Alert archive / Delaware / Flash Flood Warnings in 2023

Flash Flood Warning 5, NWS Philadelphia/Mount Holly

June 12, 2023New Castle County, Delaware; Delaware County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jun 12, 2023, 5:01 PM EDT for New Castle County, Delaware; Delaware County, Pennsylvania. It was in force for 4 hr. 5 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: Jun 12, 2023, 5:01 PM EDT (21:01 UTC)
Expired: Jun 12, 2023, 9:00 PM EDT
In force: 4 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties New Castle County, DE, Delaware County, PA

The radar

The Philadelphia radar (KDIX), 91 km from the middle of the area, began a volume at 21:03 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
Jun 12, 5:30 PM EDT	FLOOD	Upper Chichester Twp, PA	Report of Street flooding on Chichester Avenue.
Jun 12, 5:30 PM EDT	RAIN 3.49	Quarryville, DE	Mesonet station EW2337 Bellevue Hills.
Jun 12, 6:05 PM EDT	RAIN 3.08	Ashbourne Hills, DE	Mesonet station GW0481 Claymont.
Jun 12, 6:05 PM EDT	RAIN 3.92	Quarryville, DE	Mesonet station EW2337 Bellevue Hills.
Jun 12, 6:08 PM EDT	RAIN 3.28	1 Sw Greenville, DE	Mesonet station FW0380 Greenville.

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, 9.0 hours before the alert went out and 194 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: 62 J/kg
Mixed-layer CIN: -101 J/kg
Mixed-layer LCL: 756 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 144 m²/s²
0-3 km storm-relative helicity: 144 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

540 
WGUS51 KPHI 122101
FFWPHI
DEC003-PAC045-130100-
/O.NEW.KPHI.FF.W.0005.230612T2101Z-230613T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
501 PM EDT Mon Jun 12 2023

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  Northeastern New Castle County in northern Delaware...
  Southwestern Delaware County in southeastern Pennsylvania...

* Until 900 PM EDT.

* At 501 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 2 and 3 inches of rain 
  have fallen. Additional rainfall amounts of 0.5 to 1.5 inches are 
  possible in the warned area. Flash flooding is ongoing or expected 
  to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flooding of small creeks and streams, urban areas,
           highways, streets, and underpasses as well as other
           drainage and low lying areas.

* Some locations that may experience flash flooding include...
  Wilmington, Chester, Swarthmore, Arden, Chelsea, Chester Township, 
  Lima, Concordville, Elam, Nether Providence Township, Talleyville, 
  and Greenville.

This includes the following highways...
	Interstate 95 in Pennsylvania between mile markers 0 and 8.
	Interstate 95 in Delaware between mile markers 16 and 23.
	Interstate 476 in Pennsylvania between mile markers 0 and 6.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 3988 7553 3990 7551 3995 7546 3995 7533
      3986 7532 3982 7540 3977 7546 3975 7548
      3976 7563

FLASH FLOOD...RADAR INDICATED

$$

Hoeflich

1 follow-up statement

144 
WGUS71 KPHI 130052
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
852 PM EDT Mon Jun 12 2023

DEC003-PAC045-130102-
/O.EXP.KPHI.FF.W.0005.000000T0000Z-230613T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle DE-Delaware PA-
852 PM EDT Mon Jun 12 2023

...FLASH FLOOD WARNING WILL EXPIRE AT 9 PM EDT THIS EVENING FOR 
NORTHEASTERN NEW CASTLE AND SOUTHWESTERN DELAWARE COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat.

LAT...LON 3988 7553 3990 7551 3995 7546 3995 7533
      3986 7532 3982 7540 3977 7546 3975 7548
      3976 7563

$$

MJL

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 12, 3:13 PM EDT	Special Weather Statement	PHI	New Castle	32 min
Jun 12, 4:00 PM EDT	Areal Flood Advisory	PHI	New Castle	4 hr
Jun 12, 4:28 PM EDT	Flash Flood Warning	PHI	New Castle	4 hr
Jun 12, 4:15 PM EDT	Areal Flood Advisory	PHI	Delaware, Montgomery, Philadelphia	4 hr

Nearby

Flash Flood Warnings in Delaware, 2023 Flash Flood Warnings in Pennsylvania, 2023 Every flash flood warning in 2023

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.