Alert archive / Massachusetts / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 112, NWS Boston/Norton, MA

September 15, 20214 counties in Massachusetts

NWS Boston/Norton, MA issued this severe thunderstorm warning at Sep 15, 2021, 7:53 PM EDT for 4 counties in Massachusetts. It was in force for 13 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Sep 15, 2021, 7:53 PM EDT (23:53 UTC)
Expired: Sep 15, 2021, 8:06 PM EDT
In force: 13 min
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Tornado: Possible
Hail: 0.75 in
Wind: 60.0 mph

Counties Hampden County, MA, Hampshire County, MA, Middlesex County, MA, Worcester County, MA

The radar

The Boston radar (KBOX), 87 km from the middle of the area, began a volume at 23:54 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Sep 15, 3:43 PM EDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Albany, NY (KALY), launched 12:00Z, 11.9 hours before the alert went out and 160 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: 856 J/kg
Mixed-layer CIN: -92 J/kg
Mixed-layer LCL: 766 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 214 m²/s²
0-3 km storm-relative helicity: 248 m²/s²
Significant tornado parameter: 0.7
Supercell composite: 6.3

Open this sounding in Storm Lab

The text

As transmitted.

296 
WUUS51 KBOX 152353
SVRBOX
MAC013-015-017-027-160045-
/O.NEW.KBOX.SV.W.0112.210915T2353Z-210916T0045Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Boston/Norton MA
753 PM EDT Wed Sep 15 2021

The National Weather Service in Boston/Norton has issued a

* Severe Thunderstorm Warning for...
  Central Worcester County in central Massachusetts...
  Eastern Hampshire County in western Massachusetts...
  Northwestern Middlesex County in northeastern Massachusetts...
  Northeastern Hampden County in western Massachusetts...

* Until 845 PM EDT.

* At 752 PM EDT, a severe thunderstorm was located near Hardwick, or
  16 miles southeast of Orange, moving northeast at 35 mph.

  HAZARD...60 mph wind gusts and penny size hail.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to trees and power lines.

* Locations impacted include...
  Leominster, Fitchburg, Gardner, Hudson, Holden, Clinton, Palmer,
  Spencer, Lunenburg, Ware, Townsend, Lancaster, Templeton, Rutland,
  Sterling, West Boylston, Westminster, Shirley, Stow and Harvard.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Large hail and damaging winds and continuous cloud to ground
lightning is occurring with this storm. Move indoors immediately.
Lightning is one of nature's leading killers. Remember, if you can
hear thunder, you are close enough to be struck by lightning.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4268 7168 4241 7155 4223 7227 4250 7226
TIME...MOT...LOC 2352Z 245DEG 32KT 4238 7217 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

RM

1 follow-up statement

113 
WWUS51 KBOX 160006
SVSBOX

Severe Weather Statement
National Weather Service Boston/Norton MA
806 PM EDT Wed Sep 15 2021

MAC013-015-017-027-160016-
/O.CAN.KBOX.SV.W.0112.000000T0000Z-210916T0045Z/
Worcester MA-Hampshire MA-Middlesex MA-Hampden MA-
806 PM EDT Wed Sep 15 2021

...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL WORCESTER...EASTERN
HAMPSHIRE...NORTHWESTERN MIDDLESEX AND NORTHEASTERN HAMPDEN COUNTIES
IS CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning has been cancelled.  However gusty winds and
heavy rain are still possible with this thunderstorm.

A Severe Thunderstorm Watch remains in effect until 1000 PM EDT for
western and central Massachusetts.

LAT...LON 4268 7168 4241 7155 4223 7227 4250 7226
TIME...MOT...LOC 0005Z 245DEG 32KT 4244 7201 

$$

RM

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 15, 6:24 PM EDT	Special Weather Statement	BOX	Worcester	51 min
Sep 15, 6:32 PM EDT	Special Weather Statement	BOX	Franklin	43 min
Sep 15, 7:00 PM EDT	Special Weather Statement	BOX	Franklin	45 min
Sep 15, 7:10 PM EDT	Special Weather Statement	BOX	Worcester	50 min
Sep 15, 7:15 PM EDT	Special Weather Statement	BOX	Hampshire	45 min
Sep 15, 7:20 PM EDT	Special Weather Statement	BOX	Hampden	40 min
Sep 15, 7:40 PM EDT	Special Weather Statement	BOX	Middlesex	50 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.