Alert archive / Pennsylvania / Flash Flood Warnings in 2013

Flash Flood Warning 53, NWS Philadelphia/Mount Holly

August 13, 2013Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 13, 2013, 5:47 AM EDT for Chester County, Pennsylvania. It was in force for 4 hr. 3 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Aug 13, 2013, 5:47 AM EDT (09:47 UTC)
Expired: Aug 13, 2013, 9:45 AM 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 Dover AFB radar (KDOX), 128 km from the middle of the area, began a volume at 09:46 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.

What was reported inside it

Time	Report	Where	Remark
Aug 13, 6:55 AM EDT	FLASH FLOOD	Coatesville, PA	FLODING ON BLACKMORE HILL ROAD
Aug 13, 6:55 AM EDT	FLASH FLOOD	Downingtown, PA	FLOODED BUSINESS ALONG ROUTE 30
Aug 13, 9:00 AM EDT	FLASH FLOOD	Downingtown, PA	SEVERAL REPORTS OF FLOODING ON LOW POINT ROADS.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 00:00Z, 9.8 hours before the alert went out and 165 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: 1 J/kg
Mixed-layer CIN: -66 J/kg
Mixed-layer LCL: 1841 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 31 m²/s²
0-3 km storm-relative helicity: 84 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

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

988 
WGUS51 KPHI 130947
FFWPHI
PAC029-131345-
/O.NEW.KPHI.FF.W.0053.130813T0947Z-130813T1345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
547 AM EDT TUE AUG 13 2013

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  CHESTER COUNTY...

* UNTIL 945 AM EDT...

* AT 540 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  THAT ONE TO THREE INCHES OF RAIN HAVE ALREADY FALLEN THIS MORNING
  IN PARTS OF WESTERN CHESTER COUNTY. ADDITIONAL HEAVY RAIN IS
  MOVING INTO THE AREA WITH ANOTHER ONE TO THREE INCHES OF RAIN
  POSSIBLE IN A SHORT AMOUNT OF TIME.   

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO OXFORD...
  PARKESBURG...COATESVILLE AND DOWNINGTOWN.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING. 
IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY. 
RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE 
PRECAUTIONS TO PROTECT LIFE AND PROPERTY. NEVER ATTEMPT TO CROSS 
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR IN AN 
AUTOMOBILE. TURN AROUND DON'T DROWN!

&&

LAT...LON 3972 7613 3977 7607 3983 7602 3985 7603
      3988 7599 3997 7600 4003 7594 4011 7595
      4012 7593 4014 7589 4013 7555 3979 7572
      3972 7578

$$

IOVINO

1 follow-up statement

276 
WGUS71 KPHI 131143
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
743 AM EDT TUE AUG 13 2013

PAC029-131345-
/O.CON.KPHI.FF.W.0053.000000T0000Z-130813T1345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CHESTER PA-
743 AM EDT TUE AUG 13 2013

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 945 AM EDT FOR
CHESTER COUNTY...

AT 735 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR ESTIMATED 
THAT TWO TO FOUR INCHES OF RAIN HAD FALLEN IN MUCH OF CHESTER 
COUNTY. LOCATIONS TO THE SOUTH AND EAST OF PARKESBURG AND 
COATESVILLE MAY HAVE RECEIVED FOUR TO SIX INCHES OF RAIN. ANOTHER 
INCH OR TWO OF RAIN MAY FALL IN THE COUNTY...PRODUCING ADDITIONAL 
FLASH FLOODING.

LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO CHESTER
SPRINGS...GLENMOORE...HOMEVILLE...COATESVILLE...DOWNINGTOWN...
HONEY BROOK...OXFORD AND PARKESBURG.

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.

&&

LAT...LON 3972 7613 3977 7607 3983 7602 3985 7603
      3988 7599 3997 7600 4003 7594 4011 7595
      4012 7593 4014 7589 4013 7555 3979 7572
      3972 7578

$$

IOVINO

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 13, 2:45 AM EDT	Flash Flood Watch	PHI	Berks, Bucks, Carbon, Chester, Delaware, Lehigh and 4 more	9 hr
Aug 13, 5:15 AM EDT	Areal Flood Advisory	PHI	Berks, Chester, Montgomery	4 hr
Aug 13, 6:07 AM EDT	Areal Flood Advisory	PHI	Bucks, Lehigh, Northampton	7 hr
Aug 13, 6:07 AM EDT	Severe Thunderstorm Warning	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	53 min
Aug 13, 6:20 AM EDT	Areal Flood Advisory	PHI	Bucks, Delaware, Philadelphia	4 hr
Aug 13, 6:23 AM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware	67 min
Aug 13, 6:32 AM EDT	Tornado Warning	PHI	Chester	43 min
Aug 13, 6:36 AM EDT	Flash Flood Warning	PHI	Chester, Delaware, Montgomery	8 hr
Aug 13, 7:05 AM EDT	Severe Thunderstorm Warning	PHI	Delaware, Philadelphia	40 min
Aug 13, 7:14 AM EDT	Flash Flood Warning	PHI	Berks	4 hr
Aug 13, 7:42 AM EDT	Special Weather Statement	PHI	Philadelphia	48 min
Aug 13, 7:54 AM EDT	Flash Flood Warning	PHI	Delaware, Montgomery, Philadelphia	8 hr
Aug 13, 7:54 AM EDT	Special Weather Statement	PHI	Delaware, Philadelphia	66 min
Aug 13, 8:07 AM EDT	River Flood Warning	PHI	Chester	9 hr
Aug 13, 8:20 AM EDT	Flash Flood Warning	PHI	Bucks	8 hr
Aug 13, 9:50 AM EDT	Flash Flood Warning	PHI	Chester	4 hr
Aug 13, 11:22 AM EDT	River Flood Warning	PHI	Chester, Delaware	16 hr
Aug 13, 2:18 PM EDT	Areal Flood Warning	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	9 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2013 Every flash flood warning in 2013

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.