Alert archive / New Jersey / Special Marine Warnings in 2021

Special Marine Warning 113, NWS Philadelphia/Mount Holly

August 13, 2021

NWS Philadelphia/Mount Holly issued this special marine warning at Aug 13, 2021, 9:26 PM EDT. It was in force for 64 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 13, 2021, 9:26 PM EDT (01:26 UTC)
Expired
Aug 13, 2021, 10:30 PM EDT
In force
64 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
0.0 in
Wind
34.0 mph

The radar

The Dover AFB radar (KDOX), 60 km from the middle of the area, began a volume at 01:26 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

Wallops Is Stn, VA (KWAL), launched 00:00Z, 1.4 hours before the alert went out and 88 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, Wallops Is Stn, VA at 00:00Z on 2021-08-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2917 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Wallops Is Stn, VA at 00:00Z on 2021-08-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 29 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
2917 J/kg
Mixed-layer CIN
-55 J/kg
Mixed-layer LCL
1083 m above ground
0-6 km bulk shear
7 kt
0-1 km storm-relative helicity
29 m²/s²
0-3 km storm-relative helicity
46 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

561 
WHUS51 KPHI 140126
SMWPHI
ANZ431-453>455-475-140230-
/O.NEW.KPHI.MA.W.0113.210814T0126Z-210814T0230Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Special Marine Warning
National Weather Service Mount Holly NJ
926 PM EDT Fri Aug 13 2021

The National Weather Service in Mount Holly NJ has issued a

* Special Marine Warning for...
  Lower Delaware Bay...
  Coastal waters from Great Egg Inlet NJ to Fenwick Island DE out 20
  nm...
  Outer waters from Cape May NJ to Fenwick Island DE out 20 to 40
  nm...

* Until 1030 PM EDT.

* At 926 PM EDT, a strong thunderstorm was located near Cape
  Henlopen, moving east at 15 knots.

  HAZARD...Wind gusts 34 knots or greater.

  SOURCE...Radar.

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

* Locations impacted include...
  Five Fathoms Buoy, Fenwick Island, Buoy 4fb, Buoy 3fb, Cape
  Henlopen, Rehoboth Beach, Cape May Point, Indian River Inlet
  Bridge, Overfalls Shoal, Cape May Reef, Bethany Beach, Delaware
  Lightship Buoy 44009 and Buoy 2ms.

LAT...LON 3835 7471 3845 7503 3845 7509 3883 7520
      3899 7496 3895 7461 3854 7446 3833 7463
TIME...MOT...LOC 0126Z 271DEG 14KT 3876 7514 

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

$$

NC
1 follow-up statement
446 
FZUS71 KPHI 140221
MWSPHI

Marine Weather Statement
National Weather Service Mount Holly NJ
1021 PM EDT Fri Aug 13 2021

ANZ431-453>455-475-140230-
/O.EXP.KPHI.MA.W.0113.000000T0000Z-210814T0230Z/
1021 PM EDT Fri Aug 13 2021

...THE SPECIAL MARINE WARNING WILL EXPIRE AT 1030 PM EDT...

The affected areas were... 
Lower Delaware Bay...
Coastal waters from Great Egg Inlet NJ to Fenwick Island DE out 20
nm...
Outer waters from Cape May NJ to Fenwick Island DE out 20 to 40 nm...

The thunderstorm has weakened and no longer poses a significant
threat to boaters.

LAT...LON 3835 7471 3845 7503 3845 7509 3883 7520
      3899 7496 3895 7461 3854 7446 3833 7463
TIME...MOT...LOC 0220Z 271DEG 14KT 3876 7488 

$$

NC

The office that day

Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 13, 8:04 PM EDTSpecial Weather StatementPHISussex41 min
Aug 13, 8:28 PM EDTSpecial Weather StatementPHISussex62 min
Aug 13, 8:40 PM EDTAreal Flood AdvisoryPHISussex62 min

Nearby

Special Marine Warnings in New Jersey, 2021Every 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.