Alert archive / Massachusetts / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 67, NWS Boston/Norton, MA

July 14, 20214 counties in Massachusetts

NWS Boston/Norton, MA issued this severe thunderstorm warning at Jul 14, 2021, 6:05 PM EDT for 4 counties in Massachusetts. It was in force for 40 min. 7 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
Jul 14, 2021, 6:05 PM EDT (22:05 UTC)
Expired
Jul 14, 2021, 6:45 PM EDT
In force
40 min
Issued by
NWS Boston/Norton, MA
Area
Storm-based polygon
Hail
0.88 in
Wind
60.0 mph

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

The radar

The Boston radar (KBOX), 117 km from the middle of the area, began a volume at 22:08 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

TimeReportWhereRemark
Jul 14, 6:22 PM EDTHAIL 1.25Amherst, MAHALF DOLLAR SIZE HAIL
Jul 14, 6:24 PM EDTTSTM WND DMGShutesbury, MATREE DOWN ON MONTAGUE RD
Jul 14, 6:25 PM EDTTSTM WND DMGPelham, MATREE DOWN BLOCKING ROAD ON ENFIELD ROAD
Jul 14, 6:25 PM EDTHAIL 0.75Shutesbury, MA
Jul 14, 6:30 PM EDTTSTM WND DMGAmherst, MATREE DOWN ACROSS STRONG STREET
Jul 14, 6:30 PM EDTHAIL 1.75Pelham, MAGOLF BALL SIZE HAIL
Jul 14, 6:38 PM EDTTSTM WND DMGNew Salem, MATREE DOWN ACROSS DANIEL SHAYS HIGHWAY

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, 10.1 hours before the alert went out and 119 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-pSkew-T log-p diagram, Albany, NY at 12:00Z on 2021-07-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 20 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Albany, NY at 12:00Z on 2021-07-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 129 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
20 J/kg
Mixed-layer CIN
-211 J/kg
Mixed-layer LCL
871 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
129 m²/s²
0-3 km storm-relative helicity
134 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

As transmitted.

282 
WUUS51 KBOX 142205
SVRBOX
MAC011-013-015-027-142245-
/O.NEW.KBOX.SV.W.0067.210714T2205Z-210714T2245Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Boston/Norton MA
605 PM EDT Wed Jul 14 2021

The National Weather Service in Boston/Norton has issued a

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

* Until 645 PM EDT.

* At 605 PM EDT, a severe thunderstorm was located over Leverett, or
  7 miles north of Amherst, moving southeast at 15 mph.

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

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Amherst, Northampton, South Hadley, Belchertown, Palmer, Ware,
  Montague, Granby, Barre, Hadley, West Brookfield, Sunderland,
  Hatfield, Hardwick, Williamsburg, Leverett, Shutesbury, Whately,
  Pelham and Petersham.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Prepare immediately for hail and damaging winds. People outside 
should move immediately to shelter inside a strong building. Stay 
away from windows.

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

&&

LAT...LON 4237 7269 4257 7247 4239 7207 4218 7229
TIME...MOT...LOC 2205Z 308DEG 14KT 4247 7250 

HAIL...0.88IN
WIND...60MPH
 
$$
RM
1 follow-up statement
900 
WWUS51 KBOX 142221
SVSBOX

Severe Weather Statement
National Weather Service Boston/Norton MA
621 PM EDT Wed Jul 14 2021

MAC011-013-015-027-142245-
/O.CON.KBOX.SV.W.0067.000000T0000Z-210714T2245Z/
Worcester MA-Hampshire MA-Franklin MA-Hampden MA-
621 PM EDT Wed Jul 14 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 645 PM EDT
FOR WEST CENTRAL WORCESTER...SOUTHEASTERN HAMPSHIRE...SOUTHEASTERN
FRANKLIN AND NORTHEASTERN HAMPDEN COUNTIES...

At 620 PM EDT, a severe thunderstorm was located over Shutesbury, or
near Amherst, moving southeast at 15 mph.

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

SOURCE...Radar indicated.

IMPACT...Expect wind damage to trees and power lines. Minor hail 
         damage to vehicles is possible.

Locations impacted include...
Amherst, Belchertown, Palmer, Ware, Granby, Barre, Hadley, West
Brookfield, Hatfield, Hardwick, Leverett, Shutesbury, Pelham,
Petersham, New Braintree, New Salem and Wendell.

PRECAUTIONARY/PREPAREDNESS ACTIONS...


Prepare immediately for large hail and damaging winds. People outside
should move to a shelter, inside a strong building and away from
windows.

This storm has a history of producing hail. SEEK SHELTER NOW inside 
a sturdy structure and stay away from windows.

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 4234 7261 4254 7241 4239 7207 4218 7229
TIME...MOT...LOC 2220Z 308DEG 14KT 4243 7243 

HAIL...1.00IN
WIND...60MPH
 
$$

RM

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 14, 12:32 AM EDTDense Fog AdvisoryBOXBarnstable, Bristol, Dukes, Essex, Middlesex, Nantucket and 4 more9 hr
Jul 14, 3:36 AM EDTSpecial Weather StatementBOXHampden, Hampshire39 min
Jul 14, 4:15 AM EDTSpecial Weather StatementBOXHampden, Hampshire45 min
Jul 14, 4:46 PM EDTSpecial Weather StatementBOXWorcester44 min
Jul 14, 4:53 PM EDTSevere Thunderstorm WarningBOXFranklin, Worcester52 min
Jul 14, 5:30 PM EDTSevere Thunderstorm WarningBOXFranklin, Hampshire, Worcester45 min
Jul 14, 6:38 PM EDTSevere Thunderstorm WarningBOXFranklin, Hampden, Hampshire, Worcester52 min
Jul 14, 7:16 PM EDTFlash Flood WarningBOXHampshire53 min
Jul 14, 7:31 PM EDTSpecial Weather StatementBOXWorcester44 min
Jul 14, 7:33 PM EDTSpecial Weather StatementBOXHampden42 min
Jul 14, 7:46 PM EDTSevere Thunderstorm WarningBOXFranklin, Hampden, Hampshire, Worcester26 min

Nearby

Severe Thunderstorm Warnings in Massachusetts, 2021Every 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.