Alert archive / Massachusetts / Flash Flood Warnings in 2017

Flash Flood Warning 2, NWS Boston/Norton, MA

May 5, 20174 counties in Massachusetts

NWS Boston/Norton, MA issued this flash flood warning at May 5, 2017, 5:51 PM EDT for 4 counties in Massachusetts. It was in force for 114 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
May 5, 2017, 5:51 PM EDT (21:51 UTC)
Expired
May 5, 2017, 7:45 PM EDT
In force
114 min
Issued by
NWS Boston/Norton, MA
Area
Storm-based polygon
Flood severity
None

Counties Bristol County, MA, Norfolk County, MA, Plymouth County, MA, Suffolk County, MA

The radar

The Boston radar (KBOX), 25 km from the middle of the area, began a volume at 21:51 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

Chatham, MA (KCHH), launched 12:00Z, 9.9 hours before the alert went out and 87 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, Chatham, MA at 12:00Z on 2017-05-05Temperature 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, Chatham, MA at 12:00Z on 2017-05-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 68 square meters per square second.1939587897Sfc1 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
879 m above ground
0-6 km bulk shear
54 kt
0-1 km storm-relative helicity
68 m²/s²
0-3 km storm-relative helicity
108 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

097 
WGUS51 KBOX 052151
FFWBOX
MAC005-021-023-025-052345-
/O.NEW.KBOX.FF.W.0002.170505T2151Z-170505T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Taunton MA
551 PM EDT FRI MAY 5 2017

The National Weather Service in Taunton has issued a

* Flash Flood Warning for...
  Northeastern Norfolk County in eastern Massachusetts...
  Suffolk County in eastern Massachusetts...
  Plymouth County in southeastern Massachusetts...
  Northeastern Bristol County in southeastern Massachusetts...

* Until 745 PM EDT

* At 549 PM EDT, Doppler radar indicated heavy rain moving into and 
  across the warning area. Rainfall of 1 to 2 inches in an hour is 
  expected in some areas. As a result, significant urban and poor 
  drainage flooding is expected to rapidly form.

* Some locations that will experience flooding include...
  Boston, Cambridge, New Bedford, Brockton, Quincy, Newton,
  Brookline, Plymouth, Taunton, Weymouth, Revere, Everett, Braintree,
  Chelsea, Randolph, Needham, Norwood, Wellesley, Milton and
  Stoughton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Flooding will occur quickly and could become life threatening for
those who try to drive through flooded roads or underpasses. Find
alternate routes and avoid flooded areas.

&&

LAT...LON 4179 7055 4177 7062 4176 7060 4175 7063
      4170 7062 4166 7093 4233 7126 4228 7119
      4230 7117 4235 7117 4237 7112 4235 7111
      4236 7108 4239 7107 4244 7095 4206 7061
      4186 7052

$$

NMB
2 follow-up statements
162 
WGUS71 KBOX 052218
FFSBOX

Flash Flood Statement
National Weather Service Taunton MA
618 PM EDT FRI MAY 5 2017

MAC005-021-023-025-052345-
/O.CON.KBOX.FF.W.0002.000000T0000Z-170505T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Norfolk MA-Suffolk MA-Plymouth MA-Bristol MA-
618 PM EDT FRI MAY 5 2017

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 745 PM EDT FOR
NORTHEASTERN NORFOLK...SUFFOLK...PLYMOUTH AND NORTHEASTERN BRISTOL
COUNTIES...

At 615 PM EDT, Doppler radar indicated that the heaviest 
rainfall has moved eastward to a line from Hull to Weymouth to 
Plymouth. Areas of light to moderate rain continued thru the 
remainder of the warning area. 

Due to the recent heavy rains and continued light to moderate rain, 
areas of significant urban and poor drainage flooding remain likely 
in the warning area.  In addition, some quick responding small 
streams may crest near bankfull levels. 

Some locations that will experience flooding include...
Boston, Cambridge, New Bedford, Brockton, Quincy, Newton, Brookline,
Plymouth, Taunton, Weymouth, Revere, Everett, Braintree, Chelsea,
Randolph, Needham, Norwood, Wellesley, Milton and Stoughton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Flooding will occur quickly, and those who attempt to drive through 
flooded roads and underpasses may become trapped. Find alternate 
routes and avoid flooded areas.

&&

LAT...LON 4179 7055 4177 7062 4176 7060 4175 7063
      4170 7062 4166 7093 4233 7126 4228 7119
      4230 7117 4235 7117 4237 7112 4235 7111
      4236 7108 4239 7107 4244 7095 4206 7061
      4186 7052

$$

NMB
412 
WGUS71 KBOX 052330
FFSBOX

Flash Flood Statement
National Weather Service Taunton MA
730 PM EDT FRI MAY 5 2017

MAC005-021-023-025-052339-
/O.CAN.KBOX.FF.W.0002.000000T0000Z-170505T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Norfolk MA-Suffolk MA-Plymouth MA-Bristol MA-
730 PM EDT FRI MAY 5 2017

...THE FLASH FLOOD WARNING FOR NORTHEASTERN NORFOLK...SUFFOLK...
PLYMOUTH AND NORTHEASTERN BRISTOL COUNTIES IS CANCELLED...

The large area of moderate to heavy rainfall that affected southeast 
Massachusetts and the Boston area earlier this evening, has moved to 
the east. Light to briefly moderate rain may still cross the area 
this evening. However the threat for more widespread moderate to 
heavy rainfall has abated. Any lingering poor drainage flooding is 
expected to gradually recede. Thus the Flash Flood Warning is being 
allowed to expire. 

Please continue to heed any remaining road closures.

LAT...LON 4179 7055 4177 7062 4176 7060 4175 7063
      4170 7062 4166 7093 4233 7126 4228 7119
      4230 7117 4235 7117 4237 7112 4235 7111
      4236 7108 4239 7107 4244 7095 4206 7061
      4186 7052

$$

NMB

The office that day

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

IssuedProductOfficeCountiesLasted
May 5, 4:13 AM EDTFlood WatchBOXBarnstable, Bristol, Dukes, Essex, Middlesex, Nantucket and 4 more24 hr
May 5, 2:57 PM EDTSpecial Weather StatementBOXBristol33 min
May 5, 4:03 PM EDTSpecial Weather StatementBOXWorcester57 min
May 5, 4:46 PM EDTSpecial Weather StatementBOXBristol, Norfolk44 min
May 5, 5:17 PM EDTSpecial Weather StatementBOXBristol, Norfolk, Suffolk43 min
May 5, 5:25 PM EDTFlash Flood WarningBOXBristol, Norfolk, Plymouth2 hr

Nearby

Flash Flood Warnings in Massachusetts, 2017Every flash flood warning in 2017

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.