Alert archive / Pennsylvania / Areal Flood Warnings in 2012

Areal Flood Warning 36, NWS Philadelphia/Mount Holly

December 21, 2012Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood warning at Dec 21, 2012, 4:44 AM EST for Chester County, Montgomery County, Pennsylvania. It was in force for 14 hr. 2 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: Dec 21, 2012, 4:44 AM EST (09:44 UTC)
Expired: Dec 21, 2012, 6:32 PM EST
In force: 14 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 98 km from the middle of the area, began a volume at 09:48 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
Dec 21, 7:00 AM EST	FLOOD	Pottstown, PA	AREAS OF ROADWAY AND POOR DRAINAGE FLOODING IN THE COUNTY. SOME ROAD CLOSURES.
Dec 21, 9:00 AM EST	FLOOD	1 W Ambler, PA	WISSAHICKON AND PROPHECY CREEKS OVER THEIR BANKS NEAR AMBLER.

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 00:00Z, 9.7 hours before the alert went out and 195 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.

125 
WGUS41 KPHI 210944
FLWPHI

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

PAC029-091-211345-
/O.NEW.KPHI.FA.W.0036.121221T0944Z-121221T1345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MONTGOMERY PA-CHESTER PA-
444 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...
  MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA...
  CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 845 AM EST

* AT 443 AM EST AN AREA OF MODERATE TO HEAVY RAINS CONTINUE ACROSS   
  SOUTHEAST PENNSYLVANIA. THE RAINS SHOULD LAST A FEW MORE HOURS. 

* FLOODING WILL OCCUR ON VALLEY CREEK IN NORTHERN CHESTER COUNTY AND 
  OTHER NEARBY AREAS. 

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...

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.

DRIVING INTO FLOOD WATERS COULD PUT YOUR LIFE AT RISK AND COST YOU
THOUSANDS OF DOLLARS IN VEHICLE REPAIRS. FLOOD WATERS MAY BE DEEPER
THAN YOU THINK. TURN AROUND AND FIND AN ALTERNATE ROUTE.

TO REPORT FLOODING...HAVE THE NEAREST LAW ENFORCEMENT AGENCY RELAY
YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE.

&&

LAT...LON 3973 7609 3987 7599 4011 7594 4025 7569
      4044 7553 4014 7501 4005 7510 4009 7523
      4005 7526 4001 7521 3998 7527 4007 7536
      4004 7541 3999 7544 3999 7543 3987 7560
      3984 7558 3981 7570 3972 7578 3972 7614

$$

PO

5 follow-up statements

520 
WGUS41 KPHI 211307
FLWPHI

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

PAC029-091-211745-
/O.EXT.KPHI.FA.W.0036.000000T0000Z-121221T1745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MONTGOMERY PA-CHESTER PA-
807 AM EST FRI DEC 21 2012

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS EXTENDED THE

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

* UNTIL 1245 PM EST

* AT 804 AM EST...VALLEY CREEK AT VALLEY FORGE WAS ABOVE FLOOD 
STAGE, BUT WAS CRESTING. THE EAST GREENVILLE GAGE ON THE PERKIOMEN 
WAS ABOVE FLOOD STAGE AND WAS STILL RISING. THE SCHWENKSVILLE GAGE 
ON THE EAST BRANCH PERKIOMEN WAS ABOVE FLOOD STAGE AND WAS STILL 
RISING. THE FORT WASHINGTON GAGE ON THE WISSAHICKON CREEK WAS ABOVE 
FLOOD STAGE AND WAS STILL RISING. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

DRIVING INTO FLOOD WATERS COULD PUT YOUR LIFE AT RISK AND COST YOU
THOUSANDS OF DOLLARS IN VEHICLE REPAIRS. FLOOD WATERS MAY BE DEEPER
THAN YOU THINK. TURN AROUND AND FIND AN ALTERNATE ROUTE.

&&

LAT...LON 3973 7609 3987 7599 4011 7594 4025 7569
      4044 7553 4014 7501 4005 7510 4009 7523
      4005 7526 4001 7521 3998 7527 4007 7536
      4004 7541 3999 7544 3999 7543 3987 7560
      3984 7558 3981 7570 3972 7578 3972 7614

$$

KRUZDLO

053 
WGUS81 KPHI 211724
FLSPHI

FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1224 PM EST FRI DEC 21 2012

PAC029-211731-
/O.CAN.KPHI.FA.W.0036.000000T0000Z-121221T1745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CHESTER PA-
1224 PM EST FRI DEC 21 2012

...THE FLOOD WARNING HAS BEEN CANCELLED FOR URBAN AREAS AND SMALL
STREAMS IN CHESTER COUNTY...

FLOOD WATERS CONTINUE TO RECEDE. THE FLOOD WARNING HAS BEEN 
CANCELLED.

LAT...LON 4044 7553 4015 7503 4014 7501 4005 7510
      4009 7522 4006 7526 4001 7521 3998 7527
      4007 7536 4006 7539 4011 7547 4013 7547
      4014 7551 4016 7551 4015 7553 4024 7560
      4022 7561 4024 7570

$$

PAC091-211745-
/O.CON.KPHI.FA.W.0036.000000T0000Z-121221T1745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MONTGOMERY PA-
1224 PM EST FRI DEC 21 2012

...THE FLOOD WARNING REMAINS IN EFFECT UNTIL 1245 PM EST FOR URBAN
AREAS AND SMALL STREAMS IN MONTGOMERY COUNTY...

AT 1221 PM EST...THE PERKIOMEN CREEK AT EAST GREENVILLE REMAINED 
ABOUT FLOOD STAGE, BUT HAD CRESTED. THE WISSAHICKON CREEK AT FORT 
WASHINGTON ALSO HAD CRESTED, BUT REMAINED ABOVE FLOOD STAGE. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

DRIVING INTO FLOOD WATERS COULD PUT YOUR LIFE AT RISK AND COST YOU
THOUSANDS OF DOLLARS IN VEHICLE REPAIRS. FLOOD WATERS MAY BE DEEPER
THAN YOU THINK. TURN AROUND AND FIND AN ALTERNATE ROUTE.

&&

LAT...LON 4044 7553 4015 7503 4014 7501 4005 7510
      4009 7522 4006 7526 4001 7521 3998 7527
      4007 7536 4006 7539 4011 7547 4013 7547
      4014 7551 4016 7551 4015 7553 4024 7560
      4022 7561 4024 7570

$$

KRUZDLO

336 
WGUS41 KPHI 211728
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1228 PM EST FRI DEC 21 2012

PAC091-212045-
/O.EXT.KPHI.FA.W.0036.000000T0000Z-121221T2045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MONTGOMERY PA-
1228 PM EST FRI DEC 21 2012

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS EXTENDED THE

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

* UNTIL 345 PM EST

* AT 1228 PM EST...AT 1221 PM EST...THE PERKIOMEN CREEK AT EAST 
GREENVILLE REMAINED ABOUT FLOOD STAGE, BUT HAD CRESTED. THE 
WISSAHICKON CREEK AT FORT WASHINGTON ALSO HAD CRESTED, BUT REMAINED 
ABOVE FLOOD STAGE. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

DRIVING INTO FLOOD WATERS COULD PUT YOUR LIFE AT RISK AND COST YOU
THOUSANDS OF DOLLARS IN VEHICLE REPAIRS. FLOOD WATERS MAY BE DEEPER
THAN YOU THINK. TURN AROUND AND FIND AN ALTERNATE ROUTE.

&&

LAT...LON 4044 7553 4015 7503 4014 7501 4005 7510
      4009 7522 4006 7526 4001 7521 3998 7527
      4007 7536 4006 7539 4011 7547 4013 7547
      4014 7551 4016 7551 4015 7553 4024 7560
      4022 7561 4024 7570

$$

KRUZDLO

751 
WGUS41 KPHI 212027
FLWPHI

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

PAC091-220045-
/O.EXT.KPHI.FA.W.0036.000000T0000Z-121222T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MONTGOMERY PA-
327 PM EST FRI DEC 21 2012

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS EXTENDED THE

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

* UNTIL 745 PM EST

* AT 325 PM EST...THE SCHWENKSVILLE GAGE ON THE EAST BRANCH 
PERKIOMEN REMAINED ABOVE FLOOD STAGE. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

DRIVING INTO FLOOD WATERS COULD PUT YOUR LIFE AT RISK AND COST YOU
THOUSANDS OF DOLLARS IN VEHICLE REPAIRS. FLOOD WATERS MAY BE DEEPER
THAN YOU THINK. TURN AROUND AND FIND AN ALTERNATE ROUTE.

&&

LAT...LON 4044 7553 4015 7503 4014 7501 4005 7510
      4009 7522 4006 7526 4001 7521 3998 7527
      4007 7536 4006 7539 4011 7547 4013 7547
      4014 7551 4016 7551 4015 7553 4024 7560
      4022 7561 4024 7570

$$

KRUZDLO

942 
WGUS81 KPHI 212332
FLSPHI

FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
632 PM EST FRI DEC 21 2012

PAC091-212342-
/O.CAN.KPHI.FA.W.0036.000000T0000Z-121222T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MONTGOMERY PA-
632 PM EST FRI DEC 21 2012

...THE FLOOD WARNING HAS BEEN CANCELLED FOR URBAN AREAS AND SMALL
STREAMS IN MONTGOMERY COUNTY...

DRIVING INTO FLOOD WATERS COULD PUT YOUR LIFE AT RISK AND COST YOU
THOUSANDS OF DOLLARS IN VEHICLE REPAIRS. FLOOD WATERS MAY BE DEEPER
THAN YOU THINK. TURN AROUND AND FIND AN ALTERNATE ROUTE.

LAT...LON 4044 7553 4015 7503 4014 7501 4005 7510
      4009 7522 4006 7526 4001 7521 3998 7527
      4007 7536 4006 7539 4011 7547 4013 7547
      4014 7551 4016 7551 4015 7553 4024 7560
      4022 7561 4024 7570

$$

HEAVENER

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, 5:17 AM EST	Areal Flood Warning	PHI	Delaware	4 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.