Alert archive / Maryland / Flash Flood Warnings in 2020

Flash Flood Warning 31, NWS Philadelphia/Mount Holly

August 4, 20204 counties in Maryland

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 4, 2020, 2:10 AM EDT for 4 counties in Maryland. It was in force for 4 hr. 1 report 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, 2:10 AM EDT (06:10 UTC)
Expired: Aug 4, 2020, 6:15 AM EDT
In force: 4 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

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

The radar

The Dover AFB radar (KDOX), 66 km from the middle of the area, began a volume at 06:13 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, 6:25 AM EDT	HEAVY RAIN 2.4	3 Se Easton, MD	COCORAHS STATION MD-TB-5 EASTON 2.4 SE.

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 00:00Z, 6.2 hours before the alert went out and 104 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: 89 J/kg
Mixed-layer CIN: -54 J/kg
Mixed-layer LCL: 889 m above ground
0-6 km bulk shear: 43 kt
0-1 km storm-relative helicity: 65 m²/s²
0-3 km storm-relative helicity: 140 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

368 
WGUS51 KPHI 040610
FFWPHI
MDC011-029-035-041-041015-
/O.NEW.KPHI.FF.W.0031.200804T0610Z-200804T1015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Mount Holly NJ has issued a

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

* Until 615 AM EDT.

* At 208 AM EDT, Doppler radar and automated gauges indicated 
  showers and a few embedded thunderstorms producing heavy rain 
  across the warned area. Up to one inch of rain has already fallen 
  since midnight, and more rain is on the way. Flash flooding is 
  ongoing or expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar and automated gauges.

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


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.

Be especially cautious at night when it is harder to recognize the
dangers of flooding.

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

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 3886 7626 3879 7620 3879 7619 3897 7625
      3884 7637 3885 7638 3894 7636 3904 7631
      3900 7617 3917 7628 3934 7616 3938 7578
      3865 7571 3870 7590 3857 7604 3877 7631
      3867 7634 3868 7634 3876 7638

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

JJM

2 follow-up statements

184 
WGUS71 KPHI 040732
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
332 AM EDT Tue Aug 4 2020

MDC011-029-035-041-041015-
/O.CON.KPHI.FF.W.0031.000000T0000Z-200804T1015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Talbot MD-Queen Anne's MD-Caroline MD-Kent MD-
332 AM EDT Tue Aug 4 2020

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 615 AM EDT FOR
TALBOT...QUEEN ANNE'S...CAROLINE AND KENT COUNTIES...

At 330 AM EDT, Doppler radar and automated gauges indicated heavy
rain falling across the warned area. Up to two inches of rain have 
already fallen, and more rain is on the way. Flash flooding is 
expected in the areas of heaviest rain. 

HAZARD...Flash flooding caused by heavy rain.

SOURCE...Radar and automated gauges.

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

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.

Be especially cautious at night when it is harder to recognize the
dangers of flooding.

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

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 3886 7626 3879 7620 3879 7619 3897 7625
      3884 7637 3885 7638 3894 7636 3904 7631
      3900 7617 3917 7628 3934 7616 3938 7578
      3865 7571 3870 7590 3857 7604 3877 7631
      3867 7634 3868 7634 3876 7638

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

JJM

398 
WGUS71 KPHI 041009
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
609 AM EDT Tue Aug 4 2020

MDC011-029-035-041-041015-
/O.EXP.KPHI.FF.W.0031.000000T0000Z-200804T1015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Talbot MD-Queen Anne's MD-Caroline MD-Kent MD-
609 AM EDT Tue Aug 4 2020

...THE FLASH FLOOD WARNING FOR TALBOT...QUEEN ANNE'S...CAROLINE AND
KENT COUNTIES WILL EXPIRE AT 615 AM EDT...

The Flash Flood Warning will be allowed to expire.

Two to four inches of rain have fallen overnight across portions of 
the warned area. Although still raining, the intensity of the rain 
has diminished. This has allowed the water to drain.

Additional rain is expected this morning. More flood warnings are 
possible as Tropical Storm Isaias approaches the region and 
rainfall rates increase once again.

LAT...LON 3886 7626 3879 7620 3879 7619 3897 7625
      3884 7637 3885 7638 3894 7636 3904 7631
      3900 7617 3917 7628 3934 7616 3938 7578
      3865 7571 3870 7590 3857 7604 3877 7631
      3867 7634 3868 7634 3876 7638

$$

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, 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, 8:50 AM EDT	Flash Flood Warning	PHI	Caroline, Cecil, Kent, Queen Anne's	4 hr
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.