Alert archive / Massachusetts / Severe Thunderstorm Watches in 2016

Severe Thunderstorm Watch 413

July 23, 20168 counties in Massachusetts

The Storm Prediction Center issued this severe thunderstorm watch at Jul 23, 2016, 6:04 PM EDT for 8 counties in Massachusetts. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jul 23, 2016, 6:04 PM EDT (22:04 UTC)
Expired: Jul 23, 2016, 8:31 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1 in
Strongest gust expected: 50 kt

Counties Essex County, MA, Franklin County, MA, Hampden County, MA, Hampshire County, MA, Middlesex County, MA, Norfolk County, MA, Suffolk County, MA, Worcester County, MA

The radar

The Boston radar (KBOX), 101 km from the middle of the area, began a volume at 22:03 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 SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 5%
One or more EF2 to EF5 tornadoes: 2%
Ten or more severe wind reports: 30%
One or more gusts of 65 knots or more: 10%
Ten or more severe hail reports: 20%
One or more hailstones of 2 inches or more: 5%
Six or more combined severe hail and wind reports: 50%

Warnings issued inside it

5 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Jul 23, 6:38 PM EDT	Severe Thunderstorm Warning	BOX	Essex, Middlesex, Worcester	52 min
Jul 23, 6:52 PM EDT	Severe Thunderstorm Warning	BOX	Franklin	38 min
Jul 23, 7:06 PM EDT	Severe Thunderstorm Warning	BOX	Essex, Middlesex, Norfolk, Suffolk, Worcester	54 min
Jul 23, 7:15 PM EDT	Severe Thunderstorm Warning	BOX	Franklin, Hampden, Hampshire, Worcester	60 min
Jul 23, 7:29 PM EDT	Severe Thunderstorm Warning	BOX	Essex, Middlesex, Worcester	31 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Albany, NY (KALY), launched 12:00Z, 10.1 hours before the alert went out and 142 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1488 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 73 m²/s²
0-3 km storm-relative helicity: 75 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

396 
WWUS20 KWNS 232158
SEL3  
SPC WW 232158
MAZ000-240200-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 413
NWS STORM PREDICTION CENTER NORMAN OK
600 PM EDT SAT JUL 23 2016

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF 
  MUCH OF MASSACHUSETTS

* EFFECTIVE THIS SATURDAY EVENING FROM 600 PM UNTIL 1000 PM EDT.

* PRIMARY THREATS INCLUDE...
  ISOLATED DAMAGING WIND GUSTS TO 60 MPH POSSIBLE
  ISOLATED LARGE HAIL EVENTS TO 1 INCH IN DIAMETER POSSIBLE

SUMMARY...BROKEN BAND OF STRONG/SEVERE STORMS ACROSS SOUTHERN
VERMONT AND NEW HAMPSHIRE WILL CONTINUE TO THE SOUTHEAST FOR THE
NEXT FEW HOURS WITH AN ATTENDANT RISK FOR ISOLATED DAMAGING
WINDS...AND PERHAPS SOME HAIL.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 25
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 25 MILES NORTH
NORTHWEST OF WESTFIELD MASSACHUSETTS TO 5 MILES EAST OF BOSTON
MASSACHUSETTS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 411...WW 412...

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 50 KNOTS.
A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM MOTION
VECTOR 31025.


...THOMPSON

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 23, 4:43 PM EDT	Mesoscale Discussion	SPC	Berkshire, Essex, Franklin, Hampshire, Middlesex, Suffolk and 1 more	92 min
Jul 23, 6:36 PM EDT	Mesoscale Discussion	SPC	Berkshire, Essex, Franklin, Hampden, Hampshire, Middlesex and 3 more	54 min

Nearby

Severe Thunderstorm Watches in Massachusetts, 2016 Every severe thunderstorm watch 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.