Alert archive / Pennsylvania / Special Weather Statements in 2011

Special Weather Statement, NWS Philadelphia/Mount Holly

August 9, 2011Chester County, Delaware County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Aug 9, 2011, 11:46 AM EDT for Chester County, Delaware County, Montgomery County, Pennsylvania. It was in force for 59 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 9, 2011, 11:46 AM EDT (15:46 UTC)
Expired: Aug 9, 2011, 12:45 PM EDT
In force: 59 min
Issued by: NWS Philadelphia/Mount Holly

Counties Chester County, PA, Delaware County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 114 km from the middle of the area, began a volume at 15:50 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

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 3.8 hours before the alert went out and 57 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: 210 J/kg
Mixed-layer CIN: -77 J/kg
Mixed-layer LCL: 1178 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 96 m²/s²
0-3 km storm-relative helicity: 173 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.5

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

866 
WWUS81 KPHI 091546
SPSPHI

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1146 AM EDT TUE AUG 9 2011

DEZ001-MDZ008-PAZ060-067-068-070-091645-
BERKS PA-CECIL MD-CHESTER PA-DELAWARE PA-MONTGOMERY PA-NEW CASTLE DE-
1146 AM EDT TUE AUG 9 2011

...SHOWERS WITH HEAVY RAINFALL WILL AFFECT CECIL...DELAWARE...
CHESTER...MONTGOMERY...BERKS AND NEW CASTLE COUNTIES...

AT 1138 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
SHOWERS WITH HEAVY RAINFALL ALONG A LINE EXTENDING FROM SOUTHERN 
BERKS SOUTH THROUGH CHESTER COUNTY AND INTO NORTHERN CECIL COUNTY 
MARYLAND...MOVING EAST AT 25 MPH. THE SHOWERS WILL BE NEAR 
GLENMOORE...ZION...CALVERT...BAY VIEW AROUND 1150 AM...WEST 
GROVE...LOMBARD AROUND 1155 AM...PLEASANT 
HILL...BLAKE...TOUGHKENAMON AND DOWNINGTOWN AROUND NOON.

VERY HEAVY RAIN WILL FALL FROM THESE SHOWERS...AND WILL CAUSE WATER 
TO POND ON ROADS AND QUICKLY FILL ROADSIDE DITCHES AND SMALL 
STREAMS. A FEW LIGHTNING STRIKES ARE ALSO POSSIBLE WITHIN THESE 
SHOWERS.

LAT...LON 3983 7601 3994 7594 4011 7595 4014 7590
      4018 7596 4026 7597 4027 7537 3994 7530
      3985 7533 3984 7537 3980 7542 3972 7548
      3969 7554 3963 7588 3964 7617 3966 7618

$$

HEAVENER

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 9, 12:18 PM EDT	Severe Thunderstorm Warning	PHI	Gloucester	57 min
Aug 9, 12:32 PM EDT	Tornado Warning	PHI	Gloucester	28 min
Aug 9, 1:02 PM EDT	Special Weather Statement	PHI	Camden, Gloucester, Salem	58 min
Aug 9, 1:08 PM EDT	Severe Thunderstorm Warning	PHI	Atlantic, Camden, Cumberland, Gloucester, Salem	67 min
Aug 9, 1:17 PM EDT	Special Weather Statement	PHI	Burlington, Camden, Gloucester	58 min
Aug 9, 2:16 PM EDT	Special Weather Statement	PHI	Atlantic	59 min
Aug 9, 2:22 PM EDT	Areal Flood Advisory	PHI	Camden, Cumberland, Gloucester, Salem	3 hr
Aug 9, 2:22 PM EDT	Severe Thunderstorm Warning	PHI	Mercer, Middlesex, Monmouth	53 min
Aug 9, 2:53 PM EDT	Areal Flood Advisory	PHI	Middlesex, Morris, Somerset	3 hr
Aug 9, 3:27 PM EDT	Special Weather Statement	PHI	Atlantic	63 min
Aug 9, 4:13 PM EDT	Special Marine Warning	PHI		92 min
Aug 9, 5:48 PM EDT	Special Weather Statement	PHI	Gloucester	87 min
Aug 9, 6:54 PM EDT	Special Weather Statement	PHI	Atlantic, Camden, Cape May, Cumberland, Gloucester, Salem	81 min
Aug 9, 12:40 PM EDT	Special Weather Statement	PHI	Cecil	65 min
Aug 9, 5:13 PM EDT	Special Weather Statement	PHI	Kent, Queen Anne's	62 min
Aug 9, 6:35 PM EDT	Special Weather Statement	PHI	Talbot	85 min

Nearby

Special Weather Statements in Pennsylvania, 2011 Every special weather statement in 2011

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.