Alert archive / Maryland / Flash Flood Warnings in 2018

Flash Flood Warning 15, NWS Philadelphia/Mount Holly

June 10, 2018Caroline County, Maryland; Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this flash flood warning at Jun 10, 2018, 5:00 PM EDT for Caroline County, Maryland; Sussex County, Delaware. It was in force for 108 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Jun 10, 2018, 5:00 PM EDT (21:00 UTC)
Expired
Jun 10, 2018, 6:48 PM EDT
In force
108 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Sussex County, DE, Caroline County, MD

The radar

The Dover AFB radar (KDOX), 28 km from the middle of the area, began a volume at 21:01 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.

The nearest sounding before it

Wallops Is Stn, VA (KWAL), launched 12:00Z, 9.0 hours before the alert went out and 80 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-pSkew-T log-p diagram, Wallops Is Stn, VA at 12:00Z on 2018-06-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 61 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Wallops Is Stn, VA at 12:00Z on 2018-06-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 30 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
61 J/kg
Mixed-layer CIN
-100 J/kg
Mixed-layer LCL
675 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
30 m²/s²
0-3 km storm-relative helicity
21 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

796 
WGUS51 KPHI 102100
FFWPHI
DEC005-MDC011-110100-
/O.NEW.KPHI.FF.W.0015.180610T2100Z-180611T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
500 PM EDT SUN JUN 10 2018

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Southwestern Sussex County in southern Delaware...
  Southeastern Caroline County in eastern Maryland...

* Until 900 PM EDT.

* At 456 PM EDT, Doppler radar indicated a thunderstorm producing 
  very heavy rain across the warned area. This storm has produced 
  1.5 to 2 inches of rainfall in just 30 minutes across southern 
  Caroline County. Flash flooding is expected to begin shortly, 
  especially, as this storm moves southeast into the same locations 
  in southern Sussex County that saw flash flooding yesterday.

* Some locations that could experience flooding include...
  Seaford, Millsboro, Laurel, Federalsburg, Selbyville, Delmar,
  Dagsboro, Sycamore, Gumboro, Blades, Frankford and Bethel.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report flooding to your local law enforcement agency when you
can do so safely.

A Flash Flood Warning means that flooding is imminent or occurring.
If you are in the warned area move to higher ground immediately.
Residents living along streams and creeks should take immediate
precautions to protect life and property.

&&

LAT...LON 3846 7569 3864 7571 3869 7577 3868 7580
      3869 7580 3870 7582 3874 7580 3875 7574
      3870 7562 3864 7540 3855 7524 3845 7521

$$

JRK
2 follow-up statements
438 
WGUS71 KPHI 102218
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
618 PM EDT SUN JUN 10 2018

DEC005-MDC011-110100-
/O.CON.KPHI.FF.W.0015.000000T0000Z-180611T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Sussex DE-Caroline MD-
618 PM EDT SUN JUN 10 2018

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 900 PM EDT FOR
SOUTHWESTERN SUSSEX AND SOUTHEASTERN CAROLINE COUNTIES...

At 615 PM EDT, Doppler radar and automated rain gauges indicated 
thunderstorms produced heavy rain over the warned area between 430 
and 530 PM. Up to two inches of rain had fallen over Federalsburg in 
southeastern Caroline County and Seaford in west-central Sussex 
County. Flash flooding may begin shortly. 

The imminent threat for flash flooding has diminished considerably 
farther southeast as the storms that were producing the heavy rain 
have since weakened. However, additional storms developing farther 
southwest may move back into far southwestern Sussex County shortly.

Some locations that could experience flooding include...
Seaford, Laurel, Federalsburg, Selbyville, Delmar, Sycamore, Gumboro,
Blades and Bethel.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report flooding to your local law enforcement agency when you
can do so safely.

&&

LAT...LON 3846 7569 3864 7571 3869 7577 3868 7580
      3869 7580 3870 7582 3874 7580 3875 7574
      3871 7567 3870 7563 3870 7560 3868 7556
      3864 7549 3856 7544 3851 7530 3845 7521

$$

JRK
982 
WGUS71 KPHI 102248
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
648 PM EDT SUN JUN 10 2018

DEC005-MDC011-102256-
/O.CAN.KPHI.FF.W.0015.000000T0000Z-180611T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Sussex DE-Caroline MD-
648 PM EDT SUN JUN 10 2018

...THE FLASH FLOOD WARNING FOR SOUTHWESTERN SUSSEX AND SOUTHEASTERN
CAROLINE COUNTIES IS CANCELLED...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat through the first half of the evening. Please continue to 
heed any remaining road closures. 

However, there is still a potential for additional rounds of heavy 
rainfall later tonight into early Monday morning. 

LAT...LON 3846 7569 3864 7571 3869 7577 3868 7580
      3869 7580 3870 7582 3874 7580 3875 7574
      3871 7567 3870 7563 3870 7560 3868 7556
      3864 7549 3856 7544 3851 7530 3845 7521

$$

JRK

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 10, 3:48 AM EDTFlash Flood WatchPHICaroline, Cecil, Kent, Queen Anne's, Talbot28 hr
Jun 10, 3:50 PM EDTSpecial Weather StatementPHICaroline40 min
Jun 10, 7:45 PM EDTSpecial Weather StatementPHICaroline, Queen Anne's, Talbot60 min
Jun 10, 4:45 PM EDTSpecial Weather StatementPHISussex30 min
Jun 10, 6:45 PM EDTAreal Flood AdvisoryPHIKent3 hr

Nearby

Flash Flood Warnings in Maryland, 2018Flash Flood Warnings in Delaware, 2018Every 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.