Alert archive / Pennsylvania / Areal Flood Warnings in 2012

Areal Flood Warning 19, NWS Philadelphia/Mount Holly

September 3, 2012Delaware County, Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood warning at Sep 3, 2012, 5:27 PM EDT for Delaware County, Pennsylvania. It was in force for 3 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, 5:27 PM EDT (21:27 UTC)
Expired: Sep 3, 2012, 8:30 PM EDT
In force: 3 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

County Delaware County, PA

The radar

The Philadelphia radar (KDIX), 92 km from the middle of the area, began a volume at 21:28 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, 9.5 hours before the alert went out and 196 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.

668 
WGUS41 KPHI 032127
FLWPHI

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

PAC045-040030-
/O.NEW.KPHI.FA.W.0019.120903T2127Z-120904T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
DELAWARE PA-
527 PM EDT MON SEP 3 2012

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLOOD WARNING FOR URBAN AREAS AND SMALL STREAMS IN...
  DELAWARE COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 830 PM EDT

* AT 524 PM EDT WEATHER SERVICE DOPPLER RADAR CONTINUED TO INDICATE 
AN AREA OF VERY HEAVY RAINFALL LOCATED IN SOUTH-CENTRAL DELAWARE 
COUNTY. RADAR ESTIMATES OF OVER 1.5 INCHES HAS FALLEN WITHIN THE 
PAST HOUR ACROSS THE WARNED AREA. AN ADDITIONAL .75 TO 1.0 INCHES IS 
POSSIBLE OVER THE NEXT HOUR WITH THIS STORM.

A FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR HAS BEEN REPORTED.
STREAM RISES WILL BE SLOW AND FLASH FLOODING IS NOT EXPECTED.
HOWEVER...ALL INTERESTED PARTIES SHOULD TAKE NECESSARY PRECAUTIONS
IMMEDIATELY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE ELEVATED LEVELS ON
SMALL CREEKS AND STREAMS...AND PONDING OF WATER IN URBAN AREAS...
HIGHWAYS...STREETS AND UNDERPASSES AS WELL AS OTHER POOR DRAINAGE
AREAS AND LOW LYING SPOTS.

A FLOOD WARNING MEANS FLOODING IS OCCURRING OR IS IMMINENT. MOST
FLOOD RELATED DEATHS OCCUR IN AUTOMOBILES. DO NOT ATTEMPT TO CROSS
WATER COVERED BRIDGES...DIPS...OR LOW WATER CROSSINGS. NEVER TRY TO
CROSS A FLOWING STREAM...EVEN A SMALL ONE...ON FOOT. TO ESCAPE RISING
WATER MOVE UP TO HIGHER GROUND.

&&

LAT...LON 3989 7557 3994 7553 3999 7543 3999 7544
      4003 7540 3996 7525 3982 7544 3984 7559
      3984 7560 3988 7560

$$

HEAVENER

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, 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, 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.