Alert archive / Pennsylvania / Special Weather Statements in 2021

Special Weather Statement, NWS Philadelphia/Mount Holly

February 18, 2021Mercer County, Middlesex County, Monmouth County, New Jersey; 5 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Feb 18, 2021, 7:24 AM EST for Mercer County, Middlesex County, Monmouth County, New Jersey; 5 counties in Pennsylvania. It was in force for 51 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
Feb 18, 2021, 7:24 AM EST (12:24 UTC)
Expired
Feb 18, 2021, 8:15 AM EST
In force
51 min
Issued by
NWS Philadelphia/Mount Holly

Counties Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Bucks County, PA, Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 44 km from the middle of the area, began a volume at 12:24 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

Brookhaven, NY (KOKX), launched 12:00Z, 0.4 hours before the alert went out and 177 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, Brookhaven, NY at 12:00Z on 2021-02-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Brookhaven, NY at 12:00Z on 2021-02-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -2 square meters per square second.1939587897117136Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1468 m above ground
0-6 km bulk shear
82 kt
0-1 km storm-relative helicity
-2 m²/s²
0-3 km storm-relative helicity
406 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

432 
WWUS81 KPHI 181224
SPSPHI

Special Weather Statement
National Weather Service Mount Holly NJ
724 AM EST Thu Feb 18 2021

DEZ001-NJZ009-010-012>015-017>019-PAZ070-071-101>106-181315-
New Castle-Camden-Mercer-Hunterdon-Northwestern Burlington-Eastern
Monmouth-Western Monmouth-Somerset-Middlesex-Gloucester-Lower
Bucks-Eastern Montgomery-Western Chester-Philadelphia-Upper
Bucks-Western Montgomery-Delaware-Eastern Chester-
724 AM EST Thu Feb 18 2021

...AN AREA OF HEAVY SNOW WILL AFFECT NORTHERN NEW CASTLE...
NORTHWESTERN CAMDEN...MERCER...SOUTHERN SOMERSET...SOUTHEASTERN
HUNTERDON...NORTHWESTERN GLOUCESTER...NORTHWESTERN BURLINGTON...
MONMOUTH...MIDDLESEX...MONTGOMERY...SOUTHERN BUCKS...CHESTER...
PHILADELPHIA AND DELAWARE COUNTIES...

At 722 AM EST, an area of heavy snow was located along a line
extending from Parkesburg to Hatboro. Movement was northeast at 75
mph.

Snowfall rates of around an inch per hour will be common within this 
band. Given temperatures in the 20s and the cold ground, road 
conditions will continue to rapidly deteriorate. In addition, the 
visibility will be reduced to one quarter of a mile within the heavy 
snow.

Be prepared for snow covered roads. Slow down and allow extra time 
when traveling.

Locations impacted include...
Philadelphia, Trenton, Camden, Wilmington, New Brunswick, Long
Branch, West Chester, Gloucester City, Somerset, Cherry Hill,
Middletown, Old Bridge, Bensalem, East Brunswick, South Brunswick,
Sayreville, Mount Laurel, North Brunswick, Marlboro and Manalapan.

This includes the following highways...
 New Jersey Turnpike between exits 4 and 10.
 Pennsylvania Turnpike between mile markers 300 and 359.
 Northeast Extension between mile markers 21 and 35.
 Interstate 95 in Pennsylvania between mile markers 0 and 40.
 Interstate 95 in Delaware between mile markers 15 and 23.
 Interstate 76 in Pennsylvania between mile markers 327 and 351.
 Interstate 76 in New Jersey between mile markers 0 and 3.
 Interstate 195 in New Jersey between mile markers 0 and 17.
 Interstate 295 in New Jersey between mile markers 20 and 30, and
between mile markers 32 and 76.
 Interstate 676 in Pennsylvania between mile markers 0 and 1.
 Interstate 676 in New Jersey between mile markers 0 and 4.
 Interstate 476 in Pennsylvania between mile markers 0 and 19.
 Garden State Parkway between mile markers 102 and 124.

Visibilities will drop quickly to less than a quarter of a mile in
this area of heavy snow.

Conditions can deteriorate rapidly in winter weather situations. Be 
prepared for snow or ice covered roads. Slow down and allow extra 
time when traveling.

LAT...LON 4041 7396 4024 7397 4012 7462 3996 7464
      3975 7557 3972 7608 4013 7591 4020 7578
      4047 7486 4052 7442 4044 7420 4046 7418
TIME...MOT...LOC 1222Z 219DEG 67KT 3994 7589 4019 7510 

$$

BAH

The office that day

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

IssuedProductOfficeCountiesLasted
Feb 18, 5:46 AM ESTSpecial Weather StatementPHIMercer89 min
Feb 18, 5:58 AM ESTSpecial Weather StatementPHIMonmouth77 min
Feb 18, 8:24 AM ESTSpecial Weather StatementPHIMercer, Middlesex, Monmouth66 min
Feb 18, 10:43 AM ESTSpecial Weather StatementPHIHunterdon, Mercer, Middlesex, Monmouth, Somerset62 min
Feb 18, 12:06 PM ESTSpecial Weather StatementPHIBurlington, Hunterdon, Mercer, Middlesex, Monmouth, Ocean and 1 more54 min

Nearby

Special Weather Statements in Pennsylvania, 2021Special Weather Statements in New Jersey, 2021Every special weather statement 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.