Alert archive / Massachusetts / Tornado Warnings in 2021

Tornado Warning 2, NWS Boston/Norton, MA

August 19, 2021Middlesex County, Worcester County, Massachusetts

NWS Boston/Norton, MA issued this tornado warning at Aug 19, 2021, 10:21 AM EDT for Middlesex County, Worcester County, Massachusetts. It was in force for 29 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, 10:21 AM EDT (14:21 UTC)
Expired: Aug 19, 2021, 10:50 AM EDT
In force: 29 min
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 1.0 in

Counties Middlesex County, MA, Worcester County, MA

The radar

The Boston radar (KBOX), 52 km from the middle of the area, began a volume at 14:25 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, 10:21 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, 2.4 hours before the alert went out and 170 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.

942 
WFUS51 KBOX 191421
TORBOX
MAC017-027-191515-
/O.NEW.KBOX.TO.W.0002.210819T1421Z-210819T1515Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Boston/Norton MA
1021 AM EDT Thu Aug 19 2021

The National Weather Service in Boston/Norton has issued a

* Tornado Warning for...
  Southeastern Worcester County in central Massachusetts...
  Southwestern Middlesex County in northeastern Massachusetts...

* Until 1115 AM EDT.
    
* At 1021 AM EDT, a severe thunderstorm capable of producing a
  tornado was located over Webster, or 13 miles south of Worcester,
  moving northeast at 25 mph.

  HAZARD...Tornado and quarter size hail.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely.

* This dangerous storm will be near...
  Douglas around 1030 AM EDT.
  Oxford around 1035 AM EDT.
  Auburn and Sutton around 1045 AM EDT.
  Northbridge and Millbury around 1050 AM EDT.
  Worcester and Grafton around 1100 AM EDT.
  Upton around 1105 AM EDT.
  Shrewsbury around 1110 AM EDT.
  Westborough, Hopkinton, Northborough and Boylston around 1115 AM 
  EDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4223 7147 4201 7173 4201 7180 4202 7180
      4203 7203 4236 7175
TIME...MOT...LOC 1421Z 216DEG 20KT 4207 7185 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...1.00 IN

$$

Chai

1 follow-up statement

233 
WWUS51 KBOX 191450
SVSBOX

Severe Weather Statement
National Weather Service Boston/Norton MA
1050 AM EDT Thu Aug 19 2021

MAC017-027-191459-
/O.CAN.KBOX.TO.W.0002.000000T0000Z-210819T1515Z/
Worcester MA-Middlesex MA-
1050 AM EDT Thu Aug 19 2021

...THE TORNADO WARNING FOR SOUTHEASTERN WORCESTER AND SOUTHWESTERN
MIDDLESEX COUNTIES IS CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer appears capable of producing a tornado.
Therefore, the warning has been cancelled.  However gusty winds and
heavy rain are still possible with this thunderstorm.

Remember, a Severe Thunderstorm Warning still remains in effect. 

LAT...LON 4223 7147 4201 7173 4201 7180 4202 7180
      4203 7203 4236 7175
TIME...MOT...LOC 1448Z 216DEG 20KT 4220 7172 

$$

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, 10:46 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

Nearby

Tornado Warnings in Massachusetts, 2021 Every tornado warning in 2021 Tornadoes 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.