Alert archive / New Hampshire / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 48, NWS Gray, ME

July 20, 2021Grafton County, Sullivan County, New Hampshire

NWS Gray, ME issued this severe thunderstorm warning at Jul 20, 2021, 9:24 PM EDT for Grafton County, Sullivan County, New Hampshire. It was in force for 29 min. 2 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, 9:24 PM EDT (01:24 UTC)
Expired
Jul 20, 2021, 9:53 PM EDT
In force
29 min
Issued by
NWS Gray, ME
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Grafton County, NH, Sullivan County, NH

The radar

The Burlington radar (KCXX), 130 km from the middle of the area, began a volume at 01:23 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

TimeReportWhereRemark
Jul 20, 9:33 PM EDTTSTM WND DMGOrange, NHCORRECTS PREVIOUS TSTM WND DMG REPORT FROM ORANGE. TREES DOWN.
Jul 20, 9:35 PM EDTTSTM WND DMGOrange, NHTREES DOWN.

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

The nearest sounding before it

Albany, NY (KALY), launched 00:00Z, 1.4 hours before the alert went out and 160 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, Albany, NY at 00:00Z on 2021-07-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1226 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Albany, NY at 00:00Z on 2021-07-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 89 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
1226 J/kg
Mixed-layer CIN
-24 J/kg
Mixed-layer LCL
1198 m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
89 m²/s²
0-3 km storm-relative helicity
82 m²/s²
Significant tornado parameter
0.4
Supercell composite
4.6

Open this sounding in Storm Lab

The text

As transmitted.

410 
WUUS51 KGYX 210124
SVRGYX
NHC009-019-210215-
/O.NEW.KGYX.SV.W.0048.210721T0124Z-210721T0215Z/

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

The National Weather Service in Gray Maine has issued a

* Severe Thunderstorm Warning for...
  Northern Sullivan County in central New Hampshire...
  Southwestern Grafton County in northern New Hampshire...

* Until 1015 PM EDT.

* At 924 PM EDT, severe thunderstorms were located along a line
  extending from near Lebanon to 8 miles northwest of Claremont,
  moving east at 50 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...
  Lebanon, Grafton, Hanover, Enfield, Canaan, Danbury, Groton,
  Grantham, Cornish, Croydon, Hebron, Plainfield, Orange, Springfield
  and Wilmot.

This includes Interstate 89 between mile markers 39 and 60.
 
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 4354 7238 4358 7237 4360 7234 4366 7231
      4370 7180 4358 7188 4346 7200 4344 7239
      4347 7239 4349 7238 4352 7240
TIME...MOT...LOC 0124Z 255DEG 45KT 4366 7221 4346 7248 

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

Ekster
2 follow-up statements
656 
WWUS51 KGYX 210140
SVSGYX

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

NHC009-019-210215-
/O.CON.KGYX.SV.W.0048.000000T0000Z-210721T0215Z/
Sullivan NH-Grafton NH-
940 PM EDT Tue Jul 20 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1015 PM EDT
FOR NORTHERN SULLIVAN AND SOUTH CENTRAL GRAFTON COUNTIES...

At 940 PM EDT, severe thunderstorms were located along a line
extending from near Canaan to 9 miles south of Lebanon, moving east
at 50 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...
Grafton, Enfield, Canaan, Danbury, Groton, Grantham, Cornish,
Croydon, Hebron, Orange, Springfield, Wilmot and Plainfield.

This includes Interstate 89 between mile markers 41 and 49.
 
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 4350 7196 4344 7236 4344 7237 4357 7219
      4357 7217 4360 7215 4368 7204 4370 7180
      4359 7187
TIME...MOT...LOC 0140Z 255DEG 45KT 4370 7199 4350 7226 

HAIL...1.00IN
WIND...60MPH
 
$$
555 
WWUS51 KGYX 210153
SVSGYX

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

NHC009-019-210203-
/O.CAN.KGYX.SV.W.0048.000000T0000Z-210721T0215Z/
Sullivan NH-Grafton NH-
953 PM EDT Tue Jul 20 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHERN SULLIVAN AND SOUTH
CENTRAL GRAFTON COUNTIES IS CANCELLED...
    
The storms which prompted the warning have moved out of the area.
Therefore, the warning has been cancelled.  However heavy rain is
still possible with these thunderstorms.

LAT...LON 4350 7196 4344 7236 4344 7237 4357 7219
      4357 7217 4360 7215 4368 7204 4370 7180
      4359 7187
TIME...MOT...LOC 0148Z 255DEG 45KT 4373 7186 4353 7213 

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 20, 8:55 PM EDTSpecial Weather StatementGYXGrafton50 min
Jul 20, 8:58 PM EDTSevere Thunderstorm WarningGYXGrafton47 min
Jul 20, 9:15 PM EDTSpecial Weather StatementGYXSullivan30 min
Jul 20, 9:35 PM EDTSevere Thunderstorm WarningGYXBelknap, Grafton, Merrimack, Sullivan40 min
Jul 20, 9:47 PM EDTSpecial Weather StatementGYXSullivan43 min
Jul 20, 10:10 PM EDTSevere Thunderstorm WarningGYXBelknap, Carroll, Grafton50 min
Jul 20, 10:14 PM EDTSevere Thunderstorm WarningGYXCheshire, Hillsborough, Merrimack, Sullivan46 min
Jul 20, 10:15 PM EDTSpecial Weather StatementGYXRockingham45 min
Jul 20, 10:33 PM EDTSpecial Weather StatementGYXCheshire42 min
Jul 20, 10:36 PM EDTSevere Thunderstorm WarningGYXCheshire, Hillsborough39 min
Jul 20, 10:38 PM EDTSevere Thunderstorm WarningGYXBelknap, Carroll, Strafford41 min
Jul 20, 10:57 PM EDTSevere Thunderstorm WarningGYXBelknap, Cheshire, Hillsborough, Merrimack48 min
Jul 20, 11:10 PM EDTSpecial Weather StatementGYXRockingham35 min
Jul 20, 11:28 PM EDTSevere Thunderstorm WarningGYXHillsborough, Merrimack, Rockingham47 min
Jul 20, 11:32 PM EDTSpecial Weather StatementGYXStrafford43 min
Jul 20, 11:42 PM EDTSpecial Weather StatementGYXRockingham48 min
Jul 20, 11:55 PM EDTSevere Thunderstorm WarningGYXRockingham25 min
Jul 21, 12:06 AM EDTSpecial Weather StatementGYXRockingham24 min
Jul 21, 12:13 AM EDTSevere Thunderstorm WarningGYXRockingham, Strafford30 min

Nearby

Severe Thunderstorm Warnings in New Hampshire, 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.