Alert archive / Massachusetts / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 104, NWS Boston/Norton, MA

August 19, 20215 counties in Massachusetts

NWS Boston/Norton, MA issued this severe thunderstorm warning at Aug 19, 2021, 11:36 AM EDT for 5 counties in Massachusetts. It was in force for 54 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 19, 2021, 11:36 AM EDT (15:36 UTC)
Expired: Aug 19, 2021, 12:30 PM EDT
In force: 54 min
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Tornado: Possible
Hail: 1.0 in
Wind: 60.0 mph

Counties Essex County, MA, Middlesex County, MA, Norfolk County, MA, Suffolk County, MA, Worcester County, MA

The radar

The Boston radar (KBOX), 44 km from the middle of the area, began a volume at 15:38 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 19, 11:45 AM EDT	TSTM WND DMG	Medford, MA	TREE DOWN AT 900 BLOCK OF HIGHLAND AVE
Aug 19, 12:05 PM EDT	TSTM WND DMG	Malden, MA	LARGE TREE BRANCH DOWN AT SALEM AND BRANCH STREET.

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, 3.6 hours before the alert went out and 183 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: 110 J/kg
Mixed-layer CIN: -40 J/kg
Mixed-layer LCL: 884 m above ground
0-6 km bulk shear: 13 kt
0-1 km storm-relative helicity: 36 m²/s²
0-3 km storm-relative helicity: 68 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

031 
WUUS51 KBOX 191536
SVRBOX
MAC009-017-021-025-027-191630-
/O.NEW.KBOX.SV.W.0104.210819T1536Z-210819T1630Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Boston/Norton MA
1136 AM EDT Thu Aug 19 2021

The National Weather Service in Boston/Norton has issued a

* Severe Thunderstorm Warning for...
  Suffolk County in eastern Massachusetts...
  Northwestern Norfolk County in eastern Massachusetts...
  South central Essex County in northeastern Massachusetts...
  Southeastern Worcester County in central Massachusetts...
  Southeastern Middlesex County in northeastern Massachusetts...

* Until 1230 PM EDT.

* At 1136 AM EDT, a severe thunderstorm was located over Holliston,
  or near Natick, moving northeast at 25 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...
  Boston, Cambridge, Quincy, Lynn, Newton, Somerville, Framingham,
  Waltham, Malden, Brookline, Medford, Revere, Arlington, Everett,
  Woburn, Chelsea, Natick, Watertown, Franklin and Lexington.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4256 7108 4244 7096 4237 7097 4234 7087
      4236 7096 4235 7095 4238 7100 4232 7093
      4231 7097 4238 7105 4232 7100 4233 7104
      4230 7105 4231 7098 4228 7102 4211 7144
      4223 7156
TIME...MOT...LOC 1536Z 233DEG 21KT 4221 7141 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Chai

1 follow-up statement

219 
WWUS51 KBOX 191614
SVSBOX

Severe Weather Statement
National Weather Service Boston/Norton MA
1214 PM EDT Thu Aug 19 2021

MAC027-191624-
/O.CAN.KBOX.SV.W.0104.000000T0000Z-210819T1630Z/
Worcester MA-
1214 PM EDT Thu Aug 19 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN WORCESTER COUNTY
IS CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

LAT...LON 4256 7108 4244 7096 4237 7097 4234 7087
      4236 7094 4235 7095 4238 7100 4232 7093
      4231 7097 4238 7105 4232 7100 4233 7104
      4230 7105 4231 7098 4228 7102 4227 7113
      4232 7143
TIME...MOT...LOC 1614Z 233DEG 21KT 4234 7117 

$$

MAC009-017-021-025-191630-
/O.CON.KBOX.SV.W.0104.000000T0000Z-210819T1630Z/
Suffolk MA-Norfolk MA-Essex MA-Middlesex MA-
1214 PM EDT Thu Aug 19 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1230 PM EDT
FOR SUFFOLK...NORTH CENTRAL NORFOLK...SOUTH CENTRAL ESSEX AND EAST
CENTRAL MIDDLESEX COUNTIES...

At 1214 PM EDT, a severe thunderstorm was located over Watertown,
moving northeast at 25 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...
Boston, Cambridge, Quincy, Lynn, Newton, Somerville, Framingham,
Waltham, Malden, Brookline, Medford, Revere, Arlington, Everett,
Woburn, Chelsea, Natick, Watertown, Lexington and Needham.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4256 7108 4244 7096 4237 7097 4234 7087
      4236 7094 4235 7095 4238 7100 4232 7093
      4231 7097 4238 7105 4232 7100 4233 7104
      4230 7105 4231 7098 4228 7102 4227 7113
      4232 7143
TIME...MOT...LOC 1614Z 233DEG 21KT 4234 7117 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Chai

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 19, 8:14 AM EDT	Flash Flood Warning	BOX	Hampden, Worcester	3 hr
Aug 19, 9:18 AM EDT	Flash Flood Warning	BOX	Hampden, Hampshire, Worcester	3 hr
Aug 19, 10:14 AM EDT	Severe Thunderstorm Warning	BOX	Middlesex, Worcester	44 min
Aug 19, 10:21 AM EDT	Tornado Warning	BOX	Middlesex, Worcester	29 min
Aug 19, 10:46 AM EDT	Flash Flood Warning	BOX	Essex, Middlesex, Norfolk, Suffolk, Worcester	3 hr
Aug 19, 11:40 AM EDT	Flash Flood Warning	BOX	Essex, Middlesex	3 hr
Aug 19, 12:32 PM EDT	Severe Thunderstorm Warning	BOX	Essex, Middlesex, Norfolk, Suffolk	58 min
Aug 19, 12:33 PM EDT	Special Marine Warning	BOX		57 min
Aug 19, 12:49 PM EDT	Tornado Warning	BOX	Essex, Middlesex, Suffolk	39 min
Aug 19, 1:18 PM EDT	Tornado Warning	BOX	Middlesex, Worcester	27 min
Aug 19, 1:37 PM EDT	Special Weather Statement	BOX	Essex	38 min
Aug 19, 1:38 PM EDT	Special Marine Warning	BOX		67 min
Aug 19, 1:46 PM EDT	Special Weather Statement	BOX	Barnstable	59 min
Aug 19, 1:48 PM EDT	Special Marine Warning	BOX		57 min
Aug 19, 1:54 PM EDT	Special Weather Statement	BOX	Middlesex	51 min
Aug 19, 2:23 PM EDT	Severe Thunderstorm Warning	BOX	Middlesex	37 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.