Alert archive / Massachusetts / Flash Flood Watches in 2021

Flash Flood Watch 4, NWS Boston/Norton, MA

July 16, 2021Providence County, Rhode Island; 4 counties in Massachusetts; Capitol Planning Region, Northeastern Connecticut Planning Region, Connecticut

NWS Boston/Norton, MA issued this flash flood watch at Jul 16, 2021, 2:59 PM EDT for Providence County, Rhode Island; 4 counties in Massachusetts; Capitol Planning Region, Northeastern Connecticut Planning Region, Connecticut. It took effect at Jul 17, 2021, 2:00 PM EDT. It was in force for 33 hr.

The area

The counties it named.

The facts

Issued
Jul 16, 2021, 2:59 PM EDT (18:59 UTC)
In effect from
Jul 17, 2021, 2:00 PM EDT
Expired
Jul 18, 2021, 11:00 PM EDT
In force
33 hr
Issued by
NWS Boston/Norton, MA
Flood severity
None

Counties Capitol Planning Region, CT, Northeastern Connecticut Planning Region, CT, Franklin County, MA, Hampden County, MA, Hampshire County, MA, Worcester County, MA, Providence County, RI

The radar

The Boston radar (KBOX), 96 km from the middle of the area, began a volume at 19:01 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

Albany, NY (KALY), launched 12:00Z, 7.0 hours before the alert went out and 142 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, Albany, NY at 12:00Z on 2021-07-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 156 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, Albany, NY at 12:00Z on 2021-07-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 81 square meters per square second.193958Sfc1 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
156 J/kg
Mixed-layer CIN
-98 J/kg
Mixed-layer LCL
1140 m above ground
0-6 km bulk shear
42 kt
0-1 km storm-relative helicity
81 m²/s²
0-3 km storm-relative helicity
93 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.5

Open this sounding in Storm Lab

The text

As transmitted.

918 
WGUS61 KBOX 161859
FFABOX

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Boston/Norton MA
259 PM EDT Fri Jul 16 2021

CTZ002>004-MAZ002>004-008>012-170300-
/O.NEW.KBOX.FF.A.0004.210717T1800Z-210718T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hartford CT-Tolland CT-Windham CT-Western Franklin MA-Eastern
Franklin MA-Northern Worcester MA-Western Hampshire MA-Western
Hampden MA-Eastern Hampshire MA-Eastern Hampden MA-Southern
Worcester MA-
Including the cities of Milford, Fitchburg, Greenfield, Blandford, 
Union, Willimantic, Northampton, Worcester, Charlemont, Vernon, 
Amherst, Hartford, Barre, Orange, Chesterfield, Windsor Locks, 
Springfield, and Putnam
259 PM EDT Fri Jul 16 2021

...FLASH FLOOD WATCH IN EFFECT FROM SATURDAY AFTERNOON THROUGH 
SATURDAY EVENING...

The National Weather Service in Norton has issued a

* Flash Flood Watch for portions of northern Connecticut and 
  Massachusetts, including the following areas, in northern 
  Connecticut, Hartford CT, Tolland CT and Windham CT. In 
  Massachusetts, Eastern Franklin MA, Eastern Hampden MA, Eastern 
  Hampshire MA, Northern Worcester MA, Southern Worcester MA, 
  Western Franklin MA, Western Hampden MA and Western Hampshire MA.

* From Saturday afternoon through Saturday evening.

* There will be a moderate risk for excessive rainfall tomorrow 
  afternoon and evening. Scattered showers and thunderstorms will 
  overspread the watch area Saturday afternoon and evening producing 
  widespread rainfall amounts of 1 to 1.5 inches with locally higher 
  amounts possible.

* The ground is wet from recent rainfall and the expected heavy 
  rainfall may cause localized flash flooding especially in urban 
  and poor drainage areas. Some smaller streams may quickly rise out 
  of their banks.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$
6 follow-up statements
717 
WGUS61 KBOX 170122
FFABOX

Flood Watch
National Weather Service Boston/Norton MA
922 PM EDT Fri Jul 16 2021

CTZ002>004-MAZ002>004-008>012-171000-
/O.CON.KBOX.FF.A.0004.210717T1800Z-210718T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hartford CT-Tolland CT-Windham CT-Western Franklin MA-Eastern
Franklin MA-Northern Worcester MA-Western Hampshire MA-Western
Hampden MA-Eastern Hampshire MA-Eastern Hampden MA-Southern
Worcester MA-
Including the cities of Milford, Fitchburg, Greenfield, Blandford, 
Union, Willimantic, Northampton, Worcester, Charlemont, Vernon, 
Amherst, Hartford, Barre, Orange, Chesterfield, Windsor Locks, 
Springfield, and Putnam
922 PM EDT Fri Jul 16 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT FROM SATURDAY AFTERNOON 
THROUGH SATURDAY EVENING...

The Flash Flood Watch continues for

* Portions of northern Connecticut and Massachusetts, including the 
  following areas, in northern Connecticut, Hartford CT, Tolland CT 
  and Windham CT. In Massachusetts, Eastern Franklin MA, Eastern 
  Hampden MA, Eastern Hampshire MA, Northern Worcester MA, Southern 
  Worcester MA, Western Franklin MA, Western Hampden MA and Western 
  Hampshire MA.

* From Saturday afternoon through Saturday evening.

* Showers and thunderstorms will bring rainfall amounts of 1 to 1.5 
  inches with locally higher amounts possible.

* The ground is wet from recent rainfall and the expected heavy 
  rainfall may cause rapid flooding of urban areas and small streams. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued. Drivers should avoid flooded 
roads.

&&

$$

JWD
839 
WGUS61 KBOX 170648
FFABOX

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Boston/Norton MA
248 AM EDT Sat Jul 17 2021

CTZ002>004-MAZ002>004-008>012-172100-
/O.EXT.KBOX.FF.A.0004.210717T1800Z-210718T1000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hartford CT-Tolland CT-Windham CT-Western Franklin MA-Eastern
Franklin MA-Northern Worcester MA-Western Hampshire MA-Western
Hampden MA-Eastern Hampshire MA-Eastern Hampden MA-Southern
Worcester MA-
Including the cities of Milford, Fitchburg, Greenfield, Blandford, 
Union, Willimantic, Northampton, Worcester, Charlemont, Vernon, 
Amherst, Hartford, Barre, Orange, Chesterfield, Windsor Locks, 
Springfield, and Putnam
248 AM EDT Sat Jul 17 2021

...FLASH FLOOD WATCH NOW IN EFFECT FROM 2 PM EDT THIS AFTERNOON 
THROUGH LATE TONIGHT...

The Flash Flood Watch is now in effect for

* Portions of northern Connecticut and Massachusetts, including the 
  following areas, in northern Connecticut, Hartford CT, Tolland CT 
  and Windham CT. In Massachusetts, Eastern Franklin MA, Eastern 
  Hampden MA, Eastern Hampshire MA, Northern Worcester MA, Southern 
  Worcester MA, Western Franklin MA, Western Hampden MA and Western 
  Hampshire MA.

* From 2 PM EDT this afternoon through late tonight.

* Showers and thunderstorms will bring rainfall amounts of 1 to 2 
  inches through tonight with locally higher amounts possible.

* The ground remains wet from recent rainfall and the additional 
  heavy rainfall this afternoon and tonight may cause rapid flooding 
  of urban areas and small streams.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

JWD
751 
WGUS61 KBOX 171956
FFABOX

Flood Watch
National Weather Service Boston/Norton MA
356 PM EDT Sat Jul 17 2021

CTZ002>004-MAZ002>004-008>012-181000-
/O.CON.KBOX.FF.A.0004.000000T0000Z-210718T1000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hartford CT-Tolland CT-Windham CT-Western Franklin MA-Eastern
Franklin MA-Northern Worcester MA-Western Hampshire MA-Western
Hampden MA-Eastern Hampshire MA-Eastern Hampden MA-Southern
Worcester MA-
Including the cities of Milford, Fitchburg, Greenfield, Blandford, 
Union, Willimantic, Northampton, Worcester, Charlemont, Vernon, 
Amherst, Hartford, Barre, Orange, Chesterfield, Windsor Locks, 
Springfield, and Putnam
356 PM EDT Sat Jul 17 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH LATE TONIGHT...

The Flash Flood Watch continues for

* Portions of northern Connecticut and Massachusetts, including the 
  following areas, in northern Connecticut, Hartford CT, Tolland CT 
  and Windham CT. In Massachusetts, Eastern Franklin MA, Eastern 
  Hampden MA, Eastern Hampshire MA, Northern Worcester MA, Southern 
  Worcester MA, Western Franklin MA, Western Hampden MA and Western 
  Hampshire MA.

* Through late tonight.

* Showers and thunderstorms will bring rainfall amounts of 1 to 3 
  inches through tonight with locally higher amounts possible.

* The ground remains wet from recent rainfall and the additional 
  heavy rainfall this afternoon and tonight may cause rapid flooding 
  of urban areas and small streams.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

BL
666 
WGUS61 KBOX 180630
FFABOX

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Boston/Norton MA
230 AM EDT Sun Jul 18 2021

RIZ001-002-182030-
/O.EXB.KBOX.FF.A.0004.000000T0000Z-210719T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Northwest Providence RI-Southeast Providence RI-
Including the cities of Providence, Foster, and Smithfield
230 AM EDT Sun Jul 18 2021

...FLASH FLOOD WATCH IN EFFECT THROUGH THIS EVENING...

The National Weather Service in Norton has expanded the

* Flash Flood Watch to include a portion of northern Rhode Island, 
  including the following areas, Northwest Providence RI and 
  Southeast Providence RI.

* Through this evening.

* Showers and thunderstorms on Sunday will bring rainfall amounts of 
  1 to 3 inches with locally higher amounts possible.

* The ground remains wet from recent rainfall and the additional 
  heavy rainfall this afternoon and tonight may cause rapid flooding 
  of urban areas and small streams.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

CTZ002>004-MAZ002>004-008>012-182030-
/O.EXT.KBOX.FF.A.0004.000000T0000Z-210719T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hartford CT-Tolland CT-Windham CT-Western Franklin MA-Eastern
Franklin MA-Northern Worcester MA-Western Hampshire MA-Western
Hampden MA-Eastern Hampshire MA-Eastern Hampden MA-Southern
Worcester MA-
Including the cities of Milford, Fitchburg, Greenfield, Blandford, 
Union, Willimantic, Northampton, Worcester, Charlemont, Vernon, 
Amherst, Hartford, Barre, Orange, Chesterfield, Windsor Locks, 
Springfield, and Putnam
230 AM EDT Sun Jul 18 2021

...FLASH FLOOD WATCH NOW IN EFFECT THROUGH THIS EVENING...

The Flash Flood Watch is now in effect for

* Portions of northern Connecticut and Massachusetts, including the 
  following areas, in northern Connecticut, Hartford CT, Tolland CT 
  and Windham CT. In Massachusetts, Eastern Franklin MA, Eastern 
  Hampden MA, Eastern Hampshire MA, Northern Worcester MA, Southern 
  Worcester MA, Western Franklin MA, Western Hampden MA and Western 
  Hampshire MA.

* Through this evening.

* Watch has been extended as another round of showers and 
  thunderstorms will bring rainfall amounts of 1 to 3 inches this 
  afternoon and  tonight with locally higher amounts possible.

* The ground remains wet from recent rainfall and the additional 
  heavy rainfall this afternoon and tonight may cause rapid flooding 
  of urban areas and small streams.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$
094 
WGUS61 KBOX 181955
FFABOX

Flood Watch
National Weather Service Boston/Norton MA
355 PM EDT Sun Jul 18 2021

RIZ001-002-182100-
/O.CAN.KBOX.FF.A.0004.000000T0000Z-210719T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Northwest Providence RI-Southeast Providence RI-
Including the cities of Providence, Foster, and Smithfield
355 PM EDT Sun Jul 18 2021

...FLASH FLOOD WATCH IS CANCELLED FOR NORTHERN RHODE ISLAND...

The Flash Flood Watch for Providence County Rhode Island has been 
cancelled.

Although showers are still possible into tonight, flash flooding is 
no longer expected to pose a threat.

$$

CTZ002>004-MAZ002>004-008>012-190300-
/O.CON.KBOX.FF.A.0004.000000T0000Z-210719T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hartford CT-Tolland CT-Windham CT-Western Franklin MA-Eastern
Franklin MA-Northern Worcester MA-Western Hampshire MA-Western
Hampden MA-Eastern Hampshire MA-Eastern Hampden MA-Southern
Worcester MA-
Including the cities of Milford, Fitchburg, Greenfield, Blandford, 
Union, Willimantic, Northampton, Worcester, Charlemont, Vernon, 
Amherst, Hartford, Barre, Orange, Chesterfield, Windsor Locks, 
Springfield, and Putnam
355 PM EDT Sun Jul 18 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL 11 PM EDT THIS 
EVENING...

The Flash Flood Watch continues for

* Portions of northern Connecticut and Massachusetts, including the 
  following areas, in northern Connecticut, Hartford CT, Tolland CT 
  and Windham CT. In Massachusetts, Eastern Franklin MA, Eastern 
  Hampden MA, Eastern Hampshire MA, Northern Worcester MA, Southern 
  Worcester MA, Western Franklin MA, Western Hampden MA and Western 
  Hampshire MA.

* Until 11 PM EDT this evening.

* Scattered showers and isolated thunderstorms could still produce 
  an additional 1 to 2 inches of rain in localized areas this 
  evening. Given the previous rain that has fallen, these amounts 
  could be enough to trigger localized flash flooding.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

GF
213 
WGUS61 KBOX 190320
FFABOX

Flood Watch
National Weather Service Boston/Norton MA
1120 PM EDT Sun Jul 18 2021

CTZ002>004-MAZ002>004-008>012-190430-
/O.EXP.KBOX.FF.A.0004.000000T0000Z-210719T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hartford CT-Tolland CT-Windham CT-Western Franklin MA-Eastern
Franklin MA-Northern Worcester MA-Western Hampshire MA-Western
Hampden MA-Eastern Hampshire MA-Eastern Hampden MA-Southern
Worcester MA-
Including the cities of Milford, Fitchburg, Greenfield, Blandford, 
Union, Willimantic, Northampton, Worcester, Charlemont, Vernon, 
Amherst, Hartford, Barre, Orange, Chesterfield, Windsor Locks, 
Springfield, and Putnam
1120 PM EDT Sun Jul 18 2021

...FLASH FLOOD WATCH HAS EXPIRED...

The Flash Flood Watch for portions of northern Connecticut and 
Massachusetts, including the following areas, in northern 
Connecticut, Hartford CT, Tolland CT and Windham CT. In 
Massachusetts, Eastern Franklin MA, Eastern Hampden MA, Eastern 
Hampshire MA, Northern Worcester MA, Southern Worcester MA, Western 
Franklin MA, Western Hampden MA and Western Hampshire MA has expired.

The Flood Watch is cancelled. Flooding is no longer expected to pose 
additional threat. Any ongoing flooding is receding. Please continue 
to heed remaining road closures.

$$

BW

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 16, 3:04 PM EDTSevere Thunderstorm WarningBOXProvidence56 min
Jul 16, 5:05 PM EDTSevere Thunderstorm WarningBOXProvidence55 min
Jul 16, 5:47 PM EDTSevere Thunderstorm WarningBOXProvidence33 min
Jul 16, 6:17 PM EDTSpecial Weather StatementBOXBristol, Kent, Providence58 min
Jul 16, 9:38 AM EDTHeat AdvisoryBOXBristol, Essex, Middlesex, Norfolk, Plymouth, Suffolk9 hr
Jul 16, 3:41 PM EDTSpecial Weather StatementBOXHampden49 min
Jul 16, 4:26 PM EDTSpecial Weather StatementBOXNorfolk, Suffolk49 min
Jul 16, 4:36 PM EDTSevere Thunderstorm WarningBOXMiddlesex, Norfolk, Worcester35 min
Jul 16, 4:50 PM EDTSpecial Marine WarningBOX55 min
Jul 16, 6:32 PM EDTSpecial Marine WarningBOX43 min
Jul 16, 5:14 PM EDTSpecial Weather StatementBOX46 min
Jul 16, 5:31 PM EDTSevere Thunderstorm WarningBOXCapitol Planning Region, Northeastern Connecticut Planning Region42 min

Nearby

Flash Flood Watches in Massachusetts, 2021Flash Flood Watches in Connecticut, 2021Flash Flood Watches in Rhode Island, 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.