Alert archive / Pennsylvania / Special Weather Statements in 2011

Special Weather Statement, NWS Philadelphia/Mount Holly

July 29, 2011Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Jul 29, 2011, 7:13 PM EDT for Montgomery County, Pennsylvania. It was in force for 62 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 29, 2011, 7:13 PM EDT (23:13 UTC)
Expired: Jul 29, 2011, 8:15 PM EDT
In force: 62 min
Issued by: NWS Philadelphia/Mount Holly

County Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 94 km from the middle of the area, began a volume at 23:12 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, 11.2 hours before the alert went out and 205 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: 529 J/kg
Mixed-layer CIN: -105 J/kg
Mixed-layer LCL: 1236 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: 78 m²/s²
0-3 km storm-relative helicity: 128 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.

866 
WWUS81 KPHI 292313
SPSPHI

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
713 PM EDT FRI JUL 29 2011

PAZ067-068-070-300015-
CHESTER PA-DELAWARE PA-MONTGOMERY PA-
713 PM EDT FRI JUL 29 2011

...STRONG THUNDERSTORMS WILL AFFECT CHESTER...DELAWARE AND MONTGOMERY 
COUNTIES...

AT 711 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
STRONG THUNDERSTORMS 10 MILES NORTH OF WEST CHESTER...MOVING 
SOUTHEAST AT 40 MPH. THESE THUNDERSTORMS WILL BE NEAR NEWTOWN SQUARE 
AND TROUT LAKE AROUND 730 PM.

WIND GUSTS TO 50 MPH ARE POSSIBLE WITH THESE STORMS.

EXPECT SMALL HAIL AND FREQUENT...DANGEROUS CLOUD TO GROUND LIGHTNING
FROM THESE STORMS.

LAT...LON 4005 7529 3986 7548 4010 7579 4029 7564

$$

FORECASTER:
JJM

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 29, 2:42 AM EDT	Special Weather Statement	PHI	Atlantic, Burlington, Camden, Cumberland, Middlesex, Monmouth and 1 more	63 min
Jul 29, 3:45 AM EDT	Special Weather Statement	PHI	Atlantic, Burlington, Camden, Cumberland, Ocean	60 min
Jul 29, 5:12 PM EDT	Special Weather Statement	PHI	Hunterdon, Morris, Somerset, Sussex, Warren	108 min
Jul 29, 5:59 PM EDT	Severe Thunderstorm Warning	PHI	Sussex	61 min
Jul 29, 6:17 PM EDT	Special Weather Statement	PHI	Monmouth	58 min
Jul 29, 6:23 PM EDT	Special Marine Warning	PHI		97 min
Jul 29, 6:24 PM EDT	Severe Thunderstorm Warning	PHI	Monmouth, Ocean	66 min
Jul 29, 6:25 PM EDT	Severe Thunderstorm Warning	PHI	Middlesex	20 min
Jul 29, 7:03 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Mercer, Middlesex, Monmouth, Ocean	46 min
Jul 29, 7:14 PM EDT	Severe Thunderstorm Warning	PHI	Burlington	42 min
Jul 29, 7:27 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Monmouth, Ocean	63 min
Jul 29, 7:40 PM EDT	Special Marine Warning	PHI		95 min
Jul 29, 3:44 PM EDT	Special Weather Statement	PHI	Berks, Carbon, Lehigh, Monroe, Northampton	2 hr
Jul 29, 4:40 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Lehigh	65 min
Jul 29, 5:56 PM EDT	Special Weather Statement	PHI	Bucks	64 min
Jul 29, 6:05 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery	55 min
Jul 29, 6:43 PM EDT	Severe Thunderstorm Warning	PHI	Philadelphia	49 min
Jul 29, 7:31 PM EDT	Special Weather Statement	PHI	Bucks, Montgomery, Philadelphia	59 min
Jul 28, 9:10 PM EDT	Special Weather Statement	PHI	Caroline, Kent, Queen Anne's	65 min
Jul 28, 9:26 PM EDT	Severe Thunderstorm Warning	PHI	Caroline, Kent, Queen Anne's, Talbot	45 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.