Alert archive / Pennsylvania / Areal Flood Warnings in 2012

Areal Flood Warning 8, NWS Philadelphia/Mount Holly

May 27, 2012Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood warning at May 27, 2012, 5:51 PM EDT for Montgomery County, Pennsylvania. It was in force for 95 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: May 27, 2012, 5:51 PM EDT (21:51 UTC)
Expired: May 27, 2012, 7:26 PM EDT
In force: 95 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

County Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 94 km from the middle of the area, began a volume at 21:52 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, 9.9 hours before the alert went out and 220 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: 247 J/kg
Mixed-layer CIN: -198 J/kg
Mixed-layer LCL: 935 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: -1 m²/s²
0-3 km storm-relative helicity: 9 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.

996 
WGUS41 KPHI 272151
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
551 PM EDT SUN MAY 27 2012

PAC091-280045-
/O.NEW.KPHI.FA.W.0008.120527T2151Z-120528T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MONTGOMERY PA-
551 PM EDT SUN MAY 27 2012

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLOOD WARNING FOR SMALL STREAMS IN...
  CENTRAL MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 845 PM EDT

* AT 545 PM EDT, RUNOFF FROM EARLIER SHOWERS AND THUNDERSTORMS       
  ACROSS LEHIGH COUNTY IS FLOWING DOWN THE EAST BRANCH OF THE        
  PERKIOMEN. THE GAGE AT SCHWENKSVILLE INDICATES THE WATER CONTINUES 
  TO RISE TO NEAR THE FLOOD STAGE OF 7 FEET AND SHOULD EXCEED        
  THIS LEVEL SOON. GAGES UPSTREAM INDICATE THE WATER LEVEL IS        
  LOWERING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

LAT...LON 4029 7549 4030 7541 4014 7536 4013 7549

$$

GORSE

2 follow-up statements

058 
WGUS81 KPHI 272220
FLSPHI

FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
620 PM EDT SUN MAY 27 2012

PAC091-280045-
/O.CON.KPHI.FA.W.0008.000000T0000Z-120528T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MONTGOMERY PA-
620 PM EDT SUN MAY 27 2012

...THE FLOOD WARNING REMAINS IN EFFECT UNTIL 845 PM EDT FOR SMALL
STREAMS IN CENTRAL MONTGOMERY COUNTY...

AT 615 PM EDT, THE GAGE ON THE PERKIOMEN AT SCHWENKSVILLE HAD A 
STAGE OF 7.4 FEET AND RISING. FLOOD STAGE IS 7 FEET. THE RUNOFF FROM 
EARLIER SHOWERS AND THUNDERSTORMS ACROSS LEHIGH COUNTY CONTINUES TO 
FLOW DOWN THE PERKIOMEN. A GAGE UPSTREAM HOWEVER INDICATES THE WATER 
LEVEL IS RECEDING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

LAT...LON 4029 7549 4030 7541 4014 7536 4013 7549

$$

GORSE

137 
WGUS81 KPHI 272326
FLSPHI

FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
726 PM EDT SUN MAY 27 2012

PAC091-272335-
/O.CAN.KPHI.FA.W.0008.000000T0000Z-120528T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MONTGOMERY PA-
726 PM EDT SUN MAY 27 2012

...THE FLOOD WARNING HAS BEEN CANCELLED FOR SMALL STREAMS IN CENTRAL
MONTGOMERY COUNTY...

THE WATER LEVEL ON THE PERKIOMEN AT SCHWENKSVILLE HAS DROPPED BELOW 
FLOOD STAGE. THEREFORE, THE WARNING HAS BEEN CANCELLED.

LAT...LON 4029 7549 4030 7541 4014 7536 4013 7549

$$

GORSE

The office that day

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

Issued	Product	Office	Counties	Lasted
May 27, 2:19 AM EDT	Special Weather Statement	PHI	Berks, Carbon, Lehigh, Montgomery, Northampton	56 min
May 27, 2:54 AM EDT	Special Weather Statement	PHI	Bucks	66 min
May 27, 3:10 AM EDT	Areal Flood Advisory	PHI	Berks, Bucks, Lehigh, Montgomery	3 hr
May 27, 3:35 AM EDT	Special Weather Statement	PHI	Berks	55 min
May 27, 3:46 AM EDT	Special Weather Statement	PHI	Bucks, Montgomery	59 min
May 27, 4:08 AM EDT	Flash Flood Warning	PHI	Bucks, Montgomery	4 hr
May 27, 4:35 AM EDT	Special Weather Statement	PHI	Berks	55 min
May 27, 4:46 AM EDT	Special Weather Statement	PHI	Philadelphia	59 min
May 27, 4:58 AM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery, Philadelphia	83 min
May 27, 5:08 AM EDT	Areal Flood Advisory	PHI	Berks	89 min
May 27, 5:18 AM EDT	Special Weather Statement	PHI	Berks	57 min
May 27, 5:47 AM EDT	Special Weather Statement	PHI	Berks	58 min
May 27, 5:57 AM EDT	Flash Flood Warning	PHI	Bucks, Montgomery, Philadelphia	2 hr
May 27, 8:48 AM EDT	Special Weather Statement	PHI	Montgomery	42 min
May 27, 9:26 AM EDT	Special Weather Statement	PHI	Bucks, Lehigh	49 min
May 27, 10:07 AM EDT	Areal Flood Warning	PHI	Berks, Bucks, Lehigh, Montgomery, Philadelphia	3 hr
May 27, 3:01 PM EDT	Excessive Heat Warning	PHI	Delaware, Philadelphia	52 hr
May 27, 4:56 PM EDT	Special Weather Statement	PHI	Berks	49 min
May 27, 7:36 PM EDT	Special Weather Statement	PHI	Monroe	39 min
May 27, 7:45 PM EDT	Special Weather Statement	PHI	Berks	45 min

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.