Alert archive / Connecticut / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 6, NWS New York, NY

April 21, 2021Putnam County, Westchester County, New York; Greater Bridgeport Planning Region, Lower Connecticut River Valley Planning Region, Naugatuck Valley Planning Region, Connecticut

NWS New York, NY issued this severe thunderstorm warning at Apr 21, 2021, 2:53 PM EDT for Putnam County, Westchester County, New York; Greater Bridgeport Planning Region, Lower Connecticut River Valley Planning Region, Naugatuck Valley Planning Region, Connecticut. It was in force for 67 min. 1 report 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
Apr 21, 2021, 2:53 PM EDT (18:53 UTC)
Expired
Apr 21, 2021, 4:00 PM EDT
In force
67 min
Issued by
NWS New York, NY
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Greater Bridgeport Planning Region, CT, Lower Connecticut River Valley Planning Region, CT, Naugatuck Valley Planning Region, CT, Putnam County, NY, Westchester County, NY

The radar

The Brookhaven radar (KOKX), 65 km from the middle of the area, began a volume at 18:54 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
Apr 21, 3:13 PM EDTTSTM WND DMG2 Sw Georgetown, CTTREE LIMBS DOWN, POWER OUT.

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.

IssuedProductOfficeLasted
Apr 21, 12:28 PM EDTSevere Thunderstorm WatchSPC5 hr

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 6.9 hours before the alert went out and 65 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, Brookhaven, NY at 12:00Z on 2021-04-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Brookhaven, NY at 12:00Z on 2021-04-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 206 square meters per square second.19395878Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1427 m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
206 m²/s²
0-3 km storm-relative helicity
201 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

204 
WUUS51 KOKX 211853
SVROKX
CTC001-007-009-NYC079-119-212000-
/O.NEW.KOKX.SV.W.0006.210421T1853Z-210421T2000Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service New York NY
253 PM EDT Wed Apr 21 2021

The National Weather Service in Upton NY has issued a

* Severe Thunderstorm Warning for...
  Fairfield County in southern Connecticut...
  New Haven County in southern Connecticut...
  Northern Middlesex County in southern Connecticut...
  Westchester County in southeastern New York...
  Eastern Putnam County in southeastern New York...

* Until 400 PM EDT.

* At 253 PM EDT, severe thunderstorms were located along a line
  extending from Gaylordsville to Port Washington, moving east at 40
  mph.

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

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Bridgeport, New Haven, Stamford, Waterbury, Norwalk, Danbury,
  Meriden, White Plains, Milford, Middletown, Wallingford, Shelton,
  Naugatuck, Port Chester and Guilford.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4150 7344 4147 7332 4151 7316 4164 7298
      4164 7294 4156 7295 4155 7285 4163 7269
      4123 7277 4125 7292 4114 7309 4112 7330
      4105 7338 4097 7365 4087 7375 4103 7379
      4152 7362 4153 7353 4167 7352
TIME...MOT...LOC 1853Z 277DEG 36KT 4167 7351 4083 7366 

HAIL...0.75IN
WIND...60MPH
 
$$
2 follow-up statements
301 
WWUS51 KOKX 211928
SVSOKX

Severe Weather Statement
National Weather Service New York NY
328 PM EDT Wed Apr 21 2021

NYC079-119-211937-
/O.CAN.KOKX.SV.W.0006.000000T0000Z-210421T2000Z/
Westchester NY-Putnam NY-
328 PM EDT Wed Apr 21 2021

...THE SEVERE THUNDERSTORM WARNING FOR WESTCHESTER AND EASTERN PUTNAM
COUNTIES IS CANCELLED...

The storms which prompted the warning have moved out of the warned 
area. Therefore, the warning has been cancelled.

A Severe Thunderstorm Watch remains in effect until 600 PM EDT for
southern Connecticut.

LAT...LON 4156 7295 4155 7285 4158 7275 4163 7269
      4123 7277 4125 7278 4125 7292 4119 7301
      4120 7305 4117 7309 4114 7309 4116 7317
      4113 7322 4112 7330 4104 7340 4149 7325
      4151 7316 4164 7298 4164 7294
TIME...MOT...LOC 1927Z 262DEG 33KT 4161 7310 4102 7332 

$$

CTC001-007-009-212000-
/O.CON.KOKX.SV.W.0006.000000T0000Z-210421T2000Z/
Fairfield CT-New Haven CT-Middlesex CT-
328 PM EDT Wed Apr 21 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM EDT
FOR SOUTHERN FAIRFIELD...NEW HAVEN AND NORTHERN MIDDLESEX COUNTIES...

At 327 PM EDT, severe thunderstorms were located along a line
extending from Oakville to 7 miles south of Westport, moving east at
40 mph.

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

SOURCE...Radar indicated.

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

Locations impacted include...
Bridgeport, New Haven, Waterbury, Meriden, Milford, Middletown,
Wallingford, Shelton, Naugatuck, Guilford, Southbury, Wolcott,
Durham, Newtown and Fairfield.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4156 7295 4155 7285 4158 7275 4163 7269
      4123 7277 4125 7278 4125 7292 4119 7301
      4120 7305 4117 7309 4114 7309 4116 7317
      4113 7322 4112 7330 4104 7340 4149 7325
      4151 7316 4164 7298 4164 7294
TIME...MOT...LOC 1927Z 262DEG 33KT 4161 7310 4102 7332 

HAIL...0.75IN
WIND...60MPH
 
$$
556 
WWUS51 KOKX 211951
SVSOKX

Severe Weather Statement
National Weather Service New York NY
351 PM EDT Wed Apr 21 2021

CTC001-007-009-212001-
/O.EXP.KOKX.SV.W.0006.000000T0000Z-210421T2000Z/
Fairfield CT-New Haven CT-Middlesex CT-
351 PM EDT Wed Apr 21 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHERN FAIRFIELD...NEW HAVEN
AND NORTHERN MIDDLESEX COUNTIES WILL EXPIRE AT 400 PM EDT...
            
The storms which prompted the warning have weakened below severe
limits, and no longer pose an immediate threat to life or property.
Therefore, the warning will be allowed to expire.  However gusty
winds are still possible with these thunderstorms.

LAT...LON 4156 7295 4155 7285 4158 7275 4163 7269
      4123 7277 4125 7278 4125 7292 4119 7301
      4120 7305 4117 7309 4114 7309 4116 7317
      4113 7322 4112 7330 4104 7340 4149 7325
      4151 7316 4164 7298 4164 7294
TIME...MOT...LOC 1951Z 277DEG 36KT 4158 7281 4099 7303 

$$

The office that day

Everything else NWS New York, NY issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 20, 8:48 PM EDTFreeze WatchOKXOrange, Putnam7 hr
Apr 21, 3:41 AM EDTFreeze WarningOKXOrange, Putnam, Rockland, Westchester29 hr
Apr 21, 10:58 AM EDTSpecial Weather StatementOKXNassau47 min
Apr 21, 12:52 PM EDTSpecial Weather StatementOKXSuffolk23 min
Apr 21, 1:23 PM EDTSpecial Weather StatementOKXOrange, Rockland67 min
Apr 21, 1:41 PM EDTSevere Thunderstorm WarningOKXOrange, Rockland64 min
Apr 21, 2:05 PM EDTSpecial Weather StatementOKXBronx, Kings, Nassau, New York, Putnam, Queens and 2 more85 min
Apr 21, 2:10 PM EDTSevere Thunderstorm WarningOKXPutnam50 min
Apr 21, 2:12 PM EDTSevere Thunderstorm WarningOKXBronx, Nassau, New York, Queens, Westchester48 min
Apr 21, 2:14 PM EDTSpecial Marine WarningOKX61 min
Apr 21, 2:28 PM EDTSevere Thunderstorm WarningOKXWestchester47 min
Apr 21, 2:34 PM EDTSpecial Marine WarningOKX86 min
Apr 21, 3:07 PM EDTSpecial Marine WarningOKX113 min
Apr 21, 3:17 PM EDTSevere Thunderstorm WarningOKXNassau, Suffolk19 min
Apr 21, 12:59 PM EDTSpecial Weather StatementOKX46 min
Apr 21, 4:02 PM EDTSpecial Weather StatementOKX58 min

Nearby

Severe Thunderstorm Warnings in Connecticut, 2021Severe Thunderstorm Warnings in New York, 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.