Alert archive / Pennsylvania / Special Weather Statements in 2011

Special Weather Statement, NWS Philadelphia/Mount Holly

August 18, 2011Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Aug 18, 2011, 4:48 AM EDT for Chester County, Montgomery County, Pennsylvania. It was in force for 57 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 18, 2011, 4:48 AM EDT (08:48 UTC)
Expired: Aug 18, 2011, 5:45 AM EDT
In force: 57 min
Issued by: NWS Philadelphia/Mount Holly

Counties Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 123 km from the middle of the area, began a volume at 08:53 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 00:00Z, 8.8 hours before the alert went out and 181 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: 66 J/kg
Mixed-layer CIN: -24 J/kg
Mixed-layer LCL: 1883 m above ground
0-6 km bulk shear: 11 kt
0-1 km storm-relative helicity: 37 m²/s²
0-3 km storm-relative helicity: 14 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

021 
WWUS81 KPHI 180848
SPSPHI

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
448 AM EDT THU AUG 18 2011

DEZ001-MDZ008-PAZ060-067>070-180945-
BERKS PA-BUCKS PA-CECIL MD-CHESTER PA-DELAWARE PA-MONTGOMERY PA-
NEW CASTLE DE-
448 AM EDT THU AUG 18 2011

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

AT 440 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
SHOWERS WITH HEAVY RAINFALL AND ISOLATED EMBEDDED THUNDERSTORMS 
ALONG A LINE EXTENDING FROM 5 MILES EAST OF READING TO 17 MILES 
NORTHWEST OF WEST CHESTER TO 22 MILES WEST OF ELKTON...MOVING EAST 
AT 20 MPH. THE SHOWERS WILL BE NEAR MOUNT VERNON...HOMEVILLE...GLEN 
ROY AROUND 455 AM...GLENMOORE...COCHRANVILLE... WEST NOTTINGHAM... 
AMITY GARDENS AROUND 500 AM...FARMINGTON...STOWE AND OXFORD AROUND 
505 AM.

BRIEF VERY HEAVY RAIN WILL FALL FROM THESE SHOWERS...AND WILL CAUSE 
WATER TO POND ON ROADS AND IT MAY QUICKLY FILL ROADSIDE DITCHES AND 
SMALL STREAMS.

LAT...LON 3973 7615 3975 7610 3987 7601 3992 7601
      4003 7595 4011 7595 4014 7590 4019 7597
      4039 7592 4044 7552 4042 7549 4044 7547
      4047 7522 4013 7531 3969 7567 3963 7616
      3972 7624

$$

FORECASTER:DRAG

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 18, 4:53 AM EDT	Special Weather Statement	PHI	Morris, Somerset, Sussex	52 min
Aug 18, 6:35 AM EDT	Areal Flood Advisory	PHI	Burlington, Camden, Gloucester, Hunterdon, Mercer, Morris and 2 more	3 hr
Aug 18, 7:29 AM EDT	Special Weather Statement	PHI	Camden, Gloucester	61 min
Aug 18, 8:16 AM EDT	Special Weather Statement	PHI	Burlington, Camden, Gloucester	59 min
Aug 18, 8:57 AM EDT	Areal Flood Advisory	PHI	Atlantic, Burlington, Camden, Cumberland, Gloucester, Monmouth and 1 more	3 hr
Aug 18, 3:12 PM EDT	Flash Flood Watch	PHI	Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester and 10 more	29 hr
Aug 18, 3:32 PM EDT	Special Weather Statement	PHI	Burlington	58 min
Aug 18, 3:50 PM EDT	Areal Flood Advisory	PHI	Burlington, Camden	51 min
Aug 18, 4:17 PM EDT	Special Weather Statement	PHI	Monmouth	58 min
Aug 18, 4:55 PM EDT	Special Weather Statement	PHI	Burlington	65 min
Aug 18, 5:20 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Monmouth, Ocean	33 min
Aug 18, 6:12 PM EDT	Special Weather Statement	PHI	Middlesex	63 min
Aug 18, 6:33 PM EDT	Special Weather Statement	PHI	Mercer	57 min
Aug 18, 7:34 PM EDT	Special Weather Statement	PHI	Monmouth	56 min
Aug 18, 7:37 PM EDT	Severe Thunderstorm Warning	PHI	Gloucester, Salem	53 min
Aug 18, 7:43 PM EDT	Severe Thunderstorm Warning	PHI	Morris, Sussex, Warren	62 min
Aug 18, 7:47 PM EDT	Areal Flood Advisory	PHI	Sussex, Warren	3 hr
Aug 18, 7:59 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Camden	61 min
Aug 18, 2:57 AM EDT	Special Weather Statement	PHI	Berks	63 min
Aug 18, 3:53 AM EDT	Special Weather Statement	PHI	Berks	52 min
Aug 18, 5:45 AM EDT	Special Weather Statement	PHI	Delaware, Montgomery, Philadelphia	60 min
Aug 18, 6:04 AM EDT	Special Weather Statement	PHI	Berks, Chester	41 min
Aug 18, 9:29 AM EDT	Areal Flood Advisory	PHI	Delaware	2 hr
Aug 18, 5:30 PM EDT	Special Weather Statement	PHI	Monroe	60 min
Aug 18, 5:48 PM EDT	Severe Thunderstorm Warning	PHI	Chester	57 min
Aug 18, 6:18 PM EDT	Special Weather Statement	PHI	Chester	57 min
Aug 18, 6:39 PM EDT	Severe Thunderstorm Warning	PHI	Chester	66 min
Aug 18, 6:59 PM EDT	Flash Flood Warning	PHI	Chester	2 hr
Aug 18, 7:14 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware	50 min
Aug 18, 7:28 PM EDT	Special Weather Statement	PHI	Chester	62 min
Aug 18, 7:31 PM EDT	Special Weather Statement	PHI	Monroe	59 min
Aug 18, 7:58 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery	31 min
Aug 18, 6:04 PM EDT	Areal Flood Advisory	PHI	Cecil	116 min
Aug 18, 6:44 PM EDT	Special Weather Statement	PHI	New Castle	61 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.