Alert archive / Pennsylvania / Flash Flood Warnings in 2017

Flash Flood Warning 21, NWS Philadelphia/Mount Holly

July 17, 2017Berks County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 17, 2017, 1:41 PM EDT for Berks County, Pennsylvania. It was in force for 7 hr. 2 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 17, 2017, 1:41 PM EDT (17:41 UTC)
Expired: Jul 17, 2017, 8:45 PM EDT
In force: 7 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

County Berks County, PA

The radar

The State College radar (KCCX), 161 km from the middle of the area, began a volume at 17:45 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 17, 1:48 PM EDT	FLOOD	Bethel Twp, PA	ROAD CLOSURES DUE TO FLOODING ON ROUTE 501. ONE REPORT OF BASEMENT FLOODING. TIME ESTIMATED FROM RADAR.
Jul 17, 4:06 PM EDT	HEAVY RAIN 2.24	Frystown, PA	RAINFALL OF 2.24 INCHES IN 43 MINUTES.

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, 5.7 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: 1198 J/kg
Mixed-layer CIN: -50 J/kg
Mixed-layer LCL: 1021 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 40 m²/s²
0-3 km storm-relative helicity: 28 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.6

Open this sounding in Storm Lab

The text

As transmitted.

977 
WGUS51 KPHI 171741
FFWPHI
PAC011-172145-
/O.NEW.KPHI.FF.W.0021.170717T1741Z-170717T2145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
141 PM EDT MON JUL 17 2017

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Northwestern Berks County in eastern Pennsylvania...

* Until 545 PM EDT

* At 140 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 will experience flooding include...
  Hamburg, Womelsdorf, Shoemakersville, Bernville, Strausstown and 
  Centerport. This also includes Interstate 78 in western Berks 
  County.

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 4052 7634 4052 7625 4058 7605 4057 7602
      4059 7601 4053 7582 4035 7619 4039 7627
      4049 7643

$$

SFJ

5 follow-up statements

096 
WGUS71 KPHI 171822
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
222 PM EDT MON JUL 17 2017

PAC011-172145-
/O.CON.KPHI.FF.W.0021.000000T0000Z-170717T2145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-
222 PM EDT MON JUL 17 2017

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 545 PM EDT FOR
NORTHWESTERN BERKS COUNTY...

At 217 PM EDT...Doppler radar indicated the heaviest rain had ended 
across the warned area. However, up to three inches of rain have 
already fallen; it will take time for runoff to recede. In addition, 
more showers may develop over the warned area. This includes 
Interstate 78 in western Berks County.  Flash flooding is expected 
to begin shortly.

Some locations that will experience flooding include...
Hamburg and Strausstown. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

&&

LAT...LON 4052 7634 4052 7625 4058 7605 4057 7602
      4059 7601 4055 7589 4039 7627 4049 7643

$$

SFJ

732 
WGUS71 KPHI 171935
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
335 PM EDT MON JUL 17 2017

PAC011-172145-
/O.CON.KPHI.FF.W.0021.000000T0000Z-170717T2145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-
335 PM EDT MON JUL 17 2017

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 545 PM EDT FOR
NORTHWESTERN BERKS COUNTY...

At 332 PM EDT...emergency management reported flash flooding in 
Bethel Township, including closed roads and basement flooding. 
Doppler radar indicates up to three inches of rain have already 
fallen. Flash flooding is already occurring.

Some locations that will experience flooding include...
Hamburg and Strausstown. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Stay away or be swept away. River banks and culverts can become
unstable and unsafe.

If you come across a flooded roadway, turn around, don't drown. Most 
flood deaths occur in vehicles.

&&

LAT...LON 4052 7634 4052 7625 4058 7605 4057 7602
      4059 7601 4055 7589 4039 7627 4049 7643

$$

SFJ

163 
WGUS71 KPHI 172120
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
520 PM EDT MON JUL 17 2017

PAC011-172145-
/O.CON.KPHI.FF.W.0021.000000T0000Z-170717T2145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-
520 PM EDT MON JUL 17 2017

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 545 PM EDT FOR
WEST CENTRAL BERKS COUNTY...

At 518 PM EDT...Doppler radar indicated thunderstorms producing 
heavy rain have temporarily ended across the warned area. Up to 
three inches of rain has probably fallen. Other thunderstorms may 
move into this area around 6 PM which may require an extension of 
the warning.  

Flash flooding will remain over mainly rural areas of west central
Berks County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

&&

LAT...LON 4052 7634 4052 7625 4050 7619 4039 7627
      4049 7643

$$

Drag

143 
WGUS51 KPHI 172123
FFWPHI
PAC011-180045-
/O.EXT.KPHI.FF.W.0021.000000T0000Z-170718T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
523 PM EDT MON JUL 17 2017

The National Weather Service in Mount Holly NJ has extended the

* Flash Flood Warning for...
  West central Berks County in eastern Pennsylvania...

* Until 845 PM EDT

* At 521 PM EDT...Doppler radar indicated thunderstorms producing 
  heavy rain may move back into the warned area where up to three 
  inches of rain have already fallen closing some roads near Bethel. 
  
* Flash flooding should remain over mainly rural areas of west 
  central Berks County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, country roads, farmland, and other low lying
spots.

In hilly terrain there are hundreds of low water crossings which are
potentially dangerous in heavy rain. Do not attempt to cross flooded
roads. Find an alternate route.

Flooding is occurring or is imminent. It is important to know where
you are relative to streams, rivers, or creeks which can become
killers in heavy rains. Campers and hikers should avoid streams or
creeks.

&&

LAT...LON 4052 7634 4052 7625 4050 7619 4039 7627
      4049 7643

$$

Drag

894 
WGUS71 KPHI 172335
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
735 PM EDT MON JUL 17 2017

PAC011-180045-
/O.CON.KPHI.FF.W.0021.000000T0000Z-170718T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-
735 PM EDT MON JUL 17 2017

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 845 PM EDT FOR
WEST CENTRAL BERKS COUNTY...

At 732 PM EDT...Doppler radar indicated that heavy rains ended long 
ago though there are still some thunderstorms to the west. Those 
thunderstorms should diminish as they approach Berks County later 
tonight. Runoff in the Bethel area where nearly 2.5 inches of rain 
fell in a short time and temporarily closed some roads, should be 
subsiding.  

Stay away from slippery banks of any nearby fast flowing small 
streams. 

Any remaining flooding should remain over mainly rural areas of west 
central Berks County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

&&

LAT...LON 4052 7634 4052 7625 4050 7619 4039 7627
      4049 7643

$$

Drag

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 17, 1:09 PM EDT	Special Weather Statement	PHI	Lehigh	36 min
Jul 17, 1:20 PM EDT	Severe Thunderstorm Warning	PHI	Berks	40 min
Jul 17, 1:24 PM EDT	Areal Flood Advisory	PHI	Berks	5 hr
Jul 17, 1:57 PM EDT	Special Weather Statement	PHI	Lebanon	33 min
Jul 17, 3:16 PM EDT	Areal Flood Advisory	PHI	Berks	119 min
Jul 17, 3:56 PM EDT	Areal Flood Advisory	PHI	Bucks, Lehigh, Monroe, Northampton	4 hr
Jul 17, 4:24 PM EDT	Special Weather Statement	PHI	Northampton	51 min
Jul 17, 4:35 PM EDT	Areal Flood Advisory	PHI	Monroe, Northampton	115 min
Jul 17, 4:44 PM EDT	Areal Flood Advisory	PHI	Bucks, Delaware, Montgomery, Philadelphia	3 hr
Jul 17, 4:56 PM EDT	Special Weather Statement	PHI	Philadelphia	49 min
Jul 17, 4:57 PM EDT	Special Weather Statement	PHI	Chester	33 min
Jul 17, 5:51 PM EDT	Special Weather Statement	PHI	Bucks	39 min
Jul 17, 5:55 PM EDT	Special Weather Statement	PHI	Chester	50 min

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.