Alert archive / Pennsylvania / Special Weather Statements in 2017

Special Weather Statement, NWS Philadelphia/Mount Holly

February 12, 2017Berks County, Lehigh County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Feb 12, 2017, 10:20 PM EST for Berks County, Lehigh County, Montgomery County, Pennsylvania. It was in force for 70 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 12, 2017, 10:20 PM EST (03:20 UTC)
Expired
Feb 12, 2017, 11:30 PM EST
In force
70 min
Issued by
NWS Philadelphia/Mount Holly

Counties Berks County, PA, Lehigh County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 127 km from the middle of the area, began a volume at 03:20 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

Washington/Dulle, VA (KIAD), launched 00:00Z, 3.3 hours before the alert went out and 208 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, Washington/Dulle, VA at 00:00Z on 2017-02-13Temperature 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, Washington/Dulle, VA at 00:00Z on 2017-02-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -382 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
854 m above ground
0-6 km bulk shear
90 kt
0-1 km storm-relative helicity
-382 m²/s²
0-3 km storm-relative helicity
-107 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

848 
WWUS81 KPHI 130320
SPSPHI

Special Weather Statement
National Weather Service Mount Holly NJ
1020 PM EST SUN FEB 12 2017

PAZ060-061-101>106-130430-
Lower Bucks-Upper Bucks-Lehigh-Eastern Montgomery-Western
Montgomery-Western Chester-Eastern Chester-Berks-
1020 PM EST SUN FEB 12 2017

...BRIEF PERIOD OF FREEZING RAIN WILL AFFECT SPOTS IN FREEZING RAIN 
WILL AFFECT BERKS...MONTGOMERY...SOUTHERN LEHIGH...NORTHWESTERN 
BUCKS...NORTHEASTERN CHESTER AND SOUTHERN NORTHAMPTON COUNTIES...

At 1016 PM EST, an area of showers was located along a line 
extending from Hamburg to Hummelstown. Movement was east at 45 mph. 
With temperatures still at or just below freezing in some spots, a 
brief period of light freezing rain will occur late this evening. A 
light glaze of icing is possible.

Winds will increase behind these showers with gusts to 40 mph 
possible late this evening.

Locations impacted include...
Allentown, Reading, Norristown, Pottstown, Phoenixville, Lansdale,
West Norriton, East Norriton, Emmaus, Wyomissing, Quakertown,
Perkasie, Doylestown, Souderton, Bedminster, Ambler, Birdsboro,
Collegeville, Kutztown and Royersford.

Conditions can deteriorate rapidly in winter weather situations. Be 
prepared for icy roads...especially untreated secondary roads, 
bridges and overpasses. Slow down and allow extra time if traveling 
this evening.

LAT...LON 4049 7643 4054 7617 4058 7605 4057 7602
      4063 7600 4067 7592 4059 7540 4054 7533
      4057 7528 4052 7506 4011 7522 4006 7547
      4009 7580 4000 7593 4001 7595 4004 7593
      4011 7594 4014 7588
TIME...MOT...LOC 0316Z 279DEG 50KT 4054 7598 4027 7670 

$$

JRK

The office that day

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

IssuedProductOfficeCountiesLasted
Feb 12, 11:10 PM ESTSevere Thunderstorm WarningPHIAtlantic, Burlington, Camden, Cumberland, Gloucester, Monmouth and 2 more50 min
Feb 12, 11:33 PM ESTSpecial Marine WarningPHI87 min
Feb 12, 11:53 PM ESTSevere Thunderstorm WarningPHIAtlantic, Burlington, Camden, Cape May, Cumberland, Gloucester and 2 more52 min
Feb 13, 12:02 AM ESTSpecial Marine WarningPHI88 min
Feb 13, 1:25 AM ESTSpecial Weather StatementPHIMorris, Somerset, Sussex, Warren50 min
Feb 13, 12:29 PM ESTGale WarningPHI9 hr
Feb 12, 11:14 PM ESTSevere Thunderstorm WarningPHICaroline, Kent, Queen Anne's, Talbot46 min

Nearby

Special Weather Statements in Pennsylvania, 2017Every special weather statement in 2017

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.