Alert archive / Massachusetts / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 75, NWS Boston/Norton, MA

July 17, 2021Bristol County, Norfolk County, Massachusetts; Providence County, Rhode Island

NWS Boston/Norton, MA issued this severe thunderstorm warning at Jul 17, 2021, 2:53 PM EDT for Bristol County, Norfolk County, Massachusetts; Providence County, Rhode Island. It was in force for 52 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: Jul 17, 2021, 2:53 PM EDT (18:53 UTC)
Expired: Jul 17, 2021, 3:45 PM EDT
In force: 52 min
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Tornado: Possible
Hail: 1.0 in
Wind: 60.0 mph

Counties Bristol County, MA, Norfolk County, MA, Providence County, RI

The radar

The Boston radar (KBOX), 24 km from the middle of the area, began a volume at 18:58 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
Jul 17, 3:06 PM EDT	HAIL 0.75	Cumberland, RI

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, 6.9 hours before the alert went out and 168 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: 1203 J/kg
Mixed-layer CIN: -55 J/kg
Mixed-layer LCL: 1054 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 35 m²/s²
0-3 km storm-relative helicity: 46 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 1.0

Open this sounding in Storm Lab

The text

As transmitted.

660 
WUUS51 KBOX 171853
SVRBOX
MAC005-021-RIC007-171945-
/O.NEW.KBOX.SV.W.0075.210717T1853Z-210717T1945Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Boston/Norton MA
253 PM EDT Sat Jul 17 2021

The National Weather Service in Boston/Norton has issued a

* Severe Thunderstorm Warning for...
  South central Norfolk County in eastern Massachusetts...
  Northwestern Bristol County in southeastern Massachusetts...
  Northeastern Providence County in Rhode Island...

* Until 345 PM EDT.

* At 252 PM EDT, a severe thunderstorm was located over Lincoln, or
  near Cumberland, and is nearly stationary.

  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...
  Pawtucket, East Providence, Cumberland, North Providence, North
  Attleborough, Attleboro, Mansfield, Smithfield, Lincoln, Central
  Falls, Foxborough, Seekonk, North Smithfield, Rehoboth and
  Plainville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4189 7153 4196 7152 4203 7126 4184 7127
TIME...MOT...LOC 1852Z 261DEG 3KT 4192 7145 

TORNADO...POSSIBLE
HAIL...1.00IN
WIND...60MPH
 
$$

Chai

2 follow-up statements

098 
WWUS51 KBOX 171932
SVSBOX

Severe Weather Statement
National Weather Service Boston/Norton MA
332 PM EDT Sat Jul 17 2021

MAC021-171939-
/O.CAN.KBOX.SV.W.0075.000000T0000Z-210717T1945Z/
Norfolk MA-
332 PM EDT Sat Jul 17 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTH CENTRAL NORFOLK COUNTY
IS CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

LAT...LON 4188 7148 4194 7147 4201 7126 4184 7127
TIME...MOT...LOC 1929Z 261DEG 3KT 4192 7141 

$$

MAC005-RIC007-171945-
/O.CON.KBOX.SV.W.0075.000000T0000Z-210717T1945Z/
Bristol MA-Providence RI-
332 PM EDT Sat Jul 17 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 345 PM EDT
FOR NORTHWESTERN BRISTOL AND EAST CENTRAL PROVIDENCE COUNTIES...

At 329 PM EDT, a severe thunderstorm was located over Lincoln, or
near Cumberland, and is nearly stationary.

HAZARD...60 mph wind gusts and penny size hail.

SOURCE...Radar indicated.

IMPACT...Expect damage to trees and power lines.

Locations impacted include...
Pawtucket, East Providence, Cumberland, North Providence, North
Attleborough, Attleboro, Mansfield, Smithfield, Lincoln, Central
Falls, Seekonk and Rehoboth.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4188 7148 4194 7147 4201 7126 4184 7127
TIME...MOT...LOC 1929Z 261DEG 3KT 4192 7141 

HAIL...0.75IN
WIND...60MPH
 
$$

Chai

970 
WWUS51 KBOX 171941
SVSBOX

Severe Weather Statement
National Weather Service Boston/Norton MA
341 PM EDT Sat Jul 17 2021

MAC005-RIC007-171951-
/O.EXP.KBOX.SV.W.0075.000000T0000Z-210717T1945Z/
Bristol MA-Providence RI-
341 PM EDT Sat Jul 17 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN BRISTOL AND EAST
CENTRAL PROVIDENCE COUNTIES WILL EXPIRE AT 345 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.  However heavy rain is still possible with this
thunderstorm.

LAT...LON 4188 7148 4194 7147 4201 7126 4184 7127
TIME...MOT...LOC 1941Z 261DEG 3KT 4192 7140 

$$

Chai

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 17, 2:37 PM EDT	Special Weather Statement	BOX	Franklin	38 min
Jul 17, 2:45 PM EDT	Special Weather Statement	BOX	Plymouth	45 min
Jul 17, 2:53 PM EDT	Special Weather Statement	BOX	Hampshire	52 min
Jul 17, 3:36 PM EDT	Areal Flood Warning	BOX	Bristol	114 min
Jul 17, 4:05 PM EDT	Severe Thunderstorm Warning	BOX	Worcester	34 min
Jul 17, 4:15 PM EDT	Severe Thunderstorm Warning	BOX	Hampden, Worcester	60 min
Jul 17, 4:34 PM EDT	Severe Thunderstorm Warning	BOX	Middlesex, Worcester	36 min
Jul 17, 4:38 PM EDT	Severe Thunderstorm Warning	BOX	Hampden, Hampshire	67 min
Jul 17, 4:48 PM EDT	Flash Flood Warning	BOX	Worcester	3 hr
Jul 17, 4:58 PM EDT	Flash Flood Warning	BOX	Hampden	2 hr
Jul 17, 5:10 PM EDT	Severe Thunderstorm Warning	BOX	Middlesex, Worcester	65 min
Jul 17, 5:34 PM EDT	Special Weather Statement	BOX	Hampshire	41 min
Jul 17, 5:35 PM EDT	Flash Flood Warning	BOX	Hampden, Hampshire	3 hr
Jul 17, 6:04 PM EDT	Flash Flood Warning	BOX	Hampden, Hampshire	3 hr
Jul 17, 6:05 PM EDT	Severe Thunderstorm Warning	BOX	Bristol	26 min
Jul 17, 7:49 PM EDT	Areal Flood Warning	BOX	Hampden, Worcester	116 min
Jul 17, 2:14 PM EDT	Special Weather Statement	BOX	Bristol	46 min
Jul 17, 2:39 PM EDT	Areal Flood Warning	BOX	Kent, Providence	111 min
Jul 17, 2:46 PM EDT	Special Weather Statement	BOX	Providence	44 min
Jul 17, 3:26 PM EDT	Severe Thunderstorm Warning	BOX	Providence	64 min
Jul 17, 4:06 PM EDT	Flash Flood Warning	BOX	Kent, Providence	4 hr
Jul 17, 4:29 PM EDT	Severe Thunderstorm Warning	BOX	Kent, Providence	61 min
Jul 17, 5:30 PM EDT	Flash Flood Warning	BOX	Providence	3 hr
Jul 17, 5:49 PM EDT	Special Weather Statement	BOX	Bristol	41 min

Nearby

Severe Thunderstorm Warnings in Massachusetts, 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.