Alert archive / Massachusetts / Flash Flood Warnings in 2017

Flash Flood Warning 10, NWS Boston/Norton, MA

July 12, 2017Middlesex County, Massachusetts

NWS Boston/Norton, MA issued this flash flood warning at Jul 12, 2017, 5:42 PM EDT for Middlesex County, Massachusetts. It was in force for 2 hr. 6 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 12, 2017, 5:42 PM EDT (21:42 UTC)
Expired
Jul 12, 2017, 7:45 PM EDT
In force
2 hr
Issued by
NWS Boston/Norton, MA
Area
Storm-based polygon
Flood severity
None

County Middlesex County, MA

The radar

The Boston radar (KBOX), 66 km from the middle of the area, began a volume at 21:44 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

TimeReportWhereRemark
Jul 12, 6:03 PM EDTFLOODChelmsford, MAIMPASSABLE DUE TO FLOODING ON BILLERICA ROAD TO TURNPIKE ROAD
Jul 12, 6:59 PM EDTFLOODGroton, MA6 INCHES OF STANDING WATER BETWEEN ROUTE 40 AND MAIN STREET
Jul 12, 7:04 PM EDTFLOODLexington, MACARS DISABLED DUE TO FLOODING ON WALTHAM STREET AT ROUTE 2
Jul 12, 7:05 PM EDTFLOODConcord, MAHAWTHORNE LANE FLOODED
Jul 12, 7:10 PM EDTFLOOD1 Sw Idylwide, MAROUTE 128 CLOSED DUE TO FLOODING AT ROUTE 2
Jul 12, 7:45 PM EDTFLOODCountryside, MAROAD FLOODED AT 239 LOWELL STREET. IMPASSABLE.

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 12:00Z, 9.7 hours before the alert went out and 146 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 2017-07-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 358 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, Chatham, MA at 12:00Z on 2017-07-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 136 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
358 J/kg
Mixed-layer CIN
-98 J/kg
Mixed-layer LCL
1158 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
136 m²/s²
0-3 km storm-relative helicity
143 m²/s²
Significant tornado parameter
0.1
Supercell composite
0.6

Open this sounding in Storm Lab

The text

As transmitted.

581 
WGUS51 KBOX 122142
FFWBOX
MAC017-122345-
/O.NEW.KBOX.FF.W.0010.170712T2142Z-170712T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Taunton MA
542 PM EDT WED JUL 12 2017

The National Weather Service in Taunton has issued a

* Flash Flood Warning for...
  Central Middlesex County in northeastern Massachusetts...

* Until 745 PM EDT

* At 541 PM EDT, Doppler radar indicated thunderstorms repeatedly 
  developing and moving across the warned area. As a result, flash 
  flooding is expected to begin shortly. Significant urban and poor 
  drainge flooding is expected. In addition, some area streams may 
  approach or exceed bankfull levels. 

* Some locations that will experience flooding include...
  Lowell, Waltham, Malden, Medford, Arlington, Everett, Billerica,
  Woburn, Chelmsford, Andover, Lexington, Tewksbury, Melrose, Saugus,
  Wakefield, Reading, Burlington, Wilmington, Westford and Acton.

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.

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 4263 7118 4260 7117 4261 7116 4260 7113
      4261 7106 4257 7103 4257 7106 4253 7107
      4251 7104 4247 7105 4242 7103 4240 7159
      4241 7156 4246 7154 4248 7156 4253 7153
      4254 7154 4255 7162 4253 7165 4265 7167

$$

NMB
1 follow-up statement
023 
WGUS71 KBOX 122249
FFSBOX

Flash Flood Statement
National Weather Service Taunton MA
649 PM EDT WED JUL 12 2017

MAC017-122345-
/O.CON.KBOX.FF.W.0010.000000T0000Z-170712T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Middlesex MA-
649 PM EDT WED JUL 12 2017

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 745 PM EDT FOR
CENTRAL MIDDLESEX COUNTY...

At 647 PM EDT, Doppler radar indicated thunderstorms continuing to 
produce heavy rainfall across the warned area. In Bedford, nearly 
2.5 inches of rain fell inside of 40 minutes. Flash flooding is 
expected, especially in urban and poor drainage areas.

Some locations that will experience flooding include...
Lowell, Waltham, Malden, Medford, Arlington, Everett, Billerica,
Woburn, Chelmsford, Andover, Lexington, Tewksbury, Melrose, Saugus,
Wakefield, Reading, Burlington, Wilmington, Westford and Acton.

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 4263 7118 4260 7117 4261 7116 4260 7113
      4261 7106 4257 7103 4257 7106 4253 7107
      4251 7104 4247 7105 4242 7103 4240 7159
      4241 7156 4246 7154 4248 7156 4253 7153
      4254 7154 4255 7162 4253 7165 4265 7167

$$

NMB

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 12, 10:15 AM EDTFlash Flood WatchBOXBristol, Essex, Hampden, Middlesex, Norfolk, Plymouth and 2 more11 hr
Jul 12, 11:01 AM EDTSpecial Weather StatementBOXSuffolk29 min
Jul 12, 12:01 PM EDTSpecial Weather StatementBOXFranklin44 min
Jul 12, 12:05 PM EDTSpecial Weather StatementBOXWorcester40 min
Jul 12, 12:24 PM EDTSevere Thunderstorm WarningBOXMiddlesex, Norfolk, Worcester51 min
Jul 12, 12:25 PM EDTAreal Flood AdvisoryBOXFranklin65 min
Jul 12, 12:36 PM EDTSpecial Weather StatementBOXHampden39 min
Jul 12, 12:44 PM EDTAreal Flood AdvisoryBOXMiddlesex, Norfolk, Worcester61 min
Jul 12, 12:46 PM EDTSevere Thunderstorm WarningBOXMiddlesex, Norfolk44 min
Jul 12, 12:50 PM EDTSpecial Weather StatementBOXMiddlesex40 min
Jul 12, 12:53 PM EDTSevere Thunderstorm WarningBOXHampden67 min
Jul 12, 1:19 PM EDTAreal Flood AdvisoryBOXHampden56 min
Jul 12, 1:22 PM EDTSevere Thunderstorm WarningBOXHampden38 min
Jul 12, 1:39 PM EDTSpecial Weather StatementBOXWorcester51 min
Jul 12, 1:39 PM EDTSevere Thunderstorm WarningBOXBristol, Norfolk, Plymouth51 min
Jul 12, 1:41 PM EDTSpecial Weather StatementBOXMiddlesex49 min
Jul 12, 1:47 PM EDTSpecial Weather StatementBOXHampden43 min
Jul 12, 1:52 PM EDTAreal Flood AdvisoryBOXBristol, Norfolk, Plymouth53 min
Jul 12, 2:35 PM EDTAreal Flood AdvisoryBOXBristol, Plymouth55 min
Jul 12, 2:53 PM EDTFlash Flood WarningBOXBristol, Norfolk112 min
Jul 12, 3:04 PM EDTAreal Flood AdvisoryBOXMiddlesex, Norfolk, Worcester56 min
Jul 12, 3:10 PM EDTSevere Thunderstorm WarningBOXBristol50 min
Jul 12, 3:26 PM EDTFlash Flood WarningBOXBristol2 hr
Jul 12, 3:36 PM EDTSpecial Weather StatementBOXHampshire39 min
Jul 12, 3:44 PM EDTSevere Thunderstorm WarningBOXBristol35 min
Jul 12, 3:53 PM EDTSevere Thunderstorm WarningBOXBristol, Plymouth34 min
Jul 12, 4:01 PM EDTSpecial Weather StatementBOXHampden44 min
Jul 12, 4:06 PM EDTAreal Flood AdvisoryBOXBristol, Plymouth114 min
Jul 12, 4:16 PM EDTSpecial Weather StatementBOXPlymouth44 min
Jul 12, 4:18 PM EDTAreal Flood AdvisoryBOXNorfolk, Plymouth, Suffolk57 min
Jul 12, 4:24 PM EDTSpecial Marine WarningBOX66 min
Jul 12, 4:32 PM EDTSpecial Marine WarningBOX58 min
Jul 12, 4:36 PM EDTAreal Flood AdvisoryBOXFranklin, Hampden, Hampshire114 min
Jul 12, 4:39 PM EDTSpecial Marine WarningBOX66 min
Jul 12, 4:48 PM EDTSpecial Weather StatementBOXMiddlesex42 min
Jul 12, 4:53 PM EDTFlash Flood WarningBOXHampden, Hampshire112 min
Jul 12, 5:00 PM EDTAreal Flood AdvisoryBOXEssex, Middlesex60 min
Jul 12, 5:19 PM EDTAreal Flood AdvisoryBOXHampden, Worcester56 min
Jul 12, 5:21 PM EDTSevere Thunderstorm WarningBOXWorcester35 min
Jul 12, 5:36 PM EDTFlash Flood WarningBOXWorcester114 min
Jul 12, 5:36 PM EDTSpecial Weather StatementBOXMiddlesex39 min
Jul 12, 6:10 PM EDTSpecial Weather StatementBOXMiddlesex35 min
Jul 12, 6:20 PM EDTSevere Thunderstorm WarningBOXMiddlesex, Norfolk, Suffolk25 min
Jul 12, 6:29 PM EDTFlash Flood WarningBOXMiddlesex, Norfolk, Suffolk2 hr
Jul 12, 6:39 PM EDTSpecial Weather StatementBOXNorfolk36 min
Jul 12, 7:05 PM EDTSpecial Weather StatementBOXSuffolk25 min
Jul 12, 7:35 PM EDTAreal Flood WarningBOXMiddlesex115 min

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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.