Alert archive / Massachusetts / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 115, NWS Boston/Norton, MA

September 16, 2021Barnstable County, Dukes County, Massachusetts

NWS Boston/Norton, MA issued this severe thunderstorm warning at Sep 16, 2021, 7:36 AM EDT for Barnstable County, Dukes County, Massachusetts. It was in force for 54 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
Sep 16, 2021, 7:36 AM EDT (11:36 UTC)
Expired
Sep 16, 2021, 8:30 AM EDT
In force
54 min
Issued by
NWS Boston/Norton, MA
Area
Storm-based polygon
Tornado
Possible
Hail
0.75 in
Wind
60.0 mph

Counties Barnstable County, MA, Dukes County, MA

The radar

The Boston radar (KBOX), 69 km from the middle of the area, began a volume at 11:36 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 nearest sounding before it

Brookhaven, NY (KOKX), launched 00:00Z, 11.6 hours before the alert went out and 191 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-pSkew-T log-p diagram, Brookhaven, NY at 00:00Z on 2021-09-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 664 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Brookhaven, NY at 00:00Z on 2021-09-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 172 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
664 J/kg
Mixed-layer CIN
-93 J/kg
Mixed-layer LCL
1000 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
172 m²/s²
0-3 km storm-relative helicity
188 m²/s²
Significant tornado parameter
0.3
Supercell composite
3.4

Open this sounding in Storm Lab

The text

As transmitted.

705 
WUUS51 KBOX 161136
SVRBOX
MAC001-007-161230-
/O.NEW.KBOX.SV.W.0115.210916T1136Z-210916T1230Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Boston/Norton MA
736 AM EDT Thu Sep 16 2021

The National Weather Service in Boston/Norton has issued a

* Severe Thunderstorm Warning for...
  Dukes County in southeastern Massachusetts...
  Southwestern Barnstable County in southeastern Massachusetts...

* Until 830 AM EDT.

* At 736 AM EDT, a severe thunderstorm was located 10 miles west of
  Aquinnah, moving northeast at 20 mph.

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

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Falmouth, Oak Bluffs, Edgartown, Tisbury, Aquinnah, West Tisbury,
  Chilmark and Gosnold.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Large hail and damaging winds and continuous cloud to ground
lightning is occurring with this storm. Move indoors immediately.
Lightning is one of nature's leading killers. Remember, if you can
hear thunder, you are close enough to be struck by lightning.

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

&&

LAT...LON 4125 7081 4132 7077 4142 7090 4145 7086
      4138 7084 4135 7077 4143 7070 4147 7076
      4145 7084 4152 7070 4146 7063 4153 7069
      4159 7060 4155 7057 4152 7066 4148 7062
      4147 7057 4141 7056 4135 7045 4134 7073
TIME...MOT...LOC 1136Z 243DEG 19KT 4129 7101 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Loconto
1 follow-up statement
799 
WWUS51 KBOX 161221
SVSBOX

Severe Weather Statement
National Weather Service Boston/Norton MA
821 AM EDT Thu Sep 16 2021

MAC001-007-161230-
/O.EXP.KBOX.SV.W.0115.000000T0000Z-210916T1230Z/
Dukes MA-Barnstable MA-
821 AM EDT Thu Sep 16 2021

...THE SEVERE THUNDERSTORM WARNING FOR DUKES AND SOUTHWESTERN
BARNSTABLE COUNTIES WILL EXPIRE AT 830 AM EDT...
        
The storm which prompted the warning has moved out of the area.
Therefore, the warning will be allowed to expire.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
Boston/Norton.

LAT...LON 4125 7081 4132 7077 4142 7090 4145 7086
      4138 7084 4135 7077 4143 7070 4147 7076
      4145 7084 4152 7070 4146 7063 4153 7069
      4159 7060 4155 7057 4152 7066 4148 7062
      4147 7057 4141 7056 4135 7045 4134 7073
TIME...MOT...LOC 1220Z 243DEG 19KT 4140 7073 

$$

Frank

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 16, 5:43 AM EDTSpecial Marine WarningBOX62 min
Sep 16, 6:10 AM EDTSpecial Weather StatementBOXEssex, Norfolk65 min
Sep 16, 6:13 AM EDTSpecial Weather StatementBOXNorfolk62 min
Sep 16, 6:24 AM EDTSpecial Weather StatementBOXBristol66 min
Sep 16, 6:38 AM EDTSevere Thunderstorm WarningBOXBristol, Plymouth53 min
Sep 16, 6:42 AM EDTSpecial Marine WarningBOX63 min
Sep 16, 7:00 AM EDTSpecial Marine WarningBOX60 min
Sep 16, 7:13 AM EDTSevere Thunderstorm WarningBOXBarnstable, Bristol, Dukes, Plymouth62 min
Sep 16, 7:25 AM EDTSpecial Marine WarningBOX65 min
Sep 16, 7:27 AM EDTSpecial Marine WarningBOX63 min
Sep 16, 7:51 AM EDTSpecial Marine WarningBOX54 min
Sep 16, 7:59 AM EDTSpecial Weather StatementBOXBarnstable, Dukes61 min
Sep 16, 8:15 AM EDTSpecial Marine WarningBOX90 min
Sep 16, 8:37 AM EDTSpecial Marine WarningBOX40 min
Sep 16, 9:31 AM EDTSpecial Marine WarningBOX59 min
Sep 16, 3:18 PM EDTSmall Craft AdvisoryBOX3 days

Nearby

Severe Thunderstorm Warnings in Massachusetts, 2021Every 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.