Alert archive / Pennsylvania / Winter Storm Watches in 2018

Winter Storm Watch 3, NWS Philadelphia/Mount Holly

February 16, 20188 counties in Pennsylvania; 8 counties in New Jersey

NWS Philadelphia/Mount Holly issued this winter storm watch at Feb 16, 2018, 3:51 AM EST for 8 counties in Pennsylvania; 8 counties in New Jersey. It took effect at Feb 17, 2018, 4:00 PM EST. It was in force for .

The area

The counties it named.

The facts

Issued
Feb 16, 2018, 3:51 AM EST (08:51 UTC)
In effect from
Feb 17, 2018, 4:00 PM EST
Expired
Feb 17, 2018, 3:45 AM EST
In force
Issued by
NWS Philadelphia/Mount Holly

Counties Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Morris County, NJ, Somerset County, NJ, Sussex County, NJ, Warren County, NJ, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Lehigh County, PA, Monroe County, PA, Montgomery County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 90 km from the middle of the area, began a volume at 08:55 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 00:00Z, 8.9 hours before the alert went out and 189 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 00:00Z on 2018-02-16Temperature 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 00:00Z on 2018-02-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 212 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
1118 m above ground
0-6 km bulk shear
82 kt
0-1 km storm-relative helicity
212 m²/s²
0-3 km storm-relative helicity
213 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

649 
WWUS41 KPHI 160851
WSWPHI

URGENT - WINTER WEATHER MESSAGE
National Weather Service Mount Holly NJ
351 AM EST Fri Feb 16 2018

NJZ001-007-PAZ054-055-060>062-162100-
/O.NEW.KPHI.WS.A.0003.180218T0000Z-180218T1000Z/
Sussex-Warren-Carbon-Monroe-Berks-Lehigh-Northampton-
Including the cities of Newton, Washington, Jim Thorpe, 
Stroudsburg, Reading, Allentown, Bethlehem, and Easton
351 AM EST Fri Feb 16 2018

...WINTER STORM WATCH IN EFFECT FROM SATURDAY EVENING THROUGH
LATE SATURDAY NIGHT...

* WHAT...Heavy snow possible. Total snow accumulations of 4 to 6 
  inches are possible.

* WHERE...The Lehigh Valley and Berks County, the southern Poconos
  and far northwestern New Jersey.

* WHEN...From Saturday evening into very early Sunday morning.

* ADDITIONAL DETAILS...Plan on difficult travel conditions.
  Significant reductions in visibility are possible. There remains
  some uncertainty with how much precipitation extends this far
  westward, however there is the potential for a short period of
  heavy snow Saturday night which could lead to a rapid 
  deterioration in road conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is potential for significant
snow, sleet or ice accumulations that may impact travel. Continue
to monitor the latest forecasts.

&&

$$

NJZ008>010-012-015-PAZ101>106-162100-
/O.NEW.KPHI.WS.A.0003.180218T0000Z-180218T1000Z/
Morris-Hunterdon-Somerset-Middlesex-Mercer-Western Chester-
Eastern Chester-Western Montgomery-Eastern Montgomery-Upper Bucks-
Lower Bucks-
Including the cities of Morristown, Flemington, Somerville, 
New Brunswick, Trenton, Honey Brook, Oxford, West Chester, 
Kennett Square, Collegeville, Pottstown, Norristown, Lansdale, 
Chalfont, Perkasie, Morrisville, and Doylestown
351 AM EST Fri Feb 16 2018

...WINTER STORM WATCH IN EFFECT FROM SATURDAY EVENING THROUGH
LATE SATURDAY NIGHT...

* WHAT...Heavy snow possible. Total snow accumulations of 4 to 6 
  inches are possible.

* WHERE...Most of southeastern Pennsylvania and northern New 
  Jersey.

* WHEN...From Saturday evening into very early Sunday morning.

* ADDITIONAL DETAILS...Plan on difficult travel conditions.
  Significant reductions in visibility are possible. There is the
  potential for a short period of heavy snow Saturday night which
  could lead to a rapid deterioration in road conditions. The snow
  could be wet enough especially closer to Interstate 95, 
  potentially resulting in some power outages.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is potential for significant
snow, sleet or ice accumulations that may impact travel. Continue
to monitor the latest forecasts.

&&

$$

For more information from the National Weather Service visit
www.weather.gov/phi/winter
2 follow-up statements
981 
WWUS41 KPHI 162059
WSWPHI

URGENT - WINTER WEATHER MESSAGE
National Weather Service Mount Holly NJ
359 PM EST Fri Feb 16 2018



NJZ013-170900-
/O.EXB.KPHI.WS.A.0003.180217T2100Z-180218T0900Z/
Western Monmouth-
Including the city of Freehold
359 PM EST Fri Feb 16 2018

...WINTER STORM WATCH IN EFFECT FROM SATURDAY AFTERNOON THROUGH
LATE SATURDAY NIGHT...

* WHAT...Heavy snow possible. Total snow accumulations of 3 to 6 
  inches are possible.

* WHERE...Western Monmouth county.

* WHEN...From Saturday afternoon through late Saturday night.

* ADDITIONAL DETAILS...Plan on difficult travel conditions. 
  Significant reductions in visibility are possible. There is the
  potential for a short period of heavy snow Saturday night which
  could lead to a rapid deterioration in road conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is potential for significant
snow, sleet or ice accumulations that may impact travel. Continue
to monitor the latest forecasts.

&&

$$

NJZ001-007-PAZ054-055-060>062-170900-
/O.EXT.KPHI.WS.A.0003.180217T2100Z-180218T0900Z/
Sussex-Warren-Carbon-Monroe-Berks-Lehigh-Northampton-
Including the cities of Newton, Washington, Jim Thorpe, 
Stroudsburg, Reading, Allentown, Bethlehem, and Easton
359 PM EST Fri Feb 16 2018

...WINTER STORM WATCH NOW IN EFFECT FROM SATURDAY AFTERNOON
THROUGH LATE SATURDAY NIGHT...

* WHAT...Heavy snow possible. Total snow accumulations of up to 5
  inches are possible.

* WHERE...The Lehigh Valley and Berks County, the southern Poconos
  and far northwestern New Jersey.

* WHEN...From Saturday afternoon through late Saturday night.

* ADDITIONAL DETAILS...Plan on difficult travel conditions.
  Significant reductions in visibility are possible. There 
  remains some uncertainty with how much precipitation extends 
  this far westward, however there is the potential for a short 
  period of heavy snow Saturday night which could lead to a rapid 
  deterioration in road conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is potential for significant
snow, sleet or ice accumulations that may impact travel. Continue
to monitor the latest forecasts.

&&

$$

NJZ008>010-012-015-PAZ101>106-170900-
/O.EXT.KPHI.WS.A.0003.180217T2100Z-180218T0900Z/
Morris-Hunterdon-Somerset-Middlesex-Mercer-Western Chester-
Eastern Chester-Western Montgomery-Eastern Montgomery-Upper Bucks-
Lower Bucks-
Including the cities of Morristown, Flemington, Somerville, 
New Brunswick, Trenton, Honey Brook, Oxford, West Chester, 
Kennett Square, Collegeville, Pottstown, Norristown, Lansdale, 
Chalfont, Perkasie, Morrisville, and Doylestown
359 PM EST Fri Feb 16 2018

...WINTER STORM WATCH NOW IN EFFECT FROM SATURDAY AFTERNOON
THROUGH LATE SATURDAY NIGHT...

* WHAT...Heavy snow possible. Total snow accumulations of 3 to 6 
  inches are possible.

* WHERE...Most of southeastern Pennsylvania and northern New 
  Jersey.

* WHEN...From Saturday afternoon through late Saturday night.

* ADDITIONAL DETAILS...Plan on difficult travel conditions. 
  Significant reductions in visibility are possible. There is the
  potential for a short period of heavy snow Saturday night which
  could lead to a rapid deterioration in road conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is potential for significant
snow, sleet or ice accumulations that may impact travel. Continue
to monitor the latest forecasts.

&&

$$

For more information from the National Weather Service visit
www.weather.gov/phi/winter
860 
WWUS41 KPHI 170845
WSWPHI

URGENT - WINTER WEATHER MESSAGE
National Weather Service Mount Holly NJ
345 AM EST Sat Feb 17 2018

NJZ001-007>010-012-015-PAZ054-055-060>062-101>106-172100-
/O.UPG.KPHI.WS.A.0003.180217T2100Z-180218T0900Z/
/O.NEW.KPHI.WW.Y.0008.180217T2100Z-180218T0900Z/
Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-Mercer-Carbon-
Monroe-Berks-Lehigh-Northampton-Western Chester-Eastern Chester-
Western Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks-
Including the cities of Newton, Washington, Morristown, 
Flemington, Somerville, New Brunswick, Trenton, Jim Thorpe, 
Stroudsburg, Reading, Allentown, Bethlehem, Easton, Honey Brook, 
Oxford, West Chester, Kennett Square, Collegeville, Pottstown, 
Norristown, Lansdale, Chalfont, Perkasie, Morrisville, 
and Doylestown
345 AM EST Sat Feb 17 2018

...WINTER WEATHER ADVISORY IN EFFECT FROM 4 PM THIS AFTERNOON TO
4 AM EST SUNDAY...

* WHAT...Snow expected. Total snow accumulations of 3 to 5 
  inches are expected.

* WHERE...Most of eastern Pennsylvania and northern New Jersey.

* WHEN...Snow quickly overspreads the area from the southwest
  between around mid afternoon, becoming moderate to potentially
  heavy at times this evening. The snow should quickly by 4 AM.

* ADDITIONAL DETAILS...Plan on difficult travel conditions. Be
  prepared for reduced visibilities at times. The snow may fall at
  up to an inch per hour at times in parts of the region, which 
  would result in rapid deteriorating road conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Weather Advisory for snow means periods of snow will
cause primarily travel difficulties. Be prepared for snow covered
roads and limited visibilities, and use caution while driving.
The latest road conditions for the state you are calling from can
be obtained by calling 5 1 1.

&&

$$

NJZ013-172100-
/O.UPG.KPHI.WS.A.0003.180217T2100Z-180218T0900Z/
/O.NEW.KPHI.WW.Y.0008.180217T2100Z-180218T0900Z/
Western Monmouth-
Including the city of Freehold
345 AM EST Sat Feb 17 2018

...WINTER WEATHER ADVISORY IN EFFECT FROM 4 PM THIS AFTERNOON TO
4 AM EST SUNDAY...

* WHAT...Snow mixed with rain at times expected. Total snow 
  accumulations of 2 to 3 inches are expected.

* WHERE...Western Monmouth county.

* WHEN...Snow mixed with rain develops late this afternoon and
  continues through this evening. All snow will occur at times and
  could be moderate to heavy, however rain and sleet may mix in 
  again late this evening before the precipitation ends after 
  midnight.

* ADDITIONAL DETAILS...Plan on slippery road conditions. Be 
  prepared for reduced visibilities at times.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Weather Advisory for snow means periods of snow will
cause primarily travel difficulties. Be prepared for snow covered
roads and limited visibilities, and use caution while driving.
The latest road conditions for the state you are calling from can
be obtained by calling 5 1 1.

&&

$$

DEZ001-MDZ008-NJZ016>019-PAZ070-071-172100-
/O.NEW.KPHI.WW.Y.0008.180217T2100Z-180218T0900Z/
New Castle-Cecil-Salem-Gloucester-Camden-Northwestern Burlington-
Delaware-Philadelphia-
Including the cities of Wilmington, Elkton, Pennsville, 
Glassboro, Camden, Cherry Hill, Moorestown, Mount Holly, Media, 
and Philadelphia
345 AM EST Sat Feb 17 2018

...WINTER WEATHER ADVISORY IN EFFECT FROM 4 PM THIS AFTERNOON TO
4 AM EST SUNDAY...

* WHAT...Wet snow expected. Total wet snow accumulations of 2 to 
  3 inches are expected.

* WHERE...Far southeastern Pennsylvania, portions of southern New
  Jersey, northeast Maryland and northern Delaware.

* WHEN...Snow mixed with rain develops later this afternoon from 
  the southwest and changes over to wet snow for many areas, some 
  of which could be moderate to heavy at times. Some rain and 
  sleet may mix in at times through this evening, before the 
  precipitation ends after midnight.

* ADDITIONAL DETAILS...Plan on slippery road conditions. Be
  prepared for reduced visibilities at times. A burst of snow this
  evening would allow for more efficient accumulations and 
  deteriorating road conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Weather Advisory for wet snow means periods of wet snow
will cause primarily travel difficulties. Be prepared for snow
covered roads and limited visibilities, and use caution while
driving. The latest road conditions for the state you are calling
from can be obtained by calling 5 1 1.

&&

$$

For more information from the National Weather Service visit
www.weather.gov/phi/winter

The office that day

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

IssuedProductOfficeCountiesLasted
Feb 16, 3:48 AM ESTSmall Craft AdvisoryPHI24 hr

Nearby

Winter Storm Watches in Pennsylvania, 2018Winter Storm Watches in New Jersey, 2018Every winter storm watch in 2018

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.