Alert archive / New Hampshire / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 92, NWS Gray, ME

September 15, 20214 counties in New Hampshire

NWS Gray, ME issued this severe thunderstorm warning at Sep 15, 2021, 4:07 PM EDT for 4 counties in New Hampshire. It was in force for 38 min. 5 reports 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: Sep 15, 2021, 4:07 PM EDT (20:07 UTC)
Expired: Sep 15, 2021, 4:45 PM EDT
In force: 38 min
Issued by: NWS Gray, ME
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Cheshire County, NH, Hillsborough County, NH, Merrimack County, NH, Sullivan County, NH

The radar

The Portland,ME radar (KGYX), 154 km from the middle of the area, began a volume at 20:11 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
Sep 15, 4:08 PM EDT	TSTM WND DMG	Unity, NH	TREES DOWN ACROSS UNITY. TIME ESTIMATED BASED ON RADAR.
Sep 15, 4:10 PM EDT	TSTM WND DMG	Walpole, NH	NUMEROUS TREES DOWN NORTH OF WALPOLE. PENNY SIZE HAIL ALSO REPORTED.
Sep 15, 4:15 PM EDT	TSTM WND DMG	2 Wsw Sullivan, NH	TREES AND WIRES DOWN ON NH 10. DELAYED REPORT. TIME ESTIMATED FROM RADAR.
Sep 15, 4:20 PM EDT	HAIL 1.25	Washington, NH
Sep 15, 4:30 PM EDT	HAIL 1	2 Ssw Bradford, NH

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

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

Issued	Product	Office	Lasted
Sep 15, 1:15 PM EDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Gray, ME (KGYX), launched 12:00Z, 8.1 hours before the alert went out and 154 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: 101 J/kg
Mixed-layer CIN: -167 J/kg
Mixed-layer LCL: 468 m above ground
0-6 km bulk shear: 54 kt
0-1 km storm-relative helicity: 299 m²/s²
0-3 km storm-relative helicity: 318 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

As transmitted.

450 
WUUS51 KGYX 152007
SVRGYX
NHC005-011-013-019-152045-
/O.NEW.KGYX.SV.W.0092.210915T2007Z-210915T2045Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Gray ME
407 PM EDT Wed Sep 15 2021

The National Weather Service in Gray Maine has issued a

* Severe Thunderstorm Warning for...
  Southern Sullivan County in central New Hampshire...
  Northern Cheshire County in southern New Hampshire...
  Northwestern Hillsborough County in southern New Hampshire...
  Western Merrimack County in central New Hampshire...

* Until 445 PM EDT.

* At 407 PM EDT, a severe thunderstorm was located 7 miles north of
  Marlow, or 11 miles southeast of Claremont, moving east at 40 mph.

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

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* Locations impacted include...
  Concord, Claremont, Franklin, Henniker, New London, Hopkinton, New
  Boston, Antrim, Canterbury, Greenfield, Hancock, Bradford,
  Francestown, Bennington, Danbury, Nelson, Walpole, Alstead, Marlow
  and Sullivan.

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 4320 7234 4345 7234 4350 7167 4349 7164
      4344 7161 4345 7156 4329 7159 4298 7172
      4300 7244 4305 7247
TIME...MOT...LOC 2007Z 259DEG 36KT 4323 7223 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

MEC

1 follow-up statement

958 
WWUS51 KGYX 152024
SVSGYX

Severe Weather Statement
National Weather Service Gray ME
424 PM EDT Wed Sep 15 2021

NHC005-011-013-019-152045-
/O.CON.KGYX.SV.W.0092.000000T0000Z-210915T2045Z/
Sullivan NH-Cheshire NH-Hillsborough NH-Merrimack NH-
424 PM EDT Wed Sep 15 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 445 PM EDT
FOR SOUTHEASTERN SULLIVAN...NORTHEASTERN CHESHIRE...NORTHWESTERN
HILLSBOROUGH AND WESTERN MERRIMACK COUNTIES...

At 424 PM EDT, a severe thunderstorm was located over Bradford, or 10
miles south of New London, moving east at 40 mph.

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

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Concord, Franklin, Henniker, New London, Hopkinton, New Boston,
Antrim, Canterbury, Greenfield, Hancock, Bradford, Francestown,
Bennington, Danbury, Nelson, Gilsum, Windsor, Deering, Warner and
Hillsborough.

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 4323 7216 4347 7209 4350 7167 4349 7164
      4344 7161 4345 7156 4329 7159 4298 7172
      4300 7239
TIME...MOT...LOC 2024Z 259DEG 36KT 4326 7200 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

MEC

The office that day

Everything else NWS Gray, ME issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 15, 7:50 AM EDT	Special Weather Statement	GYX	Coos	55 min
Sep 15, 2:18 PM EDT	Severe Thunderstorm Warning	GYX	Coos, Grafton	57 min
Sep 15, 2:31 PM EDT	Severe Thunderstorm Warning	GYX	Belknap, Carroll, Coos, Grafton, Merrimack, Sullivan	59 min
Sep 15, 2:33 PM EDT	Severe Thunderstorm Warning	GYX	Coos	42 min
Sep 15, 3:04 PM EDT	Severe Thunderstorm Warning	GYX	Belknap, Grafton, Merrimack, Sullivan	56 min
Sep 15, 3:22 PM EDT	Severe Thunderstorm Warning	GYX	Belknap, Carroll, Coos, Grafton, Merrimack, Sullivan	53 min
Sep 15, 4:09 PM EDT	Severe Thunderstorm Warning	GYX	Belknap, Carroll, Coos, Grafton, Merrimack	51 min
Sep 15, 4:44 PM EDT	Severe Thunderstorm Warning	GYX	Belknap, Carroll, Merrimack, Strafford	46 min
Sep 15, 5:09 PM EDT	Severe Thunderstorm Warning	GYX	Cheshire, Hillsborough, Merrimack	51 min
Sep 15, 5:29 PM EDT	Severe Thunderstorm Warning	GYX	Carroll, Strafford	61 min

Nearby

Severe Thunderstorm Warnings in New Hampshire, 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.