Alert archive / Massachusetts / Flash Flood Warnings in 2019

Flash Flood Warning 7, NWS Boston/Norton, MA

July 17, 20196 counties in Massachusetts

NWS Boston/Norton, MA issued this flash flood warning at Jul 17, 2019, 5:43 PM EDT for 6 counties in Massachusetts. It was in force for 2 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, 2019, 5:43 PM EDT (21:43 UTC)
Expired
Jul 17, 2019, 7:45 PM EDT
In force
2 hr
Issued by
NWS Boston/Norton, MA
Area
Storm-based polygon
Flood severity
None

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

The radar

The Boston radar (KBOX), 29 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.

The nearest sounding before it

Chatham, MA (KCHH), launched 12:00Z, 9.7 hours before the alert went out and 103 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 2019-07-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 297 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Chatham, MA at 12:00Z on 2019-07-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 39 square meters per square second.1939Sfc1 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
297 J/kg
Mixed-layer CIN
-108 J/kg
Mixed-layer LCL
1172 m above ground
0-6 km bulk shear
11 kt
0-1 km storm-relative helicity
39 m²/s²
0-3 km storm-relative helicity
58 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

644 
WGUS51 KBOX 172143
FFWBOX
MAC005-017-021-023-025-027-172345-
/O.NEW.KBOX.FF.W.0007.190717T2143Z-190717T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Boston/Norton MA
543 PM EDT Wed Jul 17 2019

The National Weather Service in Boston/Norton has issued a

* Flash Flood Warning for...
  Eastern Worcester County in central Massachusetts...
  Norfolk County in eastern Massachusetts...
  Southern Suffolk County in eastern Massachusetts...
  Southeastern Middlesex County in northeastern Massachusetts...
  North central Bristol County in southeastern Massachusetts...
  Northern Plymouth County in southeastern Massachusetts...

* Until 745 PM EDT.

* At 542 PM EDT, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area. Up to two inches of rain have 
  already fallen. Flash flooding is expected to begin shortly 
  especially across the south Boston metro area.

* Some locations that will experience flooding include...
  Boston, Brockton, Quincy, Weymouth, Braintree, Natick, Randolph,
  Franklin, Needham, Norwood, Milford, Milton, Stoughton, Marshfield,
  Dedham, Walpole, Mansfield, Easton, Hingham and Canton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

A Flash Flood Warning means that flooding is imminent or occurring.
If you are in the warned area move to higher ground immediately.
Residents living along streams and creeks should take immediate
precautions to protect life and property.

&&

LAT...LON 4202 7150 4220 7159 4235 7089 4235 7087
      4228 7084 4227 7076 4221 7070 4217 7070
      4203 7059

$$

Sipprell

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 17, 12:22 PM EDTSmall Craft AdvisoryBOX5 hr
Jul 17, 1:24 PM EDTFlash Flood WatchBOXBarnstable, Bristol, Essex, Franklin, Hampden, Hampshire and 5 more7 hr
Jul 17, 1:31 PM EDTSpecial Weather StatementBOXWorcester59 min
Jul 17, 2:06 PM EDTSevere Thunderstorm WarningBOXFranklin, Hampshire, Worcester54 min
Jul 17, 2:44 PM EDTSevere Thunderstorm WarningBOXHampden, Hampshire61 min
Jul 17, 2:59 PM EDTSevere Thunderstorm WarningBOXMiddlesex, Norfolk, Worcester61 min
Jul 17, 3:05 PM EDTFlash Flood WarningBOXMiddlesex, Worcester115 min
Jul 17, 3:53 PM EDTSevere Thunderstorm WarningBOXMiddlesex, Norfolk, Plymouth, Suffolk67 min
Jul 17, 3:56 PM EDTSevere Thunderstorm WarningBOXFranklin, Hampshire, Middlesex, Worcester47 min
Jul 17, 3:59 PM EDTSevere Thunderstorm WarningBOXMiddlesex, Norfolk, Plymouth, Suffolk61 min
Jul 17, 4:00 PM EDTSpecial Marine WarningBOX30 min
Jul 17, 4:03 PM EDTFlash Flood WarningBOXMiddlesex, Norfolk, Plymouth, Suffolk117 min
Jul 17, 4:03 PM EDTSevere Thunderstorm WarningBOXFranklin, Hampden, Hampshire, Worcester57 min
Jul 17, 4:23 PM EDTSpecial Marine WarningBOX52 min
Jul 17, 4:24 PM EDTSpecial Marine WarningBOX66 min
Jul 17, 4:38 PM EDTSevere Thunderstorm WarningBOXBristol, Norfolk, Plymouth, Worcester52 min
Jul 17, 4:42 PM EDTSevere Thunderstorm WarningBOXEssex, Middlesex, Worcester48 min
Jul 17, 4:48 PM EDTSpecial Marine WarningBOX42 min
Jul 17, 4:49 PM EDTSevere Thunderstorm WarningBOXPlymouth26 min
Jul 17, 4:50 PM EDTSevere Thunderstorm WarningBOXEssex14 min
Jul 17, 4:51 PM EDTSpecial Marine WarningBOX39 min
Jul 17, 5:04 PM EDTSevere Thunderstorm WarningBOXMiddlesex, Norfolk, Worcester41 min
Jul 17, 5:11 PM EDTSpecial Marine WarningBOX64 min
Jul 17, 5:19 PM EDTSevere Thunderstorm WarningBOXEssex, Middlesex, Norfolk, Suffolk, Worcester41 min
Jul 17, 5:20 PM EDTFlash Flood WarningBOXHampden, Worcester115 min
Jul 17, 5:23 PM EDTSpecial Marine WarningBOX67 min
Jul 17, 5:34 PM EDTSevere Thunderstorm WarningBOXNorfolk, Plymouth26 min
Jul 17, 5:38 PM EDTSevere Thunderstorm WarningBOXMiddlesex, Norfolk, Suffolk, Worcester27 min
Jul 17, 5:41 PM EDTSpecial Marine WarningBOX49 min
Jul 17, 5:50 PM EDTSpecial Weather StatementBOXPlymouth40 min
Jul 17, 6:09 PM EDTSpecial Marine WarningBOX66 min
Jul 17, 6:30 PM EDTSpecial Marine WarningBOX60 min
Jul 17, 6:33 PM EDTSevere Thunderstorm WarningBOXBarnstable57 min
Jul 17, 6:37 PM EDTSpecial Weather StatementBOXPlymouth38 min
Jul 17, 7:01 PM EDTSpecial Marine WarningBOX59 min
Jul 17, 7:21 PM EDTSpecial Weather StatementBOXBristol39 min

Nearby

Flash Flood Warnings in Massachusetts, 2019Every flash flood warning in 2019

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.