Alert archive / Pennsylvania / Special Weather Statements in 2019

Special Weather Statement, NWS Philadelphia/Mount Holly

August 8, 2019Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Aug 8, 2019, 6:49 PM EDT for Chester County, Montgomery County, Pennsylvania. It was in force for 26 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
Aug 8, 2019, 6:49 PM EDT (22:49 UTC)
Expired
Aug 8, 2019, 7:15 PM EDT
In force
26 min
Issued by
NWS Philadelphia/Mount Holly

Counties Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 106 km from the middle of the area, began a volume at 22:50 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, 10.8 hours before the alert went out and 203 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 2019-08-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 606 joules per kilogram.LCLLFCEL10008507005003002001001 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 2019-08-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 1 square meters per square second.1939Sfc1 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
606 J/kg
Mixed-layer CIN
-54 J/kg
Mixed-layer LCL
1284 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
1 m²/s²
0-3 km storm-relative helicity
62 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.0

Open this sounding in Storm Lab

The text

As transmitted.

327 
WWUS81 KPHI 082249
SPSPHI

Special Weather Statement
National Weather Service Mount Holly NJ
649 PM EDT Thu Aug 8 2019

DEZ001-NJZ009-PAZ061-062-070-101>106-082315-
New Castle-Hunterdon-Lower Bucks-Upper Bucks-Lehigh-Eastern
Montgomery-Western Montgomery-Delaware-Western Chester-Eastern
Chester-Northampton-
649 PM EDT Thu Aug 8 2019

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT NORTHWESTERN NEW
CASTLE...SOUTHWESTERN HUNTERDON...MONTGOMERY...SOUTHEASTERN LEHIGH...
NORTHWESTERN BUCKS...CHESTER...NORTHWESTERN DELAWARE AND SOUTH
CENTRAL NORTHAMPTON COUNTIES...

At 649 PM EDT, radar indicated strong thunderstorms were located
along a line extending from near Emmaus to near Chester Springs to
Mount Vernon. Movement was east at 40 mph.

Wind gusts up to 40 mph and pea size hail are possible with these
storms.

Locations impacted include...
Allentown, West Chester, Bethlehem, Norristown, Pottstown,
Phoenixville, Lansdale, West Norriton, East Norriton, Coatesville,
Emmaus, Westtown, Quakertown, Perkasie, Doylestown, Downingtown,
Conshohocken, Souderton, Bedminster and Ambler.

Torrential rainfall is also occurring with these storms, and may
cause localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 3983 7604 3987 7599 3991 7600 4010 7575
      4035 7562 4044 7553 4046 7555 4061 7547
      4062 7520 4059 7518 4062 7516 4062 7496
      4006 7528 3970 7577 3972 7579 3972 7587
      3976 7606
TIME...MOT...LOC 2249Z 274DEG 37KT 4054 7544 4011 7569 3983 7605 

$$

MPS

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 8, 3:56 PM EDTAreal Flood AdvisoryPHIHunterdon, Mercer, Middlesex, Monmouth, Somerset104 min
Aug 8, 5:01 PM EDTSpecial Weather StatementPHIBurlington29 min
Aug 8, 5:46 PM EDTSevere Thunderstorm WarningPHIMonmouth, Ocean23 min
Aug 8, 5:50 PM EDTSpecial Marine WarningPHI20 min
Aug 8, 6:14 PM EDTSpecial Weather StatementPHISussex, Warren31 min
Aug 8, 6:39 PM EDTSpecial Weather StatementPHISussex, Warren36 min
Aug 8, 7:00 PM EDTSpecial Marine WarningPHI60 min
Aug 8, 7:01 PM EDTSevere Thunderstorm WarningPHIHunterdon, Morris, Somerset, Sussex, Warren44 min
Aug 8, 7:12 PM EDTSpecial Weather StatementPHIHunterdon33 min
Aug 8, 7:40 PM EDTSpecial Weather StatementPHISalem35 min
Aug 8, 7:49 PM EDTSpecial Weather StatementPHIMorris26 min
Aug 7, 10:36 PM EDTAreal Flood WarningPHIPhiladelphia87 min
Aug 8, 5:31 PM EDTSevere Thunderstorm WarningPHIMonroe44 min

Nearby

Special Weather Statements in Pennsylvania, 2019Every special weather statement in 2019

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.