Alert archive / Pennsylvania / Flash Flood Warnings in 2018

Flash Flood Warning 27, NWS Philadelphia/Mount Holly

July 3, 20185 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 3, 2018, 7:06 PM EDT for 5 counties in Pennsylvania. It was in force for 2 hr. 4 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: Jul 3, 2018, 7:06 PM EDT (23:06 UTC)
Expired: Jul 3, 2018, 9:33 PM EDT
In force: 2 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Bucks County, PA, Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

What was reported inside it

Time	Report	Where	Remark
Jul 3, 7:06 PM EDT	FLOOD	Berwyn, PA	ROADS FLOODED IN BERWYN/DEVON
Jul 3, 7:11 PM EDT	FLASH FLOOD	Montrose Village, PA	WATER RESCUE AT CONESTOGA ROAD NEAR COUNTY LINE ROAD.
Jul 3, 7:15 PM EDT	FLOOD	Villanova, PA	FLOODING AND ROAD DEBRIS ON INTERSTATE 476 NEAR THE VILLANOVA EXIT. TIME ESTIMATED FROM RADAR.
Jul 3, 7:32 PM EDT	HEAVY RAIN 2.9	Bryn Mawr, PA	WAS STILL RAINING AT THE TIME OF THE REPORT; HE ALSO REPORTED THAT HIS YARD WAS COMPLETELY FLOODED

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 12:00Z, 11.1 hours before the alert went out and 221 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.

118 
WGUS51 KPHI 032306
FFWPHI
PAC017-029-045-091-101-040300-
/O.NEW.KPHI.FF.W.0027.180703T2306Z-180704T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Southeastern Montgomery County in southeastern Pennsylvania...
  South central Bucks County in southeastern Pennsylvania...
  East central Chester County in southeastern Pennsylvania...
  Northern Philadelphia County in southeastern Pennsylvania...
  North central Delaware County in southeastern Pennsylvania...

* Until 1100 PM EDT.

* At 706 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...
  Philadelphia, Bensalem, Norristown, Phoenixville, West Norriton,
  East Norriton, Conshohocken, Hatboro, Ambler, Jenkintown,
  Rockledge, Abington, Bryn Athyn, Feasterville-Trevose, Bryn Mawr,
  Trout Lake, Radnor Township, Gradyville, Kensington and Newtown
  Square.

Additional rainfall amounts of up 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 4020 7526 4014 7489 3998 7514 4006 7525
      3991 7544 4006 7574

$$

SFJ

1 follow-up statement

956 
WGUS71 KPHI 040133
FFSPHI

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

PAC017-029-045-091-101-040143-
/O.CAN.KPHI.FF.W.0027.000000T0000Z-180704T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Montgomery PA-Bucks PA-Chester PA-Philadelphia PA-Delaware PA-
933 PM EDT TUE JUL 3 2018

...THE FLASH FLOOD WARNING FOR SOUTHEASTERN MONTGOMERY...SOUTH
CENTRAL BUCKS...EAST CENTRAL CHESTER...NORTHERN PHILADELPHIA AND
NORTH CENTRAL DELAWARE COUNTIES IS CANCELLED...

Flooding is no longer expected to pose a threat. Please continue to
heed any remaining road closures.

LAT...LON 4020 7526 4014 7489 3998 7514 4006 7525
      3991 7544 4006 7574

$$
jjm

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, 6:58 PM EDT	Flash Flood Warning	PHI	Chester, Delaware	4 hr
Jul 3, 7:03 PM EDT	Special Weather Statement	PHI	Northampton	57 min
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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive.