Alert archive / Massachusetts / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 99, NWS Boston/Norton, MA

August 12, 20214 counties in Massachusetts

NWS Boston/Norton, MA issued this severe thunderstorm warning at Aug 12, 2021, 5:51 PM EDT for 4 counties in Massachusetts. It was in force for 39 min. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Aug 12, 2021, 5:51 PM EDT (21:51 UTC)
Expired: Aug 12, 2021, 6:30 PM EDT
In force: 39 min
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Damage threat: Considerable
Hail: 0.75 in
Wind: 70.0 mph

Counties Franklin County, MA, Hampden County, MA, Hampshire County, MA, Worcester County, MA

The radar

The Boston radar (KBOX), 88 km from the middle of the area, began a volume at 21:53 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.

What was reported inside it

Time	Report	Where	Remark
Aug 12, 6:25 PM EDT	TSTM WND DMG	Warren, MA	TREE AND WIRES DOWN ON OLD DOUGLAS ROAD
Aug 12, 6:38 PM EDT	TSTM WND DMG	Worcester, MA	TREES AND WIRES DOWN ON FERDINAND STREET

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Albany, NY (KALY), launched 12:00Z, 9.9 hours before the alert went out and 148 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 58 J/kg
Mixed-layer CIN: -212 J/kg
Mixed-layer LCL: 1178 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 62 m²/s²
0-3 km storm-relative helicity: 56 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

610 
WUUS51 KBOX 122151
SVRBOX
MAC011-013-015-027-122230-
/O.NEW.KBOX.SV.W.0099.210812T2151Z-210812T2230Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Boston/Norton MA
551 PM EDT Thu Aug 12 2021

The National Weather Service in Boston/Norton has issued a

* Severe Thunderstorm Warning for...
  Southern Worcester County in central Massachusetts...
  Southeastern Hampshire County in western Massachusetts...
  Southeastern Franklin County in western Massachusetts...
  East central Hampden County in western Massachusetts...

* Until 630 PM EDT.

* At 550 PM EDT, a severe thunderstorm was located near Palmer, or 11
  miles east of Chicopee, moving east at 45 mph.

  HAZARD...70 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Expect considerable damage to trees and power lines. 
           Damage is likely to mobile homes and outbuildings.

* Locations impacted include...
  Worcester, Shrewsbury, Ludlow, Grafton, Holden, Webster,
  Southbridge, Auburn, Belchertown, Wilbraham, Northborough, Oxford,
  Millbury, Charlton, Palmer, Spencer, Dudley, Leicester, Ware and
  Sturbridge.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These storms have a history of producing wind damage. For your 
protection move to an interior room on the lowest floor of a 
building.

&&

LAT...LON 4212 7244 4236 7244 4238 7167 4202 7175
TIME...MOT...LOC 2150Z 275DEG 41KT 4223 7235 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...70 MPH

$$

Nash

The office that day

Everything else NWS Boston/Norton, MA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 12, 2:53 PM EDT	Heat Advisory	BOX	Barnstable, Bristol, Essex, Franklin, Hampden, Hampshire and 5 more	29 hr
Aug 12, 3:45 PM EDT	Special Weather Statement	BOX	Franklin, Hampshire	60 min
Aug 12, 4:45 PM EDT	Special Weather Statement	BOX	Franklin, Hampden, Hampshire	60 min
Aug 12, 5:02 PM EDT	Severe Thunderstorm Warning	BOX	Franklin, Hampden, Hampshire	58 min
Aug 12, 5:35 PM EDT	Severe Thunderstorm Warning	BOX	Hampden, Hampshire, Worcester	55 min
Aug 12, 5:42 PM EDT	Special Weather Statement	BOX	Worcester	48 min
Aug 12, 6:13 PM EDT	Severe Thunderstorm Warning	BOX	Bristol, Hampden, Middlesex, Norfolk, Worcester	62 min
Aug 12, 6:52 PM EDT	Special Marine Warning	BOX		53 min
Aug 12, 7:14 PM EDT	Special Weather Statement	BOX	Bristol, Plymouth	61 min

Nearby

Severe Thunderstorm Warnings in Massachusetts, 2021 Every severe thunderstorm warning 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.