Alert archive / Pennsylvania / Special Weather Statements in 2011

Special Weather Statement, NWS Philadelphia/Mount Holly

August 21, 2011Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Aug 21, 2011, 1:11 PM EDT for Montgomery County, Pennsylvania. It was in force for 64 min. 3 reports 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 21, 2011, 1:11 PM EDT (17:11 UTC)
Expired: Aug 21, 2011, 2:15 PM EDT
In force: 64 min
Issued by: NWS Philadelphia/Mount Holly

County Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 88 km from the middle of the area, began a volume at 17:14 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 21, 1:45 PM EDT	TSTM WND DMG	Lower Gwynedd Twp, PA	WIRES DOWN IN LOWER GWYNEDD
Aug 21, 1:45 PM EDT	TSTM WND DMG	Upper Gwynedd Twp, PA	WIRES DOWN IN UPPER GWYNEDD
Aug 21, 1:49 PM EDT	TSTM WND GST 50	Spring City, PA	50 MPH WIND GUST ESTIMATED BY NWS EMPLOYEE

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 12:00Z, 5.2 hours before the alert went out and 214 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: 1589 J/kg
Mixed-layer CIN: -99 J/kg
Mixed-layer LCL: 969 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 131 m²/s²
0-3 km storm-relative helicity: 125 m²/s²
Significant tornado parameter: 0.6
Supercell composite: 4.9

Open this sounding in Storm Lab

The text

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

024 
WWUS81 KPHI 211711
SPSPHI

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
111 PM EDT SUN AUG 21 2011

PAZ067>069-211815-
BUCKS PA-CHESTER PA-MONTGOMERY PA-
111 PM EDT SUN AUG 21 2011

...A STRONG THUNDERSTORM WILL AFFECT PARTS OF BUCKS...CHESTER AND 
MONTGOMERY COUNTIES...

AT 110 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A 
STRONG THUNDERSTORM NEAR PUGHTOWN AND CHESTER SPRINGS...MOVING EAST 
AT 25 MPH. THE THUNDERSTORM WILL BE NEAR EVANSBURG AND COLLEGEVILLE 
AROUND 130 PM...SKIPPACK AND KULPSVILLE AROUND 145 
PM...MONTGOMERYVILLE AND NORTH WALES AROUND 200 PM AND NEW BRITAIN 
AND HORSHAM AROUND 215 PM.

VERY HEAVY RAINFALL WILL OCCUR OVER NEARLY SATURATED GROUND. BE 
ALERT FOR THE POSSIBILITY OF LOCALIZED FLOODING.

WIND GUSTS TO 50 MPH ARE POSSIBLE WITH THIS STORM.

LAT...LON 4018 7581 4024 7571 4028 7567 4044 7521
      4012 7505 4007 7510 4006 7515 4009 7523
      4005 7527 4004 7535 4006 7538 4004 7543
      4002 7543 3998 7573

$$

IOVINO

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 21, 3:24 AM EDT	Small Craft Advisory	PHI		30 hr
Aug 21, 3:28 AM EDT	Flash Flood Watch	PHI	Burlington, Camden, Cumberland, Gloucester, Hunterdon, Mercer and 6 more	17 hr
Aug 21, 8:41 AM EDT	Special Weather Statement	PHI	Salem	64 min
Aug 21, 10:33 AM EDT	Special Marine Warning	PHI		57 min
Aug 21, 11:07 AM EDT	Special Marine Warning	PHI		83 min
Aug 21, 12:20 PM EDT	Special Weather Statement	PHI	Morris	55 min
Aug 21, 12:33 PM EDT	Severe Thunderstorm Warning	PHI	Morris	33 min
Aug 21, 12:39 PM EDT	Special Weather Statement	PHI	Burlington, Camden	66 min
Aug 21, 1:47 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Camden, Mercer	58 min
Aug 21, 2:33 PM EDT	Areal Flood Advisory	PHI	Burlington, Camden, Mercer	117 min
Aug 21, 2:43 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Camden, Gloucester, Mercer	62 min
Aug 21, 3:08 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Mercer, Middlesex, Monmouth, Ocean	67 min
Aug 21, 3:21 PM EDT	Severe Thunderstorm Warning	PHI	Monmouth, Ocean	54 min
Aug 21, 3:22 PM EDT	Special Marine Warning	PHI		83 min
Aug 21, 3:46 PM EDT	Flash Flood Warning	PHI	Burlington	2 hr
Aug 21, 4:14 PM EDT	Severe Thunderstorm Warning	PHI	Monmouth, Ocean	46 min
Aug 21, 4:26 PM EDT	Special Marine Warning	PHI		57 min
Aug 21, 4:35 PM EDT	Areal Flood Advisory	PHI	Burlington, Camden, Mercer, Middlesex, Monmouth, Ocean	3 hr
Aug 21, 5:44 PM EDT	Special Weather Statement	PHI	Mercer	61 min
Aug 21, 6:05 PM EDT	Flash Flood Warning	PHI	Burlington	6 hr
Aug 21, 6:12 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Mercer, Middlesex, Monmouth, Ocean	63 min
Aug 21, 6:20 PM EDT	Special Weather Statement	PHI	Hunterdon	55 min
Aug 21, 6:54 PM EDT	Areal Flood Advisory	PHI	Hunterdon, Middlesex, Morris, Somerset, Sussex, Warren	111 min
Aug 21, 7:08 PM EDT	Special Weather Statement	PHI	Hunterdon, Middlesex, Somerset	52 min
Aug 21, 7:18 PM EDT	Severe Thunderstorm Warning	PHI	Monmouth, Ocean	42 min
Aug 21, 7:21 PM EDT	Special Marine Warning	PHI		84 min
Aug 21, 7:24 PM EDT	Flash Flood Warning	PHI	Mercer, Monmouth, Ocean	5 hr
Aug 21, 7:35 PM EDT	Areal Flood Advisory	PHI	Burlington, Mercer, Middlesex, Monmouth, Ocean	115 min
Aug 21, 1:25 PM EDT	Areal Flood Advisory	PHI	Bucks, Chester, Montgomery	110 min
Aug 21, 3:31 PM EDT	Flash Flood Warning	PHI	Philadelphia	8 hr
Aug 21, 4:11 PM EDT	Special Weather Statement	PHI	Carbon, Monroe	64 min
Aug 21, 4:19 PM EDT	Areal Flood Advisory	PHI	Carbon, Monroe	3 hr
Aug 21, 4:53 PM EDT	Special Weather Statement	PHI	Lehigh, Northampton	67 min
Aug 21, 6:41 PM EDT	Special Weather Statement	PHI	Berks	64 min
Aug 21, 8:01 AM EDT	Special Weather Statement	PHI	Cecil, Kent	59 min
Aug 21, 9:08 AM EDT	Special Weather Statement	PHI	Cecil, Kent	52 min
Aug 21, 9:36 AM EDT	Areal Flood Advisory	PHI	Cecil, Kent, Queen Anne's	2 hr
Aug 21, 2:01 PM EDT	Severe Thunderstorm Warning	PHI	Cecil, Kent, Queen Anne's	59 min
Aug 21, 2:43 PM EDT	Areal Flood Advisory	PHI	Cecil, Kent, Queen Anne's	3 hr
Aug 21, 2:55 PM EDT	Severe Thunderstorm Warning	PHI	Kent, Queen Anne's, Talbot	65 min
Aug 21, 3:11 PM EDT	Areal Flood Advisory	PHI	Kent, Queen Anne's	2 hr
Aug 21, 4:03 PM EDT	Special Weather Statement	PHI	Caroline, Kent, Queen Anne's, Talbot	57 min
Aug 21, 4:45 PM EDT	Flash Flood Warning	PHI	Kent	3 hr
Aug 21, 5:09 PM EDT	Severe Thunderstorm Warning	PHI	Caroline, Kent, Queen Anne's, Talbot	37 min
Aug 21, 5:20 PM EDT	Areal Flood Advisory	PHI	Caroline, Queen Anne's, Talbot	115 min
Aug 21, 7:17 PM EDT	Areal Flood Advisory	PHI	Caroline	118 min
Aug 21, 9:19 AM EDT	Special Weather Statement	PHI	Kent	56 min
Aug 21, 10:15 AM EDT	Special Weather Statement	PHI	Kent	60 min
Aug 21, 10:33 AM EDT	Severe Thunderstorm Warning	PHI	Kent	57 min
Aug 21, 6:29 PM EDT	Special Weather Statement	PHI	Sussex	61 min
Aug 21, 7:03 PM EDT	Severe Thunderstorm Warning	PHI	Kent, Sussex	42 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.