Alert archive / Massachusetts / Mesoscale Discussions in 2021
Mesoscale Discussion 1133
The Storm Prediction Center issued this mesoscale discussion at Jun 30, 2021, 2:16 PM EDT for 5 states. It was in force for 119 min.
The area
The outline as issued.
The facts
- Issued
- Jun 30, 2021, 2:16 PM EDT (18:16 UTC)
- Expired
- Jun 30, 2021, 4:15 PM EDT
- In force
- 119 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...severe thunderstorm watch likely
- Chance of a watch
- 80%
All 29 counties
Berkshire County, MA, Essex 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, Sussex County, NJ, Albany County, NY, Columbia County, NY, Dutchess County, NY, Greene County, NY, Orange County, NY, Putnam County, NY, Sullivan County, NY, Ulster County, NY, Carbon County, PA, Lackawanna County, PA, Luzerne County, PA, Monroe County, PA, Pike County, PA, Wayne County, PA, Wyoming County, PA, Bristol County, RI, Kent County, RI, Providence County, RI
The radar
The Albany radar (KENX), 121 km from the middle of the area, began a volume at 18:16 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
Albany, NY (KALY), launched 12:00Z, 6.3 hours before the alert went out and 112 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
- 113 J/kg
- Mixed-layer CIN
- -257 J/kg
- Mixed-layer LCL
- 1162 m above ground
- 0-6 km bulk shear
- 45 kt
- 0-1 km storm-relative helicity
- 66 m²/s²
- 0-3 km storm-relative helicity
- 98 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
987
ACUS11 KWNS 301817
SWOMCD
SPC MCD 301816
MAZ000-RIZ000-CTZ000-NYZ000-NJZ000-PAZ000-302015-
Mesoscale Discussion 1133
NWS Storm Prediction Center Norman OK
0116 PM CDT Wed Jun 30 2021
Areas affected...Portions of northeastern PA...far northern
NJ...southern NY...CT...RI...and MA
Concerning...Severe potential...Severe Thunderstorm Watch likely
Valid 301816Z - 302015Z
Probability of Watch Issuance...80 percent
SUMMARY...Storms posing a threat for mainly severe/damaging winds
should continue to move eastward this afternoon. Severe Thunderstorm
Watch issuance is likely.
DISCUSSION...Convection is gradually increasing in coverage and
intensity across parts of central PA into central/eastern NY
along/east of a weak surface trough and zone of differential
heating. Some of these storms have a history of producing both
marginally severe hail and damaging wind gusts across central NY.
Recent surface observations and area VWPs show low-level winds are
generally veered to west-southwesterly, which is limiting low-level
convergence. Still, current expectations are for the ongoing
convection to gradually spread eastward across parts of northeastern
PA into far northern NJ, southern NY, and CT/RI/MA through the
remainder of the afternoon. Around 30-40 kt of deep-layer shear and
1000-1500 J/kg of MLCAPE should be sufficient for an organized
severe threat. The primary risk should be scattered severe/damaging
wind gusts as storms will probably tend to form into small bowing
clusters with eastward extent. But, occasional marginally severe
hail may also occur with any convection that can remain
semi-discrete. A downstream Severe Thunderstorm Watch will likely be
needed.
..Gleason/Thompson.. 06/30/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BOX...OKX...ALY...PHI...BGM...
LAT...LON 41037604 41657616 41857511 42187445 42697412 42697325
42637125 42827101 42847078 42697056 42517072 42337079
42177063 42027069 41797103 41617147 41347351 40727569
41037604SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 30, 3:21 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 | 7 hr |
| Jun 30, 6:58 PM EDT | Mesoscale Discussion | SPC | 92 min | |
| Jun 30, 4:48 PM EDT | Mesoscale Discussion | SPC | Berkshire, Franklin, Hampden, Hampshire, Middlesex, Norfolk and 2 more | 87 min |
| Jun 30, 11:04 AM EDT | Mesoscale Discussion | SPC | Albany, Allegany, Broome, Cayuga, Chemung, Chenango and 29 more | 116 min |
| Jun 30, 11:47 AM EDT | Severe Thunderstorm Watch | SPC | Albany, Allegany, Broome, Cattaraugus, Cayuga, Chautauqua and 27 more | 7 hr |
| Jun 30, 12:06 PM EDT | Severe Thunderstorm Watch | SPC | Essex | 7 hr |
| Jun 30, 1:52 PM EDT | Mesoscale Discussion | SPC | Fulton, Montgomery, Saratoga, Schenectady, Warren, Washington | 83 min |
| Jun 30, 11:30 AM EDT | Mesoscale Discussion | SPC | Allegheny, Armstrong, Beaver, Blair, Butler, Cambria and 23 more | 2 hr |
| Jun 30, 12:46 PM EDT | Severe Thunderstorm Watch | SPC | Bedford, Blair, Cambria, Cameron, Centre, Clearfield and 20 more | 7 hr |
| Jun 30, 3:29 PM EDT | Mesoscale Discussion | SPC | Allegheny, Armstrong, Bedford, Blair, Cambria, Centre and 16 more | 2 hr |
| Jun 30, 4:41 PM EDT | Mesoscale Discussion | SPC | Adams, Bedford, Berks, Blair, Columbia, Cumberland and 17 more | 2 hr |
| Jun 30, 4:51 PM EDT | Severe Thunderstorm Watch | SPC | Adams, Cumberland, Dauphin, Franklin, Lancaster, Lebanon and 3 more | 3 hr |
Nearby
Mesoscale Discussions in Massachusetts, 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.