Alert archive / Connecticut / Flash Flood Warnings in 2021

Flash Flood Warning 11, NWS Boston/Norton, MA

July 17, 2021Capitol Planning Region, Northeastern Connecticut Planning Region, Connecticut

NWS Boston/Norton, MA issued this flash flood warning at Jul 17, 2021, 5:21 PM EDT for Capitol Planning Region, Northeastern Connecticut Planning Region, Connecticut. It was in force for 5 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jul 17, 2021, 5:21 PM EDT (21:21 UTC)
Expired: Jul 17, 2021, 10:30 PM EDT
In force: 5 hr
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Flood severity: None

Counties Capitol Planning Region, CT, Northeastern Connecticut Planning Region, CT

The radar

The Boston radar (KBOX), 105 km from the middle of the area, began a volume at 21:22 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, 9.4 hours before the alert went out and 118 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.

739 
WGUS51 KBOX 172121
FFWBOX
CTC003-013-015-180030-
/O.NEW.KBOX.FF.W.0011.210717T2121Z-210718T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Boston/Norton MA
521 PM EDT Sat Jul 17 2021

The National Weather Service in Norton has issued a

* Flash Flood Warning for...
  East Central Hartford County in northern Connecticut...
  Central Tolland County in northern Connecticut...
  West Central Windham County in northern Connecticut...

* Until 830 PM EDT.

* At 521 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 3 inches of rain 
  have fallen. 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...
  Manchester, East Hartford, Vernon, Windsor, Mansfield, South 
  Windsor, Ellington, Tolland, Coventry, East Windsor, Willington, 
  Bolton, Ashford and Chaplin.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 4192 7240 4194 7221 4181 7215 4175 7259
      4188 7267

FLASH FLOOD...RADAR INDICATED

$$

BL

3 follow-up statements

443 
WGUS71 KBOX 172317
FFSBOX

Flash Flood Statement
National Weather Service Boston/Norton MA
717 PM EDT Sat Jul 17 2021

CTC003-172327-
/O.CAN.KBOX.FF.W.0011.000000T0000Z-210718T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hartford CT-
717 PM EDT Sat Jul 17 2021

...FLASH FLOOD WARNING IS CANCELLED FOR EAST CENTRAL HARTFORD 
COUNTY...

Flooding is no longer expected to pose a threat. Please continue to 
heed remaining road closures.

A Flash Flood Watch remains in effect until 600 AM EDT Sunday for 
portions of northern Connecticut and Massachusetts.

LAT...LON 4192 7240 4194 7221 4181 7215 4181 7248
      4191 7249

$$

CTC013-015-180030-
/O.CON.KBOX.FF.W.0011.000000T0000Z-210718T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Tolland CT-Windham CT-
717 PM EDT Sat Jul 17 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 830 PM EDT THIS 
EVENING FOR CENTRAL TOLLAND AND WEST CENTRAL WINDHAM COUNTIES...

At 717 PM EDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 2 and 4 inches of rain have 
fallen. 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...
  Manchester, Vernon, Mansfield, Ellington, Tolland, Coventry, 
  Willington, Ashford and Chaplin.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 4192 7240 4194 7221 4181 7215 4181 7248
      4191 7249

FLASH FLOOD...RADAR INDICATED

$$

BL

129 
WGUS51 KBOX 172330
FFWBOX
CTC013-015-180230-
/O.EXT.KBOX.FF.W.0011.000000T0000Z-210718T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Boston/Norton MA
730 PM EDT Sat Jul 17 2021

The National Weather Service in Norton has extended the

* Flash Flood Warning for...
  Central Tolland County in northern Connecticut...
  West Central Windham County in northern Connecticut...

* Until 1030 PM EDT.

* At 730 PM EDT, the Mount Hope River gauge at Warrenville was at 
  10.3 feet at 719 PM, this is in major flood stage. Doppler radar 
  estimates between 2 and 4 inches of rain have fallen. Flash 
  flooding is ongoing or expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar and automated gauges.

  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...
  Manchester, Vernon, Mansfield, Ellington, Tolland, Coventry, 
  Willington, Ashford and Chaplin.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 4192 7240 4194 7221 4181 7215 4181 7248
      4191 7249

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

BL

234 
WGUS71 KBOX 180221
FFSBOX

Flash Flood Statement
National Weather Service Boston/Norton MA
1021 PM EDT Sat Jul 17 2021

CTC013-015-180231-
/O.EXP.KBOX.FF.W.0011.000000T0000Z-210718T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Tolland CT-Windham CT-
1021 PM EDT Sat Jul 17 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1030 PM EDT THIS EVENING FOR 
CENTRAL TOLLAND AND WEST CENTRAL WINDHAM COUNTIES...

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 600 AM EDT Sunday for 
portions of northern Connecticut and Massachusetts.

LAT...LON 4192 7240 4194 7221 4181 7215 4181 7248
      4191 7249

$$

BL

The office that day

Everything else NWS Boston/Norton, MA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 17, 1:59 PM EDT	Special Weather Statement	BOX		46 min
Jul 17, 3:26 PM EDT	Severe Thunderstorm Warning	BOX	Northeastern Connecticut Planning Region	64 min
Jul 17, 3:47 PM EDT	Areal Flood Warning	BOX	Northeastern Connecticut Planning Region	118 min
Jul 17, 4:14 PM EDT	Flash Flood Warning	BOX	Northeastern Connecticut Planning Region	5 hr
Jul 17, 4:15 PM EDT	Severe Thunderstorm Warning	BOX	Northeastern Connecticut Planning Region	60 min
Jul 17, 4:18 PM EDT	Severe Thunderstorm Warning	BOX	Northeastern Connecticut Planning Region	57 min
Jul 17, 4:20 PM EDT	Special Weather Statement	BOX		40 min
Jul 17, 4:29 PM EDT	Severe Thunderstorm Warning	BOX	Northeastern Connecticut Planning Region	61 min
Jul 17, 4:38 PM EDT	Severe Thunderstorm Warning	BOX	Capitol Planning Region	67 min
Jul 17, 4:58 PM EDT	Flash Flood Warning	BOX	Capitol Planning Region	2 hr
Jul 17, 5:30 PM EDT	Flash Flood Warning	BOX	Northeastern Connecticut 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.