Alert archive / Massachusetts / Flash Flood Warnings in 2018

Flash Flood Warning 21, NWS Boston/Norton, MA

August 4, 2018Barnstable County, Massachusetts

NWS Boston/Norton, MA issued this flash flood warning at Aug 4, 2018, 8:29 PM EDT for Barnstable County, Massachusetts. It was in force for 74 min. 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: Aug 4, 2018, 8:29 PM EDT (00:29 UTC)
Expired: Aug 4, 2018, 9:43 PM EDT
In force: 74 min
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Flood severity: None

County Barnstable County, MA

The radar

The Boston radar (KBOX), 92 km from the middle of the area, began a volume at 00:33 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
Aug 4, 8:35 PM EDT	FLOOD	Wellfleet, MA	CAR FLOATING DUE TO FLOOD WATERS ON HAMBLIN FARM ROAD AT CHEQUESSETT NECK ROAD
Aug 4, 8:39 PM EDT	FLOOD	Wellfleet, MA	CAR TOWED OUT OF FLOOD WATERS ON COVE ROAD
Aug 4, 9:06 PM EDT	FLOOD	Wellfleet, MA	BASEMENT FLOODED ON KENDRICK AVE. UNABLE TO ACCESS.

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

The nearest sounding before it

Chatham, MA (KCHH), launched 00:00Z, 0.5 hours before the alert went out and 25 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: 1305 J/kg
Mixed-layer CIN: -5 J/kg
Mixed-layer LCL: 485 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 209 m²/s²
0-3 km storm-relative helicity: 231 m²/s²
Significant tornado parameter: 0.8
Supercell composite: 5.1

Open this sounding in Storm Lab

The text

As transmitted.

158 
WGUS51 KBOX 050029
FFWBOX
MAC001-050230-
/O.NEW.KBOX.FF.W.0021.180805T0029Z-180805T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Boston/Norton MA
829 PM EDT SAT AUG 4 2018

The National Weather Service in Boston/Norton has issued a

* Flash Flood Warning for...
  Northeastern Barnstable County in southeastern Massachusetts...

* Until 1030 PM EDT.

* At 828 PM EDT...Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Trained weather spotters have 
  reported upwards of 4 inches of rain across the warned area. Road 
  closures are being reported in Eastham and Wellfleet MA. Flash 
  flooding is ongoing.

* Some locations that will experience flooding include...
  Eastham, Wellfleet and Truro. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Warning means that flooding will occur quickly, and
could be life threatening for those who try to drive through flooded
roads or underpasses. Find alternate routes. Those near small streams
need to get to higher ground immediately.

&&

LAT...LON 4183 7002 4188 7001 4191 7005 4187 7005
      4187 7009 4198 7009 4199 6998 4185 6993

$$

Sipprell

1 follow-up statement

576 
WGUS71 KBOX 050143
FFSBOX

Flash Flood Statement
National Weather Service Boston/Norton MA
943 PM EDT SAT AUG 4 2018

MAC001-050152-
/O.CAN.KBOX.FF.W.0021.000000T0000Z-180805T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Barnstable MA-
943 PM EDT SAT AUG 4 2018

...THE FLASH FLOOD WARNING FOR NORTHEASTERN BARNSTABLE COUNTY IS
CANCELLED...

The heavy rain has ended. Flooding is no longer expected to pose a
threat. Please continue to heed any remaining road closures.

LAT...LON 4183 7002 4188 7001 4191 7005 4187 7005
      4187 7009 4198 7009 4199 6998 4185 6993

$$

DUNTEN

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 4, 8:18 PM EDT	Areal Flood Advisory	BOX	Barnstable	117 min
Aug 5, 4:00 AM EDT	Dense Fog Advisory	BOX	Barnstable, Essex, Norfolk, Plymouth, Suffolk	5 hr
Aug 5, 2:58 PM EDT	Heat Advisory	BOX	Barnstable, Bristol, Essex, Franklin, Hampden, Hampshire and 5 more	53 hr

Nearby

Flash Flood Warnings in Massachusetts, 2018 Every flash flood warning in 2018

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.