Alert archive / Massachusetts / Flash Flood Warnings in 2021

Flash Flood Warning 14, NWS Boston/Norton, MA

July 17, 2021Hampden County, Hampshire County, Massachusetts

NWS Boston/Norton, MA issued this flash flood warning at Jul 17, 2021, 6:04 PM EDT for Hampden County, Hampshire County, Massachusetts. It was in force for 3 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, 6:04 PM EDT (22:04 UTC)
Expired
Jul 17, 2021, 9:15 PM EDT
In force
3 hr
Issued by
NWS Boston/Norton, MA
Area
Storm-based polygon
Flood severity
None

Counties Hampden County, MA, Hampshire County, MA

The radar

The Albany radar (KENX), 101 km from the middle of the area, began a volume at 22:04 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, 10.1 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-pSkew-T log-p diagram, Albany, NY at 12:00Z on 2021-07-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2021-07-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 83 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
958 m above ground
0-6 km bulk shear
34 kt
0-1 km storm-relative helicity
83 m²/s²
0-3 km storm-relative helicity
163 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

As transmitted.

150 
WGUS51 KBOX 172204
FFWBOX
MAC013-015-180115-
/O.NEW.KBOX.FF.W.0014.210717T2204Z-210718T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Norton has issued a

* Flash Flood Warning for...
  Northwestern Hampden County in western Massachusetts...
  Southwestern Hampshire County in western Massachusetts...

* Until 915 PM EDT.

* At 604 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 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...
  Holyoke, Northampton, South Hadley, Easthampton, Southampton, 
  Hadley, Hatfield, Williamsburg, Huntington, Russell, Westhampton, 
  Chester, Blandford, Chesterfield, Montgomery and Tolland.

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 4215 7306 4217 7303 4222 7301 4225 7301
      4225 7300 4228 7300 4230 7300 4237 7273
      4235 7261 4226 7259 4221 7278 4215 7303
      4215 7305 4214 7307 4215 7307

FLASH FLOOD...RADAR INDICATED

$$

BL
2 follow-up statements
442 
WGUS71 KBOX 172317 RRA
FFSBOX

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

MAC013-015-180115-
/O.CON.KBOX.FF.W.0014.000000T0000Z-210718T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hampden MA-Hampshire MA-
717 PM EDT Sat Jul 17 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 915 PM EDT THIS 
EVENING FOR NORTHWESTERN HAMPDEN AND SOUTHWESTERN HAMPSHIRE 
COUNTIES...

At 717 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...
  Northampton, Easthampton, Southampton, Hadley, Hatfield, 
  Huntington, Russell, Westhampton, Chester, Blandford and 
  Montgomery.

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 4219 7302 4222 7301 4223 7301 4225 7301
      4225 7300 4228 7300 4230 7293 4236 7274
      4235 7261 4230 7262 4224 7279 4218 7295
      4217 7303

FLASH FLOOD...RADAR INDICATED

$$

BL
406 
WGUS71 KBOX 180111
FFSBOX

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

MAC013-015-180121-
/O.EXP.KBOX.FF.W.0014.000000T0000Z-210718T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hampden MA-Hampshire MA-
911 PM EDT Sat Jul 17 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 915 PM EDT THIS EVENING FOR 
NORTHWESTERN HAMPDEN AND SOUTHWESTERN HAMPSHIRE 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 4219 7302 4222 7301 4223 7301 4225 7301
      4225 7300 4228 7300 4230 7293 4236 7274
      4235 7261 4230 7262 4224 7279 4218 7295
      4217 7303

$$

BL

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 17, 2:37 PM EDTSpecial Weather StatementBOXFranklin38 min
Jul 17, 2:45 PM EDTSpecial Weather StatementBOXPlymouth45 min
Jul 17, 2:53 PM EDTSpecial Weather StatementBOXHampshire52 min
Jul 17, 2:53 PM EDTSevere Thunderstorm WarningBOXBristol, Norfolk52 min
Jul 17, 3:36 PM EDTAreal Flood WarningBOXBristol114 min
Jul 17, 4:05 PM EDTSevere Thunderstorm WarningBOXWorcester34 min
Jul 17, 4:15 PM EDTSevere Thunderstorm WarningBOXHampden, Worcester60 min
Jul 17, 4:34 PM EDTSevere Thunderstorm WarningBOXMiddlesex, Worcester36 min
Jul 17, 4:38 PM EDTSevere Thunderstorm WarningBOXHampden, Hampshire67 min
Jul 17, 4:48 PM EDTFlash Flood WarningBOXWorcester3 hr
Jul 17, 4:58 PM EDTFlash Flood WarningBOXHampden2 hr
Jul 17, 5:10 PM EDTSevere Thunderstorm WarningBOXMiddlesex, Worcester65 min
Jul 17, 5:34 PM EDTSpecial Weather StatementBOXHampshire41 min
Jul 17, 5:35 PM EDTFlash Flood WarningBOXHampden, Hampshire3 hr
Jul 17, 6:05 PM EDTSevere Thunderstorm WarningBOXBristol26 min
Jul 17, 7:49 PM EDTAreal Flood WarningBOXHampden, Worcester116 min

Nearby

Flash Flood Warnings in Massachusetts, 2021Every 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.