Alert archive / New Jersey / Special Marine Warnings in 2021

Special Marine Warning 129, NWS Philadelphia/Mount Holly

August 30, 2021

NWS Philadelphia/Mount Holly issued this special marine warning at Aug 30, 2021, 7:31 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: Aug 30, 2021, 7:31 PM EDT (23:31 UTC)
Expired: Aug 30, 2021, 8:30 PM EDT
In force: 59 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), 49 km from the middle of the area, began a volume at 23:33 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 12:00Z, 11.5 hours before the alert went out and 107 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: 392 J/kg
Mixed-layer CIN: -89 J/kg
Mixed-layer LCL: 791 m above ground
0-6 km bulk shear: 8 kt
0-1 km storm-relative helicity: -19 m²/s²
0-3 km storm-relative helicity: -9 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

474 
WHUS51 KPHI 302331
SMWPHI
ANZ453>455-473-310030-
/O.NEW.KPHI.MA.W.0129.210830T2331Z-210831T0030Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Special Marine Warning
National Weather Service Mount Holly NJ
731 PM EDT Mon Aug 30 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 Great Egg Inlet to Cape May NJ out 20 to 40 nm...

* Until 830 PM EDT.

* At 731 PM EDT, strong thunderstorms were located along a line
  extending from Wildwood to near Cape Henlopen, moving southeast 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...
  Overfalls Shoal, Five Fathoms Buoy, Buoy 2fb, Buoy 4fb, Buoy 3fb,
  Cape May Reef, Cape Henlopen, Rehoboth Beach, Cape May Point, Buoy
  2ms, Wildwood Reef and Wildwood.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move to safe harbor until hazardous weather passes.

Frequent lightning is occurring with these storms. If caught on the
open water, stay below deck if possible and keep away from ungrounded
metal objects.

&&

LAT...LON 3863 7511 3875 7517 3878 7515 3879 7509
      3880 7510 3892 7498 3896 7496 3897 7495
      3897 7496 3902 7491 3896 7439 3880 7450
      3880 7452 3875 7457 3864 7473 3849 7471
TIME...MOT...LOC 2331Z 303DEG 13KT 3899 7484 3876 7503 

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

$$

Gorse

2 follow-up statements

369 
FZUS71 KPHI 302354
MWSPHI

Marine Weather Statement
National Weather Service Mount Holly NJ
754 PM EDT Mon Aug 30 2021

ANZ453>455-473-310030-
/O.CON.KPHI.MA.W.0129.000000T0000Z-210831T0030Z/
754 PM EDT Mon Aug 30 2021

...A SPECIAL MARINE WARNING REMAINS IN EFFECT UNTIL 830 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 Great Egg Inlet NJ to Cape May NJ out 20 to 40 nm...

At 753 PM EDT, strong thunderstorms were located along a line
extending from Buoy 3fb to 6 nm east of Rehoboth Beach, moving
southeast at 15 knots.

HAZARD...Wind gusts 34 knots or greater.

SOURCE...Radar indicated.

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

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move to safe harbor until hazardous weather passes.

Frequent lightning is occurring with these storms. If caught on the
open water, stay below deck if possible and keep away from ungrounded
metal objects.

&&

LAT...LON 3869 7507 3889 7493 3901 7480 3896 7439
      3880 7450 3880 7452 3873 7459 3864 7473
      3862 7473
TIME...MOT...LOC 2353Z 292DEG 16KT 3896 7473 3872 7494 

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

$$

Gorse

381 
FZUS71 KPHI 310025
MWSPHI

Marine Weather Statement
National Weather Service Mount Holly NJ
825 PM EDT Mon Aug 30 2021

ANZ453>455-473-310035-
/O.EXP.KPHI.MA.W.0129.000000T0000Z-210831T0030Z/
825 PM EDT Mon Aug 30 2021

...THE SPECIAL MARINE WARNING WILL EXPIRE AT 830 PM EDT...

The affected areas were... 

Coastal waters from Great Egg Inlet NJ to Fenwick Island DE out 20
nm...
Outer waters from Great Egg Inlet to Cape May NJ out 20 to 40 nm...

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

LAT...LON 3869 7507 3889 7493 3901 7480 3896 7439
      3880 7450 3880 7452 3873 7459 3864 7473
      3862 7473
TIME...MOT...LOC 0025Z 303DEG 13KT 3890 7461 3866 7482 

$$

Gorse

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 30, 5:00 AM EDT	Flash Flood Watch	PHI	Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester and 10 more	71 hr
Aug 30, 5:44 AM EDT	Dense Fog Advisory	PHI	Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester and 3 more	3 hr
Aug 30, 4:48 PM EDT	Special Weather Statement	PHI	Atlantic, Cumberland	27 min
Aug 30, 5:16 PM EDT	Severe Thunderstorm Warning	PHI	Atlantic, Cape May, Cumberland	44 min
Aug 30, 5:21 PM EDT	Special Weather Statement	PHI	Atlantic	24 min
Aug 30, 5:26 PM EDT	Special Marine Warning	PHI		64 min
Aug 30, 5:44 PM EDT	Special Marine Warning	PHI		61 min
Aug 30, 5:53 PM EDT	Special Weather Statement	PHI	Atlantic	22 min
Aug 30, 5:56 PM EDT	Special Weather Statement	PHI	Cape May	49 min
Aug 30, 6:16 PM EDT	Special Marine Warning	PHI		89 min
Aug 30, 6:41 PM EDT	Special Weather Statement	PHI	Cape May	34 min
Aug 30, 7:20 PM EDT	Special Weather Statement	PHI	Cape May	25 min
Aug 30, 3:44 PM EDT	Special Weather Statement	PHI	New Castle	31 min
Aug 30, 4:14 PM EDT	Special Weather Statement	PHI	Kent	31 min
Aug 30, 6:02 PM EDT	Severe Thunderstorm Warning	PHI	Kent, Sussex	28 min

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.