Alert archive / Pennsylvania / Flash Flood Warnings in 2019

Flash Flood Warning 48, NWS Philadelphia/Mount Holly

July 11, 2019Bucks County, Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 11, 2019, 5:20 PM EDT for Bucks County, Chester County, Montgomery County, Pennsylvania. It was in force for 4 hr. 8 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 11, 2019, 5:20 PM EDT (21:20 UTC)
Expired: Jul 11, 2019, 9:15 PM EDT
In force: 4 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Bucks County, PA, Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 102 km from the middle of the area, began a volume at 21:21 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 11, 5:39 PM EDT	FLASH FLOOD	1 Ese Telford, PA	WATER RESCUE AT INTERSECTION OF BETHLEHEM PIKE AND CHERRY RD.
Jul 11, 6:05 PM EDT	FLOOD	1 Nnw Downington, PA	MUDDY WATER ON RT. 30 APPROACHING 282.
Jul 11, 6:10 PM EDT	FLASH FLOOD	East Caln Twp, PA	WATER RESCUE ON LANCASTER AVE AT COUNTRY CLUB RD.
Jul 11, 6:15 PM EDT	HEAVY RAIN 3.38	East Caln Twp, PA	COCORAHS STATION PA-CH-46 DOWNINGTOWN 1.7 NE.
Jul 11, 6:25 PM EDT	FLASH FLOOD	1 N Uwchlan Twp, PA	WATER RESCUE ON UPPER PINE CREEK RD AT DAVIS RD.
Jul 11, 7:28 PM EDT	HEAVY RAIN 3.3	Ottsville, PA	REPORTED AT OTTSVILLE, PA.
Jul 11, 8:34 PM EDT	FLASH FLOOD	1 Sw Chester Springs, PA	PICKERING CREEK FLOODED OVER LOCAL ROADS 401 AND 113.
Jul 11, 8:50 PM EDT	HEAVY RAIN 2.09	2 Ese Downington, PA	MESONET STATION EW9938 DOWNINGTOWN.

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, 9.3 hours before the alert went out and 213 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: 114 J/kg
Mixed-layer CIN: -122 J/kg
Mixed-layer LCL: 1075 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 74 m²/s²
0-3 km storm-relative helicity: 102 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

105 
WGUS51 KPHI 112120
FFWPHI
PAC017-029-091-120115-
/O.NEW.KPHI.FF.W.0048.190711T2120Z-190712T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
520 PM EDT Thu Jul 11 2019

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Central Montgomery County in southeastern Pennsylvania...
  Northwestern Bucks County in southeastern Pennsylvania...
  Central Chester County in southeastern Pennsylvania...

* Until 915 PM EDT.

* At 519 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across portions of the warned area. Flash flooding is 
  expected to begin shortly in the areas of heaviest rain.

* Some locations that could experience flooding include...
  West Chester, Phoenixville, Lansdale, West Norriton, East Norriton,
  Coatesville, Quakertown, Perkasie, Downingtown, Souderton,
  Bedminster, Collegeville, Royersford, Chalfont, Tinicum,
  Parkesburg, Trappe, Hatfield, Dublin and Schwenksville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4010 7582 4016 7566 4035 7547 4056 7531
      4057 7528 4041 7505 3988 7563 3994 7597

$$

Kruzdlo

1 follow-up statement

143 
WGUS71 KPHI 120110
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
910 PM EDT Thu Jul 11 2019

PAC017-029-091-120118-
/O.EXP.KPHI.FF.W.0048.000000T0000Z-190712T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Montgomery PA-Bucks PA-Chester PA-
910 PM EDT Thu Jul 11 2019

...THE FLASH FLOOD WARNING FOR CENTRAL MONTGOMERY...NORTHWESTERN
BUCKS AND CENTRAL CHESTER COUNTIES WILL EXPIRE AT 915 PM EDT...

With several creeks and streams above flood stage, this flash flood 
warning will be converted to an areal flood warning. 

LAT...LON 4010 7582 4016 7566 4035 7547 4056 7531
      4057 7528 4041 7505 3988 7563 3994 7597

$$

Kruzdlo

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 11, 3:44 AM EDT	Flash Flood Watch	PHI	Berks, Bucks, Chester, Delaware, Lehigh, Montgomery and 2 more	18 hr
Jul 11, 12:33 PM EDT	Special Weather Statement	PHI	Chester	57 min
Jul 11, 1:23 PM EDT	Special Weather Statement	PHI	Chester, Delaware	52 min
Jul 11, 1:44 PM EDT	Severe Thunderstorm Warning	PHI	Delaware, Montgomery, Philadelphia	61 min
Jul 11, 2:41 PM EDT	Special Weather Statement	PHI	Philadelphia	64 min
Jul 11, 2:44 PM EDT	Special Weather Statement	PHI	Bucks, Montgomery	61 min
Jul 11, 2:50 PM EDT	Areal Flood Advisory Emergency	PHI	Berks, Chester, Montgomery	4 hr
Jul 11, 3:00 PM EDT	Flash Flood Warning	PHI	Berks, Chester, Montgomery	8 hr
Jul 11, 3:13 PM EDT	Areal Flood Advisory	PHI	Bucks, Carbon, Lehigh, Monroe, Northampton	4 hr
Jul 11, 3:33 PM EDT	Areal Flood Advisory	PHI	Northampton	4 hr
Jul 11, 3:45 PM EDT	Flash Flood Warning	PHI	Berks, Bucks, Lehigh, Montgomery, Northampton	4 hr
Jul 11, 4:45 PM EDT	Flash Flood Warning Emergency	PHI	Berks, Montgomery	4 hr
Jul 11, 5:12 PM EDT	Flash Flood Warning	PHI	Chester	4 hr
Jul 11, 5:33 PM EDT	Areal Flood Advisory	PHI	Bucks	4 hr
Jul 11, 6:14 PM EDT	Severe Thunderstorm Warning	PHI	Delaware, Montgomery, Philadelphia	61 min
Jul 11, 6:15 PM EDT	Flash Flood Warning	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	4 hr
Jul 11, 6:17 PM EDT	Areal Flood Advisory	PHI	Bucks	4 hr
Jul 11, 6:28 PM EDT	River Flood Warning	PHI	Montgomery	22 hr
Jul 11, 6:57 PM EDT	River Flood Warning	PHI	Montgomery	12 hr
Jul 11, 7:03 PM EDT	River Flood Warning	PHI	Chester, Montgomery, Philadelphia	26 hr
Jul 11, 7:19 PM EDT	River Flood Warning	PHI	Chester	7 hr
Jul 11, 7:47 PM EDT	Flash Flood Warning	PHI	Berks, Bucks, Lehigh, Montgomery	3 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2019 Every flash flood warning in 2019

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.