Alert archive / Pennsylvania / Areal Flood Warnings in 2011

Areal Flood Warning 71, NWS Philadelphia/Mount Holly

September 6, 2011Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood warning at Sep 6, 2011, 6:32 PM EDT for Montgomery County, Pennsylvania. It was in force for 26 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 6, 2011, 6:32 PM EDT (22:32 UTC)
Expired: Sep 7, 2011, 8:30 PM EDT
In force: 26 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

County Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 104 km from the middle of the area, began a volume at 22:33 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

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 10.5 hours before the alert went out and 108 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: 739 m above ground
0-6 km bulk shear: 63 kt
0-1 km storm-relative helicity: 63 m²/s²
0-3 km storm-relative helicity: 555 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.

274 
WGUS41 KPHI 062232
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
632 PM EDT TUE SEP 6 2011

PAC091-070430-
/O.NEW.KPHI.FA.W.0071.110906T2232Z-110907T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MONTGOMERY PA-
632 PM EDT TUE SEP 6 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 1230 AM EDT

* AT 631 PM EDT...THE PERKIOMEN CREEK AT EAST GREENVILLE WAS JUST ABOUT
  TO GO ABOVE FLOOD STAGE. ADDITIONAL HEAVY RAIN THIS EVENING WILL PUSH
  THE CREEK ABOVE FLOOD STAGE LATER THIS EVENING.

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...

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

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.

&&

LAT...LON 4038 7559 4040 7556 4040 7546 4030 7534
      4020 7551 4027 7566

$$

HAYES/PIETRAFESA

3 follow-up statements

698 
WGUS41 KPHI 070428
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1228 AM EDT WED SEP 7 2011

PAC091-071030-
/O.EXT.KPHI.FA.W.0071.000000T0000Z-110907T1030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MONTGOMERY PA-
1228 AM EDT WED SEP 7 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS EXTENDED THE

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

* UNTIL 630 AM EDT

* WHILE WIDESPREAD HEAVY RAIN HAS MOVED OUT OF THE AREA...SMALL      
  STREAMS ARE RUNNING HIGH...SOME ABOVE FLOOD STAGE. IN              
  PARTICULAR...THE PERKIOMEN CREEK AT EAST GREENVILLE...AND THE EAST 
  BRANCH OF THE PERKIOMEN CREEK AT SCHWENKSVILLE REMAIN ABOVE FLOOD  
  STAGE AT 1215 AM. THE AREAL FLOOD WARNING HAS THEREFORE CONTINUES  
  UNTIL 630 AM EDT.

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...

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

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.

&&

LAT...LON 4038 7559 4040 7556 4040 7546 4030 7534
      4020 7551 4027 7566

$$

JJM

722 
WGUS41 KPHI 071018
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
618 AM EDT WED SEP 7 2011

PAC091-072030-
/O.EXT.KPHI.FA.W.0071.000000T0000Z-110907T2030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MONTGOMERY PA-
618 AM EDT WED SEP 7 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS EXTENDED THE

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

* UNTIL 430 PM EDT WEDNESDAY

* AT 615 AM EDT SMALL STREAMS CONTINUE OUT OF THEIR BANKS IN THE 
AREA. MORE RAIN IS ON TAP FOR TODAY. THIS EXPECTED RAIN...IN 
CONJUNCTION WITH THE ALREADY WET CONDITIONS...WILL ALLOW FOR RENEWED 
RISES ON SMALL STREAMS. THE AREAL FLOOD WARNING HAS THEREFORE BEEN 
EXTENDED INTO THE LATE AFTERNOON HOURS.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

DO NOT STAY IN AREAS SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

&&

LAT...LON 4038 7559 4040 7556 4040 7546 4030 7534
      4020 7551 4027 7566

$$

JJM

845 
WGUS41 KPHI 071738
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
138 PM EDT WED SEP 7 2011

PAC091-080030-
/O.EXT.KPHI.FA.W.0071.000000T0000Z-110908T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MONTGOMERY PA-
138 PM EDT WED SEP 7 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS EXTENDED THE

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

* UNTIL 830 PM EDT

* AT 136 PM EDT...SMALL STREAM FLOODING CONTINUED ACROSS PORTIONS OF 
THE WARNED AREA. THE WATER LEVEL ON THE EAST BRANCH OF THE PERKIOMEN 
AT SCHWENKSVILLE WAS 7.81 FEET AND WAS FALLING. FLOOD STAGE IS 7.0 
FEET.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

&&

LAT...LON 4038 7559 4040 7556 4040 7546 4030 7534
      4020 7551 4027 7566

$$

KRUZDLO

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 5, 8:19 PM EDT	Areal Flood Advisory	PHI	Berks, Bucks, Lehigh, Montgomery, Northampton	116 min
Sep 5, 9:32 PM EDT	Areal Flood Warning	PHI	Montgomery	9 hr
Sep 5, 10:18 PM EDT	Flash Flood Warning	PHI	Lehigh, Northampton	4 hr
Sep 5, 10:53 PM EDT	Areal Flood Advisory	PHI	Chester, Montgomery	3 hr
Sep 5, 11:04 PM EDT	Areal Flood Advisory	PHI	Bucks	6 hr
Sep 5, 11:25 PM EDT	Flash Flood Warning	PHI	Berks	4 hr
Sep 6, 12:22 AM EDT	Areal Flood Advisory	PHI	Delaware, Philadelphia	3 hr
Sep 6, 1:42 AM EDT	Areal Flood Advisory	PHI	Chester, Montgomery	3 hr
Sep 6, 2:09 AM EDT	Areal Flood Advisory	PHI	Lehigh, Northampton	3 hr
Sep 6, 3:40 AM EDT	Areal Flood Warning	PHI	Berks	3 hr
Sep 6, 5:43 PM EDT	Areal Flood Advisory	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	3 hr
Sep 6, 5:49 PM EDT	Areal Flood Warning	PHI	Philadelphia	20 hr
Sep 6, 6:10 PM EDT	Areal Flood Warning	PHI	Bucks, Monroe, Northampton	71 hr
Sep 6, 6:38 PM EDT	Areal Flood Warning	PHI	Montgomery, Philadelphia	23 hr
Sep 6, 6:44 PM EDT	Areal Flood Warning	PHI	Chester, Delaware	15 hr
Sep 6, 6:48 PM EDT	Areal Flood Warning	PHI	Bucks	31 hr
Sep 6, 7:03 PM EDT	River Flood Warning	PHI	Chester	16 hr
Sep 6, 7:41 PM EDT	River Flood Warning	PHI	Delaware	5 hr
Sep 6, 7:52 PM EDT	River Flood Warning	PHI	Bucks	52 hr

Nearby

Areal Flood Warnings in Pennsylvania, 2011 Every areal flood warning in 2011

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.