Alert archive / Massachusetts / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 103, NWS Boston/Norton, MA

August 19, 2021Middlesex County, Worcester County, Massachusetts; Northeastern Connecticut Planning Region, Connecticut; Providence County, Rhode Island

NWS Boston/Norton, MA issued this severe thunderstorm warning at Aug 19, 2021, 10:14 AM EDT for Middlesex County, Worcester County, Massachusetts; Northeastern Connecticut Planning Region, Connecticut; Providence County, Rhode Island. It was in force for 44 min. 3 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, 10:14 AM EDT (14:14 UTC)
Expired: Aug 19, 2021, 10:58 AM EDT
In force: 44 min
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Tornado: Possible
Hail: 1.0 in
Wind: 60.0 mph

Counties Northeastern Connecticut Planning Region, CT, Middlesex County, MA, Worcester County, MA, Providence County, RI

The radar

The Boston radar (KBOX), 54 km from the middle of the area, began a volume at 14:17 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, 10:15 AM EDT	TORNADO	Thompson, CT	NWS CONFIRMED AN EF0 TORNADO WITH MAXIMUM WINDS OF 85 MPH, WITH A WIDTH OF 50 YARDS. IT BEGAN NEAR QUINEBAUG ROAD AND RIVERSIDE DRIVE IN THOMPSON, CT. IT THEN TRAVELED NORTHEAST ON A DISCONTINUOUS PATH FOR 4.7 MILES, ENDING AS A WATERSPOUT ON LAKE CHAUBUNAGUNG
Aug 19, 10:21 AM EDT	TORNADO	Webster, MA	THE EF0 TORNADO THAT TOUCHED DOWN IN THOMPSON, CT AT 1015 AM CONTINUED NORTHEAST ON A DISCONTINUOUS PATH THROUGH WEBSTER, MA. AT 1021 AM, A TRAINED SPOTTER VIDEO TAPED THE TORNADO OVER THE WATER ON LAKE CHAUBUNAGUNGAMAUG, WHICH IS WHERE IT FINALLY DISSIPATED.
Aug 19, 10:21 AM EDT	WATERSPOUT	Webster, MA	WATER SPOUT ON WEBSTER LAKE

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

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 2.2 hours before the alert went out and 167 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: 1927 J/kg
Mixed-layer CIN: 0 J/kg
Mixed-layer LCL: 459 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 113 m²/s²
0-3 km storm-relative helicity: 137 m²/s²
Significant tornado parameter: 1.0
Supercell composite: 5.5

Open this sounding in Storm Lab

The text

As transmitted.

950 
WUUS51 KBOX 191414
SVRBOX
CTC015-MAC017-027-RIC007-191515-
/O.NEW.KBOX.SV.W.0103.210819T1414Z-210819T1515Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Boston/Norton MA
1014 AM EDT Thu Aug 19 2021

The National Weather Service in Boston/Norton has issued a

* Severe Thunderstorm Warning for...
  Northeastern Windham County in northern Connecticut...
  Southeastern Worcester County in central Massachusetts...
  South central Middlesex County in northeastern Massachusetts...
  Northwestern Providence County in Rhode Island...

* Until 1115 AM EDT.

* At 1014 AM EDT, a severe thunderstorm was located over Webster, or
  16 miles south of Worcester, 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...
  Worcester, Framingham, Marlborough, Shrewsbury, Natick, Milford,
  Hudson, Westborough, Grafton, Webster, Southbridge, Ashland,
  Auburn, Burrillville, Northbridge, Hopkinton, Northborough, Oxford,
  Clinton and Uxbridge.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4192 7184 4202 7204 4245 7168 4229 7139
TIME...MOT...LOC 1414Z 216DEG 20KT 4204 7188 

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

124 
WWUS51 KBOX 191458
SVSBOX

Severe Weather Statement
National Weather Service Boston/Norton MA
1058 AM EDT Thu Aug 19 2021

CTC015-MAC017-027-RIC007-191508-
/O.CAN.KBOX.SV.W.0103.000000T0000Z-210819T1515Z/
Windham CT-Worcester MA-Middlesex MA-Providence RI-
1058 AM EDT Thu Aug 19 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN WINDHAM...
SOUTHEASTERN WORCESTER...SOUTH CENTRAL MIDDLESEX AND NORTHWESTERN
PROVIDENCE COUNTIES IS CANCELLED...
        
The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning has
been cancelled.  However heavy rain is still possible with this
thunderstorm.

LAT...LON 4192 7184 4202 7204 4245 7168 4229 7139
TIME...MOT...LOC 1457Z 216DEG 20KT 4224 7168 

$$

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, 10:21 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, 11:36 AM EDT	Severe Thunderstorm Warning	BOX	Essex, Middlesex, Norfolk, Suffolk, Worcester	54 min
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
Aug 19, 7:32 AM EDT	Areal Flood Warning	BOX	Capitol Planning Region	5 hr
Aug 19, 10:01 AM EDT	Special Weather Statement	BOX	Providence	44 min

Nearby

Severe Thunderstorm Warnings in Massachusetts, 2021 Severe Thunderstorm Warnings in Connecticut, 2021 Severe Thunderstorm Warnings in Rhode Island, 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.