Alert archive / Pennsylvania / Areal Flood Warnings in 2012

Areal Flood Warning 16, NWS Philadelphia/Mount Holly

September 3, 2012Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood warning at Sep 3, 2012, 6:24 AM 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, 6:24 AM EDT (10:24 UTC)
Expired: Sep 3, 2012, 10:15 AM 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), 91 km from the middle of the area, began a volume at 10:24 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, 10.4 hours before the alert went out and 209 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: 1211 J/kg
Mixed-layer CIN: -6 J/kg
Mixed-layer LCL: 671 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: 41 m²/s²
0-3 km storm-relative helicity: 162 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.4

Open this sounding in Storm Lab

The text

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

081 
WGUS41 KPHI 031024
FLWPHI

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

PAC029-031415-
/O.NEW.KPHI.FA.W.0016.120903T1024Z-120903T1415Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CHESTER PA-
624 AM EDT MON SEP 3 2012

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 1015 AM EDT

* AT 620 AM EDT...THE HEAVY RAIN IN CHESTER COUNTY WAS DIMINISHING.
  HOWEVER...RUNOFF FROM THE ONE TO THREE INCHES OF RAIN THAT FELL
  DURING THE NIGHT HAS CAUSED MINOR FLOOD ALONG VALLEY CREEK. THE
  MINOR FLOODING SHOULD PERSIST UNTIL MID TO LATE MORNING.

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

LAT...LON 4015 7551 4013 7550 4013 7546 4011 7547
      4009 7545 4009 7542 4006 7539 4007 7537
      4004 7541 4003 7541 3997 7547 4004 7560

$$

IOVINO

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, 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, 12:04 PM EDT	Areal Flood Warning	PHI	Chester	4 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.