Alert archive / New York / Flash Flood Warnings in 2011

Flash Flood Warning 39, NWS New York, NY

September 23, 2011Orange County, Putnam County, Westchester County, New York

NWS New York, NY issued this flash flood warning at Sep 23, 2011, 4:05 PM EDT for Orange County, Putnam County, Westchester County, New York. 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
Sep 23, 2011, 4:05 PM EDT (20:05 UTC)
Expired
Sep 23, 2011, 5:02 PM EDT
In force
57 min
Issued by
NWS New York, NY
Area
Storm-based polygon
Flood severity
None

Counties Orange County, NY, Putnam County, NY, Westchester County, NY

The radar

The Brookhaven radar (KOKX), 116 km from the middle of the area, began a volume at 20:07 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
Sep 23, 4:05 PM EDTFLASH FLOODNorth Pelham, NYHUTCHINSON RIVER PARKWAY CLOSED NORTHBOUND FROM EXIT 8 TO EXIT 13
Sep 23, 4:30 PM EDTFLASH FLOODMount Vernon, NYALL NORTHBOUND LANES OF BRONX RIVER PARKWAY CLOSED

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

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 8.1 hours before the alert went out and 116 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 2011-09-23Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 454 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 12:00Z on 2011-09-23The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 53 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
454 J/kg
Mixed-layer CIN
-7 J/kg
Mixed-layer LCL
434 m above ground
0-6 km bulk shear
36 kt
0-1 km storm-relative helicity
53 m²/s²
0-3 km storm-relative helicity
90 m²/s²
Significant tornado parameter
0.1
Supercell composite
1.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

257 
WGUS51 KOKX 232005
FFWOKX
NYC071-079-119-232200-
/O.NEW.KOKX.FF.W.0039.110923T2005Z-110923T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE NEW YORK NY
405 PM EDT FRI SEP 23 2011

THE NATIONAL WEATHER SERVICE IN UPTON NY HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  WESTCHESTER COUNTY IN SOUTHEAST NEW YORK...
  PUTNAM COUNTY IN SOUTHEAST NEW YORK...
  ORANGE COUNTY IN SOUTHEAST NEW YORK...

* UNTIL 600 PM EDT...

* AT 403 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
MODERATE TO HEAVY RAINFALL MOVING ACROSS THE WARNING AREA. RAINFALL 
RATES OF ONE TO ONE AN A HALF INCHES PER HOUR ARE POSSIBLE WITH 
LOCALLY HIGHER AMOUNTS. EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL 
CAUSE FLOODING OF SMALL CREEKS AND STREAMS...URBAN AREAS... 
HIGHWAYS...STREETS AND UNDERPASSES AS WELL AS OTHER DRAINAGE AREAS 
AND LOW LYING SPOTS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE 
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS 
SAFELY. MOVE TO HIGHER GROUND.

A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY.
RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE
PRECAUTIONS TO PROTECT LIFE AND PROPERTY. DO NOT ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR BY
AUTOMOBILE.

TO REPORT FLOODING...HAVE THE NEAREST LAW ENFORCEMENT AGENCY RELAY
YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE IN UPTON
NY.

&&

LAT...LON 4151 7448 4160 7438 4163 7427 4160 7421
      4161 7413 4158 7396 4153 7399 4145 7398
      4150 7392 4152 7354 4137 7355 4134 7382
      4089 7380 4093 7391 4114 7390 4123 7396
      4129 7395 4132 7398 4115 7425 4149 7476

$$
1 follow-up statement
304 
WGUS71 KOKX 232102
FFSOKX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE NEW YORK NY
502 PM EDT FRI SEP 23 2011

NYC071-079-119-232110-
/O.CAN.KOKX.FF.W.0039.000000T0000Z-110923T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
ORANGE NY-PUTNAM NY-WESTCHESTER NY-
502 PM EDT FRI SEP 23 2011

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR WESTCHESTER...
PUTNAM AND ORANGE COUNTIES...

RAINFALL INTENSITY HAS WEAKENED OVER THE AREA ENDING THE IMMINENT 
THREAT FOR FLASH FLOODING...THEREFORE THE FLASH FLOOD WARNING HAS 
BEEN CANCELLED.

LAT...LON 4151 7448 4160 7438 4163 7427 4160 7421
      4161 7413 4158 7396 4153 7399 4145 7398
      4150 7392 4152 7354 4137 7355 4134 7382
      4089 7380 4093 7391 4114 7390 4123 7396
      4129 7395 4132 7398 4115 7425 4149 7476

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 23, 2:36 AM EDTMarine Dense Fog AdvisoryOKX8 hr
Sep 23, 2:37 AM EDTDense Fog AdvisoryOKXNassau, Orange, Putnam, Rockland, Suffolk, Westchester6 hr
Sep 23, 12:09 PM EDTAreal Flood AdvisoryOKXBronx, Kings, New York, Queens, Richmond111 min
Sep 23, 2:04 PM EDTAreal Flood AdvisoryOKXBronx, New York, Rockland, Westchester86 min
Sep 23, 3:13 PM EDTFlash Flood WarningOKXKings, Nassau, Queens, Westchester103 min
Sep 23, 6:38 PM EDTAreal Flood WarningOKXOrange, Putnam, Rockland5 hr
Sep 23, 7:38 PM EDTAreal Flood AdvisoryOKXBronx, Kings, New York, Putnam, Queens, Richmond and 2 more3 hr

Nearby

Flash Flood Warnings in New York, 2011Every flash flood warning in 2011

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.