Alert archive / Pennsylvania / Flash Flood Warnings in 2008

Flash Flood Warning 25, NWS Philadelphia/Mount Holly

August 10, 2008Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 10, 2008, 3:05 PM EDT for Chester County, Pennsylvania. It was in force for 3 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: Aug 10, 2008, 3:05 PM EDT (19:05 UTC)
Expired: Aug 10, 2008, 6:00 PM EDT
In force: 3 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

County Chester County, PA

The radar

The Philadelphia radar (KDIX), 121 km from the middle of the area, began a volume at 19:08 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, 7.1 hours before the alert went out and 175 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: 771 J/kg
Mixed-layer CIN: -66 J/kg
Mixed-layer LCL: 923 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 3 m²/s²
0-3 km storm-relative helicity: 85 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.8

Open this sounding in Storm Lab

The text

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

000 
WGUS51 KPHI 101905
FFWPHI
PAC029-102200-
/O.NEW.KPHI.FF.W.0025.080810T1905Z-080810T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
305 PM EDT SUN AUG 10 2008

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 600 PM EDT

* AT 302 PM...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED       
  ADDITIONAL THUNDERSTORMS WITH HEAVY RAIN MOVING ACROSS THE WARNED  
  AREA. DOPPLER RADAR ALSO INDICATED THAT RAINFALL RATES OF UP TO 2 
  INCHES PER HOUR IS OCCURRING WITH THIS ACTIVITY.

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

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. DO NOT ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR BY
AUTOMOBILE.

LAT...LON 3987 7601 3988 7600 3989 7601 4010 7593
      4025 7567 4006 7543 3993 7554 3984 7567
      3982 7603

$$

GORSE

1 follow-up statement

000 
WGUS71 KPHI 102129
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
529 PM EDT SUN AUG 10 2008

PAC029-102200-
/O.CON.KPHI.FF.W.0025.000000T0000Z-080810T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CHESTER PA-
529 PM EDT SUN AUG 10 2008

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 600 PM EDT FOR
CHESTER COUNTY...

AT 525 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO 
INDICATE THUNDERSTORMS PRODUCING HEAVY RAINFALL MOVING THROUGH THE 
WARNED AREA. AREAS OF POOR DRAINAGE FLOODING WAS REPORTED 
EARLIER...AND ADDITIONAL RUNOFF MAY WORSEN ANY ONGOING FLOODING.

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

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 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. 

LAT...LON 3987 7601 3988 7600 3989 7601 4010 7593
      4025 7567 4006 7543 3993 7554 3984 7567
      3982 7603

$$

GORSE

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 10, 10:18 AM EDT	Severe Thunderstorm Warning	PHI	Chester	57 min
Aug 10, 10:44 AM EDT	Severe Thunderstorm Warning	PHI	Delaware	61 min
Aug 10, 11:09 AM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	66 min
Aug 10, 11:32 AM EDT	Areal Flood Advisory	PHI	Chester, Delaware	3 hr
Aug 10, 11:46 AM EDT	Severe Thunderstorm Warning	PHI	Delaware	59 min
Aug 10, 12:09 PM EDT	Tornado Warning	PHI	Delaware	36 min
Aug 10, 12:17 PM EDT	Flash Flood Warning	PHI	Chester, Delaware, Montgomery	4 hr
Aug 10, 12:21 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Lehigh, Montgomery	84 min
Aug 10, 12:40 PM EDT	Severe Thunderstorm Warning	PHI	Delaware, Philadelphia	95 min
Aug 10, 1:05 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Carbon, Lehigh, Monroe, Northampton	115 min
Aug 10, 1:10 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester, Montgomery	65 min
Aug 10, 1:47 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Montgomery	58 min
Aug 10, 3:35 PM EDT	Severe Thunderstorm Warning	PHI	Berks	40 min
Aug 10, 4:45 PM EDT	Severe Thunderstorm Warning	PHI	Chester	75 min
Aug 10, 5:25 PM EDT	Areal Flood Advisory	PHI	Berks, Montgomery	110 min
Aug 10, 5:45 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware	75 min
Aug 10, 5:59 PM EDT	Areal Flood Advisory	PHI	Chester, Delaware	2 hr
Aug 10, 6:45 PM EDT	Areal Flood Advisory	PHI	Philadelphia	2 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2008 Every flash flood warning in 2008

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.