hazard as
storms move east/southeast through the early evening hours.
Farther south across WW 336, latest visible imagery shows increasing
vertical development of a cumulus field within a weakly confluent
zone over southeast PA, where strong instability is in place with
MLCAPE in excess of 2500 J/kg. Isolated thunderstorm development
has occurred over the past hour, and additional development is
expected through early evening with multicell clusters posing a risk
for damaging winds and perhaps hail.
..Bunting.. 07/06/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GYX...BOX...OKX...ALY...PHI...BGM...CTP...LWX...
LAT...LON 42117592 42857301 42857147 42597081 42077068 41457105
41017251 40637398 39867416 39137490 39007513 39267607
39687662 40037688 41047665 42117592SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 6, 12:33 PM EDT | Mesoscale Discussion | SPC | 2 hr | |
| Jul 6, 1:13 PM EDT | Severe Thunderstorm Watch | SPC | Capitol Planning Region, Northwest Hills Planning Region, Northeastern Connecticut Planning Region | 7 hr |
| Jul 6, 1:32 PM EDT | Severe Thunderstorm Watch | SPC | Greater Bridgeport Planning Region, Lower Connecticut River Valley Planning Region, Naugatuck Valley Planning Region, Southeastern Connecticut Planning Region | 8 hr |
| Jul 6, 5:25 PM EDT | Mesoscale Discussion | SPC | Bergen, Essex, Hudson, Hunterdon, Middlesex, Morris and 5 more | 95 min |
| Jul 5, 9:14 PM EDT | Mesoscale Discussion | SPC | Cayuga, Jefferson, Lewis, Monroe, Oneida, Onondaga and 5 more | 2 hr |
Nearby
Mesoscale Discussions in Pennsylvania, 2021Mesoscale Discussions in New Jersey, 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.