Alert archive / Massachusetts / Tornado Warnings in 2020

Tornado Warning 7, NWS Boston/Norton, MA

August 4, 2020Middlesex County, Worcester County, Massachusetts

NWS Boston/Norton, MA issued this tornado warning at Aug 4, 2020, 4:58 PM EDT for Middlesex County, Worcester County, Massachusetts. It was in force for 21 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 4, 2020, 4:58 PM EDT (20:58 UTC)
Expired: Aug 4, 2020, 5:19 PM EDT
In force: 21 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), 83 km from the middle of the area, began a volume at 21:02 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.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Aug 4, 12:43 PM EDT	Tornado Watch	SPC	6 hr

The nearest sounding before it

Chatham, MA (KCHH), launched 12:00Z, 9.0 hours before the alert went out and 172 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: 652 J/kg
Mixed-layer CIN: -50 J/kg
Mixed-layer LCL: 786 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 47 m²/s²
0-3 km storm-relative helicity: 128 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.8

Open this sounding in Storm Lab

The text

As transmitted.

872 
WFUS51 KBOX 042058
TORBOX
MAC017-027-042145-
/O.NEW.KBOX.TO.W.0007.200804T2058Z-200804T2145Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Boston/Norton MA
458 PM EDT Tue Aug 4 2020

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 545 PM EDT.
    
* At 458 PM EDT, a severe thunderstorm capable of producing a tornado
  was located over Lancaster, or near Leominster, moving north at 55
  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...
  Fitchburg around 505 PM EDT.
  Groton, Lunenburg, Townsend and Shirley around 510 PM EDT.
  Pepperell and Ashby around 515 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 4271 7158 4270 7152 4240 7150 4239 7176
      4271 7182
TIME...MOT...LOC 2058Z 174DEG 49KT 4248 7164 

TORNADO...RADAR INDICATED
HAIL...0.00IN

$$

Frank

2 follow-up statements

123 
WWUS51 KBOX 042108
SVSBOX

Severe Weather Statement
National Weather Service Boston/Norton MA
508 PM EDT Tue Aug 4 2020

MAC017-027-042145-
/O.CON.KBOX.TO.W.0007.000000T0000Z-200804T2145Z/
Worcester MA-Middlesex MA-
508 PM EDT Tue Aug 4 2020

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 545 PM EDT FOR
NORTHEASTERN WORCESTER AND NORTHWESTERN MIDDLESEX COUNTIES...
    
At 507 PM EDT, a severe thunderstorm capable of producing a tornado
was located over Shirley, or 8 miles east of Fitchburg, moving north
at 55 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 tornadic thunderstorm will remain over mainly rural areas of
NORTHEASTERN WORCESTER AND NORTHWESTERN MIDDLESEX COUNTIES.

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 4271 7158 4270 7152 4240 7150 4239 7169
      4271 7182
TIME...MOT...LOC 2107Z 174DEG 49KT 4261 7166 

TORNADO...RADAR INDICATED
HAIL...0.00IN

$$

Frank

533 
WWUS51 KBOX 042119
SVSBOX

Severe Weather Statement
National Weather Service Boston/Norton MA
519 PM EDT Tue Aug 4 2020

MAC017-027-042128-
/O.CAN.KBOX.TO.W.0007.000000T0000Z-200804T2145Z/
Worcester MA-Middlesex MA-
519 PM EDT Tue Aug 4 2020

...THE TORNADO WARNING FOR NORTHEASTERN WORCESTER AND NORTHWESTERN
MIDDLESEX COUNTIES IS CANCELLED...
        
The storm which prompted the warning has moved out of the area.
Therefore, the warning has been cancelled.

A Tornado Watch remains in effect until 900 PM EDT for central and
northeastern Massachusetts.

LAT...LON 4271 7158 4270 7152 4240 7150 4239 7169
      4271 7182
TIME...MOT...LOC 2118Z 174DEG 49KT 4277 7168 

$$

Frank

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 4, 3:24 AM EDT	Coastal Flood Advisory	BOX	Bristol, Plymouth	17 hr
Aug 4, 8:37 AM EDT	Special Weather Statement	BOX	Berkshire	23 min
Aug 4, 8:45 AM EDT	Tornado Warning	BOX	Franklin, Hampshire	45 min
Aug 4, 9:27 AM EDT	Severe Thunderstorm Warning	BOX	Franklin	15 min
Aug 4, 9:30 AM EDT	Tornado Warning	BOX	Franklin	13 min
Aug 4, 1:57 PM EDT	Tornado Warning	BOX	Middlesex, Worcester	25 min
Aug 4, 3:07 PM EDT	Special Marine Warning	BOX		38 min
Aug 4, 3:44 PM EDT	Special Marine Warning	BOX		91 min
Aug 4, 4:14 PM EDT	Special Marine Warning	BOX		31 min
Aug 4, 5:10 PM EDT	Special Marine Warning	BOX		50 min

Nearby

Tornado Warnings in Massachusetts, 2020 Every tornado warning in 2020 Tornadoes in 2020

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.