Alert archive / Maryland / Flash Flood Warnings in 2020

Flash Flood Warning 62, NWS Philadelphia/Mount Holly

August 13, 2020Kent County, Queen Anne's County, Maryland

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 13, 2020, 10:14 AM EDT for Kent County, Queen Anne's County, Maryland. It was in force for 4 hr. 12 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 13, 2020, 10:14 AM EDT (14:14 UTC)
Expired
Aug 13, 2020, 2:15 PM EDT
In force
4 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties Kent County, MD, Queen Anne's County, MD

The radar

The Dover AFB radar (KDOX), 73 km from the middle of the area, began a volume at 14:18 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

TimeReportWhereRemark
Aug 13, 10:53 AM EDTFLASH FLOODChester, MDFLASH FLOODING HAS CLOSED PORTIONS OF STATE HIGHWAY 18 NEAR UNION WESLEY CIRCLE. TIME BASED ON DISPATCH REPORT.
Aug 13, 10:53 AM EDTFLASH FLOODChester, MDFLASH FLOODING HAS CLOSED PORTIONS OF STATE HIGHWAY 18 NEAR UNION WESLEY CIRCLE. TIME BASED ON DISPATCH REPORT.
Aug 13, 11:00 AM EDTFLASH FLOOD1 S Stevensville, MDFLOODING HAS CLOSED MAIN STREET EAST OF DUKE STREET IN STEVENSVILLE. DISABLED VEHICLES ALSO REPORTED ON THIS ROAD. TIME BASED ON DISPATCH REPORTS.
Aug 13, 11:00 AM EDTFLASH FLOOD1 S Stevensville, MDFLOODING HAS CLOSED MAIN STREET EAST OF DUKE STREET IN STEVENSVILLE. DISABLED VEHICLES ALSO REPORTED ON THIS ROAD. TIME BASED ON DISPATCH REPORTS.
Aug 13, 11:47 AM EDTFLASH FLOOD1 Nne Chester, MDFLASH FLOODING NEAR THE INTERSECTION OF PINEY CREEK ROAD AND STATE HIGHWAY 18 WITH ROAD CLOSURES IN PLACE. TIME BASED ON DISPATCH REPORT.
Aug 13, 11:47 AM EDTFLASH FLOOD1 Nne Chester, MDFLASH FLOODING NEAR THE INTERSECTION OF PINEY CREEK ROAD AND STATE HIGHWAY 18 WITH ROAD CLOSURES IN PLACE. TIME BASED ON DISPATCH REPORT.
Aug 13, 12:55 PM EDTHEAVY RAIN 2.93Bay Bridge Airport (Kw2, MD
Aug 13, 12:55 PM EDTHEAVY RAIN 2.93Bay Bridge Airport (Kw2, MD
Aug 13, 12:59 PM EDTFLASH FLOOD1 E Grasonville, MDSTATE HIGHWAY 18 NEAR GRASONVILLE CEMETERY ROAD CLOSED FROM FLOODING. TIME BASED ON DISPATCH REPORT.
Aug 13, 12:59 PM EDTFLASH FLOOD1 E Grasonville, MDSTATE HIGHWAY 18 NEAR GRASONVILLE CEMETERY ROAD CLOSED FROM FLOODING. TIME BASED ON DISPATCH REPORT.
Aug 13, 1:04 PM EDTHEAVY RAIN 3.612 Ese Grasonville, MD
Aug 13, 1:04 PM EDTHEAVY RAIN 3.612 Ese Grasonville, MD

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, 2.2 hours before the alert went out and 98 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, Washington/Dulle, VA at 12:00Z on 2020-08-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 646 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, Washington/Dulle, VA at 12:00Z on 2020-08-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -37 square meters per square second.193958Sfc1 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
646 J/kg
Mixed-layer CIN
-243 J/kg
Mixed-layer LCL
481 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
-37 m²/s²
0-3 km storm-relative helicity
-5 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

856 
WGUS51 KPHI 131414
FFWPHI
MDC029-035-131815-
/O.NEW.KPHI.FF.W.0062.200813T1414Z-200813T1815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
1014 AM EDT Thu Aug 13 2020

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Southwestern Queen Anne's County in northeastern Maryland...
  Southwestern Kent County in northeastern Maryland...

* Until 215 PM EDT.

* At 1013 AM EDT, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area. Up to two inches of rain have
  already fallen. Flash flooding is ongoing or expected to begin
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar indicated.

  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 could experience flooding include...
  Chester, Stevensville, Overton, Grasonville, Queenstown and
  Stevensville South.

Additional rainfall amounts of 1 to 2 inches are possible in the 
warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

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

&&

LAT...LON 3894 7636 3904 7631 3903 7631 3898 7628
      3897 7622 3900 7617 3903 7624 3906 7623
      3905 7613 3889 7615 3890 7620 3896 7625
      3892 7625 3894 7627 3893 7630 3896 7631
      3891 7634 3887 7634 3885 7638

FLASH FLOOD...RADAR INDICATED

$$

JEO
3 follow-up statements
996 
WGUS71 KPHI 131517
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
1117 AM EDT Thu Aug 13 2020

MDC029-035-131815-
/O.CON.KPHI.FF.W.0062.000000T0000Z-200813T1815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Queen Anne's MD-Kent MD-
1117 AM EDT Thu Aug 13 2020

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 215 PM EDT FOR
SOUTHWESTERN QUEEN ANNE'S AND SOUTHWESTERN KENT COUNTIES...

At 1115 AM EDT, law enforcement reported thunderstorms producing 
heavy rain over Kent Island. Portions of Maryland State Highway 18 
have been closed in the area due to flash flooding. Additional heavy 
rainfall is now occurring over eastern portions of the warning area 
near Grasonville, and could lead to additional flash flooding. Up to 
four inches of rain have fallen on Kent Island. Flash flooding is 
already occurring and is expected to continue.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Law enforcement.

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 could experience flooding include...
Chester, Stevensville, Overton, Grasonville, Queenstown and
Stevensville South.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

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

&&

LAT...LON 3894 7636 3904 7631 3903 7631 3898 7628
      3897 7622 3900 7617 3903 7624 3906 7623
      3905 7613 3889 7615 3890 7620 3896 7625
      3892 7625 3894 7627 3893 7630 3896 7631
      3891 7634 3887 7634 3885 7638

FLASH FLOOD...OBSERVED

$$

JEO
142 
WGUS71 KPHI 131638
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
1238 PM EDT Thu Aug 13 2020

MDC029-035-131815-
/O.CON.KPHI.FF.W.0062.000000T0000Z-200813T1815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Queen Anne's MD-Kent MD-
1238 PM EDT Thu Aug 13 2020

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 215 PM EDT FOR
SOUTHWESTERN QUEEN ANNE'S AND SOUTHWESTERN KENT COUNTIES...

At 1237 PM EDT, law enforcement continued to report thunderstorms 
producing heavy rain and flash flooding on Kent Island. Portions of 
Maryland State Highway 18 remain closed due to flooding. Up to 4 
inches of rain have fallen. Heavy rain is tapering off, but residual 
flooding will continue. 

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Law enforcement.

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 could experience flooding include...
Chester, Stevensville, Overton, Grasonville, Queenstown and
Stevensville South.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

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

&&

LAT...LON 3894 7636 3904 7631 3903 7631 3898 7628
      3897 7622 3900 7617 3903 7624 3906 7623
      3905 7613 3889 7615 3890 7620 3896 7625
      3892 7625 3894 7627 3893 7630 3896 7631
      3891 7634 3887 7634 3885 7638

FLASH FLOOD...OBSERVED

$$

JEO
996 
WGUS71 KPHI 131808
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
208 PM EDT Thu Aug 13 2020

MDC029-035-131815-
/O.EXP.KPHI.FF.W.0062.000000T0000Z-200813T1815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Queen Anne's MD-Kent MD-
208 PM EDT Thu Aug 13 2020

...THE FLASH FLOOD WARNING FOR SOUTHWESTERN QUEEN ANNE'S AND
SOUTHWESTERN KENT COUNTIES WILL EXPIRE AT 215 PM EDT...

The heavy rain has ended, and flood waters are receding. Flash 
flooding is no longer expected to pose a threat. The warning will be 
allowed to expire. However, please continue to heed any remaining 
road closures.

LAT...LON 3894 7636 3904 7631 3903 7631 3898 7628
      3897 7622 3900 7617 3903 7624 3906 7623
      3905 7613 3889 7615 3890 7620 3896 7625
      3892 7625 3894 7627 3893 7630 3896 7631
      3891 7634 3887 7634 3885 7638

$$

JEO

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 13, 3:02 AM EDTFlash Flood WatchPHICaroline, Cecil, Kent, Queen Anne's, Talbot17 hr
Aug 13, 11:28 AM EDTAreal Flood AdvisoryPHICaroline, Kent, Queen Anne's, Talbot4 hr
Aug 13, 11:46 AM EDTAreal Flood AdvisoryPHICecil, Kent3 hr
Aug 13, 12:02 PM EDTFlash Flood WarningPHIKent, Queen Anne's2 hr

Nearby

Flash Flood Warnings in Maryland, 2020Every flash flood warning in 2020

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.