Alert archive / Pennsylvania / Flash Flood Warnings in 2018

Flash Flood Warning 26, NWS Philadelphia/Mount Holly

July 3, 2018Chester County, Delaware County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 3, 2018, 6:58 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 3, 2018, 6:58 PM EDT (22:58 UTC)
Expired: Jul 3, 2018, 11:00 PM 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 nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 11.0 hours before the alert went out and 179 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: 574 J/kg
Mixed-layer CIN: -189 J/kg
Mixed-layer LCL: 1257 m above ground
0-6 km bulk shear: 7 kt
0-1 km storm-relative helicity: 14 m²/s²
0-3 km storm-relative helicity: 55 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

322 
WGUS51 KPHI 032258 RRA
FFWPHI
PAC029-045-040300-
/O.NEW.KPHI.FF.W.0026.180703T2258Z-180704T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
658 PM EDT TUE JUL 3 2018

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Central Chester County in southeastern Pennsylvania...
  Southwestern Delaware County in southeastern Pennsylvania...

* Until 1100 PM EDT.

* At 658 PM EDT, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area. Up to two inches of rain have
  already fallen. Flash flooding is expected to begin shortly in the
  areas of heaviest rain.

* Some locations that could experience flooding include...
  Wilmington, West Chester, Coatesville, Westtown, Downingtown,
  Kennett Square, New Castle, Parkesburg, West Grove, Arden,
  Cochranville, Cheyney, Elam, Marshallton, Lima, Chelsea, Glenmoore,
  Ladenberg, Concordville and Chester Township.

Additional rainfall amounts of one to two inches are possible in the 
warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around...don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

&&

LAT...LON 4000 7596 4003 7594 4010 7579 3989 7538
      3981 7543 3982 7548 3974 7553 3972 7552
      3972 7551 3964 7556 3965 7558 3967 7555
      3971 7552 3974 7554 3983 7548 3984 7562
      3976 7575 3991 7600 3995 7600

$$

SFJ

1 follow-up statement

136 
WGUS71 KPHI 032314
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
714 PM EDT TUE JUL 3 2018

PAC029-045-040300-
/O.CON.KPHI.FF.W.0026.000000T0000Z-180704T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-Delaware PA-
714 PM EDT TUE JUL 3 2018

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1100 PM EDT FOR
CENTRAL CHESTER AND SOUTHWESTERN DELAWARE COUNTIES...

At 713 PM EDT, Doppler radar indicated thunderstorms producing heavy
rain across the warned area. Up to two inches of rain have already
fallen. Flash flooding is expected to begin shortly.

Some locations that could experience flooding include...
West Chester, Coatesville, Westtown, Downingtown, Kennett Square,
Parkesburg, West Grove, Cochranville, Cheyney, Elam, Marshallton,
Lima, Chelsea, Glenmoore, Ladenberg, Concordville, Chester Township,
Hockessin, North Star and West Goshen.

Additional rainfall amounts of over 2 inches are possible in the 
warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around...don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

&&

LAT...LON 4000 7596 4003 7594 4010 7579 3989 7538
      3981 7543 3982 7548 3983 7548 3984 7562
      3976 7575 3991 7600 3995 7600

$$

SFJ

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 3, 2:15 PM EDT	Special Weather Statement	PHI	Delaware	30 min
Jul 3, 3:00 PM EDT	Special Weather Statement	PHI	Philadelphia	60 min
Jul 3, 3:11 PM EDT	Flash Flood Warning	PHI	Montgomery, Philadelphia	50 min
Jul 3, 4:06 PM EDT	Special Weather Statement	PHI	Montgomery	54 min
Jul 3, 4:30 PM EDT	Special Weather Statement	PHI	Bucks	60 min
Jul 3, 5:24 PM EDT	Areal Flood Advisory	PHI	Delaware, Montgomery, Philadelphia	4 hr
Jul 3, 5:29 PM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery, Philadelphia	4 hr
Jul 3, 5:30 PM EDT	Special Weather Statement	PHI	Philadelphia	30 min
Jul 3, 5:45 PM EDT	Flash Flood Warning	PHI	Delaware, Montgomery, Philadelphia	4 hr
Jul 3, 6:03 PM EDT	Special Weather Statement	PHI	Monroe	57 min
Jul 3, 6:15 PM EDT	Special Weather Statement	PHI	Chester	60 min
Jul 3, 6:18 PM EDT	Severe Thunderstorm Warning	PHI	Delaware, Philadelphia	42 min
Jul 3, 6:21 PM EDT	Special Weather Statement	PHI	Delaware	24 min
Jul 3, 6:25 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Philadelphia	50 min
Jul 3, 6:37 PM EDT	Flash Flood Warning	PHI	Bucks, Philadelphia	3 hr
Jul 3, 6:40 PM EDT	Areal Flood Advisory	PHI	Chester, Delaware	4 hr
Jul 3, 6:50 PM EDT	Special Weather Statement	PHI	Delaware	55 min
Jul 3, 6:54 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware	51 min
Jul 3, 7:03 PM EDT	Special Weather Statement	PHI	Northampton	57 min
Jul 3, 7:06 PM EDT	Flash Flood Warning	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	2 hr
Jul 3, 7:22 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	21 min
Jul 3, 7:35 PM EDT	Special Weather Statement	PHI	Chester	25 min
Jul 3, 7:39 PM EDT	Severe Thunderstorm Warning	PHI	Chester	51 min
Jul 3, 7:54 PM EDT	Flash Flood Warning	PHI	Chester	4 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2018 Every flash flood warning in 2018

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.