Alert archive / Connecticut / Flash Flood Warnings in 2021

Flash Flood Warning 13, NWS Albany, NY

July 17, 2021Northwest Hills Planning Region, Connecticut

NWS Albany, NY issued this flash flood warning at Jul 17, 2021, 4:20 PM EDT for Northwest Hills Planning Region, Connecticut. It was in force for 3 hr. 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: Jul 17, 2021, 4:20 PM EDT (20:20 UTC)
Expired: Jul 17, 2021, 6:58 PM EDT
In force: 3 hr
Issued by: NWS Albany, NY
Area: Storm-based polygon
Flood severity: None

County Northwest Hills Planning Region, CT

The radar

The Brookhaven radar (KOKX), 89 km from the middle of the area, began a volume at 20:20 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
Jul 17, 4:30 PM EDT	FLASH FLOOD	New Milford, CT	LAW ENFORCEMENT REPORTS FLOODING OF STREETS ALONG THE HOUSATONIC RIVER IN NEW MILFORD. TIME ESTIMATED BY RADAR.
Jul 17, 4:36 PM EDT	FLASH FLOOD	Watertown, CT	LAW ENFORCEMENT REPORTS NUMEROUS STREETS FLOODED IN WATERTOWN. SOME CREEKS AND STREAMS HAVE ALSO OVERFLOWED THEIR BANKS. TIME ESTIMATED BY RADAR.

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, 8.3 hours before the alert went out and 89 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: 1203 J/kg
Mixed-layer CIN: -55 J/kg
Mixed-layer LCL: 1054 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 35 m²/s²
0-3 km storm-relative helicity: 46 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 1.0

Open this sounding in Storm Lab

The text

As transmitted.

224 
WGUS51 KALY 172020
FFWALY
CTC005-172330-
/O.NEW.KALY.FF.W.0013.210717T2020Z-210717T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Albany NY
420 PM EDT Sat Jul 17 2021

The National Weather Service in Albany has issued a

* Flash Flood Warning for...
  Southern Litchfield County in northern Connecticut...

* Until 730 PM EDT.

* At 420 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 2 and 3 inches of rain 
  have fallen. Additional rainfall amounts up to 1 inch are possible 
  in the warned area. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Torrington, New Milford, Thomaston, Kent, Litchfield, New Preston, 
  Woodbury Center, Oakville, Northwest Harwinton, Gaylordsville, 
  Terryville, Watertown, Plymouth, Woodbury, Harwinton, Bethlehem, 
  Washington, Morris, Roxbury and Bridgewater.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 4176 7350 4181 7295 4180 7302 4164 7298
      4163 7302 4161 7302 4161 7306 4159 7306
      4157 7309 4156 7316 4152 7316 4151 7332
      4149 7333 4147 7331 4149 7337 4151 7339
      4149 7344 4164 7350 4165 7349 4166 7350

FLASH FLOOD...RADAR INDICATED

$$

NAS

2 follow-up statements

699 
WGUS71 KALY 172110
FFSALY

Flash Flood Statement
National Weather Service Albany NY
510 PM EDT Sat Jul 17 2021

CTC005-172330-
/O.CON.KALY.FF.W.0013.000000T0000Z-210717T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Litchfield CT-
510 PM EDT Sat Jul 17 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 730 PM EDT THIS 
EVENING FOR SOUTHERN LITCHFIELD COUNTY...

At 510 PM EDT, local law enforcement reported thunderstorms 
producing heavy rain in Law Enforcement has reported flooded roads 
near Watertown, Oakville and New Milford. Between 2 and 3 inches of 
rain have fallen. Flash flooding is already occurring.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Law enforcement reported.

IMPACT...Flash flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Torrington, New Milford, Thomaston, Kent, Litchfield, New Preston, 
  Woodbury Center, Oakville, Northwest Harwinton, Gaylordsville, 
  Terryville, Watertown, Plymouth, Woodbury, Harwinton, Bethlehem, 
  Washington, Morris, Roxbury and Bridgewater.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 4176 7350 4181 7295 4180 7302 4164 7298
      4163 7302 4161 7302 4161 7306 4159 7306
      4157 7309 4156 7316 4152 7316 4151 7332
      4149 7333 4147 7331 4149 7337 4151 7339
      4149 7344 4164 7350 4165 7349 4166 7350

FLASH FLOOD...OBSERVED

$$

NAS

557 
WGUS71 KALY 172258
FFSALY

Flash Flood Statement
National Weather Service Albany NY
658 PM EDT Sat Jul 17 2021

CTC005-172308-
/O.CAN.KALY.FF.W.0013.000000T0000Z-210717T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Litchfield CT-
658 PM EDT Sat Jul 17 2021

...FLASH FLOOD WARNING IS CANCELLED FOR SOUTHERN LITCHFIELD COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

A Flash Flood Watch remains in effect until 1200 PM EDT Sunday for 
portions of northwestern Connecticut, western Massachusetts, New 
York and southern Vermont.

LAT...LON 4176 7350 4181 7295 4180 7302 4164 7298
      4163 7302 4161 7302 4161 7306 4159 7306
      4157 7309 4156 7316 4152 7316 4151 7332
      4149 7333 4147 7331 4149 7337 4151 7339
      4149 7344 4164 7350 4165 7349 4166 7350

$$

NAS

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 17, 3:09 PM EDT	Special Weather Statement	ALY		51 min
Jul 17, 3:17 PM EDT	Areal Flood Advisory	ALY	Northwest Hills Planning Region	3 hr
Jul 17, 3:22 PM EDT	Severe Thunderstorm Warning	ALY	Northwest Hills Planning Region	53 min
Jul 17, 4:18 PM EDT	Special Weather Statement	ALY		27 min
Jul 17, 5:23 PM EDT	Areal Flood Advisory	ALY	Northwest Hills Planning Region	3 hr

Nearby

Flash Flood Warnings in Connecticut, 2021 Every flash flood 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.