Alert archive / Massachusetts / Mesoscale Discussions in 2021
Mesoscale Discussion 1137
The Storm Prediction Center issued this mesoscale discussion at Jun 30, 2021, 4:48 PM EDT for 8 counties in Massachusetts; 7 counties in New York; Lackawanna County, Susquehanna County, Wayne County, Pennsylvania. It was in force for 87 min.
The area
The outline as issued.
The facts
- Issued
- Jun 30, 2021, 4:48 PM EDT (20:48 UTC)
- Expired
- Jun 30, 2021, 6:15 PM EDT
- In force
- 87 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 326...329
Counties Berkshire County, MA, Franklin County, MA, Hampden County, MA, Hampshire County, MA, Middlesex County, MA, Norfolk County, MA, Suffolk County, MA, Worcester County, MA, Albany County, NY, Columbia County, NY, Delaware County, NY, Greene County, NY, Schoharie County, NY, Sullivan County, NY, Ulster County, NY, Lackawanna County, PA, Susquehanna County, PA, Wayne County, PA
The radar
The Albany radar (KENX), 56 km from the middle of the area, began a volume at 20:46 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, 8.8 hours before the alert went out and 58 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.
497
ACUS11 KWNS 302048
SWOMCD
SPC MCD 302048
MAZ000-CTZ000-NYZ000-PAZ000-302215-
Mesoscale Discussion 1137
NWS Storm Prediction Center Norman OK
0348 PM CDT Wed Jun 30 2021
Areas affected...Portions of far northeastern PA into
central/southern NY...MA...and northern CT
Concerning...Severe Thunderstorm Watch 326...329...
Valid 302048Z - 302215Z
The severe weather threat for Severe Thunderstorm Watch 326, 329
continues.
SUMMARY...The threat for scattered damaging winds and isolated
severe hail should focus across parts of central/southern New York
into Massachusetts and vicinity over the next couple of hours.
DISCUSSION...Two loosely organized clusters of storms are present
this afternoon, one over far northeastern PA into central NY, and
the other over western into central MA. Strong boundary-layer
heating has occurred ahead of these storms, and rather steep
low-level lapse rates around 8-9 C/km have developed downstream.
This region remains on the southern fringe of the stronger mid-level
westerly flow. Still, recent VWPs from KBGM and KENX show modestly
strengthening westerly winds with height through mid levels, and
around 30-40 kt of deep-layer shear remain present. Multicell
clusters will likely continue to pose a threat for scattered
damaging wind gusts. Some marginally severe hail may also occur,
particularly with any embedded supercell within the cluster in
western/central MA. It appears the greatest overall severe threat
may focus across MA in the short term, where the best overlap of
steep low-level lapse rates, moderate instability, and sufficient
deep-layer shear overlap.
..Gleason.. 06/30/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BOX...ALY...BGM...
LAT...LON 41737614 42327567 42717444 42717327 42687188 42687087
42197085 42027180 41857346 41387581 41737614SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 30, 2:16 PM EDT | Mesoscale Discussion | SPC | Berkshire, Essex, Franklin, Hampden, Hampshire, Middlesex and 4 more | 119 min |
| Jun 30, 3:21 PM EDT | Severe Thunderstorm Watch | SPC | Berkshire, Bristol, Essex, Franklin, Hampden, Hampshire and 5 more | 7 hr |
| Jun 30, 6:58 PM EDT | Mesoscale Discussion | SPC | Bristol, Norfolk, Plymouth | 92 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.