Alert archive / Maryland / Flash Flood Warnings in 2018

Flash Flood Warning 68, NWS Philadelphia/Mount Holly

August 11, 2018Kent County, Delaware; Caroline County, Queen Anne's County, Talbot County, Maryland

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 11, 2018, 6:45 PM EDT for Kent County, Delaware; Caroline County, Queen Anne's County, Talbot County, Maryland. It was in force for 5 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: Aug 11, 2018, 6:45 PM EDT (22:45 UTC)
Expired: Aug 11, 2018, 11:28 PM EDT
In force: 5 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Kent County, DE, Caroline County, MD, Queen Anne's County, MD, Talbot County, MD

The radar

The Dover AFB radar (KDOX), 47 km from the middle of the area, began a volume at 22:47 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
Aug 11, 8:37 PM EDT	FLOOD	Denton, MD	FLOODING ON STATE HIGHWAY 404 ON THE SOUTH SIDE OF DENTON.
Aug 11, 9:52 PM EDT	FLOOD	Fausley, MD	VAN TRAPPED IN HIGH WATER ON COMMERCE DRIVE. 7 PEOPLE RESCUED.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Wallops Is Stn, VA (KWAL), launched 12:00Z, 10.8 hours before the alert went out and 119 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: 1571 J/kg
Mixed-layer CIN: -26 J/kg
Mixed-layer LCL: 1008 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 40 m²/s²
0-3 km storm-relative helicity: 50 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.7

Open this sounding in Storm Lab

The text

As transmitted.

492 
WGUS51 KPHI 112245
FFWPHI
DEC001-MDC011-035-041-120145-
/O.NEW.KPHI.FF.W.0068.180811T2245Z-180812T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
645 PM EDT SAT AUG 11 2018

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Kent County in central Delaware...
  Talbot County in eastern Maryland...
  Queen Anne's County in northeastern Maryland...
  Caroline County in eastern Maryland...

* Until 945 PM EDT.

* At 642 PM EDT, Doppler radar indicated a line of strong 
  thunderstorms producing heavy rain across the northern portions of 
  the Delmarva. This line is moving southeast, and will move into 
  the warned area by 700 PM. Rainfall rates of 1 to 2 inches per 
  hour will cause flash flooding where the heaviest rainbands occur.
  
* Some locations that could experience flooding include...  Dover, 
  Easton, Centerville, Talbot, Smyrna, Milford, Denton, 
  Centreville, Harrington, Camden, Clayton, Lewes, Federalsburg, 
  Greensboro, Oakland, Ridgely, Cheswold, Trappe, St. Michaels and 
  Church Hill.

LAT...LON 3904 7631 3898 7628 3899 7625 3900 7617
      3924 7601 3932 7533 3905 7537 3880 7506
      3879 7525 3896 7539 3883 7572 3868 7571
      3861 7608 3877 7631 3876 7631 3867 7634
      3868 7634 3897 7625 3885 7638 3886 7638

$$

JJM

4 follow-up statements

317 
WGUS71 KPHI 120031
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
831 PM EDT SAT AUG 11 2018

DEC001-MDC011-035-041-120145-
/O.CON.KPHI.FF.W.0068.000000T0000Z-180812T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kent DE-Talbot MD-Queen Anne's MD-Caroline MD-
831 PM EDT SAT AUG 11 2018

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 945 PM EDT FOR
KENT...TALBOT...QUEEN ANNE'S AND CAROLINE COUNTIES...

At 826 PM EDT, Doppler radar indicated a line of thunderstorms 
producing very heavy rain extending from Tilghman Island east-
northeast to Easton...then further east to Harrington DE. Rainfall 
rates between one and two inches per hour are falling along this 
line. Some training of these storms is taking place and this will 
increase the total precipitation from this event.  

Some locations that could experience flooding include...
Dover, Easton, Centerville, Talbot, Smyrna, Milford, Denton,
Centreville, Harrington, Camden, Clayton, Lewes, Federalsburg,
Greensboro, Oakland, Ridgely, Cheswold, Trappe, St. Michaels and
Church Hill.

LAT...LON 3904 7631 3898 7628 3899 7625 3900 7617
      3924 7601 3932 7533 3905 7537 3880 7506
      3879 7525 3896 7539 3883 7572 3868 7571
      3861 7608 3877 7631 3876 7631 3867 7634
      3868 7634 3897 7625 3885 7638 3886 7638

$$

jjm

641 
WGUS71 KPHI 120120
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
920 PM EDT SAT AUG 11 2018

DEC001-MDC011-035-041-120145-
/O.CON.KPHI.FF.W.0068.000000T0000Z-180812T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kent DE-Talbot MD-Queen Anne's MD-Caroline MD-
920 PM EDT SAT AUG 11 2018

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 945 PM EDT FOR
SOUTHERN KENT...TALBOT...SOUTHWESTERN QUEEN ANNE'S AND CAROLINE
COUNTIES...

At 919 PM EDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area.  Flash flooding can be expected in 
the heaviest rain bands..

Some locations that could experience flooding include...
Easton, Talbot, Milford, Denton, Harrington, Lewes, Federalsburg,
Greensboro, Oakland, Ridgely, Trappe, St. Michaels, Preston, Queen
Anne, Smithville, Grasonville, Starr, Copperville, Cape Henlopen
State Park and Jumptown.

LAT...LON 3904 7631 3897 7622 3905 7537 3880 7506
      3879 7525 3896 7539 3883 7572 3868 7571
      3861 7608 3876 7622 3869 7634 3886 7626
      3886 7625 3879 7620 3879 7619 3897 7625
      3893 7631 3896 7631 3887 7636 3889 7637

$$

jjm

776 
WGUS51 KPHI 120124
FFWPHI
DEC001-MDC011-035-041-120445-
/O.EXT.KPHI.FF.W.0068.000000T0000Z-180812T0445Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
924 PM EDT SAT AUG 11 2018

The National Weather Service in Mount Holly NJ has extended the

* Flash Flood Warning for...
  Southern Kent County in central Delaware...
  Talbot County in eastern Maryland...
  Southwestern Queen Anne's County in northeastern Maryland...
  Caroline County in eastern Maryland...

* Until 1245 AM EDT.

* At 921 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain had moved into southern Queen Anne's County, and 
  central Talbot and Caroline Counties. With hourly rainfall rates 
  in the one to two inch range, flash flooding is still likely under 
  the heavier rain bands.

* Some locations that could experience flooding include...
  Easton, Talbot, Milford, Denton, Harrington, Lewes, Federalsburg,
  Greensboro, Oakland, Ridgely, Trappe, St. Michaels, Preston, Queen
  Anne, Smithville, Grasonville, Starr, Copperville, Cape Henlopen
  State Park and Jumptown.

LAT...LON 3904 7631 3897 7622 3905 7537 3880 7506
      3879 7525 3896 7539 3883 7572 3868 7571
      3861 7608 3876 7622 3869 7634 3886 7626
      3886 7625 3879 7620 3879 7619 3897 7625
      3893 7631 3896 7631 3887 7636 3889 7637

$$

jjm

827 
WGUS71 KPHI 120328
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
1128 PM EDT SAT AUG 11 2018

DEC001-MDC011-035-041-120336-
/O.CAN.KPHI.FF.W.0068.000000T0000Z-180812T0445Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kent DE-Talbot MD-Queen Anne's MD-Caroline MD-
1128 PM EDT SAT AUG 11 2018

...THE FLASH FLOOD WARNING FOR SOUTHERN KENT...TALBOT...SOUTHWESTERN
QUEEN ANNE'S AND CAROLINE COUNTIES IS CANCELLED...

While rain continues in the area, the threat of heavy flooding rain 
has ended.

LAT...LON 3904 7631 3897 7622 3905 7537 3880 7506
      3879 7525 3896 7539 3883 7572 3868 7571
      3861 7608 3876 7622 3869 7634 3886 7626
      3886 7625 3879 7620 3879 7619 3897 7625
      3893 7631 3896 7631 3887 7636 3889 7637

$$

Iovino

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 11, 3:24 AM EDT	Flash Flood Watch	PHI	Kent, New Castle	20 hr
Aug 11, 4:26 AM EDT	Coastal Flood Advisory	PHI	Kent, New Castle, Sussex	24 hr
Aug 11, 1:23 PM EDT	Severe Thunderstorm Warning	PHI	Sussex	37 min
Aug 11, 4:19 PM EDT	Areal Flood Advisory	PHI	New Castle	3 hr
Aug 11, 4:19 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	29 min
Aug 11, 5:20 PM EDT	Areal Flood Advisory	PHI	Kent, New Castle	4 hr
Aug 11, 6:08 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	52 min
Aug 11, 6:12 PM EDT	Flash Flood Warning	PHI	Kent, New Castle	3 hr
Aug 11, 6:55 PM EDT	Severe Thunderstorm Warning	PHI	Kent	50 min
Aug 11, 7:42 PM EDT	Special Weather Statement	PHI	Kent	48 min
Aug 11, 5:24 PM EDT	Special Weather Statement	PHI	Cecil	36 min

Nearby

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