Alert archive / New Jersey / Special Marine Warnings in 2021

Special Marine Warning 108, NWS Philadelphia/Mount Holly

July 29, 2021

NWS Philadelphia/Mount Holly issued this special marine warning at Jul 29, 2021, 9:15 PM EDT. It was in force for 2 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jul 29, 2021, 9:15 PM EDT (01:15 UTC)
Expired: Jul 29, 2021, 11:15 PM EDT
In force: 2 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 49.0 mph

The radar

The Philadelphia radar (KDIX), 82 km from the middle of the area, began a volume at 01:18 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

Brookhaven, NY (KOKX), launched 00:00Z, 1.3 hours before the alert went out and 147 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: 635 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 502 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: 381 m²/s²
0-3 km storm-relative helicity: 515 m²/s²
Significant tornado parameter: 1.3
Supercell composite: 5.0

Open this sounding in Storm Lab

The text

As transmitted.

960 
WHUS51 KPHI 300115
SMWPHI
ANZ451-471-300315-
/O.NEW.KPHI.MA.W.0108.210730T0115Z-210730T0315Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Special Marine Warning
National Weather Service Mount Holly NJ
915 PM EDT Thu Jul 29 2021

The National Weather Service in Mount Holly NJ has issued a

* Special Marine Warning for...
  
Coastal and outer waters from Manasquan Inlet to Little Egg Inlet
NJ...

* Until 1115 PM EDT.

* At 915 PM EDT, a severe thunderstorm producing waterspouts was
  located over Barnegat Light, moving east at 25 knots.

  HAZARD...Waterspouts, wind gusts to nearly 50 knots, and large 
           hail.

  SOURCE...Radar.

  IMPACT...Waterspouts can easily overturn boats and create locally 
           hazardous seas. Small craft could be damaged in briefly 
           higher winds and suddenly higher waves. Large hail could 
           result in structural damage.

* Locations impacted include...
  Barnegat Light, Garden State North Reef, Harvey Cedars, Forked
  River and Barnegat Light Reef.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 1000 PM EDT for southern New
Jersey...and the adjacent coastal waters.

Boaters should seek safe harbor immediately until this storm passes.
Wind gusts to nearly 50 knots, large hail, high waves, dangerous
lightning, and heavy rain are possible with this storm.

&&

LAT...LON 3966 7331 3956 7334 3947 7338 3931 7348
      3970 7423 3986 7414 3980 7330 3977 7330
TIME...MOT...LOC 0115Z 291DEG 24KT 3976 7410 

WATERSPOUT...OBSERVED
HAIL...>.75IN
WIND...49KTS

$$

Staarmann

2 follow-up statements

835 
FZUS71 KPHI 300148
MWSPHI

Marine Weather Statement
National Weather Service Mount Holly NJ
948 PM EDT Thu Jul 29 2021

ANZ451-471-300315-
/O.CON.KPHI.MA.W.0108.000000T0000Z-210730T0315Z/
948 PM EDT Thu Jul 29 2021

...A SPECIAL MARINE WARNING REMAINS IN EFFECT UNTIL 1115 PM EDT...

For the following areas...
Coastal waters from Manasquan Inlet to Little Egg Inlet NJ out 20
nm...
Waters from Manasquan Inlet NJ to Little Egg Inlet NJ out 20 to 40
nm...

At 947 PM EDT, a severe thunderstorm producing waterspouts was
located 8 nm east of Garden State North Reef, moving east at 25
knots.

HAZARD...Waterspouts, wind gusts to nearly 50 knots, and large hail.

SOURCE...Radar indicated.

IMPACT...Waterspouts can easily overturn boats and create locally 
         hazardous seas. Small craft could be damaged in briefly 
         higher winds and suddenly higher waves. Large hail could 
         result in structural damage.

The severe thunderstorm will remain over mainly open waters.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 1000 PM EDT for the adjacent
coastal waters.

Boaters should seek safe harbor immediately until this storm passes.
Wind gusts to nearly 50 knots, large hail, high waves, dangerous
lightning, and heavy rain are possible with this storm.

&&

LAT...LON 3961 7403 3983 7391 3977 7330 3966 7331
      3956 7334 3947 7338 3933 7347
TIME...MOT...LOC 0147Z 290DEG 24KT 3968 7386 

WATERSPOUT...OBSERVED
HAIL...>.75IN
WIND...49KTS

$$

Fitzsimmons

539 
FZUS71 KPHI 300215
MWSPHI

Marine Weather Statement
National Weather Service Mount Holly NJ
1015 PM EDT Thu Jul 29 2021

ANZ451-300224-
/O.CAN.KPHI.MA.W.0108.000000T0000Z-210730T0315Z/
1015 PM EDT Thu Jul 29 2021

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

The affected areas were...

Coastal waters from Manasquan Inlet to Little Egg Inlet NJ out 20
nm...

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

LAT...LON 3958 7379 3978 7371 3976 7330 3966 7331
      3956 7334 3947 7338 3944 7340
TIME...MOT...LOC 0214Z 287DEG 23KT 3967 7370 

$$

ANZ471-300315-
/O.CON.KPHI.MA.W.0108.000000T0000Z-210730T0315Z/
1015 PM EDT Thu Jul 29 2021

...A SPECIAL MARINE WARNING REMAINS IN EFFECT UNTIL 1115 PM EDT...

For the following areas...
Waters from Manasquan Inlet NJ to Little Egg Inlet NJ out 20 to 40
nm...

At 1014 PM EDT, a severe thunderstorm producing waterspouts was
located 15 nm east of Garden State North Reef, moving east at 25
knots.

HAZARD...Waterspouts, wind gusts to nearly 50 knots, and large hail.

SOURCE...Radar indicated.

IMPACT...Waterspouts can easily overturn boats and create locally 
         hazardous seas. Small craft could be damaged in briefly 
         higher winds and suddenly higher waves. Large hail could 
         result in structural damage.

The severe thunderstorm will remain over mainly open waters.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Boaters should seek safe harbor immediately until this storm passes.
Wind gusts to nearly 50 knots, large hail, high waves, dangerous
lightning, and heavy rain are possible with this storm.

&&

LAT...LON 3958 7379 3978 7371 3976 7330 3966 7331
      3956 7334 3947 7338 3944 7340
TIME...MOT...LOC 0214Z 287DEG 23KT 3967 7370 

WATERSPOUT...OBSERVED
HAIL...>.75IN
WIND...49KTS

$$

Fitzsimmons

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 29, 8:03 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Monmouth, Ocean	57 min
Jul 29, 8:03 PM EDT	Tornado Warning	PHI	Ocean	27 min
Jul 29, 8:19 PM EDT	Flash Flood Warning	PHI	Burlington, Monmouth, Ocean	4 hr
Jul 29, 8:39 PM EDT	Tornado Warning	PHI	Burlington, Ocean	51 min
Jul 29, 8:42 PM EDT	Tornado Warning	PHI	Monmouth	19 min
Jul 29, 8:43 PM EDT	Flash Flood Warning	PHI	Monmouth, Ocean	3 hr
Jul 29, 11:25 PM EDT	Special Weather Statement	PHI	Pike	35 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.