Alert archive / Pennsylvania / Areal Flood Warnings in 2012

Areal Flood Warning 37, NWS Philadelphia/Mount Holly

December 21, 2012Delaware County, Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood warning at Dec 21, 2012, 5:17 AM EST for Delaware 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: Dec 21, 2012, 5:17 AM EST (10:17 UTC)
Expired: Dec 21, 2012, 9:15 AM EST
In force: 4 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

County Delaware County, PA

The radar

The Philadelphia radar (KDIX), 84 km from the middle of the area, began a volume at 10:17 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, 10.3 hours before the alert went out and 203 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 0 m above ground
0-6 km bulk shear: 72 kt
0-1 km storm-relative helicity: 607 m²/s²
0-3 km storm-relative helicity: 893 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.

554 
WGUS41 KPHI 211017
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
517 AM EST FRI DEC 21 2012

PAC045-211415-
/O.NEW.KPHI.FA.W.0037.121221T1017Z-121221T1415Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
DELAWARE PA-
517 AM EST FRI DEC 21 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 915 AM EST

* AT 516 AM EST MODERATE TO HEAVY RAINS WILL CONTINUE FOR ANOTHER 
FEW HOURS. 

* CRUM CREEK AND OTHER NEARBY CREEKS WILL BE AFFECTED BY FLOODING    
  EARLY THIS MORNING. 

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.

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLOODING IS OBSERVED ACT QUICKLY. MOVE UP TO
HIGHER GROUND TO ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS SUBJECT TO
FLOODING WHEN WATER BEGINS RISING.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY. MOVE TO HIGHER GROUND.

&&

LAT...LON 3994 7553 3998 7545 4003 7541 4004 7541
      4007 7536 3996 7525 3994 7524 3988 7526
      3987 7521 3986 7523 3985 7533 3980 7541
      3983 7549 3984 7560 3987 7560

$$

PO

The office that day

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

Issued	Product	Office	Counties	Lasted
Dec 20, 9:00 PM EST	Winter Weather Advisory	PHI	Carbon, Monroe	2 hr
Dec 20, 9:11 PM EST	Wind Advisory	PHI	Bucks, Delaware, Montgomery, Philadelphia	12 hr
Dec 21, 12:27 AM EST	Coastal Flood Warning	PHI	Delaware, Philadelphia	11 hr
Dec 21, 4:44 AM EST	Areal Flood Warning	PHI	Chester, Montgomery	14 hr
Dec 21, 5:39 AM EST	Areal Flood Warning	PHI	Bucks	10 hr
Dec 21, 7:15 AM EST	River Flood Warning	PHI	Delaware	4 hr
Dec 21, 7:36 AM EST	Areal Flood Warning	PHI	Monroe, Northampton	15 hr
Dec 21, 7:49 AM EST	Areal Flood Warning	PHI	Philadelphia	11 hr
Dec 21, 9:24 AM EST	Areal Flood Warning	PHI	Delaware	4 hr
Dec 21, 9:36 AM EST	River Flood Warning	PHI	Bucks	10 hr
Dec 21, 12:08 PM EST	River Flood Warning	PHI	Chester, Delaware	5 hr
Dec 21, 3:16 PM EST	Wind Advisory	PHI	Berks, Bucks, Carbon, Chester, Delaware, Lehigh and 4 more	27 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.