Alert archive / Pennsylvania / Areal Flood Advisories in 2012

Areal Flood Advisory 39, NWS Philadelphia/Mount Holly

May 29, 20125 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood advisory at May 29, 2012, 7:35 PM EDT for 5 counties in Pennsylvania. It was in force for 115 min.

The area

The outline as issued.

The facts

Issued
May 29, 2012, 7:35 PM EDT (23:35 UTC)
Expired
May 29, 2012, 9:30 PM EDT
In force
115 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Bucks County, PA, Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 88 km from the middle of the area, began a volume at 23:37 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, 11.6 hours before the alert went out and 86 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-pSkew-T log-p diagram, Phillips Aaf/Abe, MD at 12:00Z on 2012-05-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 667 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Phillips Aaf/Abe, MD at 12:00Z on 2012-05-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -39 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
667 J/kg
Mixed-layer CIN
-217 J/kg
Mixed-layer LCL
1153 m above ground
0-6 km bulk shear
6 kt
0-1 km storm-relative helicity
-39 m²/s²
0-3 km storm-relative helicity
-10 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.

920 
WGUS81 KPHI 292335
FLSPHI

FLOOD ADVISORY
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
735 PM EDT TUE MAY 29 2012

PAC017-029-045-091-101-300130-
/O.NEW.KPHI.FA.Y.0039.120529T2335Z-120530T0130Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BUCKS PA-MONTGOMERY PA-PHILADELPHIA PA-DELAWARE PA-CHESTER PA-
735 PM EDT TUE MAY 29 2012

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED AN

* URBAN AND SMALL STREAM FLOOD ADVISORY FOR...
  SOUTHEASTERN BUCKS COUNTY IN SOUTHEAST PENNSYLVANIA...
  SOUTHERN MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA...
  PHILADELPHIA COUNTY IN SOUTHEAST PENNSYLVANIA...
  DELAWARE COUNTY IN SOUTHEAST PENNSYLVANIA...
  CENTRAL CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 930 PM EDT

* AT 731 PM EDT BANDS OF HEAVY SHOWERS AND THUNDERSTORMS WILL BE 
  OVERSPREADING THE ENTIRE PHILADELPHIA METROPOLITAN AREA BETWEEN NOW
  AND 830 PM AND CONTINUE THROUGH AT LEAST 930 PM. THE RAINFALL
  RATES IN THESE URBAN AREAS WILL CAUSE POOR DRAINAGE STREET
  FLOODING.   

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.

&&

LAT...LON 3989 7597 4016 7544 4039 7508 4018 7475
      3982 7540

$$
DRAG

The office that day

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

IssuedProductOfficeCountiesLasted
May 29, 12:29 PM EDTFlash Flood WatchPHIBerks, Carbon, Delaware, Lehigh, Monroe, Northampton and 1 more8 hr
May 29, 1:36 PM EDTSpecial Weather StatementPHIMonroe54 min
May 29, 1:50 PM EDTAreal Flood AdvisoryPHICarbon, Monroe115 min
May 29, 5:06 PM EDTSpecial Weather StatementPHIBerks, Carbon, Lehigh, Monroe, Northampton114 min
May 29, 5:25 PM EDTSevere Thunderstorm WarningPHIBerks, Carbon, Lehigh95 min
May 29, 5:45 PM EDTSevere Thunderstorm WarningPHIMonroe, Northampton75 min
May 29, 6:14 PM EDTSevere Thunderstorm WarningPHIBerks, Lehigh, Northampton91 min
May 29, 6:23 PM EDTFlash Flood WarningPHICarbon, Monroe112 min
May 29, 6:44 PM EDTAreal Flood AdvisoryPHIBerks, Bucks, Lehigh, Montgomery3 hr
May 29, 6:46 PM EDTSpecial Weather StatementPHIBucks, Chester, Delaware, Montgomery, Philadelphia89 min
May 29, 6:52 PM EDTSevere Thunderstorm WarningPHIBucks, Chester, Montgomery53 min
May 29, 7:34 PM EDTSpecial Weather StatementPHIDelaware, Philadelphia56 min
May 29, 7:44 PM EDTSpecial Weather StatementPHIBucks61 min

Nearby

Areal Flood Advisories in Pennsylvania, 2012Every areal flood advisory 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.