Alert archive / Pennsylvania / Flash Flood Warnings in 2014

Flash Flood Warning 57, NWS Philadelphia/Mount Holly

September 6, 2014Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Sep 6, 2014, 3:51 PM EDT for Chester County, Pennsylvania. It was in force for 4 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, 2014, 3:51 PM EDT (19:51 UTC)
Expired
Sep 6, 2014, 7:45 PM EDT
In force
4 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

County Chester County, PA

The radar

The Philadelphia radar (KDIX), 117 km from the middle of the area, began a volume at 19:53 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, 7.9 hours before the alert went out and 185 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 2014-09-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1444 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 2014-09-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 18 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
1444 J/kg
Mixed-layer CIN
-42 J/kg
Mixed-layer LCL
867 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
18 m²/s²
0-3 km storm-relative helicity
65 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.

940 
WGUS51 KPHI 061951
FFWPHI
PAC029-062345-
/O.NEW.KPHI.FF.W.0057.140906T1951Z-140906T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
351 PM EDT SAT SEP 6 2014

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  NORTHERN CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...
  THIS INCLUDES THE CITY OF WEST CHESTER...

* UNTIL 745 PM EDT

* AT 348 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  VERY HEAVY RAIN FROM A THUNDERSTORM OVER THE WARNED AREA.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
  LIONVILLE...HONEY BROOK...DOWNINGTOWN...COATESVILLE...PUGHTOWN...
  GLENMOORE AND CHESTER SPRINGS

PRECAUTIONARY/PREPAREDNESS ACTIONS...

ADDITIONAL RAINFALL AMOUNTS OF UP TO TWO INCHES ARE POSSIBLE IN THE 
WARNED AREA.

&&

LAT...LON 3997 7600 4004 7594 4010 7595 4020 7558
      4019 7557 4021 7556 4020 7555 3990 7556
      3989 7558 3988 7599 3990 7600

$$

SFJ
2 follow-up statements
510 
WGUS71 KPHI 062123
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
523 PM EDT SAT SEP 6 2014

PAC029-062345-
/O.CON.KPHI.FF.W.0057.000000T0000Z-140906T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CHESTER PA-
523 PM EDT SAT SEP 6 2014

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 745 PM EDT FOR
NORTHERN CHESTER COUNTY...

AT 520 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED THE 
HEAVY RAIN HAD MOSTLY LEFT THE REGION. HOWEVER...SOME LOCATIONS MAY 
HAVE RECEIVED OVER 3 INCHES OF RAIN. THUS...ANY RUNOFF WILL BE SLOW 
TO RECEDE. THUS...THE FLASH FLOOD WARNING REMAINS IN EFFECT.

LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO LIONVILLE...
HONEY BROOK...PUGHTOWN...GLENMOORE AND CHESTER SPRINGS

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.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM EDT
SATURDAY EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW
JERSEY AND EASTERN PENNSYLVANIA.

&&

LAT...LON 3997 7600 4004 7594 4010 7595 4020 7558
      4019 7557 4021 7556 4020 7555 3990 7556
      3989 7558 3988 7599 3990 7600

$$

SFJ
718 
WGUS71 KPHI 062252
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
652 PM EDT SAT SEP 6 2014

PAC029-062300-
/O.CAN.KPHI.FF.W.0057.000000T0000Z-140906T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CHESTER PA-
652 PM EDT SAT SEP 6 2014

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR NORTHERN CHESTER
COUNTY...

THE HEAVY RAIN HAS LEFT THE WARNING AREA. HOWEVER...ADDITIONAL 
THUNDERSTORMS WILL BE POSSIBLE THIS EVENING.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM EDT
SATURDAY EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW
JERSEY AND EASTERN PENNSYLVANIA.

LAT...LON 3997 7600 4004 7594 4010 7595 4020 7558
      4019 7557 4021 7556 4020 7555 3990 7556
      3989 7558 3988 7599 3990 7600

$$

SFJ

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 6, 1:37 PM EDTSpecial Weather StatementPHINorthampton53 min
Sep 6, 2:13 PM EDTSpecial Weather StatementPHIChester62 min
Sep 6, 2:19 PM EDTSevere Thunderstorm WarningPHIChester43 min
Sep 6, 2:43 PM EDTAreal Flood AdvisoryPHIChester4 hr
Sep 6, 3:21 PM EDTSpecial Weather StatementPHIBerks, Bucks, Lehigh, Montgomery54 min
Sep 6, 3:45 PM EDTSevere Thunderstorm WarningPHIBucks, Montgomery60 min
Sep 6, 4:52 PM EDTSevere Thunderstorm WarningPHIDelaware36 min
Sep 6, 7:36 PM EDTSevere Thunderstorm WarningPHIBerks, Carbon, Lehigh, Monroe, Northampton54 min

Nearby

Flash Flood Warnings in Pennsylvania, 2014Every flash flood warning in 2014

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.