Alert archive / Pennsylvania / Flash Flood Warnings in 2015

Flash Flood Warning 30, NWS Philadelphia/Mount Holly

July 6, 2015Chester County, Delaware County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 6, 2015, 7:55 PM EDT for Chester County, Delaware 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
Jul 6, 2015, 7:55 PM EDT (23:55 UTC)
Expired
Jul 7, 2015, 12:00 AM EDT
In force
4 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Chester County, PA, Delaware County, PA

The radar

The Philadelphia radar (KDIX), 87 km from the middle of the area, began a volume at 23:58 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, 11.9 hours before the alert went out and 202 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 2015-07-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 349 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 2015-07-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 41 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
349 J/kg
Mixed-layer CIN
-15 J/kg
Mixed-layer LCL
648 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
41 m²/s²
0-3 km storm-relative helicity
99 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.3

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

204 
WGUS51 KPHI 062355
FFWPHI
PAC029-045-070400-
/O.NEW.KPHI.FF.W.0030.150706T2355Z-150707T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
755 PM EDT MON JUL 6 2015

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ  HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  CENTRAL DELAWARE COUNTY IN SOUTHEASTERN PENNSYLVANIA...
  EAST CENTRAL CHESTER COUNTY IN SOUTHEASTERN PENNSYLVANIA...

* UNTIL MIDNIGHT EDT
    
* AT 754 PM EDT...DOPPLER RADAR INDICATED A THUNDERSTORM PRODUCING 
  HEAVY RAIN ACROSS THE WARNED AREA. UP TO ONE AND A HALF INCHES OF 
  RAIN HAS ALREADY FALLEN WITH AN ADDITIONAL INCH OR MORE POSSIBLE. 
 
* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
  LIMA...CONCORDVILLE...CHELSEA...GRADYVILLE...TROUT LAKE...ELAM...
  NEWTOWN SQUARE...CHEYNEY...BROOMALL...PAOLI...CHESTER TOWNSHIP...
  NETHER PROVIDENCE TOWNSHIP...RADNOR TOWNSHIP...BROOKHAVEN...
  MEDIA...CHESTER HEIGHTS...ROSE VALLEY...BOOTHWYN...VILLAGE
  GREEN-GREEN RIDGE AND UPPER PROVIDENCE TOWNSHIP.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TURN AROUND...DON'T DROWN WHEN ENCOUNTERING FLOODED ROADS. MOST FLOOD
DEATHS OCCUR IN VEHICLES.

&&

LAT...LON 4000 7534 3982 7543 3986 7557 4004 7549

$$

ROBERTSON
2 follow-up statements
043 
WGUS71 KPHI 070022
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
822 PM EDT MON JUL 6 2015

PAC029-045-070400-
/O.CON.KPHI.FF.W.0030.000000T0000Z-150707T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
DELAWARE PA-CHESTER PA-
822 PM EDT MON JUL 6 2015

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL MIDNIGHT EDT FOR
CENTRAL DELAWARE AND EAST CENTRAL CHESTER COUNTIES...

AT 821 PM EDT...DOPPLER RADAR INDICATED THUNDERSTORMS PRODUCING HEAVY
RAIN ACROSS THE WARNED AREA. UP TO THREE INCHES OF RAIN HAVE ALREADY 
FALLEN IN SOME AREAS WITH ADDITIONAL HEAVY RAINFALL OCCURRING WHICH 
WILL PRODUCE ANOTHER INCH OR MORE.

SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
LIMA...CONCORDVILLE...CHELSEA...GRADYVILLE...TROUT LAKE...ELAM...
NEWTOWN SQUARE...CHEYNEY...BROOMALL...PAOLI...CHESTER TOWNSHIP...
NETHER PROVIDENCE TOWNSHIP...RADNOR TOWNSHIP...BROOKHAVEN...MEDIA...
CHESTER HEIGHTS...ROSE VALLEY...BOOTHWYN...VILLAGE GREEN-GREEN RIDGE
AND UPPER PROVIDENCE TOWNSHIP.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DO NOT ENTER OR CROSS FLOWING WATER OR WATER OF UNKNOWN DEPTH. 

TURN AROUND...DON'T DROWN WHEN ENCOUNTERING FLOODED ROADS. MOST FLOOD
DEATHS OCCUR IN VEHICLES.

&&

LAT...LON 4000 7534 3982 7543 3986 7557 4004 7549

$$

ROBERTSON
687 
WGUS71 KPHI 070137
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
937 PM EDT MON JUL 6 2015

PAC029-045-070145-
/O.CAN.KPHI.FF.W.0030.000000T0000Z-150707T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
DELAWARE PA-CHESTER PA-
937 PM EDT MON JUL 6 2015

...THE FLASH FLOOD WARNING FOR CENTRAL DELAWARE AND EAST CENTRAL
CHESTER COUNTIES IS CANCELLED...

THE HEAVY RAIN HAS ENDED...AND FLOODING IS NO LONGER EXPECTED TO 
POSE A THREAT.

IF THERE IS WATER ON ROADWAYS...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. BE ESPECIALLY CAUTIOUS AT NIGHT 
WHEN IT IS HARDER TO RECOGNIZE THE DANGERS OF FLOODING.


LAT...LON 4000 7534 3982 7543 3986 7557 4004 7549

$$

ROBERTSON

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 6, 6:50 PM EDTSpecial Weather StatementPHIBerks, Montgomery40 min
Jul 6, 7:10 PM EDTSpecial Weather StatementPHIDelaware50 min
Jul 6, 7:19 PM EDTAreal Flood AdvisoryPHIChester, Delaware, Montgomery4 hr
Jul 6, 7:49 PM EDTSpecial Weather StatementPHILehigh, Northampton41 min

Nearby

Flash Flood Warnings in Pennsylvania, 2015Every flash flood warning in 2015

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.