Alert archive / Maryland / Flash Flood Warnings in 2020

Flash Flood Warning 35, NWS Philadelphia/Mount Holly

August 4, 20204 counties in Maryland

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 4, 2020, 8:50 AM EDT for 4 counties in Maryland. It was in force for 4 hr. 7 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 4, 2020, 8:50 AM EDT (12:50 UTC)
Expired: Aug 4, 2020, 12:45 PM EDT
In force: 4 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

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

The radar

The Dover AFB radar (KDOX), 81 km from the middle of the area, began a volume at 12:54 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 4, 10:45 AM EDT	HEAVY RAIN 5.02	4 W Brantwood, MD	MESONET STATION AR187 ELKTON.
Aug 4, 11:20 AM EDT	FLASH FLOOD	1 W North East, MD	FLOODING CLOSED STATE HIGHWAY 7 AT WELLS CAMP ROAD. TIME BASED ON DISPATCH REPORT.
Aug 4, 11:22 AM EDT	FLASH FLOOD	1 Sw Chesapeake City, MD	FLOODING CLOSED STATE HIGHWAY 213 AT BASIL AVENUE. TIME BASED ON DISPATCH REPORT.
Aug 4, 11:41 AM EDT	FLASH FLOOD	North East, MD	STATE HIGHWAY 272 SOUTHBOUND AT RONEY AVENUE CLOSED FROM FLOODING. TIME BASED ON DISPATCH REPORT.
Aug 4, 12:30 PM EDT	HEAVY RAIN 4.54	1 Se Earleville, MD	MESONET STATION EW8787 KENNEDYVILLE.
Aug 4, 12:32 PM EDT	HEAVY RAIN 4.87	Centreville, MD	MESONET STATION EW3797 CENTREVILLE.
Aug 4, 12:50 PM EDT	HEAVY RAIN 4.83	2 Sw Starkey Corner, MD	MESONET STATION 9140D 2 WSW STARKEY CORNER.

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, 0.8 hours before the alert went out and 168 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: 472 J/kg
Mixed-layer CIN: -6 J/kg
Mixed-layer LCL: 648 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: 254 m²/s²
0-3 km storm-relative helicity: 273 m²/s²
Significant tornado parameter: 0.8
Supercell composite: 2.9

Open this sounding in Storm Lab

The text

As transmitted.

833 
WGUS51 KPHI 041250
FFWPHI
MDC011-015-029-035-041645-
/O.NEW.KPHI.FF.W.0035.200804T1250Z-200804T1645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
850 AM EDT Tue Aug 4 2020

The National Weather Service in Mount Holly NJ has issued a

* Flash Flood Warning for...
  Queen Anne's County in northeastern Maryland...
  Northeastern Caroline County in eastern Maryland...
  Kent County in northeastern Maryland...
  Southeastern Cecil County in northeastern Maryland...

* Until 1245 PM EDT.

* At 848 AM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Up to two inches of rain have 
  fallen over the last hour. This is on top of the heavy rain that 
  fell overnight. In addition, higher tides will affect runoff. As a 
  result, 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...
  Elkton, Centerville, Chestertown, Centreville, North East, Rock
  Hall, Charlestown, Church Hill, Cecilton, Millington, Sudlersville,
  Betterton, Goldsboro, Warwick, Old Town, Bohemias Mills, Newtown,
  Brantwood, Morgnec and Crumpton.

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.

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 3925 7623 3929 7617 3932 7618 3934 7616
      3933 7614 3937 7611 3937 7606 3943 7600
      3946 7601 3952 7598 3955 7603 3955 7608
      3961 7612 3961 7579 3900 7574 3903 7624
      3909 7623 3917 7628

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1-3 INCHES IN 1 HOUR

$$

Kruzdlo

1 follow-up statement

748 
WGUS71 KPHI 041642
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
1242 PM EDT Tue Aug 4 2020

MDC011-015-029-035-041652-
/O.EXP.KPHI.FF.W.0035.000000T0000Z-200804T1645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Queen Anne's MD-Caroline MD-Kent MD-Cecil MD-
1242 PM EDT Tue Aug 4 2020

...THE FLASH FLOOD WARNING FOR QUEEN ANNE'S...NORTHEASTERN
CAROLINE...KENT AND SOUTHEASTERN CECIL COUNTIES WILL EXPIRE AT 1245
PM EDT...

The heavy rain has ended. Water is receding. Please continue to heed 
any remaining road closures.

LAT...LON 3925 7623 3929 7617 3932 7618 3934 7616
      3933 7614 3937 7611 3937 7606 3943 7600
      3946 7601 3952 7598 3955 7603 3955 7608
      3961 7612 3961 7579 3900 7574 3903 7624
      3909 7623 3917 7628

$$

Kruzdlo

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 4, 1:33 AM EDT	Areal Flood Advisory	PHI	Caroline, Kent, Queen Anne's, Talbot	4 hr
Aug 4, 2:10 AM EDT	Flash Flood Warning	PHI	Caroline, Kent, Queen Anne's, Talbot	4 hr
Aug 4, 5:17 AM EDT	Areal Flood Advisory	PHI	Cecil, Kent	4 hr
Aug 4, 6:55 AM EDT	Tornado Warning	PHI	Kent, Queen Anne's	35 min
Aug 4, 7:22 AM EDT	Tornado Warning	PHI	Kent, Queen Anne's	23 min
Aug 4, 7:50 AM EDT	Flash Flood Warning	PHI	Caroline, Kent, Queen Anne's, Talbot	4 hr
Aug 4, 8:13 AM EDT	Tornado Warning	PHI	Kent, Queen Anne's, Talbot	26 min
Aug 4, 8:27 AM EDT	Tornado Warning	PHI	Caroline, Cecil, Kent, Queen Anne's	33 min
Aug 4, 8:56 AM EDT	Tornado Warning	PHI	Cecil	34 min
Aug 4, 9:23 AM EDT	Flash Flood Warning	PHI	Cecil	4 hr
Aug 4, 9:23 AM EDT	Tornado Warning Tornado observed	PHI	Cecil	22 min
Aug 4, 1:59 PM EDT	Areal Flood Warning	PHI	Cecil	9 hr

Nearby

Flash Flood Warnings in Maryland, 2020 Every 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.