Alert archive / New York / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 7, NWS New York, NY

April 21, 2021Nassau County, Suffolk County, New York

NWS New York, NY issued this severe thunderstorm warning at Apr 21, 2021, 3:17 PM EDT for Nassau County, Suffolk County, New York. It was in force for 19 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, 3:17 PM EDT (19:17 UTC)
Expired: Apr 21, 2021, 3:36 PM EDT
In force: 19 min
Issued by: NWS New York, NY
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Nassau County, NY, Suffolk County, NY

The radar

The Brookhaven radar (KOKX), 39 km from the middle of the area, began a volume at 19:17 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
Apr 21, 3:30 PM EDT	MARINE TSTM WIND 42	1 Se Amityville, NY	36 KNOTS, MESONET STATION XHCK GREAT SOUTH BAY.

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
Apr 21, 12:28 PM EDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 7.3 hours before the alert went out and 39 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: 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.

086 
WUUS51 KOKX 211917
SVROKX
NYC059-103-212045-
/O.NEW.KOKX.SV.W.0007.210421T1917Z-210421T2045Z/

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

The National Weather Service in Upton NY has issued a

* Severe Thunderstorm Warning for...
  Western Suffolk County in southeastern New York...
  Nassau County in southeastern New York...

* Until 445 PM EDT.

* At 317 PM EDT, severe thunderstorms were located along a line
  extending from Darien to 10 miles south of Lido Beach, moving east
  at 20 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Islip, Brentwood, Levittown, Freeport, Commack, Huntington Station,
  Centereach, Deer Park, Lindenhurst, Plainview, Medford, Massapequa,
  Hauppauge, Ronkonkoma and Syosset.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4057 7366 4092 7359 4093 7352 4094 7350
      4095 7346 4094 7342 4097 7340 4094 7334
      4095 7329 4092 7322 4093 7317 4099 7312
      4098 7306 4098 7286 4069 7292
TIME...MOT...LOC 1917Z 251DEG 16KT 4104 7351 4045 7362 

HAIL...<.75IN
WIND...60MPH
 
$$

1 follow-up statement

623 
WWUS51 KOKX 211936
SVSOKX

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

NYC059-103-211946-
/O.CAN.KOKX.SV.W.0007.000000T0000Z-210421T2045Z/
Suffolk NY-Nassau NY-
336 PM EDT Wed Apr 21 2021

...THE SEVERE THUNDERSTORM WARNING FOR WESTERN SUFFOLK AND NASSAU
COUNTIES IS CANCELLED...
            
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 has been cancelled.

A Severe Thunderstorm Watch remains in effect until 600 PM EDT for
southeastern New York.

LAT...LON 4057 7366 4092 7359 4093 7352 4094 7350
      4095 7346 4094 7342 4097 7340 4094 7334
      4095 7329 4092 7322 4093 7317 4099 7312
      4098 7306 4098 7286 4069 7292
TIME...MOT...LOC 1935Z 251DEG 16KT 4107 7341 4048 7352 

$$

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 20, 8:48 PM EDT	Freeze Watch	OKX	Orange, Putnam	7 hr
Apr 21, 3:41 AM EDT	Freeze Warning	OKX	Orange, Putnam, Rockland, Westchester	29 hr
Apr 21, 10:58 AM EDT	Special Weather Statement	OKX	Nassau	47 min
Apr 21, 12:52 PM EDT	Special Weather Statement	OKX	Suffolk	23 min
Apr 21, 1:23 PM EDT	Special Weather Statement	OKX	Orange, Rockland	67 min
Apr 21, 1:41 PM EDT	Severe Thunderstorm Warning	OKX	Orange, Rockland	64 min
Apr 21, 2:05 PM EDT	Special Weather Statement	OKX	Bronx, Kings, Nassau, New York, Putnam, Queens and 2 more	85 min
Apr 21, 2:10 PM EDT	Severe Thunderstorm Warning	OKX	Putnam	50 min
Apr 21, 2:12 PM EDT	Severe Thunderstorm Warning	OKX	Bronx, Nassau, New York, Queens, Westchester	48 min
Apr 21, 2:14 PM EDT	Special Marine Warning	OKX		61 min
Apr 21, 2:28 PM EDT	Severe Thunderstorm Warning	OKX	Westchester	47 min
Apr 21, 2:34 PM EDT	Special Marine Warning	OKX		86 min
Apr 21, 2:53 PM EDT	Severe Thunderstorm Warning	OKX	Putnam, Westchester	67 min
Apr 21, 3:07 PM EDT	Special Marine Warning	OKX		113 min

Nearby

Severe Thunderstorm Warnings in New York, 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.