Alert archive / Massachusetts / Flash Flood Watches in 2021

Flash Flood Watch 7, NWS Boston/Norton, MA

September 23, 2021Franklin County, Hampden County, Hampshire County, Massachusetts; Capitol Planning Region, Connecticut

NWS Boston/Norton, MA issued this flash flood watch at Sep 23, 2021, 2:48 PM EDT for Franklin County, Hampden County, Hampshire County, Massachusetts; Capitol Planning Region, Connecticut. It took effect at Sep 24, 2021, 12:00 AM EDT. It was in force for 10 hr.

The area

The counties it named.

The facts

Issued
Sep 23, 2021, 2:48 PM EDT (18:48 UTC)
In effect from
Sep 24, 2021, 12:00 AM EDT
Expired
Sep 24, 2021, 9:38 AM EDT
In force
10 hr
Issued by
NWS Boston/Norton, MA
Flood severity
None

Counties Capitol Planning Region, CT, Franklin County, MA, Hampden County, MA, Hampshire County, MA

The radar

The Boston radar (KBOX), 125 km from the middle of the area, began a volume at 18:48 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, 6.8 hours before the alert went out and 113 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 2021-09-23Temperature 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, Albany, NY at 12:00Z on 2021-09-23The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 283 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
17 J/kg
Mixed-layer CIN
-12 J/kg
Mixed-layer LCL
775 m above ground
0-6 km bulk shear
43 kt
0-1 km storm-relative helicity
283 m²/s²
0-3 km storm-relative helicity
308 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

811 
WGUS61 KBOX 231848
FFABOX

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Boston/Norton MA
248 PM EDT Thu Sep 23 2021

CTZ002-MAZ002-003-008>011-240700-
/O.NEW.KBOX.FF.A.0007.210924T0400Z-210924T1600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hartford CT-Western Franklin MA-Eastern Franklin MA-Western
Hampshire MA-Western Hampden MA-Eastern Hampshire MA-Eastern Hampden
MA-
Including the cities of Greenfield, Northampton, Charlemont, 
Hartford, Amherst, Orange, Chesterfield, Windsor Locks, Springfield, 
and Blandford
248 PM EDT Thu Sep 23 2021

...FLASH FLOOD WATCH IN EFFECT FROM MIDNIGHT EDT TONIGHT THROUGH 
FRIDAY MORNING...

The National Weather Service in Norton has issued a

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

* From Midnight EDT tonight through Friday morning.

* A slow moving frontal boundary will bring a period of moderate to 
  heavy rainfall to the area. Some embedded thunderstorms are also 
  possible. Total rainfall amounts of 1 to 3 inches are forecast, 
  with locally higher amounts.

* Heavy rainfall may cause flooding of roads and ponding of water in 
  low lying areas, as well as isolated to scattered flash flooding. 
  Morning commute may also be impacted.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

Chai
2 follow-up statements
730 
WGUS61 KBOX 240056
FFABOX

Flood Watch
National Weather Service Boston/Norton MA
856 PM EDT Thu Sep 23 2021

CTZ002-MAZ002-003-008>011-241600-
/O.CON.KBOX.FF.A.0007.210924T0400Z-210924T1600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hartford CT-Western Franklin MA-Eastern Franklin MA-Western
Hampshire MA-Western Hampden MA-Eastern Hampshire MA-Eastern Hampden
MA-
Including the cities of Greenfield, Northampton, Charlemont, 
Hartford, Amherst, Orange, Chesterfield, Windsor Locks, Springfield, 
and Blandford
856 PM EDT Thu Sep 23 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT FROM MIDNIGHT EDT TONIGHT 
THROUGH FRIDAY MORNING...

The Flash Flood Watch continues for

* Portions of northern Connecticut and western Massachusetts, 
  including the following areas, in northern Connecticut, Hartford 
  CT. In western Massachusetts, Eastern Franklin MA, Eastern Hampden 
  MA, Eastern Hampshire MA, Western Franklin MA, Western Hampden MA 
  and Western Hampshire MA.

* From Midnight EDT tonight through Friday morning.

* A slow-moving front will bring a period of moderate to heavy 
  rainfall to the area. Some embedded thunderstorms are also 
  possible. Total rainfall amounts of 1 to 3 inches are forecast, 
  with locally higher amounts.

* Heavy rainfall may cause flooding of roads and ponding of water in 
  low lying areas, as well as isolated to scattered flash flooding. 
  The morning commute may also be impacted.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

$$

Belk
977 
WGUS61 KBOX 241338
FFABOX

Flood Watch
National Weather Service Boston/Norton MA
938 AM EDT Fri Sep 24 2021

CTZ002-MAZ002-003-008>011-241445-
/O.CAN.KBOX.FF.A.0007.000000T0000Z-210924T1600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hartford CT-Western Franklin MA-Eastern Franklin MA-Western
Hampshire MA-Western Hampden MA-Eastern Hampshire MA-Eastern Hampden
MA-
Including the cities of Greenfield, Northampton, Charlemont, 
Hartford, Amherst, Orange, Chesterfield, Windsor Locks, Springfield, 
and Blandford
938 AM EDT Fri Sep 24 2021

...FLASH FLOOD WATCH IS CANCELLED...

The Flash Flood Watch for portions of northern Connecticut and 
western Massachusetts, including the following areas, in northern 
Connecticut, Hartford CT. In western Massachusetts, Eastern Franklin 
MA, Eastern Hampden MA, Eastern Hampshire MA, Western Franklin MA, 
Western Hampden MA and Western Hampshire MA has been cancelled.

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

$$

KS

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 23, 9:28 AM EDTRip Current StatementBOXBarnstable, Bristol, Dukes, Essex, Nantucket, Norfolk and 2 more35 hr
Sep 23, 9:31 AM EDTSmall Craft AdvisoryBOX30 hr

Nearby

Flash Flood Watches in Massachusetts, 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.