Alert archive / Massachusetts / Flash Flood Warnings in 2021

Flash Flood Warning 16, NWS Boston/Norton, MA

July 18, 2021Franklin County, Hampshire County, Worcester County, Massachusetts

NWS Boston/Norton, MA issued this flash flood warning at Jul 18, 2021, 9:26 PM EDT for Franklin County, Hampshire County, Worcester County, Massachusetts. It was in force for 3 hr. 3 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 18, 2021, 9:26 PM EDT (01:26 UTC)
Expired: Jul 19, 2021, 12:30 AM EDT
In force: 3 hr
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Flood severity: None

Counties Franklin County, MA, Hampshire County, MA, Worcester County, MA

The radar

The Albany radar (KENX), 116 km from the middle of the area, began a volume at 01:28 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 18, 9:42 PM EDT	FLOOD	Deerfield, MA	CAR STUCK IN FLOOD WATERS ON WAPPING ROAD AT DEPOT ROAD. PART OF CONWAY ROAD WASHED OUT.
Jul 18, 10:02 PM EDT	FLOOD	Montague, MA	FLOOD WATERS GOING INTO BUSINESS.
Jul 18, 10:19 PM EDT	FLOOD	Deerfield, MA	ROUTE 5 CLOSED DUE TO FLOODING.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Albany, NY (KALY), launched 00:00Z, 1.4 hours before the alert went out and 99 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: 12 J/kg
Mixed-layer CIN: -208 J/kg
Mixed-layer LCL: 527 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: 9 m²/s²
0-3 km storm-relative helicity: 31 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

912 
WGUS51 KBOX 190126
FFWBOX
MAC011-015-027-190430-
/O.NEW.KBOX.FF.W.0016.210719T0126Z-210719T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Boston/Norton MA
926 PM EDT Sun Jul 18 2021

The National Weather Service in Norton has issued a

* Flash Flood Warning for...
  Northwestern Worcester County in central Massachusetts...
  Central Franklin County in western Massachusetts...
  Central Hampshire County in western Massachusetts...

* Until 1230 AM EDT.

* At 926 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Given the heavy rain that occurred last night, it 
  will not take much rain to produce flooding. Additional rainfall 
  amounts of 0.5 to 1 inch are possible in the warned area. Flash 
  flooding is already occurring.

  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...
  Amherst, Greenfield, Orange, Deerfield, Athol, Winchendon, 
  Montague, Templeton, Ashburnham, Hadley, Sunderland, Hatfield, 
  Northfield, Williamsburg, Bernardston, Buckland, Conway, 
  Shelburne, Leverett and Erving.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4248 7287 4272 7253 4270 7193 4243 7251
      4239 7261 4241 7268 4241 7270 4245 7270
      4246 7276 4247 7282 4248 7284

FLASH FLOOD...RADAR INDICATED

$$

BW

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 18, 9:15 PM EDT	Special Weather Statement	BOX	Franklin	90 min
Jul 18, 10:37 PM EDT	Areal Flood Warning	BOX	Hampden, Hampshire	4 hr
Jul 19, 12:26 AM EDT	Areal Flood Warning	BOX	Hampshire	119 min
Jul 19, 12:32 AM EDT	Areal Flood Warning	BOX	Franklin, Worcester	118 min
Jul 19, 4:25 AM EDT	Areal Flood Warning	BOX	Hampden	2 hr
Jul 19, 6:24 AM EDT	River Flood Warning	BOX	Hampden, Hampshire	5 hr

Nearby

Flash Flood Warnings in Massachusetts, 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.