Alert archive / New York / Flash Flood Watches in 2021

Flash Flood Watch 4, NWS New York, NY

July 11, 20214 counties in Connecticut; 5 counties in New Jersey; 11 counties in New York

NWS New York, NY issued this flash flood watch at Jul 11, 2021, 4:24 PM EDT for 4 counties in Connecticut; 5 counties in New Jersey; 11 counties in New York. It took effect at Jul 12, 2021, 2:00 PM EDT. It was in force for 13 hr.

The area

The counties it named.

The facts

Issued
Jul 11, 2021, 4:24 PM EDT (20:24 UTC)
In effect from
Jul 12, 2021, 2:00 PM EDT
Expired
Jul 13, 2021, 3:12 AM EDT
In force
13 hr
Issued by
NWS New York, NY
Flood severity
None

Counties Greater Bridgeport Planning Region, CT, Lower Connecticut River Valley Planning Region, CT, Naugatuck Valley Planning Region, CT, Southeastern Connecticut Planning Region, CT, Bergen County, NJ, Essex County, NJ, Hudson County, NJ, Passaic County, NJ, Union County, NJ, Bronx County, NY, Kings County, NY, Nassau County, NY, New York County, NY, Orange County, NY, Putnam County, NY, Queens County, NY, Richmond County, NY, Rockland County, NY, Suffolk County, NY, Westchester County, NY

The radar

The Brookhaven radar (KOKX), 71 km from the middle of the area, began a volume at 20:25 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 12:00Z, 8.4 hours before the alert went out and 71 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 2021-07-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 17 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 2021-07-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 14 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
17 J/kg
Mixed-layer CIN
-45 J/kg
Mixed-layer LCL
715 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
14 m²/s²
0-3 km storm-relative helicity
56 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

719 
WGUS61 KOKX 112024
FFAOKX

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service New York NY
424 PM EDT Sun Jul 11 2021

...HEAVY RAIN AND FLASH FLOODING POSSIBLE MONDAY AFTERNOON INTO
EARLY TUESDAY MORNING...

CTZ005>012-NJZ002-004-006-103>108-NYZ067>075-078-080-176>179-
120930-
/O.NEW.KOKX.FF.A.0004.210712T1800Z-210713T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Northern Fairfield-Northern New Haven-Northern Middlesex-
Northern New London-Southern Fairfield-Southern New Haven-
Southern Middlesex-Southern New London-Western Passaic-
Eastern Passaic-Hudson-Western Bergen-Eastern Bergen-
Western Essex-Eastern Essex-Western Union-Eastern Union-Orange-
Putnam-Rockland-Northern Westchester-Southern Westchester-
New York (Manhattan)-Bronx-Richmond (Staten Island)-
Kings (Brooklyn)-Northwest Suffolk-Southwest Suffolk-
Northern Queens-Northern Nassau-Southern Queens-Southern Nassau-
424 PM EDT Sun Jul 11 2021

...FLASH FLOOD WATCH IN EFFECT FROM MONDAY AFTERNOON THROUGH
TUESDAY MORNING...

The National Weather Service in Upton has issued a

* Flash Flood Watch for all of southern Connecticut and northeast
  New Jersey, and most of southeast New York, including the
  following areas, in southern Connecticut, Fairfield, New Haven,
  Middlesex, and New London counties. In northeast New Jersey,
  Bergen, Essex, Hudson, Passaic, and Union counties, In 
  southeast New York, all five boroughs of New York City, 
  Westchester, Orange, Putnam, Rockland, Nassau, and Western 
  Suffolk counties. 

* From Monday afternoon through Tuesday morning. 

* As a warm front lifts into the area on Monday, scattered to
  numerous thunderstorms will develop Monday afternoon. As the
  front sinks back to the south Monday night, the front will
  continue to focus thunderstorm activity and heavy rain potential
  over the watch area, especially in and around the New York City
  Tri-State area. This rain will be falling in areas hard hit by
  heavy rain and flash flooding late last week. 

* Rainfall amounts of 2 to 3 inches are likely, with localized
  amounts over 4 inches possible. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Watch means that conditions may develop that lead
to flash flooding. Flash flooding is a very dangerous situation.
You should monitor later forecasts and be prepared to take action
should flash flood warnings be issued.

&&

$$
4 follow-up statements
775 
WGUS61 KOKX 120724
FFAOKX

Flood Watch
National Weather Service New York NY
324 AM EDT Mon Jul 12 2021

...HEAVY RAIN AND FLASH FLOODING POSSIBLE THIS AFTERNOON INTO 
EARLY TUESDAY MORNING...

CTZ005>012-NJZ002-004-006-103>108-NYZ067>075-078-080-176>179-
122200-
/O.CON.KOKX.FF.A.0004.210712T1800Z-210713T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Northern Fairfield-Northern New Haven-Northern Middlesex-
Northern New London-Southern Fairfield-Southern New Haven-
Southern Middlesex-Southern New London-Western Passaic-
Eastern Passaic-Hudson-Western Bergen-Eastern Bergen-
Western Essex-Eastern Essex-Western Union-Eastern Union-Orange-
Putnam-Rockland-Northern Westchester-Southern Westchester-
New York (Manhattan)-Bronx-Richmond (Staten Island)-
Kings (Brooklyn)-Northwest Suffolk-Southwest Suffolk-
Northern Queens-Northern Nassau-Southern Queens-Southern Nassau-
324 AM EDT Mon Jul 12 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT FROM 2 PM EDT THIS
AFTERNOON THROUGH TUESDAY MORNING...

The Flash Flood Watch continues for

* Portions of southern Connecticut, northeast New Jersey, and
  southeast New York, including the following areas, in southern
  Connecticut, Fairfield, Middlesex, New Haven, and New London
  counties. In northeast New Jersey, Bergen, Essex, Passaic,
  Union, and Hudson counties. In southeast New York, all five
  boroughs of New York City, Nassau, Westchester, Orange, Putnam,
  Rockland, and Western Suffolk counties. 

* From 2 PM EDT this afternoon through Tuesday morning

* Scattered to numerous thunderstorms are expected to develop this
  afternoon in the vicinity of a warm front. As this front sinks
  back to the south tonight it will continue to focus thunderstorm
  activity and heavy rain potential over the watch area,
  especially in and around the New York City Tri-State area. This
  rain will be falling in areas hard hit by heavy rain and flash 
  flooding late last week. 

* Rainfall amounts of 1 to 3 inches are likely, with localized 
  amounts over 4 inches possible. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Watch means that conditions may develop that lead
to flash flooding. Flash flooding is a very dangerous situation.
You should monitor later forecasts and be prepared to take action
should flash flood warnings be issued.

&&

$$
983 
WGUS61 KOKX 121745
FFAOKX

Flood Watch
National Weather Service New York NY
145 PM EDT Mon Jul 12 2021

...HEAVY RAIN AND FLASH FLOODING POSSIBLE THIS AFTERNOON INTO
EARLY TUESDAY MORNING...

CTZ005>008-010>012-121845-
/O.CAN.KOKX.FF.A.0004.210712T1800Z-210713T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Northern Fairfield-Northern New Haven-Northern Middlesex-
Northern New London-Southern New Haven-Southern Middlesex-
Southern New London-
145 PM EDT Mon Jul 12 2021

...FLASH FLOOD WATCH IS CANCELLED...

The Flash Flood Watch has been cancelled for most of southern
Connecticut. Heavy rain and the threat of flash flooding are
likely to remain to the south and west. 


$$

CTZ009-NJZ002-004-006-103>108-NYZ067>075-078-080-176>179-130645-
/O.CON.KOKX.FF.A.0004.210712T1800Z-210713T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Southern Fairfield-Western Passaic-Eastern Passaic-Hudson-
Western Bergen-Eastern Bergen-Western Essex-Eastern Essex-
Western Union-Eastern Union-Orange-Putnam-Rockland-
Northern Westchester-Southern Westchester-New York (Manhattan)-
Bronx-Richmond (Staten Island)-Kings (Brooklyn)-Northwest Suffolk-
Southwest Suffolk-Northern Queens-Northern Nassau-Southern Queens-
Southern Nassau-
145 PM EDT Mon Jul 12 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH TUESDAY MORNING...

The Flash Flood Watch continues for

* All of northeast New Jersey, most of Southeast New York, and a
  small portion of southern Connecticut, including the following
  areas. In northeast New Jersey, Bergen, Essex, Hudson, Passaic,
  and Union counties. In southeast New York, all five boroughs of
  New York City, and Nassau, Western Suffolk, Westchester, 
  Rockland, Orange, and Putnam counties. In southern Connecticut, 
  Southern Fairfield county. 

* Through Tuesday morning. 

* Scattered to numerous showers and thunderstorms are expected to
  develop this afternoon near a frontal boundary over or just
  south of the watch area. The front will continue to focus 
  shower and thunderstorm over the watch area tonight, especially 
  in and around the New York City Tri-State area. This rain will 
  be falling in areas hard hit by heavy rain and flash flooding 
  late last week.

* Rainfall amounts of 1 to 3 inches are likely, with localized 
  amounts over 4 inches possible. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Watch means that conditions may develop that lead
to flash flooding. Flash flooding is a very dangerous situation.
You should monitor later forecasts and be prepared to take action
should flash flood warnings be issued.

&&

$$
174 
WGUS61 KOKX 130627
FFAOKX

Flood Watch
National Weather Service New York NY
227 AM EDT Tue Jul 13 2021

...HEAVY RAIN AND FLASH FLOODING POSSIBLE THROUGH EARLY THIS 
MORNING...

CTZ009-NJZ002-004-006-103>108-NYZ067>075-078-080-176>179-131400-
/O.CON.KOKX.FF.A.0004.000000T0000Z-210713T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Southern Fairfield-Western Passaic-Eastern Passaic-Hudson-
Western Bergen-Eastern Bergen-Western Essex-Eastern Essex-
Western Union-Eastern Union-Orange-Putnam-Rockland-
Northern Westchester-Southern Westchester-New York (Manhattan)-
Bronx-Richmond (Staten Island)-Kings (Brooklyn)-Northwest Suffolk-
Southwest Suffolk-Northern Queens-Northern Nassau-Southern Queens-
Southern Nassau-
227 AM EDT Tue Jul 13 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL 10 AM EDT THIS
MORNING...

The Flash Flood Watch continues for

* Portions of southern Connecticut, northeast New Jersey, and
  southeast New York, including the following areas, in southern
  Connecticut, Southern Fairfield County. In northeast New Jersey,
  Bergen, Essex, Passaic, Union, and Hudson Counties. In southeast
  New York, Bronx, Kings (Brooklyn), New York (Manhattan), Queens,
  Richmond (Staten Island), Nassau, Westchester, Orange, Putnam,
  Rockland, and Western Suffolk Counties.
 
* Until 10 AM EDT this morning

* Scattered showers and thunderstorms continue to develop
  southwest of the region and track towards the area. This rain
  may fall across areas with abnormally wet antecedent conditions
  due to heavy rain and flash flooding late last week.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Watch means that conditions may develop that lead
to flash flooding. Flash flooding is a very dangerous situation.
You should monitor later forecasts and be prepared to take action
should flash flood warnings be issued.

&&

$$
864 
WGUS61 KOKX 130712
FFAOKX

Flood Watch
National Weather Service New York NY
312 AM EDT Tue Jul 13 2021

CTZ009-NJZ002-004-006-103>108-NYZ067>075-078-080-176>179-130815-
/O.CAN.KOKX.FF.A.0004.000000T0000Z-210713T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Southern Fairfield-Western Passaic-Eastern Passaic-Hudson-
Western Bergen-Eastern Bergen-Western Essex-Eastern Essex-
Western Union-Eastern Union-Orange-Putnam-Rockland-
Northern Westchester-Southern Westchester-New York (Manhattan)-
Bronx-Richmond (Staten Island)-Kings (Brooklyn)-Northwest Suffolk-
Southwest Suffolk-Northern Queens-Northern Nassau-Southern Queens-
Southern Nassau-
312 AM EDT Tue Jul 13 2021

...FLASH FLOOD WATCH IS CANCELLED...

The Flash Flood Watch for portions of southern Connecticut,
northeast New Jersey, and southeast New York has been cancelled.
Additional showers will continue to move across the area early
this morning, but rainfall intensity has decreased significantly 
and flash flooding is no longer a concern.

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 10, 8:19 PM EDTAreal Flood AdvisoryOKXBergen, Hudson64 min
Jul 10, 8:54 PM EDTAreal Flood AdvisoryOKXEssex, Hudson53 min
Jul 10, 8:50 PM EDTAreal Flood AdvisoryOKXBronx, New York, Queens56 min
Jul 11, 2:24 PM EDTRip Current StatementOKXSuffolk7 hr

Nearby

Flash Flood Watches in New York, 2021Flash Flood Watches in New Jersey, 2021Flash Flood Watches in Connecticut, 2021Every flash flood watch 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.