Alert archive / New York / Tornado Warnings in 2021

Tornado Warning 9, NWS New York, NY

August 19, 2021Putnam County, Rockland County, Westchester County, New York

NWS New York, NY issued this tornado warning at Aug 19, 2021, 4:44 AM EDT for Putnam County, Rockland County, Westchester County, New York. It was in force for 31 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 19, 2021, 4:44 AM EDT (08:44 UTC)
Expired
Aug 19, 2021, 5:15 AM EDT
In force
31 min
Issued by
NWS New York, NY
Area
Storm-based polygon
Tornado
Radar indicated
Hail
0.75 in

Counties Putnam County, NY, Rockland County, NY, Westchester County, NY

The radar

The Brookhaven radar (KOKX), 84 km from the middle of the area, began a volume at 08:45 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.

The nearest sounding before it

Brookhaven, NY (KOKX), launched 00:00Z, 8.7 hours before the alert went out and 84 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 00:00Z on 2021-08-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 491 joules per kilogram.LCLLFCEL10008507005003002001001 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 00:00Z on 2021-08-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 62 square meters per square second.1939Sfc1 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
491 J/kg
Mixed-layer CIN
-11 J/kg
Mixed-layer LCL
580 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
62 m²/s²
0-3 km storm-relative helicity
103 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

023 
WFUS51 KOKX 190844
TOROKX
NYC079-087-119-190915-
/O.NEW.KOKX.TO.W.0009.210819T0844Z-210819T0915Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service New York NY
444 AM EDT Thu Aug 19 2021

The National Weather Service in Upton NY has issued a

* Tornado Warning for...
  Northern Westchester County in southeastern New York...
  Eastern Putnam County in southeastern New York...
  Rockland County in southeastern New York...

* Until 515 AM EDT.
    
* At 443 AM EDT, a severe thunderstorm capable of producing a tornado
  was located over Upper Nyack, or over Nyack, moving northeast at 30
  mph.

  HAZARD...Tornado.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely.

* This dangerous storm will be near...
  Mount Kisco around 500 AM EDT.
  Yorktown Heights around 505 AM EDT.
  Mahopac around 515 AM EDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4134 7355 4130 7355 4101 7384 4110 7405
      4142 7379
TIME...MOT...LOC 0843Z 211DEG 28KT 4112 7390 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...<.75 IN

$$

JC
2 follow-up statements
050 
WWUS51 KOKX 190902
SVSOKX

Severe Weather Statement
National Weather Service New York NY
502 AM EDT Thu Aug 19 2021

NYC087-190911-
/O.CAN.KOKX.TO.W.0009.000000T0000Z-210819T0915Z/
Rockland NY-
502 AM EDT Thu Aug 19 2021

...THE TORNADO WARNING FOR ROCKLAND COUNTY IS CANCELLED...
    
The tornadic thunderstorm which prompted the warning has moved out 
of the warned area. Therefore, the warning has been cancelled.

LAT...LON 4134 7355 4130 7355 4113 7375 4120 7388
      4142 7379
TIME...MOT...LOC 0901Z 211DEG 28KT 4125 7380 

$$

NYC079-119-190915-
/O.CON.KOKX.TO.W.0009.000000T0000Z-210819T0915Z/
Westchester NY-Putnam NY-
502 AM EDT Thu Aug 19 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 515 AM EDT FOR NORTHERN
WESTCHESTER AND EASTERN PUTNAM COUNTIES...
    
At 501 AM EDT, a severe thunderstorm capable of producing a tornado
was located over Yorktown Heights, or near Mount Kisco, moving
northeast at 30 mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

This dangerous storm will be near...
  Yorktown Heights around 505 AM EDT.
  Mahopac around 520 AM EDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4134 7355 4130 7355 4113 7375 4120 7388
      4142 7379
TIME...MOT...LOC 0901Z 211DEG 28KT 4125 7380 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...<.75 IN

$$

JC
873 
WWUS51 KOKX 190915
SVSOKX

Severe Weather Statement
National Weather Service New York NY
515 AM EDT Thu Aug 19 2021

NYC079-119-190924-
/O.EXP.KOKX.TO.W.0009.000000T0000Z-210819T0915Z/
Westchester NY-Putnam NY-
515 AM EDT Thu Aug 19 2021

...THE TORNADO WARNING FOR NORTHERN WESTCHESTER AND EASTERN PUTNAM
COUNTIES WILL EXPIRE AT 515 AM EDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer appears capable of producing a tornado.
Therefore, the warning will be allowed to expire.  

LAT...LON 4134 7355 4130 7355 4113 7375 4120 7388
      4142 7379
TIME...MOT...LOC 0914Z 211DEG 28KT 4134 7373 

$$

JC

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 19, 3:21 AM EDTSpecial Weather StatementOKXRockland24 min
Aug 19, 3:30 AM EDTAreal Flood AdvisoryOKXRockland2 hr
Aug 19, 3:48 AM EDTTornado WarningOKXOrange, Rockland, Westchester27 min
Aug 19, 4:17 AM EDTTornado WarningOKXRockland, Westchester28 min
Aug 19, 3:00 PM EDTSmall Craft AdvisoryOKX14 hr

Nearby

Tornado Warnings in New York, 2021Every tornado warning in 2021Tornadoes 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.