Alert archive / Massachusetts / Special Weather Statements in 2011

Special Weather Statement, NWS Boston/Norton, MA

August 20, 2011Norfolk County, Massachusetts

NWS Boston/Norton, MA issued this special weather statement at Aug 20, 2011, 2:39 PM EDT for Norfolk County, Massachusetts. It was in force for 66 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
Aug 20, 2011, 2:39 PM EDT (18:39 UTC)
Expired
Aug 20, 2011, 3:45 PM EDT
In force
66 min
Issued by
NWS Boston/Norton, MA

County Norfolk County, MA

The radar

The Boston radar (KBOX), 21 km from the middle of the area, began a volume at 18:38 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, 6.7 hours before the alert went out and 117 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 2011-08-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 571 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 2011-08-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -10 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
571 J/kg
Mixed-layer CIN
-34 J/kg
Mixed-layer LCL
782 m above ground
0-6 km bulk shear
16 kt
0-1 km storm-relative helicity
-10 m²/s²
0-3 km storm-relative helicity
-11 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

828 
WWUS81 KBOX 201839
SPSBOX

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TAUNTON MA
239 PM EDT SAT AUG 20 2011

MAZ013-201945-
WESTERN NORFOLK MA-
239 PM EDT SAT AUG 20 2011

AT 233 PM EDT NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM CAPABLE OF PRODUCING SMALL HAIL 2 MILES SOUTH OF
NORFOLK...OR ABOUT 4 MILES EAST OF FRANKLIN...MOVING NORTHEAST AT 10
MPH.

* SOME LOCATIONS AFFECTED INCLUDE...FOXBOROUGH...WALPOLE...SHARON AND
  NORWOOD.

FOR YOUR SAFETY...GET INSIDE WHEN THIS STORM APPROACHES. WINDS MAY BE
STRONG ENOUGH TO BRING DOWN SMALL BRANCHES. MINOR STREET FLOODING AND
PONDING OF WATER IN POOR DRAINAGE AREAS IS ALSO POSSIBLE.

&&

LAT...LON 4221 7119 4209 7110 4203 7136 4209 7138

$$

RLG

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 20, 12:06 PM EDTSevere Thunderstorm WarningBOXBarnstable, Plymouth39 min
Aug 20, 12:17 PM EDTSpecial Marine WarningBOX58 min
Aug 20, 12:55 PM EDTSpecial Weather StatementBOXPlymouth65 min
Aug 20, 2:48 PM EDTSpecial Weather StatementBOXEssex57 min
Aug 20, 3:59 PM EDTSpecial Weather StatementBOXEssex61 min
Aug 20, 12:02 PM EDTSpecial Weather StatementBOXProvidence58 min
Aug 20, 1:40 PM EDTSpecial Weather StatementBOXBristol65 min
Aug 19, 8:18 PM EDTSpecial Weather StatementBOX42 min

Nearby

Special Weather Statements in Massachusetts, 2011Every special weather statement in 2011

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.