Alert archive / Pennsylvania / Flash Flood Warnings in 2013

Flash Flood Warning 43, NWS Philadelphia/Mount Holly

July 23, 2013Chester County, Pennsylvania; Cecil County, Maryland

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 23, 2013, 12:25 AM EDT for Chester County, Pennsylvania; Cecil County, Maryland. It was in force for 4 hr. 1 report 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: Jul 23, 2013, 12:25 AM EDT (04:25 UTC)
Expired: Jul 23, 2013, 4:30 AM EDT
In force: 4 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Cecil County, MD, Chester County, PA

The radar

The Dover AFB radar (KDOX), 120 km from the middle of the area, began a volume at 04:27 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
Jul 23, 1:30 AM EDT	FLASH FLOOD	Pughtown, PA	A FEW ROADS WERE FLOODED THROUGHOUT THE COUNTY.

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, 4.4 hours before the alert went out and 159 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: 1248 J/kg
Mixed-layer CIN: -10 J/kg
Mixed-layer LCL: 1188 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 53 m²/s²
0-3 km storm-relative helicity: 74 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 2.5

Open this sounding in Storm Lab

The text

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

317 
WGUS51 KPHI 230425
FFWPHI
MDC015-PAC029-230830-
/O.NEW.KPHI.FF.W.0043.130723T0425Z-130723T0830Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1225 AM EDT TUE JUL 23 2013

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 430 AM EDT...

* AT 1221 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  VERY HEAVY RAIN FROM A THUNDERSTORM NEAR RICHARDSMERE...OR 13 MILES
  NORTH OF ABERDEEN...MOVING NORTHEAST AT 35 MPH.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO WEST
  CHESTER.

NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED ONE TO TWO INCHES 
OF RAIN HAD ALREADY FALLEN ACROSS PORTIONS OF THE WARNED AREA AND AN 
ADDTIONAL ONE TO TWO INCHES IS POSSIBLE.  

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!

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLASH FLOODING IS OBSERVED ACT QUICKLY. MOVE
UP TO HIGHER GROUND TO ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS
SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

&&

LAT...LON 3973 7614 3979 7605 3983 7602 3985 7603
      3988 7599 3997 7600 4003 7594 4012 7593
      4024 7567 4007 7540 3982 7567 3978 7573
      3949 7599 3952 7599 3955 7605 3972 7623

$$

NIERENBERG

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 22, 9:19 PM EDT	Areal Flood Advisory	PHI	Carbon, Monroe	3 hr
Jul 22, 9:53 PM EDT	Areal Flood Advisory	PHI	Berks, Lehigh	3 hr
Jul 22, 11:09 PM EDT	Areal Flood Advisory	PHI	Berks, Chester	3 hr
Jul 22, 11:39 PM EDT	Flash Flood Warning	PHI	Berks, Lehigh	4 hr
Jul 23, 12:11 AM EDT	Special Weather Statement	PHI	Chester	94 min
Jul 23, 1:50 AM EDT	Areal Flood Advisory	PHI	Bucks, Delaware, Montgomery, Philadelphia	4 hr
Jul 23, 2:11 AM EDT	Flash Flood Warning	PHI	Bucks, Delaware, Montgomery, Philadelphia	4 hr
Jul 23, 3:49 AM EDT	Flash Flood Watch	PHI	Berks, Bucks, Chester, Delaware, Lehigh, Montgomery and 2 more	11 hr
Jul 23, 4:10 PM EDT	Special Weather Statement	PHI	Bucks, Delaware, Philadelphia	2 hr
Jul 23, 2:20 AM EDT	Areal Flood Advisory	PHI	Kent, Queen Anne's	4 hr
Jul 23, 2:22 AM EDT	Special Weather Statement	PHI	Caroline, Queen Anne's, Talbot	2 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2013 Flash Flood Warnings in Maryland, 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.