Alert archive / Massachusetts / Tornado Warnings in 2021

Tornado Warning 7, NWS Boston/Norton, MA

August 23, 2021Middlesex County, Worcester County, Massachusetts

NWS Boston/Norton, MA issued this tornado warning at Aug 23, 2021, 1:35 PM EDT for Middlesex County, Worcester County, Massachusetts. It was in force for 40 min. 1 report 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 23, 2021, 1:35 PM EDT (17:35 UTC)
Expired: Aug 23, 2021, 2:15 PM EDT
In force: 40 min
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.0 in

Counties Middlesex County, MA, Worcester County, MA

The radar

The Boston radar (KBOX), 81 km from the middle of the area, began a volume at 17:39 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 23, 1:35 PM EDT	FUNNEL CLOUD	Boxborough, MA	SPOTTER REPORTED A ROTATING FUNNEL CLOUD LOWERING AT THE TIME OF THE REPORT.

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, 5.6 hours before the alert went out and 176 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: -7 J/kg
Mixed-layer LCL: 497 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: 57 m²/s²
0-3 km storm-relative helicity: 77 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

415 
WFUS51 KBOX 231735
TORBOX
MAC017-027-231815-
/O.NEW.KBOX.TO.W.0007.210823T1735Z-210823T1815Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Boston/Norton MA
135 PM EDT Mon Aug 23 2021

The National Weather Service in Boston/Norton has issued a

* Tornado Warning for...
  Northeastern Worcester County in central Massachusetts...
  Northwestern Middlesex County in northeastern Massachusetts...

* Until 215 PM EDT.

* At 134 PM EDT, a storm capable of producing a tornado was located 
  over Littleton, or 9 miles southwest of Chelmsford, moving north 
  at 20 mph.

  HAZARD...Tornado.

  SOURCE...Weather spotters reported funnel cloud in West Acton.

  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.

* Locations impacted include...
  Fitchburg, Westford, Pepperell, Tyngsborough, Groton, Lunenburg,
  Townsend, Littleton, Ayer, Shirley, Harvard, Ashburnham,
  Boxborough, Dunstable and Ashby.

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 or in
a vehicle, move to the closest substantial shelter and protect
yourself from flying debris.

Motorists should not take shelter under highway overpasses. If you
cannot safely drive away from the tornado, as a last resort, either
park your vehicle and stay put, or abandon your vehicle and lie down
in a low lying area and protect yourself from flying debris.

&&

LAT...LON 4270 7142 4251 7146 4248 7153 4271 7192
TIME...MOT...LOC 1734Z 166DEG 19KT 4253 7152 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...0.00 IN

$$

Gaucher

2 follow-up statements

444 
WWUS51 KBOX 231755
SVSBOX

Severe Weather Statement
National Weather Service Boston/Norton MA
155 PM EDT Mon Aug 23 2021

MAC017-027-231815-
/O.CON.KBOX.TO.W.0007.000000T0000Z-210823T1815Z/
Worcester MA-Middlesex MA-
155 PM EDT Mon Aug 23 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 215 PM EDT FOR
NORTHEASTERN WORCESTER AND NORTHWESTERN MIDDLESEX COUNTIES...
    
At 155 PM EDT, a storm capable of producing a brief and weak tornado 
was located over Ayer, or 9 miles west of Chelmsford, moving 
northwest 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.

Locations impacted include...
Pepperell, Tyngsborough, Groton, Lunenburg, Townsend, Ayer, Shirley,
Harvard, Dunstable and Ashby.

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 or in
a vehicle, move to the closest substantial shelter and protect
yourself from flying debris.

Motorists should not take shelter under highway overpasses. If you
cannot safely drive away from the tornado, as a last resort, either
park your vehicle and stay put, or abandon your vehicle and lie down
in a low lying area and protect yourself from flying debris.

&&

LAT...LON 4253 7156 4271 7186 4270 7145 4260 7150
TIME...MOT...LOC 1754Z 156DEG 17KT 4259 7156 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...0.00 IN

$$

Gaucher

416 
WWUS51 KBOX 231810
SVSBOX

Severe Weather Statement
National Weather Service Boston/Norton MA
210 PM EDT Mon Aug 23 2021

MAC017-027-231820-
/O.EXP.KBOX.TO.W.0007.000000T0000Z-210823T1815Z/
Worcester MA-Middlesex MA-
210 PM EDT Mon Aug 23 2021

...THE TORNADO WARNING FOR NORTHEASTERN WORCESTER AND NORTHWESTERN
MIDDLESEX COUNTIES WILL EXPIRE AT 215 PM EDT...
                
The storm which prompted the warning has weakened, and no longer 
appears capable of producing a tornado. Therefore, the warning will 
be allowed to expire.

LAT...LON 4253 7156 4271 7186 4270 7145 4260 7150
TIME...MOT...LOC 1810Z 166DEG 25KT 4266 7157 

$$

Gaucher

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 23, 11:30 AM EDT	Special Weather Statement	BOX	Middlesex	45 min
Aug 23, 11:45 AM EDT	Tornado Warning	BOX	Middlesex, Worcester	45 min
Aug 23, 12:26 PM EDT	Tornado Warning	BOX	Middlesex, Worcester	43 min
Aug 23, 4:15 PM EDT	Special Weather Statement	BOX	Middlesex	45 min
Aug 23, 5:19 PM EDT	Special Weather Statement	BOX	Middlesex	41 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.