Alert archive / Pennsylvania / Flash Flood Warnings in 2017

Flash Flood Warning 25, NWS Philadelphia/Mount Holly

July 23, 2017Berks County, Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 23, 2017, 7:20 PM EDT for Berks County, Chester County, Montgomery County, Pennsylvania. It was in force for 6 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, 2017, 7:20 PM EDT (23:20 UTC)
Expired: Jul 24, 2017, 1:15 AM EDT
In force: 6 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Berks County, PA, Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 142 km from the middle of the area, began a volume at 23:23 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, 10:04 PM EDT	HEAVY RAIN 1.82	Upper Uwchlan Twp, PA	DAILY RAINFALL TODAY SO FAR.

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, 11.3 hours before the alert went out and 202 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: 186 J/kg
Mixed-layer CIN: -43 J/kg
Mixed-layer LCL: 983 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 19 m²/s²
0-3 km storm-relative helicity: 31 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

207 
WGUS51 KPHI 232320
FFWPHI
PAC011-029-091-240515-
/O.NEW.KPHI.FF.W.0025.170723T2320Z-170724T0515Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
720 PM EDT SUN JUL 23 2017

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Berks County in eastern Pennsylvania...
  Montgomery County in southeastern Pennsylvania...
  Northeastern Chester County in southeastern Pennsylvania...

* Until 115 AM EDT

* At 719 PM EDT...Doppler radar indicated thunderstorms producing 
  heavy rain moving into the warned area. Flash flooding is expected 
  to begin shortly in the areas of heaviest rain.

* Some locations that could experience flooding include...
  Reading, Norristown, Pottstown, Phoenixville, West Norriton, East
  Norriton, Wyomissing, Souderton, Birdsboro, Collegeville, Kutztown,
  Royersford, Hamburg, Fleetwood, Sinking Spring, Laureldale, Trappe,
  East Greenville, Womelsdorf and Wernersville.

Rainfall amounts of 2 to 4 inches are possible in the warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Do not drive through flood waters. The water may be deeper than you 
think it is. A vehicle can easily become trapped in flood waters 
endangering its occupants and those who come to their rescue.

If you live in a flood prone location be prepared to move to higher 
ground.

&&

LAT...LON 4052 7634 4052 7625 4058 7605 4057 7602
      4064 7598 4068 7589 4031 7530 4005 7535
      4009 7591 4010 7594 4014 7588 4049 7643

$$

Iovino

1 follow-up statement

131 
WGUS71 KPHI 240152
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
952 PM EDT SUN JUL 23 2017

PAC011-029-091-240200-
/O.CAN.KPHI.FF.W.0025.000000T0000Z-170724T0515Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-Montgomery PA-Chester PA-
952 PM EDT SUN JUL 23 2017

...THE FLASH FLOOD WARNING FOR BERKS...MONTGOMERY AND NORTHEASTERN
CHESTER COUNTIES IS CANCELLED...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat this evening. Please continue to heed any remaining road 
closures.

Additional heavy rain may move back into the area overnight tonight.

LAT...LON 4052 7634 4052 7625 4058 7605 4057 7602
      4064 7598 4068 7589 4031 7530 4005 7535
      4009 7591 4010 7594 4014 7588 4049 7643

$$

JRK

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 22, 10:52 PM EDT	Areal Flood Advisory	PHI	Bucks	4 hr
Jul 23, 3:16 PM EDT	Flash Flood Watch	PHI	Berks, Bucks, Carbon, Chester, Delaware, Lehigh and 4 more	15 hr
Jul 23, 4:26 PM EDT	Areal Flood Advisory	PHI	Chester	3 hr
Jul 23, 4:48 PM EDT	Areal Flood Advisory	PHI	Chester, Delaware	4 hr
Jul 23, 5:22 PM EDT	Special Weather Statement	PHI	Delaware	23 min
Jul 23, 6:08 PM EDT	Special Weather Statement	PHI	Delaware	37 min
Jul 23, 6:53 PM EDT	Flash Flood Warning	PHI	Chester, Delaware	14 hr
Jul 23, 7:41 PM EDT	Flash Flood Warning	PHI	Bucks, Delaware, Montgomery, Philadelphia	6 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2017 Every flash flood warning in 2017

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.