Alert archive / New York / Mesoscale Discussions in 2021
Mesoscale Discussion 1180
The Storm Prediction Center issued this mesoscale discussion at Jul 7, 2021, 1:50 PM EDT for 7 states. It was in force for 115 min.
The area
The outline as issued.
The facts
- Issued
- Jul 7, 2021, 1:50 PM EDT (17:50 UTC)
- Expired
- Jul 7, 2021, 3:45 PM EDT
- In force
- 115 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch likely
- Chance of a watch
- 80%
All 55 counties
Berkshire County, MA, Franklin County, MA, Hampden County, MA, Hampshire County, MA, Middlesex County, MA, Norfolk County, MA, Worcester County, MA, Cheshire County, NH, Bergen County, NJ, Essex County, NJ, Hudson County, NJ, Hunterdon County, NJ, Middlesex 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, Columbia County, NY, Delaware County, NY, Dutchess County, NY, Greene County, NY, Kings County, NY, Montgomery County, NY, Nassau County, NY, New York County, NY, Orange County, NY, Otsego County, NY, Putnam County, NY, Queens County, NY, Rensselaer County, NY, Richmond County, NY, Rockland County, NY, Saratoga County, NY, Schenectady County, NY, Schoharie County, NY, Suffolk County, NY, Sullivan County, NY, Ulster County, NY, Westchester County, NY, Lackawanna County, PA, Monroe County, PA, Northampton County, PA, Pike County, PA, Wayne County, PA, Bristol County, RI, Kent County, RI, Newport County, RI, Providence County, RI, Washington County, RI, Bennington County, VT, Windham County, VT
The radar
The Brookhaven radar (KOKX), 107 km from the middle of the area, began a volume at 17:52 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Brookhaven, NY (KOKX), launched 12:00Z, 5.8 hours before the alert went out and 107 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
- 568 J/kg
- Mixed-layer CIN
- -83 J/kg
- Mixed-layer LCL
- 901 m above ground
- 0-6 km bulk shear
- 26 kt
- 0-1 km storm-relative helicity
- 79 m²/s²
- 0-3 km storm-relative helicity
- 109 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.3
The text
As transmitted.
454
ACUS11 KWNS 071750
SWOMCD
SPC MCD 071750
MAZ000-RIZ000-NHZ000-CTZ000-NYZ000-VTZ000-NJZ000-PAZ000-071945-
Mesoscale Discussion 1180
NWS Storm Prediction Center Norman OK
1250 PM CDT Wed Jul 07 2021
Areas affected...Northeast PA...southeast NY...southern
VT...MA...CT...RI...northern NJ
Concerning...Severe potential...Watch likely
Valid 071750Z - 071945Z
Probability of Watch Issuance...80 percent
SUMMARY...Thunderstorms will increase in coverage this afternoon and
be capable of damaging downburst winds and isolated instances of
large hail. A Severe Thunderstorm Watch will be needed prior to
1830z.
DISCUSSION...Latest surface analysis showed a stationary front
extending from near the MA/NH border west to near the eastern tip of
Lake Erie. Strong diabatic heating of a very moist (upper 60s-lower
70s surface dew points) air mass continues south of the front,
contributing to MLCAPE ranging from 1000-2000 J/kg. The discussion
area is on the southern periphery of stronger mid-level westerly
flow, and this will contribute to effective shear values ranging
from 25-35 kts. Largely southwest/west flow in the low-mid levels
will support multicells and clusters as the primary modes. Steep
low-level lapse rates and a very moist environment will support
damaging downburst winds as the primary hazard, especially as storm
coverage/clustering increases later this afternoon. A few instances
of large hail will be possible, especially with the strongest
multicell updrafts.
Convective trends are being monitored and a Severe Thunderstorm
Watch is likely prior to 1830z.
..Bunting/Guyer.. 07/07/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GYX...BOX...OKX...ALY...PHI...BGM...
LAT...LON 40277387 40427529 41907582 42967525 43177329 42997223
42627121 41797112 41287127 40277387SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 7, 2:41 PM EDT | Severe Thunderstorm Watch | SPC | Greater Bridgeport Planning Region, Capitol Planning Region, Northwest Hills Planning Region, Lower Connecticut River Valley Planning Region, Naugatuck Valley Planning Region, Southeastern Connecticut Planning Region and 1 more | 10 hr |
| Jul 7, 4:48 PM EDT | Mesoscale Discussion | SPC | 87 min | |
| Jul 7, 7:11 PM EDT | Mesoscale Discussion | SPC | 2 hr | |
| Jul 7, 3:31 PM EDT | Severe Thunderstorm Watch | SPC | Allegany, Cattaraugus, Chautauqua | 7 hr |
| Jul 7, 1:31 PM EDT | Severe Thunderstorm Watch | SPC | Crawford, Erie | 7 hr |
| Jul 7, 3:59 PM EDT | Mesoscale Discussion | SPC | Crawford, Erie | 91 min |
Nearby
Mesoscale Discussions in New York, 2021Mesoscale Discussions in New Jersey, 2021Mesoscale Discussions in Connecticut, 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.