Alert archive / Pennsylvania / Areal Flood Warnings in 2012

Areal Flood Warning 18, NWS Philadelphia/Mount Holly

September 3, 2012Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood warning at Sep 3, 2012, 12:04 PM EDT for Chester County, Pennsylvania. It was in force for 4 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Sep 3, 2012, 12:04 PM EDT (16:04 UTC)
Expired: Sep 3, 2012, 4:00 PM EDT
In force: 4 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

County Chester County, PA

The radar

The Philadelphia radar (KDIX), 94 km from the middle of the area, began a volume at 16:07 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, 4.1 hours before the alert went out and 207 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: 383 J/kg
Mixed-layer CIN: -34 J/kg
Mixed-layer LCL: 718 m above ground
0-6 km bulk shear: 12 kt
0-1 km storm-relative helicity: 77 m²/s²
0-3 km storm-relative helicity: 86 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.

931 
WGUS41 KPHI 031604
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1204 PM EDT MON SEP 3 2012

PAC029-032000-
/O.NEW.KPHI.FA.W.0018.120903T1604Z-120903T2000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CHESTER PA-
1204 PM EDT MON SEP 3 2012

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLOOD WARNING FOR SMALL STREAMS IN...
  EAST CENTRAL CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 400 PM EDT

* AT NOON EDT THE VALLEY CREEK AT VALLEY FORGE HAS RISEN ABOVE FLOOD 
STAGE DUE TO THE HEAVY RAINFALL THIS MORNING. ADDITIONAL RAINFALL IS 
POSSIBLE THIS AFTERNOON.

A FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR HAS BEEN REPORTED.
ALL INTERESTED PARTIES SHOULD TAKE NECESSARY PRECAUTIONS IMMEDIATELY.

LAT...LON 4007 7565 4016 7550 4014 7551 4012 7549
      4013 7548 4013 7547 4011 7547 4009 7545
      4009 7542 4006 7538 3997 7552

$$

ROBERTSON

1 follow-up statement

705 
WGUS81 KPHI 031953
FLSPHI

FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
353 PM EDT MON SEP 3 2012

PAC029-032002-
/O.EXP.KPHI.FA.W.0018.000000T0000Z-120903T2000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CHESTER PA-
353 PM EDT MON SEP 3 2012

...THE FLOOD WARNING WILL EXPIRE AT 400 PM EDT FOR SMALL STREAMS IN
EAST CENTRAL CHESTER COUNTY...

MORE RAINFALL IS EXPECTED LATE THIS AFTERNOON AND THIS EVENING...SO 
ADDITIONAL FLOODING IS POSSIBLE.

LAT...LON 4007 7565 4016 7550 4014 7551 4012 7549
      4013 7548 4013 7547 4011 7547 4009 7545
      4009 7542 4006 7538 3997 7552

$$

ROBERTSON

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 3, 12:24 AM EDT	Areal Flood Advisory	PHI	Chester, Delaware	3 hr
Sep 3, 12:58 AM EDT	Flash Flood Warning	PHI	Chester, Delaware	5 hr
Sep 3, 4:19 AM EDT	River Flood Warning	PHI	Delaware	91 min
Sep 3, 4:44 AM EDT	Areal Flood Advisory	PHI	Chester, Montgomery	3 hr
Sep 3, 6:24 AM EDT	Areal Flood Warning	PHI	Chester	4 hr
Sep 3, 8:05 AM EDT	Areal Flood Advisory	PHI	Chester, Delaware, Montgomery, Philadelphia	3 hr
Sep 3, 8:23 AM EDT	Flash Flood Warning	PHI	Delaware	82 min
Sep 3, 9:15 AM EDT	Flash Flood Warning	PHI	Chester, Delaware, Montgomery	3 hr
Sep 3, 10:28 AM EDT	Special Weather Statement	PHI	Philadelphia	62 min
Sep 3, 11:14 AM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery, Philadelphia	2 hr
Sep 3, 2:44 PM EDT	Areal Flood Advisory	PHI	Chester	119 min
Sep 3, 3:00 PM EDT	Flash Flood Watch	PHI	Delaware, Philadelphia	49 hr
Sep 3, 5:27 PM EDT	Areal Flood Warning	PHI	Delaware	3 hr
Sep 3, 6:41 PM EDT	River Flood Warning	PHI	Delaware	2 hr

Nearby

Areal Flood Warnings in Pennsylvania, 2012 Every areal flood warning in 2012

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.