Alert archive / New Jersey / Special Marine Warnings in 2021

Special Marine Warning 13, NWS Philadelphia/Mount Holly

May 4, 2021

NWS Philadelphia/Mount Holly issued this special marine warning at May 4, 2021, 8:12 PM EDT. It was in force for 63 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: May 4, 2021, 8:12 PM EDT (00:12 UTC)
Expired: May 4, 2021, 9:15 PM EDT
In force: 63 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 40.0 mph

The radar

The Dover AFB radar (KDOX), 53 km from the middle of the area, began a volume at 00:10 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, 0.2 hours before the alert went out and 87 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: 361 J/kg
Mixed-layer CIN: -95 J/kg
Mixed-layer LCL: 1356 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 106 m²/s²
0-3 km storm-relative helicity: 118 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.6

Open this sounding in Storm Lab

The text

As transmitted.

289 
WHUS51 KPHI 050012
SMWPHI
ANZ453>455-475-050115-
/O.NEW.KPHI.MA.W.0013.210505T0012Z-210505T0115Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Special Marine Warning
National Weather Service Mount Holly NJ
812 PM EDT Tue May 4 2021

The National Weather Service in Mount Holly NJ has issued a

* Special Marine Warning for...
  
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 915 PM EDT.

* At 811 PM EDT, strong thunderstorms were located along a line
  extending from Cape Henlopen to near Bethany Beach, moving
  northeast at 40 knots.

  HAZARD...Wind gusts to 40 knots and small hail.

  SOURCE...Radar.

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

* Locations impacted include...
  Five Fathoms Buoy, Buoy 4fb, Buoy 3fb, Cape May Reef, Buoy 2ms,
  Wildwood Reef, Fenwick Island and Bethany Beach.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

Move to safe harbor until hazardous weather passes.

&&

LAT...LON 3846 7504 3845 7505 3880 7507 3900 7463
      3864 7451 3844 7498
TIME...MOT...LOC 0011Z 219DEG 38KT 3881 7505 3850 7506 

HAIL...<.75IN
WIND...40KTS

$$

JEO

2 follow-up statements

496 
FZUS71 KPHI 050040
MWSPHI

Marine Weather Statement
National Weather Service Mount Holly NJ
840 PM EDT Tue May 4 2021

ANZ453>455-475-050115-
/O.CON.KPHI.MA.W.0013.000000T0000Z-210505T0115Z/
840 PM EDT Tue May 4 2021

...A SPECIAL MARINE WARNING REMAINS IN EFFECT UNTIL 915 PM EDT...

For the following areas...
Coastal waters from Cape Henlopen to Fenwick Island DE out 20 nm...
Coastal waters from Cape May NJ to Cape Henlopen DE out 20 nm...
Coastal waters from Great Egg Inlet to Cape May NJ out 20 nm...
Waters from Cape May NJ to Fenwick Island DE out 20 to 40 nm...

At 840 PM EDT, strong thunderstorms were located along a line
extending from near Wildwood Reef to 8 nm southwest of Five Fathoms
Buoy, moving northeast at 40 knots.

HAZARD...Wind gusts to 40 knots.

SOURCE...Radar indicated.

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

Locations impacted include...
Five Fathoms Buoy, Buoy 2ms, Buoy 4fb, Buoy 3fb, Wildwood Reef and
Cape May Reef.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

Move to safe harbor until hazardous weather passes.

&&

LAT...LON 3860 7491 3889 7488 3900 7463 3864 7451
      3849 7486
TIME...MOT...LOC 0040Z 224DEG 41KT 3901 7471 3870 7472 

HAIL...0.00IN
WIND...40KTS

$$

Meola

536 
FZUS71 KPHI 050107
MWSPHI

Marine Weather Statement
National Weather Service Mount Holly NJ
907 PM EDT Tue May 4 2021

ANZ453>455-475-050117-
/O.EXP.KPHI.MA.W.0013.000000T0000Z-210505T0115Z/
907 PM EDT Tue May 4 2021

...THE SPECIAL MARINE WARNING WILL EXPIRE AT 915 PM EDT...

The affected areas were... 

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 thunderstorms have weakened and no longer pose a significant
threat to boaters.

LAT...LON 3860 7491 3889 7488 3900 7463 3864 7451
      3849 7486
TIME...MOT...LOC 0107Z 219DEG 38KT 3922 7449 3891 7450 

$$

Meola

The office that day

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

Issued	Product	Office	Counties	Lasted
May 4, 8:34 PM EDT	Special Marine Warning	PHI		56 min
May 5, 3:16 AM EDT	Small Craft Advisory	PHI		30 hr

Nearby

Special Marine Warnings in New Jersey, 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.