Alert archive / Massachusetts / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 109, NWS Boston/Norton, MA

September 1, 2021Nantucket County, Massachusetts

NWS Boston/Norton, MA issued this severe thunderstorm warning at Sep 1, 2021, 4:52 PM EDT for Nantucket County, Massachusetts. It was in force for 38 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 1, 2021, 4:52 PM EDT (20:52 UTC)
Expired: Sep 1, 2021, 5:30 PM EDT
In force: 38 min
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Tornado: Possible
Hail: 0.75 in
Wind: 60.0 mph

County Nantucket County, MA

The radar

The Boston radar (KBOX), 115 km from the middle of the area, began a volume at 20:55 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 12:00Z, 8.9 hours before the alert went out and 239 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: 51 J/kg
Mixed-layer CIN: -80 J/kg
Mixed-layer LCL: 1274 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 31 m²/s²
0-3 km storm-relative helicity: 201 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted.

540 
WUUS51 KBOX 012052
SVRBOX
MAC019-012130-
/O.NEW.KBOX.SV.W.0109.210901T2052Z-210901T2130Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Boston/Norton MA
452 PM EDT Wed Sep 1 2021

The National Weather Service in Boston/Norton has issued a

* Severe Thunderstorm Warning for...
  Nantucket County in southeastern Massachusetts...

* Until 530 PM EDT.

* At 449 PM EDT, a severe thunderstorm was located 22 miles south of
  Edgartown, moving northeast at 65 mph.

  HAZARD...60 mph wind gusts. While not imminent, a brief tornado is 
           possible.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Nantucket.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Boaters and mariners should get away from the water and move indoors 
or inside a vehicle. Remember, lightning can strike out to 15 miles 
from the parent thunderstorm. If you can hear thunder, you are close 
enough to be struck by lightning. Move to safe shelter now!  Do not 
be caught on the water in a thunderstorm.

&&

LAT...LON 4124 7000 4124 7012 4128 7023 4128 7020
      4130 7019 4130 7010 4128 7009 4129 7007
      4130 7009 4130 7007 4132 7000 4135 7002
      4133 7004 4139 7004 4128 6996 4126 6996
TIME...MOT...LOC 2049Z 233DEG 55KT 4105 7044 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Loconto

1 follow-up statement

543 
WWUS51 KBOX 012121
SVSBOX

Severe Weather Statement
National Weather Service Boston/Norton MA
521 PM EDT Wed Sep 1 2021

MAC019-012130-
/O.CON.KBOX.SV.W.0109.000000T0000Z-210901T2130Z/
Nantucket MA-
521 PM EDT Wed Sep 1 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 PM EDT
FOR SOUTHEASTERN NANTUCKET COUNTY...

At 520 PM EDT, a severe thunderstorm was located 13 miles south of
Nantucket, moving northeast at 30 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
Nantucket.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Boaters and mariners should get away from the water and move indoors 
or inside a vehicle. Remember, lightning can strike out to 15 miles 
from the parent thunderstorm. If you can hear thunder, you are close 
enough to be struck by lightning. Move to safe shelter now!  Do not 
be caught on the water in a thunderstorm.

&&

LAT...LON 4124 7000 4124 7010 4126 7009 4127 7008
      4129 7004 4131 6998 4128 6996 4126 6996
TIME...MOT...LOC 2120Z 240DEG 28KT 4111 7020 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Loconto

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 1, 3:26 AM EDT	Gale Watch	BOX		31 hr
Sep 1, 3:26 AM EDT	Gale Warning	BOX		35 hr
Sep 1, 2:34 PM EDT	Special Marine Warning	BOX		56 min
Sep 1, 3:29 PM EDT	Special Marine Warning	BOX		61 min
Sep 1, 4:00 PM EDT	Wind Advisory	BOX	Barnstable, Essex, Norfolk, Plymouth, Suffolk	19 hr
Sep 1, 4:13 PM EDT	Special Marine Warning	BOX		62 min
Sep 1, 5:10 PM EDT	Special Marine Warning	BOX		65 min
Sep 1, 5:49 PM EDT	Special Weather Statement	BOX	Nantucket	41 min
Sep 1, 6:09 PM EDT	Special Marine Warning	BOX		66 min

Nearby

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