Alert archive / Connecticut / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 79, NWS Boston/Norton, MA

July 17, 2021Northeastern Connecticut Planning Region, Connecticut

NWS Boston/Norton, MA issued this severe thunderstorm warning at Jul 17, 2021, 4:18 PM EDT for Northeastern Connecticut Planning Region, Connecticut. It was in force for 57 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 17, 2021, 4:18 PM EDT (20:18 UTC)
Expired: Jul 17, 2021, 5:15 PM EDT
In force: 57 min
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

County Northeastern Connecticut Planning Region, CT

The radar

The Boston radar (KBOX), 88 km from the middle of the area, began a volume at 20:23 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

Time	Report	Where	Remark
Jul 17, 4:20 PM EDT	TSTM WND DMG	Willington, CT	TREES AND WIRES DOWN ON PINNEY HILL ROAD
Jul 17, 5:00 PM EDT	TSTM WND DMG	Mansfield, CT	TREES AND WIRES DOWN ON CODFISH FALLS ROAD

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
Jul 17, 1:13 PM EDT	Severe Thunderstorm Watch	SPC	10 hr

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 8.3 hours before the alert went out and 123 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: 1203 J/kg
Mixed-layer CIN: -55 J/kg
Mixed-layer LCL: 1054 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 35 m²/s²
0-3 km storm-relative helicity: 46 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 1.0

Open this sounding in Storm Lab

The text

As transmitted.

723 
WUUS51 KBOX 172018
SVRBOX
CTC013-015-172115-
/O.NEW.KBOX.SV.W.0079.210717T2018Z-210717T2115Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Boston/Norton MA
418 PM EDT Sat Jul 17 2021

The National Weather Service in Boston/Norton has issued a

* Severe Thunderstorm Warning for...
  Central Windham County in northern Connecticut...
  Central Tolland County in northern Connecticut...

* Until 515 PM EDT.

* At 418 PM EDT, a severe thunderstorm was located near Coventry, or
  near Mansfield, moving east at 10 mph.

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

  SOURCE...Radar indicated.

  IMPACT...Expect wind damage to trees and power lines. Minor hail 
           damage to vehicles is possible.

* Locations impacted include...
  Mansfield, Tolland, Coventry, Thompson, Brooklyn, Woodstock,
  Willington, Ashford, Pomfret, Chaplin, Hampton and Eastford.

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 4178 7235 4188 7234 4202 7195 4176 7193
TIME...MOT...LOC 2018Z 256DEG 8KT 4183 7230 

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

Chai

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 17, 1:59 PM EDT	Special Weather Statement	BOX		46 min
Jul 17, 3:26 PM EDT	Severe Thunderstorm Warning	BOX	Northeastern Connecticut Planning Region	64 min
Jul 17, 3:47 PM EDT	Areal Flood Warning	BOX	Northeastern Connecticut Planning Region	118 min
Jul 17, 4:14 PM EDT	Flash Flood Warning	BOX	Northeastern Connecticut Planning Region	5 hr
Jul 17, 4:15 PM EDT	Severe Thunderstorm Warning	BOX	Northeastern Connecticut Planning Region	60 min
Jul 17, 4:20 PM EDT	Special Weather Statement	BOX		40 min
Jul 17, 4:29 PM EDT	Severe Thunderstorm Warning	BOX	Northeastern Connecticut Planning Region	61 min
Jul 17, 4:38 PM EDT	Severe Thunderstorm Warning	BOX	Capitol Planning Region	67 min
Jul 17, 4:58 PM EDT	Flash Flood Warning	BOX	Capitol Planning Region	2 hr
Jul 17, 5:21 PM EDT	Flash Flood Warning	BOX	Capitol Planning Region, Northeastern Connecticut Planning Region	5 hr
Jul 17, 5:30 PM EDT	Flash Flood Warning	BOX	Northeastern Connecticut Planning Region	3 hr

Nearby

Severe Thunderstorm Warnings in Connecticut, 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.