Alert archive / Pennsylvania / Special Weather Statements in 2018

Special Weather Statement, NWS Philadelphia/Mount Holly

July 17, 2018Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Jul 17, 2018, 2:21 PM EDT for Chester County, Pennsylvania. It was in force for 39 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: Jul 17, 2018, 2:21 PM EDT (18:21 UTC)
Expired: Jul 17, 2018, 3:00 PM EDT
In force: 39 min
Issued by: NWS Philadelphia/Mount Holly

County Chester County, PA

The radar

The Philadelphia radar (KDIX), 109 km from the middle of the area, began a volume at 18:22 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, 6.4 hours before the alert went out and 186 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 644 J/kg
Mixed-layer CIN: -93 J/kg
Mixed-layer LCL: 959 m above ground
0-6 km bulk shear: 11 kt
0-1 km storm-relative helicity: 39 m²/s²
0-3 km storm-relative helicity: 74 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

664 
WWUS81 KPHI 171821
SPSPHI

Special Weather Statement
National Weather Service Mount Holly NJ
221 PM EDT TUE JUL 17 2018

PAZ070-101>104-171900-
Eastern Montgomery-Western Montgomery-Delaware-Western
Chester-Eastern Chester-
221 PM EDT TUE JUL 17 2018

...AN AREA OF STRONG THUNDERSTORMS WILL AFFECT SOUTHWESTERN
MONTGOMERY...CENTRAL CHESTER AND NORTH CENTRAL DELAWARE COUNTIES...

At 221 PM EDT, a cluster of strong thunderstorms was near
Coatesville, or 11 miles west of West Chester, moving northeast at 25
mph.

Winds up to 50 mph and pea size hail are possible with this storm.

Locations impacted include...
West Chester, Phoenixville, West Norriton, Coatesville, Downingtown,
Collegeville, Royersford, Parkesburg, Trappe, West Grove, Pughtown,
Marshallton, Radnor Township, Lionville-Marchwood, Valley Forge,
Glenmoore, Paoli, Chester Springs, Lionville and King Of Prussia.

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

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

To report severe weather, contact your nearest law enforcement
agency. They can relay your report to the National Weather Service
office in Mount Holly NJ.

LAT...LON 3981 7583 3995 7597 4027 7553 4005 7531
TIME...MOT...LOC 1821Z 232DEG 23KT 3993 7582 

$$

MPS

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 17, 3:36 AM EDT	Flash Flood Watch	PHI	Burlington, Camden, Gloucester, Hunterdon, Mercer, Middlesex and 3 more	15 hr
Jul 17, 12:35 PM EDT	Special Weather Statement	PHI	Sussex	25 min
Jul 17, 1:31 PM EDT	Special Weather Statement	PHI	Hunterdon	44 min
Jul 17, 1:45 PM EDT	Special Weather Statement	PHI	Morris	30 min
Jul 17, 2:05 PM EDT	Areal Flood Advisory	PHI	Hunterdon, Morris, Somerset, Sussex, Warren	3 hr
Jul 17, 2:09 PM EDT	Special Weather Statement	PHI	Morris	36 min
Jul 17, 2:44 PM EDT	Special Weather Statement	PHI	Middlesex	31 min
Jul 17, 2:48 PM EDT	Special Weather Statement	PHI	Mercer	27 min
Jul 17, 2:50 PM EDT	Areal Flood Advisory	PHI	Hunterdon, Mercer, Middlesex, Morris, Somerset	3 hr
Jul 17, 2:58 PM EDT	Severe Thunderstorm Warning	PHI	Mercer	32 min
Jul 17, 3:09 PM EDT	Special Weather Statement	PHI	Monmouth	36 min
Jul 17, 3:48 PM EDT	Special Weather Statement	PHI	Ocean	57 min
Jul 17, 3:51 PM EDT	Special Weather Statement	PHI	Monmouth	24 min
Jul 17, 3:54 PM EDT	Special Marine Warning	PHI		66 min
Jul 17, 3:58 PM EDT	Special Weather Statement	PHI	Ocean	32 min
Jul 17, 4:00 PM EDT	Special Weather Statement	PHI	Cumberland	45 min
Jul 17, 4:03 PM EDT	Areal Flood Advisory	PHI	Burlington, Mercer, Middlesex, Monmouth, Ocean	2 hr
Jul 17, 4:21 PM EDT	Special Marine Warning	PHI		24 min
Jul 17, 4:35 PM EDT	Flash Flood Warning	PHI	Ocean	4 hr
Jul 17, 4:38 PM EDT	Special Marine Warning	PHI		52 min
Jul 17, 4:48 PM EDT	Special Weather Statement	PHI	Cumberland, Ocean	57 min
Jul 17, 1:49 PM EDT	Special Weather Statement	PHI	Chester, Montgomery	41 min
Jul 17, 2:27 PM EDT	Flash Flood Warning	PHI	Berks, Chester, Montgomery	4 hr
Jul 17, 3:35 PM EDT	Special Weather Statement	PHI	Delaware, Montgomery	25 min
Jul 17, 4:02 PM EDT	Special Weather Statement	PHI	Kent	13 min
Jul 17, 4:30 PM EDT	Special Weather Statement	PHI	Kent	30 min
Jul 17, 5:07 PM EDT	Special Weather Statement	PHI	Kent	23 min
Jul 17, 5:44 PM EDT	Special Weather Statement	PHI	Sussex	31 min
Jul 17, 2:34 PM EDT	Special Weather Statement	PHI	Kent	41 min
Jul 17, 3:41 PM EDT	Special Weather Statement	PHI	Queen Anne's	49 min
Jul 17, 4:31 PM EDT	Special Weather Statement	PHI	Caroline, Queen Anne's, Talbot	29 min
Jul 17, 5:06 PM EDT	Special Weather Statement	PHI	Caroline, Talbot	24 min
Jul 17, 5:28 PM EDT	Special Weather Statement	PHI	Caroline	47 min

Nearby

Special Weather Statements in Pennsylvania, 2018 Every special weather statement 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.