Alert archive / Pennsylvania / Special Weather Statements in 2017

Special Weather Statement, NWS Philadelphia/Mount Holly

March 3, 2017Delaware County, Montgomery County, Philadelphia County, Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Mar 3, 2017, 3:42 PM EST for Delaware County, Montgomery County, Philadelphia County, Pennsylvania. It was in force for 33 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
Mar 3, 2017, 3:42 PM EST (20:42 UTC)
Expired
Mar 3, 2017, 4:15 PM EST
In force
33 min
Issued by
NWS Philadelphia/Mount Holly

Counties Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 75 km from the middle of the area, began a volume at 20:46 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 12:00Z, 8.7 hours before the alert went out and 221 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 12:00Z on 2017-03-03Temperature 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 12:00Z on 2017-03-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -136 square meters per square second.1939587897117136156Sfc1 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
950 m above ground
0-6 km bulk shear
93 kt
0-1 km storm-relative helicity
-136 m²/s²
0-3 km storm-relative helicity
35 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

332 
WWUS81 KPHI 032042
SPSPHI

Special Weather Statement
National Weather Service Mount Holly NJ
342 PM EST FRI MAR 3 2017

NJZ018-PAZ070-071-101>106-032115-
Camden-Lower Bucks-Upper Bucks-Eastern Montgomery-Western
Montgomery-Delaware-Western Chester-Eastern Chester-Philadelphia-
342 PM EST FRI MAR 3 2017

...A SNOW SQUALL WILL AFFECT NORTHWESTERN CAMDEN...NORTHWESTERN
BURLINGTON...MONTGOMERY...SOUTHEASTERN BUCKS...NORTHEASTERN
CHESTER...PHILADELPHIA AND CENTRAL DELAWARE COUNTIES...

At 340 PM EST, a snow squall was located along a line extending from
Hatfield to Lionville to near Honey Brook. Movement was east at 35
mph.

This squall will be near...
  Norristown, Lansdale, East Norriton and Hatfield around 345 PM 
  EST. 
  Phoenixville and Plymouth Meeting around 350 PM EST. 
  Ambler and Valley Forge around 355 PM EST. 
  Paoli around 400 PM EST. 
  Hatboro, Jenkintown, Abington, Bryn Athyn, Ivyland, Willow Grove, 
  Gradyville and Lima around 405 PM EST. 
  Rockledge, Broomall, Newtown Square, Trout Lake, Radnor Township 
  and Richboro around 410 PM EST. 
  Philadelphia, Bensalem, Yeadon, Bristol, Folcroft, Swarthmore, 
  Narberth, East Lansdowne, Langhorne and Feasterville around 415 PM 
  EST. 

Visibilities in this squall will drop quickly to a quarter mile in 
spots for a few minutes. Wind gusts up to 40 mph are also possible. 
Any snowfall accumulations will be minor and limited to grassy 
surfaces.

Use extra caution and reduce speed if traveling into or through this 
snow squall. Rapid changes in visibility could lead to accidents. 

LAT...LON 4011 7594 4012 7592 4013 7568 4030 7532
      4016 7473 4012 7478 4013 7482 4008 7487
      4007 7494 4002 7504 3996 7513 3992 7514
      3988 7524 3996 7569
TIME...MOT...LOC 2040Z 291DEG 29KT 4026 7532 4007 7567 4010 7585 

$$

JRK

The office that day

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

IssuedProductOfficeCountiesLasted
Mar 3, 3:04 PM ESTSpecial Weather StatementPHIGloucester, Salem41 min
Mar 3, 3:18 PM ESTSpecial Weather StatementPHISussex, Warren57 min
Mar 3, 4:08 PM ESTSpecial Weather StatementPHIWarren37 min
Mar 3, 4:48 PM ESTSpecial Weather StatementPHIHunterdon, Mercer42 min
Mar 3, 4:54 PM ESTSpecial Weather StatementPHIMorris, Somerset36 min
Mar 3, 5:31 PM ESTSpecial Weather StatementPHICamden, Mercer29 min
Mar 3, 5:52 PM ESTSpecial Weather StatementPHIBurlington, Camden, Gloucester23 min
Mar 3, 6:17 PM ESTSpecial Weather StatementPHIBurlington, Ocean28 min
Mar 3, 3:08 PM ESTSpecial Weather StatementPHIMontgomery37 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.