Alert archive / Pennsylvania / Special Weather Statements in 2011

Special Weather Statement, NWS Philadelphia/Mount Holly

August 18, 2011Delaware County, Montgomery County, Philadelphia County, Pennsylvania; Cecil County, Maryland; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this special weather statement at Aug 18, 2011, 5:45 AM EDT for Delaware County, Montgomery County, Philadelphia County, Pennsylvania; Cecil County, Maryland; New Castle County, Delaware. It was in force for 60 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, 5:45 AM EDT (09:45 UTC)
Expired: Aug 18, 2011, 6:45 AM EDT
In force: 60 min
Issued by: NWS Philadelphia/Mount Holly

Counties New Castle County, DE, Cecil County, MD, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Dover AFB radar (KDOX), 95 km from the middle of the area, began a volume at 09:45 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, 9.8 hours before the alert went out and 175 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.

109 
WWUS81 KPHI 180945
SPSPHI

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

DEZ001-MDZ008-012-NJZ016>018-PAZ067-068-070-071-181045-
CAMDEN NJ-CECIL MD-CHESTER PA-DELAWARE PA-GLOUCESTER NJ-KENT MD-
MONTGOMERY PA-NEW CASTLE DE-PHILADELPHIA PA-SALEM NJ-
545 AM EDT THU AUG 18 2011

...HEAVY SHOWERS AND SCATTERED STRONG THUNDERSTORMS WILL AFFECT 
CAMDEN...CECIL...CHESTER...DELAWARE...GLOUCESTER...KENT...MONTGOMERY.
..NEW CASTLE...PHILADELPHIA AND SALEM COUNTIES...

AT 539 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A 
LINE OF HEAVY SHOWERS AND SCATTERED STRONG THUNDERSTORMS FROM 20 
MILES NORTH OF WEST CHESTER TO 12 MILES NORTHEAST OF WEST CHESTER TO 
8 MILES SOUTH OF WEST CHESTER TO 21 MILES SOUTHWEST OF 
ELKTON...MOVING EAST AT 15 MPH. THE THUNDERSTORMS WILL BE NEAR 
CHEYNEY...DEVON-BERWYN...COLLEGEVILLE...AUDUBON AROUND 550 
AM...GRADYVILLE...ELAM...CONCORDVILLE...EVANSBURG AROUND 555 
AM...SKIPPACK AND HARLEYSVILLE AROUND 600 AM.  THEY SHOULD REACH THE 
CITY OF PHILADELPHIA BETWEEN 6 AM AND 630 AM 

VERY HEAVY RAINFALL WILL OCCUR OVER AREAS THAT RECEIVED HEAVY RAINS
EARLIER. BE ALERT FOR THE POSSIBILITY OF LOCALIZED FLOODING.

WIND GUSTS TO 40 MPH ARE POSSIBLE WITH THESE STORMS.

LAT...LON 3944 7600 3953 7599 3957 7611 3988 7573
      4012 7555 4036 7559 4014 7503 4002 7501
      3999 7507 3994 7501 3972 7518 3945 7554
      3946 7555 3958 7556 3946 7558 3943 7553
      3930 7569 3926 7588 3934 7615

$$

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, 4:48 AM EDT	Special Weather Statement	PHI	Chester, Montgomery	57 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 Special Weather Statements in Maryland, 2011 Special Weather Statements in Delaware, 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.