Alert archive / Massachusetts / Special Marine Warnings in 2021

Special Marine Warning 21, NWS Boston/Norton, MA

June 30, 2021

NWS Boston/Norton, MA issued this special marine warning at Jun 30, 2021, 8:16 PM EDT. It was in force for 59 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: Jun 30, 2021, 8:16 PM EDT (00:16 UTC)
Expired: Jun 30, 2021, 9:15 PM EDT
In force: 59 min
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Hail: 0.0 in
Wind: 34.0 mph

The radar

The Boston radar (KBOX), 46 km from the middle of the area, began a volume at 00:15 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

Gray, ME (KGYX), launched 00:00Z, 0.3 hours before the alert went out and 192 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: 505 J/kg
Mixed-layer CIN: -92 J/kg
Mixed-layer LCL: 1353 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: 98 m²/s²
0-3 km storm-relative helicity: 125 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.8

Open this sounding in Storm Lab

The text

As transmitted.

868 
WHUS51 KBOX 010016
SMWBOX
ANZ230-250-251-010115-
/O.NEW.KBOX.MA.W.0021.210701T0016Z-210701T0115Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Special Marine Warning
National Weather Service Boston/Norton MA
816 PM EDT Wed Jun 30 2021

The National Weather Service in Boston/Norton has issued a

* Special Marine Warning for...
  Boston Harbor...
  Coastal waters east of Ipswich Bay and the Stellwagen Bank National
  Marine Sanctuary...
  Massachusetts Bay and Ipswich Bay...

* Until 915 PM EDT.

* At 815 PM EDT, a strong thunderstorm was located over Hingham, or
  near Weymouth, moving east at 35 knots.

  HAZARD...Wind gusts 34 knots or greater and frequent lightning.

  SOURCE...Radar.

  IMPACT...Small craft could be damaged in briefly higher winds and 
           suddenly higher waves.

* Locations impacted include...
  Boston Buoy 44013, Boston Light, Stellwagen Bank, Quincy Harbor,
  The Coastal Waters East Of Boston Harbor, Scituate Harbor, Minot
  Light, Ocean Bluff-Brant Rock and Race Point.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

&&

LAT...LON 4206 7020 4209 7068 4211 7068 4215 7075
      4221 7074 4224 7082 4224 7090 4221 7092
      4221 7097 4229 7106 4247 7023
TIME...MOT...LOC 0015Z 256DEG 33KT 4218 7088 

HAIL...0.00IN
WIND...>34KTS

$$

Nocera

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 30, 8:08 PM EDT	Severe Thunderstorm Warning	BOX	Bristol, Norfolk, Worcester	67 min
Jun 30, 8:14 PM EDT	Severe Thunderstorm Warning	BOX	Norfolk, Plymouth, Suffolk	46 min
Jun 30, 8:31 PM EDT	Severe Thunderstorm Warning	BOX	Bristol, Norfolk, Plymouth	59 min
Jun 30, 8:41 PM EDT	Special Marine Warning	BOX		64 min
Jun 30, 8:57 PM EDT	Special Marine Warning	BOX		63 min
Jun 30, 9:54 PM EDT	Special Marine Warning	BOX		66 min
Jul 1, 4:01 PM EDT	Special Weather Statement	BOX	Bristol, Plymouth	59 min
Jul 1, 4:02 PM EDT	Small Craft Advisory	BOX		4 days
Jul 1, 4:29 PM EDT	Special Marine Warning	BOX		61 min
Jul 1, 5:03 PM EDT	Special Weather Statement	BOX	Barnstable	42 min
Jul 1, 5:21 PM EDT	Special Marine Warning	BOX		54 min
Jul 1, 7:05 PM EDT	Special Weather Statement	BOX	Hampden	55 min
Jul 1, 7:59 PM EDT	Areal Flood Warning	BOX	Hampden, Hampshire	3 hr

Nearby

Special Marine Warnings in Massachusetts, 2021 Every special marine warning in 2021

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.