Alert archive / Pennsylvania / Special Weather Statements in 2021

Special Weather Statement, NWS Philadelphia/Mount Holly

January 20, 2021Hunterdon County, Somerset County, Warren County, New Jersey; 5 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Jan 20, 2021, 9:52 AM EST for Hunterdon County, Somerset County, Warren County, New Jersey; 5 counties in Pennsylvania. It was in force for 53 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
Jan 20, 2021, 9:52 AM EST (14:52 UTC)
Expired
Jan 20, 2021, 10:45 AM EST
In force
53 min
Issued by
NWS Philadelphia/Mount Holly

Counties Hunterdon County, NJ, Somerset County, NJ, Warren County, NJ, Berks County, PA, Bucks County, PA, Lehigh County, PA, Montgomery County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 99 km from the middle of the area, began a volume at 14:55 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, 2.9 hours before the alert went out and 206 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 2021-01-20Temperature 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 2021-01-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -7 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
1247 m above ground
0-6 km bulk shear
74 kt
0-1 km storm-relative helicity
-7 m²/s²
0-3 km storm-relative helicity
195 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

313 
WWUS81 KPHI 201452
SPSPHI

Special Weather Statement
National Weather Service Mount Holly NJ
952 AM EST Wed Jan 20 2021

NJZ001-007>010-012-015-PAZ055-060>062-101-103>106-201545-
Mercer-Morris-Hunterdon-Sussex-Somerset-Middlesex-Warren-Lower
Bucks-Lehigh-Eastern Montgomery-Western Chester-Northampton-Upper
Bucks-Monroe-Western Montgomery-Berks-
952 AM EST Wed Jan 20 2021

...A SNOW SQUALL WILL AFFECT WARREN...NORTHWESTERN MERCER...
SOMERSET...SOUTHWESTERN MORRIS...HUNTERDON...SOUTHWESTERN SUSSEX...
NORTH CENTRAL MIDDLESEX...NORTHERN MONTGOMERY...SOUTHEASTERN
MONROE...BERKS...LEHIGH...BUCKS...NORTHEASTERN CHESTER AND
NORTHAMPTON COUNTIES...

At 950 AM EST, a snow squall was located along a line extending from
Delaware Water Gap to near Jordan Valley to near Fort Indiantown Gap.
Movement was southeast at 35 mph. Visibilities could briefly drop 
under a half mile and a coating of snow of roadways.

Locations impacted include...
Allentown, Reading, Easton, Somerville, Somerset, Bethlehem,
Bridgewater, Pottstown, Phoenixville, Lansdale, Forks, Middlesex,
Emmaus, Wyomissing, Bound Brook, Manville, Northampton, East
Stroudsburg, Hackettstown and Quakertown.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 296 and 308.
 Northeast Extension between mile markers 26 and 69.
 Interstate 78 in Pennsylvania near mile marker 8, and between mile
markers 10 and 76.
 Interstate 78 in New Jersey between mile markers 0 and 41.
 Interstate 80 in Pennsylvania between mile markers 310 and 314.
 Interstate 80 in New Jersey between mile markers 0 and 28.
 Interstate 287 in New Jersey between mile markers 4 and 32.
 Interstate 176 in Pennsylvania between mile markers 1 and 11.
 Garden State Parkway near mile marker 133.

Use extra caution if you must travel into or through this dangerous
snow squall. Rapid changes in visibility and potentially slick roads
are likely to lead to accidents. Consider delaying travel until the
squall passes your location.

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 4057 7602 4065 7598 4081 7548 4084 7549
      4112 7494 4069 7444 4066 7445 4065 7440
      4060 7446 4061 7435 4058 7432 4027 7501
      4003 7594 4011 7594 4014 7588 4049 7643
TIME...MOT...LOC 1450Z 311DEG 29KT 4096 7515 4073 7567 4048 7664 

$$

NC

The office that day

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

IssuedProductOfficeCountiesLasted
Jan 20, 10:42 AM ESTSpecial Weather StatementPHIHunterdon, Mercer, Middlesex, Monmouth, Morris, Somerset63 min
Jan 20, 12:02 PM ESTSpecial Marine WarningPHI58 min
Jan 20, 1:00 PM ESTSpecial Marine WarningPHI65 min
Jan 20, 8:56 AM ESTSpecial Weather StatementPHICarbon, Monroe49 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.