Alert archive / Pennsylvania / Areal Flood Advisories in 2009

Areal Flood Advisory 21, NWS Philadelphia/Mount Holly

June 13, 2009Chester County, Pennsylvania; Cecil County, Maryland

NWS Philadelphia/Mount Holly issued this areal flood advisory at Jun 13, 2009, 4:59 PM EDT for Chester County, Pennsylvania; Cecil County, Maryland. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
Jun 13, 2009, 4:59 PM EDT (20:59 UTC)
Expired
Jun 13, 2009, 9:00 PM EDT
In force
4 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Cecil County, MD, Chester County, PA

The radar

The Dover AFB radar (KDOX), 113 km from the middle of the area, began a volume at 21:02 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, 9.0 hours before the alert went out and 161 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, Washington/Dulle, VA at 12:00Z on 2009-06-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 18 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, Washington/Dulle, VA at 12:00Z on 2009-06-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -30 square meters per square second.19395878Sfc1 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
18 J/kg
Mixed-layer CIN
-76 J/kg
Mixed-layer LCL
989 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
-30 m²/s²
0-3 km storm-relative helicity
38 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.

000 
WGUS81 KPHI 132059
FLSPHI

FLOOD ADVISORY
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
459 PM EDT SAT JUN 13 2009

MDC015-PAC029-140100-
/O.NEW.KPHI.FA.Y.0021.090613T2059Z-090614T0100Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CECIL MD-CHESTER PA-
459 PM EDT SAT JUN 13 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED AN

* URBAN AND SMALL STREAM FLOOD ADVISORY FOR...
  CECIL COUNTY IN NORTHEAST MARYLAND...
  THIS INCLUDES THE CITY OF ELKTON...
  CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...
  THIS INCLUDES THE CITY OF WEST CHESTER...

* UNTIL 900 PM EDT

* AT 457 PM EDT DOPPLER RADAR WAS INDICATING WIDELY SCATTERED
  THUNDERSTORMS WITH HEAVY RAIN OVER CHESTER AND CECIL COUNTIES.
  THUNDERSTORMS HAVE HAD A HISTORY OF PRODUCING HEAVY RAIN AND
  WILL CAUSE SOME POOR DRAINAGE AND URBAN FLOODING. IF THE FLOOD
  THREAT INCREASES A FLASH FLOOD WARNING MIGHT BECOME NECESSARY.
  PLEASE LISTEN FOR FURTHER UPDATES AND STATEMENTS.

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.

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE ELEVATED LEVELS ON
SMALL CREEKS AND STREAMS...AND PONDING OF WATER ON COUNTRY ROADS AND
FARMLAND ALONG THE BANKS OF CREEKS AND STREAMS.

&&

LAT...LON 3973 7617 3976 7609 3987 7601 4011 7595
      4025 7569 4020 7555 4009 7545 4007 7537
      3987 7562 3984 7560 3982 7570 3972 7579
      3939 7577 3938 7603 3956 7598 3953 7600
      3954 7607 3962 7616 3966 7619

$$


GIGI

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 13, 2:27 PM EDTAreal Flood AdvisoryPHIChester4 hr
Jun 13, 2:32 PM EDTFlash Flood WarningPHIBucks2 hr
Jun 13, 2:33 PM EDTFlash Flood WarningPHICarbon, Lehigh, Monroe, Northampton112 min
Jun 13, 2:57 PM EDTFlash Flood WarningPHIMontgomery2 hr
Jun 13, 3:17 PM EDTAreal Flood AdvisoryPHIBucks3 hr
Jun 13, 4:07 PM EDTFlash Flood WarningPHIBucks, Montgomery, Philadelphia6 hr
Jun 13, 5:16 PM EDTRiver Flood WarningPHIBucks13 hr
Jun 13, 6:06 PM EDTFlash Flood WarningPHIChester2 hr
Jun 13, 6:39 PM EDTSevere Thunderstorm WarningPHIMonroe66 min
Jun 13, 7:29 PM EDTSevere Thunderstorm WarningPHICarbon, Monroe61 min
Jun 13, 3:02 PM EDTSevere Thunderstorm WarningPHICecil58 min
Jun 13, 4:50 PM EDTAreal Flood AdvisoryPHICaroline3 hr
Jun 13, 4:52 PM EDTSevere Thunderstorm WarningPHICaroline53 min

Nearby

Areal Flood Advisories in Pennsylvania, 2009Areal Flood Advisories in Maryland, 2009Every areal flood advisory in 2009

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.