Alert archive / Pennsylvania / Special Weather Statements in 2018

Special Weather Statement, NWS Philadelphia/Mount Holly

August 13, 2018Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Aug 13, 2018, 8:13 PM EDT for Montgomery County, Pennsylvania. It was in force for 32 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Aug 13, 2018, 8:13 PM EDT (00:13 UTC)
Expired: Aug 13, 2018, 8:45 PM EDT
In force: 32 min
Issued by: NWS Philadelphia/Mount Holly

County Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 96 km from the middle of the area, began a volume at 00:14 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.

What was reported inside it

Time	Report	Where	Remark
Aug 13, 8:33 PM EDT	TSTM WND GST 60	Knickerbocker, PA	REPORT OF LARGE TREES AND LIMBS DOWN IN A WOODED AREA NEAR PAOLI HOSPITAL AS WELL.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 00:00Z, 0.2 hours before the alert went out and 210 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: 874 J/kg
Mixed-layer CIN: -24 J/kg
Mixed-layer LCL: 919 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: -36 m²/s²
0-3 km storm-relative helicity: -10 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

485 
WWUS81 KPHI 140013
SPSPHI

Special Weather Statement
National Weather Service Mount Holly NJ
813 PM EDT MON AUG 13 2018

PAZ070-101>104-140045-
Eastern Montgomery-Western Montgomery-Delaware-Western
Chester-Eastern Chester-
813 PM EDT MON AUG 13 2018

...AN AREA OF STRONG THUNDERSTORMS WILL AFFECT WESTERN MONTGOMERY...
NORTHEASTERN CHESTER AND WESTERN DELAWARE COUNTIES...

At 811 PM EDT, a cluster of strong thunderstorms was from western 
Delaware County across northeastern Chester County and the upper 
portions of Montgomery County, moving north at 20 mph.

Winds up to 40 mph are possible with some of the stronger storms.

Locations impacted include...
West Chester, Norristown, Pottstown, Phoenixville, Lansdale, West
Norriton, East Norriton, Westtown, Souderton, Collegeville,
Royersford, Trappe, Hatfield, East Greenville, Schwenksville, Green
Lane, Cheyney, Elam, Chelsea and Spring Mount.

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

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

LAT...LON 4044 7554 4029 7528 3982 7545 3984 7550
      3984 7561 4035 7562
TIME...MOT...LOC 0011Z 196DEG 18KT 3994 7552 

$$

Gorse

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 13, 9:14 PM EDT	Areal Flood Warning	PHI	Ocean	4 hr
Aug 13, 9:16 PM EDT	Severe Thunderstorm Warning	PHI	Hunterdon	44 min
Aug 14, 12:50 PM EDT	Areal Flood Advisory	PHI	Hunterdon, Warren	4 hr
Aug 14, 3:24 PM EDT	Special Weather Statement	PHI	Burlington	51 min
Aug 14, 3:36 PM EDT	Special Weather Statement	PHI	Monmouth	39 min
Aug 14, 3:48 PM EDT	Special Weather Statement	PHI	Monmouth	57 min
Aug 14, 4:00 PM EDT	Special Marine Warning	PHI		60 min
Aug 14, 4:45 PM EDT	Special Weather Statement	PHI	Hunterdon, Somerset	45 min
Aug 13, 8:16 PM EDT	Areal Flood Advisory	PHI	Chester, Delaware, Montgomery, Philadelphia	3 hr
Aug 13, 8:51 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery	54 min
Aug 13, 9:00 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	60 min
Aug 14, 3:22 PM EDT	Special Weather Statement	PHI	Lehigh	53 min
Aug 14, 3:58 PM EDT	Special Weather Statement	PHI	Montgomery	47 min
Aug 14, 1:46 AM EDT	River Flood Warning	PHI	New Castle	8 hr
Aug 13, 8:55 PM EDT	Special Weather Statement	PHI	Caroline	50 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.