Alert archive / Pennsylvania / Mesoscale Discussions in 2021
Mesoscale Discussion 709
The Storm Prediction Center issued this mesoscale discussion at May 23, 2021, 1:20 PM EDT for 5 states. It was in force for 115 min.
The area
The outline as issued.
The facts
- Issued
- May 23, 2021, 1:20 PM EDT (17:20 UTC)
- Expired
- May 23, 2021, 3:15 PM EDT
- In force
- 115 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
All 88 counties
Barnstable County, MA, Berkshire County, MA, Bristol County, MA, Dukes County, MA, Franklin County, MA, Hampden County, MA, Hampshire County, MA, Middlesex County, MA, Nantucket County, MA, Norfolk County, MA, Plymouth County, MA, Suffolk County, MA, Worcester County, MA, Bergen County, NJ, Essex County, NJ, Hudson County, NJ, Hunterdon County, NJ, Morris County, NJ, Passaic County, NJ, Somerset County, NJ, Sussex County, NJ, Union County, NJ, Warren County, NJ, Albany County, NY, Bronx County, NY, Broome County, NY, Chemung County, NY, Chenango County, NY, Columbia County, NY, Delaware County, NY, Dutchess County, NY, Greene County, NY, Kings County, NY, Nassau County, NY, New York County, NY, Orange County, NY, Otsego County, NY, Putnam County, NY, Queens County, NY, Richmond County, NY, Rockland County, NY, Schoharie County, NY, Schuyler County, NY, Steuben County, NY, Suffolk County, NY, Sullivan County, NY, Tioga County, NY, Tompkins County, NY, Ulster County, NY, Westchester County, NY, Berks County, PA, Bradford County, PA, Cameron County, PA, Carbon County, PA, Centre County, PA, Clearfield County, PA, Clinton County, PA, Columbia County, PA, Dauphin County, PA, Elk County, PA, Forest County, PA, Jefferson County, PA, Juniata County, PA, Lackawanna County, PA, Lehigh County, PA, Luzerne County, PA, Lycoming County, PA, McKean County, PA, Mifflin County, PA, Monroe County, PA, Montour County, PA, Northampton County, PA, Northumberland County, PA, Pike County, PA, Potter County, PA, Schuylkill County, PA, Snyder County, PA, Sullivan County, PA, Susquehanna County, PA, Tioga County, PA, Union County, PA, Wayne County, PA, Wyoming County, PA, Bristol County, RI, Kent County, RI, Newport County, RI, Providence County, RI, Washington County, RI
The radar
The Binghamton radar (KBGM), 119 km from the middle of the area, began a volume at 17:21 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
Albany, NY (KALY), launched 12:00Z, 5.3 hours before the alert went out and 168 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
- 908 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 150 m²/s²
- 0-3 km storm-relative helicity
- 162 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
722
ACUS11 KWNS 231720
SWOMCD
SPC MCD 231720
MAZ000-RIZ000-NHZ000-CTZ000-NYZ000-VTZ000-NJZ000-PAZ000-231915-
Mesoscale Discussion 0709
NWS Storm Prediction Center Norman OK
1220 PM CDT Sun May 23 2021
Areas affected...Southern New York...Northern Pennsylvania...and
Southern New England
Concerning...Severe potential...Watch unlikely
Valid 231720Z - 231915Z
Probability of Watch Issuance...5 percent
SUMMARY...Isolated storms capable of a few damaging wind gusts
possible this afternoon, watch issuance unlikely.
DISCUSSION...Visible satellite shows early morning clearing ahead of
an east-west oriented cold front moving into portions of southern
New York and vicinity has allowed for modest destabilization and
widespread cumulus development across the region, with a few higher
dBZ returns now showing up on KBGM. Surface temperatures have
already warmed into the mid-80s F, with surface dew point
temperatures in the low 60s F. This is yielding approximately
500-1000 J/kg of SBCAPE/MUCAPE despite marginal mid- and low-level
lapse rates. Effective shear ranges from 30-40 kt across the region,
increasing with eastern extent, amid a northwesterly unidirectional
flow regime.
As surface heating/destabilization continues, isolated thunderstorm
development is expected to continue along the advancing cold front.
Convection will be capable of mixing moderately strong flow aloft
toward the surface, as indicated by DCAPE values of 400-800 J/kg.
Thus a few isolated damaging wind gusts are possible this afternoon.
Storm cores may be a little more organized in/near the southern New
England area, given slightly higher values of deep-layer shear, and
thus, perhaps better potential for severe wind gusts. However, given
the expectation for isolated storm coverage, watch issuance is not
anticipated at this time.
..Karstens/Guyer.. 05/23/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GYX...BOX...OKX...ALY...PHI...BGM...BUF...CTP...
PBZ...
LAT...LON 40807875 41257945 41937909 42447696 42687492 42747176
42377067 41866997 41207002 40767170 40477390 40367627
40457737 40807875Nearby
Mesoscale Discussions in Pennsylvania, 2021Mesoscale Discussions in New York, 2021Mesoscale Discussions in Massachusetts, 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.