Alert archive / Massachusetts / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 90, NWS Boston/Norton, MA

July 23, 2021Bristol County, Norfolk County, Plymouth County, Massachusetts

NWS Boston/Norton, MA issued this severe thunderstorm warning at Jul 23, 2021, 6:42 PM EDT for Bristol County, Norfolk County, Plymouth County, Massachusetts. It was in force for 48 min. 9 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 23, 2021, 6:42 PM EDT (22:42 UTC)
Expired: Jul 23, 2021, 7:30 PM EDT
In force: 48 min
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Bristol County, MA, Norfolk County, MA, Plymouth County, MA

The radar

The Boston radar (KBOX), 34 km from the middle of the area, began a volume at 22:43 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
Jul 23, 6:47 PM EDT	HAIL 0.5	East Bridgewater, MA
Jul 23, 6:47 PM EDT	HAIL 0.75	East Bridgewater, MA
Jul 23, 6:48 PM EDT	HAIL 0.75	Brockton, MA
Jul 23, 6:57 PM EDT	HAIL 0.88	Whitman, MA
Jul 23, 7:10 PM EDT	HAIL 0.75	Plymouth, MA
Jul 23, 7:13 PM EDT	HAIL 0.5	Whitman, MA
Jul 23, 7:20 PM EDT	HAIL 0.5	Halifax, MA
Jul 23, 7:25 PM EDT	HAIL 1	3 Wnw Kingston, MA	RANGED FROM HALF-INCH UP TO 1 INCH DIAMETER. TIME ESTIMATED FROM RADAR.
Jul 23, 7:33 PM EDT	HAIL 0.75	Plymouth, MA	VIDEO ON SOCIAL MEDIA.

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

The nearest sounding before it

Gray, ME (KGYX), launched 12:00Z, 10.7 hours before the alert went out and 210 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: 16 J/kg
Mixed-layer CIN: -94 J/kg
Mixed-layer LCL: 1504 m above ground
0-6 km bulk shear: 10 kt
0-1 km storm-relative helicity: -19 m²/s²
0-3 km storm-relative helicity: -5 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

374 
WUUS51 KBOX 232242
SVRBOX
MAC005-021-023-232330-
/O.NEW.KBOX.SV.W.0090.210723T2242Z-210723T2330Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Boston/Norton MA
642 PM EDT Fri Jul 23 2021

The National Weather Service in Boston/Norton has issued a

* Severe Thunderstorm Warning for...
  East central Norfolk County in eastern Massachusetts...
  Northwestern Plymouth County in southeastern Massachusetts...
  Northern Bristol County in southeastern Massachusetts...

* Until 730 PM EDT.

* At 642 PM EDT, a severe thunderstorm was located over Brockton,
  moving east 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...
  Brockton, Plymouth, Weymouth, Braintree, Randolph, Stoughton,
  Bridgewater, Marshfield, Middleborough, Easton, Hingham, Scituate,
  Pembroke, Rockland, Abington, Duxbury, Whitman, Hanover, East
  Bridgewater and Raynham.

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.

&&

LAT...LON 4196 7066 4195 7065 4196 7106 4214 7111
      4227 7082 4226 7080 4203 7067 4202 7068
      4202 7067 4201 7068 4201 7070 4200 7071
      4197 7067 4198 7065
TIME...MOT...LOC 2242Z 259DEG 11KT 4207 7099 

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

Loconto

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 23, 2:28 PM EDT	Special Weather Statement	BOX	Middlesex	32 min
Jul 23, 2:49 PM EDT	Coastal Flood Statement	BOX	Barnstable, Essex, Nantucket, Norfolk, Plymouth, Suffolk	11 hr
Jul 23, 3:04 PM EDT	Special Weather Statement	BOX	Essex	26 min
Jul 23, 3:28 PM EDT	Severe Thunderstorm Warning	BOX	Essex, Middlesex, Suffolk	47 min
Jul 23, 3:29 PM EDT	Special Marine Warning	BOX		61 min
Jul 23, 4:41 PM EDT	Special Weather Statement	BOX	Essex	34 min
Jul 23, 4:57 PM EDT	Severe Thunderstorm Warning	BOX	Essex, Middlesex	63 min
Jul 23, 5:23 PM EDT	Special Weather Statement	BOX	Bristol	52 min
Jul 23, 5:50 PM EDT	Special Marine Warning	BOX		55 min
Jul 23, 6:09 PM EDT	Severe Thunderstorm Warning	BOX	Bristol, Plymouth	26 min
Jul 23, 6:25 PM EDT	Special Weather Statement	BOX	Plymouth	50 min
Jul 23, 6:32 PM EDT	Special Weather Statement	BOX	Worcester	43 min
Jul 23, 7:28 PM EDT	Severe Thunderstorm Warning	BOX	Plymouth	34 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.