Alert archive / Massachusetts / Tornado Warnings in 2021

Tornado Warning 4, NWS Boston/Norton, MA

August 19, 2021Middlesex County, Worcester County, Massachusetts

NWS Boston/Norton, MA issued this tornado warning at Aug 19, 2021, 1:18 PM EDT for Middlesex County, Worcester County, Massachusetts. It was in force for 27 min. 6 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, 1:18 PM EDT (17:18 UTC)
Expired: Aug 19, 2021, 1:45 PM EDT
In force: 27 min
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

Counties Middlesex County, MA, Worcester County, MA

The radar

The Boston radar (KBOX), 67 km from the middle of the area, began a volume at 17:18 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, 1:30 PM EDT	TSTM WND DMG	1 E Clinton, MA	TREE AND WIRES DOWNED ON BEECH ST IN CLINTON. RELAYED BY AMATEUR RADIO
Aug 19, 1:30 PM EDT	TSTM WND DMG	1 Ene Clinton, MA	POWERLINE WIRES DOWNED ON CENTENNIAL ST IN CLINTON. RELAYED BY AMATEUR RADIO
Aug 19, 1:30 PM EDT	TSTM WND DMG	Clinton, MA	TREE DOWN ON CEDAR ST. RELAYED BY AMATEUR RADIO
Aug 19, 1:30 PM EDT	TORNADO	Clinton, MA	A NWS SURVEY CONFIRMED AN EFO TORNADO IN CLINTON, MA. MAXIMUM WINDS WERE ESTIMATED AT 80 MPH. THE PATH WIDTH WAS 35 YARDS AND THE PATH LENGTH WAS 0.5 MILES. IT BEGAN NEAR CEDAR AND CHURCH STREETS, TRAVELED NORTHEAST, AND ENDED NEAR WATER STREET AT BEECH STREET
Aug 19, 1:35 PM EDT	TSTM WND DMG	Harvard, MA	MULTIPLE TREE DOWN ON HOUGTON LANE
Aug 19, 1:40 PM EDT	TSTM WND DMG	2 N Harvard, MA	LARGE TREE DOWNED ON HOUGHTON LANE IN HARVARD. 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

Albany, NY (KALY), launched 12:00Z, 5.3 hours before the alert went out and 182 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: 5 J/kg
Mixed-layer CIN: -104 J/kg
Mixed-layer LCL: 523 m above ground
0-6 km bulk shear: 11 kt
0-1 km storm-relative helicity: 194 m²/s²
0-3 km storm-relative helicity: 350 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

As transmitted.

335 
WFUS51 KBOX 191718
TORBOX
MAC017-027-191745-
/O.NEW.KBOX.TO.W.0004.210819T1718Z-210819T1745Z/

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

The National Weather Service in Boston/Norton has issued a

* Tornado Warning for...
  East central Worcester County in central Massachusetts...
  Central Middlesex County in northeastern Massachusetts...

* Until 145 PM EDT.
    
* At 118 PM EDT, a severe thunderstorm capable of producing a tornado
  was located over Clinton, or 8 miles northwest of Marlborough,
  moving northeast at 20 mph.

  HAZARD...Tornado.

  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...
  Bolton around 130 PM EDT.
  Hudson and Lancaster around 135 PM EDT.
  Stow around 140 PM EDT.
  Acton, Maynard, Littleton, Ayer, Harvard and Boxborough around 145 
  PM 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 4237 7169 4243 7176 4258 7157 4245 7143
TIME...MOT...LOC 1718Z 231DEG 19KT 4241 7168 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...<.75 IN

$$

Chai

2 follow-up statements

431 
WWUS51 KBOX 191734
SVSBOX

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

MAC017-027-191745-
/O.CON.KBOX.TO.W.0004.000000T0000Z-210819T1745Z/
Worcester MA-Middlesex MA-
134 PM EDT Thu Aug 19 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 145 PM EDT FOR EAST
CENTRAL WORCESTER AND WESTERN MIDDLESEX COUNTIES...
    
At 132 PM EDT, a severe thunderstorm capable of producing a tornado
was located over Bolton, or 7 miles north of Marlborough, moving
northeast at 20 mph.

HAZARD...Tornado.

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...
  Ayer around 145 PM EDT.
  Boxborough around 150 PM EDT.
  Acton and Littleton around 200 PM 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 4243 7162 4246 7167 4258 7157 4249 7147
TIME...MOT...LOC 1732Z 231DEG 19KT 4246 7160 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...<.75 IN

$$

Chai

433 
WWUS51 KBOX 191743
SVSBOX

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

MAC017-027-191753-
/O.EXP.KBOX.TO.W.0004.000000T0000Z-210819T1745Z/
Worcester MA-Middlesex MA-
143 PM EDT Thu Aug 19 2021

...THE TORNADO WARNING FOR EAST CENTRAL WORCESTER AND WESTERN
MIDDLESEX COUNTIES WILL EXPIRE AT 145 PM EDT...
        
The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning will
be allowed to expire.

LAT...LON 4243 7162 4246 7167 4258 7157 4249 7147
TIME...MOT...LOC 1743Z 231DEG 19KT 4249 7154 

$$

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, 11:36 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, 1:37 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.