Alert archive / New Jersey / Special Marine Warnings in 2021

Special Marine Warning 5, NWS Philadelphia/Mount Holly

March 18, 2021

NWS Philadelphia/Mount Holly issued this special marine warning at Mar 18, 2021, 11:23 PM EDT. It was in force for 20 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
Mar 18, 2021, 11:23 PM EDT (03:23 UTC)
Expired
Mar 18, 2021, 11:43 PM EDT
In force
20 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), 106 km from the middle of the area, began a volume at 03:24 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, 3.4 hours before the alert went out and 114 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 2021-03-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 791 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 2021-03-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 155 square meters per square second.19395878Sfc1 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
791 J/kg
Mixed-layer CIN
-41 J/kg
Mixed-layer LCL
450 m above ground
0-6 km bulk shear
51 kt
0-1 km storm-relative helicity
155 m²/s²
0-3 km storm-relative helicity
251 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.3

Open this sounding in Storm Lab

The text

As transmitted.

776 
WHUS51 KPHI 190323
SMWPHI
ANZ475-190400-
/O.NEW.KPHI.MA.W.0005.210319T0323Z-210319T0400Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Special Marine Warning
National Weather Service Mount Holly NJ
1123 PM EDT Thu Mar 18 2021

The National Weather Service in Mount Holly NJ has issued a

* Special Marine Warning for...
  
Outer waters from Cape May NJ to Fenwick Island DE out 20 to 40 nm...

* Until midnight EDT.

* At 1122 PM EDT, a strong thunderstorm was located 13 nm north of
  Chicken Bone, moving northeast at 40 knots.

  HAZARD...Wind gusts 34 knots or greater.

  SOURCE...Radar.

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

* The strong thunderstorm will remain over mainly open waters.

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 3850 7449 3864 7417 3861 7417 3857 7420
      3851 7426 3843 7426 3837 7427 3836 7427
      3833 7439
TIME...MOT...LOC 0322Z 246DEG 42KT 3845 7436 

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

$$

MPS
1 follow-up statement
670 
FZUS71 KPHI 190343
MWSPHI

Marine Weather Statement
National Weather Service Mount Holly NJ
1143 PM EDT Thu Mar 18 2021

ANZ475-190353-
/O.CAN.KPHI.MA.W.0005.000000T0000Z-210319T0400Z/
1143 PM EDT Thu Mar 18 2021

...THE SPECIAL MARINE WARNING IS CANCELLED...

The affected areas were... 

Outer waters from Cape May NJ to Fenwick Island DE out 20 to 40 nm...

The thunderstorm has moved out of the area and no longer poses a
significant threat to boaters.

LAT...LON 3850 7449 3864 7417 3861 7417 3857 7420
      3851 7426 3843 7426 3837 7427 3836 7427
      3833 7439
TIME...MOT...LOC 0341Z 246DEG 42KT 3855 7407 

$$

MPS

The office that day

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

IssuedProductOfficeCountiesLasted
Mar 19, 12:52 PM EDTSmall Craft AdvisoryPHI30 hr

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.