Alert archive / Massachusetts / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 91, NWS Boston/Norton, MA

July 23, 2021Plymouth County, Massachusetts

NWS Boston/Norton, MA issued this severe thunderstorm warning at Jul 23, 2021, 7:28 PM EDT for Plymouth County, Massachusetts. It was in force for 34 min. 5 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, 7:28 PM EDT (23:28 UTC)
Expired: Jul 23, 2021, 8:02 PM EDT
In force: 34 min
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

County Plymouth County, MA

The radar

The Boston radar (KBOX), 40 km from the middle of the area, began a volume at 23:30 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, 7:30 PM EDT	HAIL 0.75	Kingston, MA
Jul 23, 7:33 PM EDT	HAIL 0.75	Plymouth, MA	VIDEO ON SOCIAL MEDIA.
Jul 23, 7:40 PM EDT	HAIL 1.25	Kingston, MA
Jul 23, 7:49 PM EDT	TSTM WND DMG	Halifax, MA	LARGE TREE BRANCH DOWN IN THE ROAD AT OAK STREET AND MARILYN WAY. RELAYED BY AMATEUR RADIO.
Jul 23, 7:50 PM EDT	HAIL 1	Kingston, MA	PHOTOS POSTED TO SOCIAL MEDIA. RELAYED BY AMATEUR RADIO.

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, 11.5 hours before the alert went out and 216 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.

693 
WUUS51 KBOX 232328
SVRBOX
MAC023-240030-
/O.NEW.KBOX.SV.W.0091.210723T2328Z-210724T0030Z/

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

The National Weather Service in Boston/Norton has issued a

* Severe Thunderstorm Warning for...
  Central Plymouth County in southeastern Massachusetts...

* Until 830 PM EDT.

* At 727 PM EDT, a severe thunderstorm was located over Kingston, or
  7 miles northwest of Plymouth, moving east at 20 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...
  Plymouth, Middleborough, Pembroke, Duxbury, Kingston, Carver,
  Hanson, Halifax and Plympton.

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 4182 7055 4180 7059 4193 7092 4209 7084
      4205 7064 4204 7064 4204 7066 4201 7067
      4201 7060 4200 7061 4199 7063 4201 7071
      4197 7067 4198 7065 4195 7065 4195 7058
      4192 7054
TIME...MOT...LOC 2327Z 291DEG 16KT 4197 7073 

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

Gaucher/RM

1 follow-up statement

233 
WWUS51 KBOX 240002
SVSBOX

Severe Weather Statement
National Weather Service Boston/Norton MA
802 PM EDT Fri Jul 23 2021

MAC023-240012-
/O.CAN.KBOX.SV.W.0091.000000T0000Z-210724T0030Z/
Plymouth MA-
802 PM EDT Fri Jul 23 2021

...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL PLYMOUTH COUNTY 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.

LAT...LON 4182 7055 4180 7059 4193 7092 4209 7084
      4205 7064 4204 7064 4204 7066 4201 7067
      4201 7060 4200 7061 4199 7063 4201 7071
      4197 7067 4198 7065 4195 7065 4195 7058
      4192 7054
TIME...MOT...LOC 0000Z 291DEG 16KT 4191 7053 

$$

Gaucher

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, 6:42 PM EDT	Severe Thunderstorm Warning	BOX	Bristol, Norfolk, Plymouth	48 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.