Alert archive / New Hampshire / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 49, NWS Gray, ME

July 20, 20214 counties in New Hampshire

NWS Gray, ME issued this severe thunderstorm warning at Jul 20, 2021, 9:35 PM EDT for 4 counties in New Hampshire. It was in force for 40 min. 6 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: Jul 20, 2021, 9:35 PM EDT (01:35 UTC)
Expired: Jul 20, 2021, 10:15 PM EDT
In force: 40 min
Issued by: NWS Gray, ME
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Belknap County, NH, Grafton County, NH, Merrimack County, NH, Sullivan County, NH

The radar

The Portland,ME radar (KGYX), 123 km from the middle of the area, began a volume at 01:37 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 20, 9:35 PM EDT	TSTM WND DMG	Orange, NH	TREES DOWN.
Jul 20, 10:00 PM EDT	HAIL 1	2 Nw Hebron, NH
Jul 20, 10:10 PM EDT	TSTM WND DMG	1 Ne New Hampton, NH	TREES DOWN ALL ACROSS TOWN. UNCONFIRMED POWER OUTAGES VIA SOCIAL MEDIA. TIME ESTIMATED BY RADAR.
Jul 20, 10:10 PM EDT	TSTM WND GST 65	Bristol, NH
Jul 20, 10:10 PM EDT	HAIL 1.25	Bristol, NH	QUARTER SIZE HAIL FOR 3 TO 5 MINUTES WITH LARGEST STONES TO 1.25 INCHES.
Jul 20, 10:15 PM EDT	TSTM WND DMG	4 Wnw Hill, NH	TREES AND WIRES DOWN.

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

The nearest sounding before it

Gray, ME (KGYX), launched 00:00Z, 1.6 hours before the alert went out and 122 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: 66 J/kg
Mixed-layer CIN: -39 J/kg
Mixed-layer LCL: 1282 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: -22 m²/s²
0-3 km storm-relative helicity: 35 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -1.1

Open this sounding in Storm Lab

The text

As transmitted.

814 
WUUS51 KGYX 210135
SVRGYX
NHC001-009-013-019-210215-
/O.NEW.KGYX.SV.W.0049.210721T0135Z-210721T0215Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Gray ME
935 PM EDT Tue Jul 20 2021

The National Weather Service in Gray Maine has issued a

* Severe Thunderstorm Warning for...
  Northeastern Sullivan County in central New Hampshire...
  Southeastern Grafton County in northern New Hampshire...
  Northwestern Belknap County in central New Hampshire...
  Northwestern Merrimack County in central New Hampshire...

* Until 1015 PM EDT.

* At 935 PM EDT, severe thunderstorms were located along a line
  extending from 8 miles southeast of Piermont to near Groton to 6
  miles south of Enfield, moving east at 30 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...
  Franklin, Plymouth, Meredith, Moultonborough, Grafton, Enfield,
  Canaan, Holderness, Ashland, Danbury, Groton, Woodstock, Piermont,
  Sandwich, Bristol, Grantham, Center Harber, Hill, Croydon and
  Hebron.

This includes the following highways...
 Interstate 89 between mile markers 41 and 47.
 Interstate 93 between mile markers 66 and 96.

This also includes...
  Rumney Rocks, Squam Lake, Carr Mountain, Stinson Mountain, and
Mount Tecumseh.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 4348 7222 4374 7198 4395 7201 4400 7153
      4390 7151 4389 7156 4377 7153 4374 7149
      4350 7168
TIME...MOT...LOC 0135Z 268DEG 26KT 4390 7193 4374 7192 4354 7214 

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

Ekster

1 follow-up statement

130 
WWUS51 KGYX 210203
SVSGYX

Severe Weather Statement
National Weather Service Gray ME
1003 PM EDT Tue Jul 20 2021

NHC001-009-013-019-210215-
/O.CON.KGYX.SV.W.0049.000000T0000Z-210721T0215Z/
Sullivan NH-Grafton NH-Belknap NH-Merrimack NH-
1003 PM EDT Tue Jul 20 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1015 PM EDT
FOR EASTERN SULLIVAN...SOUTHEASTERN GRAFTON...NORTHWESTERN BELKNAP
AND NORTHWESTERN MERRIMACK COUNTIES...

At 1002 PM EDT, severe thunderstorms were located along a line
extending from near Woodstock to Plymouth to Danbury, moving east at
30 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...
Franklin, Plymouth, Meredith, Moultonborough, Grafton, Holderness,
Ashland, Danbury, Groton, Woodstock, Sandwich, Bristol, Center
Harber, Hill, Hebron, Ellsworth, Thornton, Rumney, Campton and New
Hampton.

This also includes...
  Rumney Rocks, Squam Lake, Carr Mountain, Stinson Mountain, and
Mount Tecumseh.
 
This includes Interstate 93 between mile markers 66 and 96.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 4349 7198 4371 7185 4394 7188 4400 7153
      4390 7151 4389 7156 4377 7153 4374 7149
      4350 7168
TIME...MOT...LOC 0202Z 268DEG 26KT 4391 7167 4375 7166 4355 7188 

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

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 20, 8:55 PM EDT	Special Weather Statement	GYX	Grafton	50 min
Jul 20, 8:58 PM EDT	Severe Thunderstorm Warning	GYX	Grafton	47 min
Jul 20, 9:15 PM EDT	Special Weather Statement	GYX	Sullivan	30 min
Jul 20, 9:24 PM EDT	Severe Thunderstorm Warning	GYX	Grafton, Sullivan	29 min
Jul 20, 9:47 PM EDT	Special Weather Statement	GYX	Sullivan	43 min
Jul 20, 10:10 PM EDT	Severe Thunderstorm Warning	GYX	Belknap, Carroll, Grafton	50 min
Jul 20, 10:14 PM EDT	Severe Thunderstorm Warning	GYX	Cheshire, Hillsborough, Merrimack, Sullivan	46 min
Jul 20, 10:15 PM EDT	Special Weather Statement	GYX	Rockingham	45 min
Jul 20, 10:33 PM EDT	Special Weather Statement	GYX	Cheshire	42 min
Jul 20, 10:36 PM EDT	Severe Thunderstorm Warning	GYX	Cheshire, Hillsborough	39 min
Jul 20, 10:38 PM EDT	Severe Thunderstorm Warning	GYX	Belknap, Carroll, Strafford	41 min
Jul 20, 10:57 PM EDT	Severe Thunderstorm Warning	GYX	Belknap, Cheshire, Hillsborough, Merrimack	48 min
Jul 20, 11:10 PM EDT	Special Weather Statement	GYX	Rockingham	35 min
Jul 20, 11:28 PM EDT	Severe Thunderstorm Warning	GYX	Hillsborough, Merrimack, Rockingham	47 min
Jul 20, 11:32 PM EDT	Special Weather Statement	GYX	Strafford	43 min
Jul 20, 11:42 PM EDT	Special Weather Statement	GYX	Rockingham	48 min
Jul 20, 11:55 PM EDT	Severe Thunderstorm Warning	GYX	Rockingham	25 min
Jul 21, 12:06 AM EDT	Special Weather Statement	GYX	Rockingham	24 min
Jul 21, 12:13 AM EDT	Severe Thunderstorm Warning	GYX	Rockingham, Strafford	30 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.