Alert archive / Massachusetts / Mesoscale Discussions in 2016

Mesoscale Discussion 154

February 25, 20166 counties in Massachusetts; Hillsborough County, Rockingham County, New Hampshire; 5 counties in Rhode Island

The Storm Prediction Center issued this mesoscale discussion at Feb 25, 2016, 2:40 AM EST for 6 counties in Massachusetts; Hillsborough County, Rockingham County, New Hampshire; 5 counties in Rhode Island. It was in force for 95 min.

The area

The outline as issued.

The facts

Issued: Feb 25, 2016, 2:40 AM EST (07:40 UTC)
Expired: Feb 25, 2016, 4:15 AM EST
In force: 95 min
Issued by: the Storm Prediction Center

Counties Bristol County, MA, Essex County, MA, Middlesex County, MA, Norfolk County, MA, Suffolk County, MA, Worcester County, MA, Hillsborough County, NH, Rockingham County, NH, Bristol County, RI, Kent County, RI, Newport County, RI, Providence County, RI, Washington County, RI

The radar

The Boston radar (KBOX), 60 km from the middle of the area, began a volume at 07:42 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

Brookhaven, NY (KOKX), launched 00:00Z, 7.7 hours before the alert went out and 129 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: 38 J/kg
Mixed-layer CIN: -81 J/kg
Mixed-layer LCL: 479 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 529 m²/s²
0-3 km storm-relative helicity: 504 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.9

Open this sounding in Storm Lab

The text

As transmitted.

933 
ACUS11 KWNS 250741
SWOMCD
SPC MCD 250740 
MEZ000-MAZ000-NHZ000-RIZ000-CTZ000-NYZ000-250915-

MESOSCALE DISCUSSION 0154
NWS STORM PREDICTION CENTER NORMAN OK
0140 AM CST THU FEB 25 2016

AREAS AFFECTED...SOUTHERN NEW ENGLAND AND EASTERN LONG ISLAND

CONCERNING...SEVERE THUNDERSTORM WATCH 31...32...

VALID 250740Z - 250915Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
31...32...CONTINUES.

SUMMARY...DAMAGING WIND GUSTS ARE LIKELY AHEAD OF SQUALL LINE AS IT
PROGRESSES ACROSS SOUTHERN NEW ENGLAND AND EASTERN LONG ISLAND.

DISCUSSION...BROKEN SQUALL LINE IS PROGRESSING EWD AT ROUGHLY 30KT
ACROSS SRN NEW ENGLAND...EXTENDING SOUTH ACROSS ERN LONG ISLAND. 
STRONG STORMS EXTEND WELL SOUTH OF LONG ISLAND WITH INDIVIDUAL CELLS
RACING NNEWD AT SPEEDS APPROACHING 50KT.  WHILE CONVECTION IS LIKELY
ELEVATED IN NATURE...VERY STRONG FLOW JUST OFF THE SURFACE APPEARS
TO BE PARTLY RESPONSIBLE FOR DOWNWARD MOMENTUM AND ASSOCIATED
MEASURED SEVERE WIND GUSTS AT SEVERAL LOCATIONS ALONG/AHEAD OF THE
SQUALL LINE.  GIVEN THE CURRENT SPEED OF THIS ACTIVITY THE STRONGEST
PORTION OF THE LINE SHOULD MOVE OFF ALL BUT THE OUTER CAPE REGION OF
MA BY 0930Z.

AIR MASS IS RECOVERING RAPIDLY ACROSS SERN NH INTO EXTREME SRN
MAINE.  THERE IS SOME CONCERN LOCALLY SEVERE WIND GUSTS COULD
ACCOMPANY THE NRN PORTION OF THE SQUALL LINE BUT PRIMARY THREAT IS
EXPECTED TO REMAIN ACROSS MA AND POINTS SOUTH.

..DARROW.. 02/25/2016

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...GYX...BOX...OKX...

LAT...LON   40707276 43507156 42947044 40517122 40707276

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 24, 7:44 PM EST	Severe Thunderstorm Watch	SPC	Greater Bridgeport Planning Region, Lower Connecticut River Valley Planning Region, Naugatuck Valley Planning Region, Southeastern Connecticut Planning Region	8 hr
Feb 24, 10:39 PM EST	Mesoscale Discussion	SPC		66 min
Feb 24, 11:51 PM EST	Severe Thunderstorm Watch	SPC	Capitol Planning Region, Northwest Hills Planning Region, Northeastern Connecticut Planning Region	4 hr
Feb 25, 1:22 AM EST	Severe Thunderstorm Watch	SPC	Barnstable, Bristol, Dukes, Essex, Middlesex, Nantucket and 3 more	4 hr

Nearby

Mesoscale Discussions in Massachusetts, 2016 Mesoscale Discussions in Rhode Island, 2016 Mesoscale Discussions in Connecticut, 2016 Every mesoscale discussion in 2016

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.