Alert archive / Maryland / Flash Flood Warnings in 2021

Flash Flood Warning 33, NWS Philadelphia/Mount Holly

August 9, 2021Caroline County, Queen Anne's County, Maryland; Kent County, Delaware

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 9, 2021, 4:59 PM EDT for Caroline County, Queen Anne's County, Maryland; Kent County, Delaware. It was in force for 79 min. 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 9, 2021, 4:59 PM EDT (20:59 UTC)
Expired: Aug 9, 2021, 6:18 PM EDT
In force: 79 min
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

The radar

The Dover AFB radar (KDOX), 39 km from the middle of the area, began a volume at 20:59 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 9, 5:30 PM EDT	FLOOD	3 N Sandtown, DE	WATER REPORTED OVER MUD MILL ROAD AND STILL ROAD NEAR MAHANS CORNER ROAD. TIME ESTIMATED FROM RADAR.

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, 9.0 hours before the alert went out and 130 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: 927 J/kg
Mixed-layer CIN: -47 J/kg
Mixed-layer LCL: 869 m above ground
0-6 km bulk shear: 8 kt
0-1 km storm-relative helicity: 25 m²/s²
0-3 km storm-relative helicity: 18 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

900 
WGUS51 KPHI 092059
FFWPHI
DEC001-MDC011-035-100030-
/O.NEW.KPHI.FF.W.0033.210809T2059Z-210810T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Mount Holly NJ
459 PM EDT Mon Aug 9 2021

The National Weather Service in Mount Holly has issued a

* Flash Flood Warning for...
  West Central Kent County in central Delaware...
  Northeastern Caroline County in eastern Maryland...
  Eastern Queen Anne's County in northeastern Maryland...

* Until 830 PM EDT.

* At 459 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 2 and 3 inches of rain 
  have fallen. Additional rainfall amounts of 1 to 2 inches are 
  possible in the warned area. Flash flooding is ongoing or expected 
  to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  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 will experience flash flooding include...
  Goldsboro, Sandtown, Henderson, and Marydel.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3909 7589 3913 7586 3913 7577 3911 7571
      3900 7560 3891 7571

FLASH FLOOD...RADAR INDICATED

$$

Robertson

1 follow-up statement

703 
WGUS71 KPHI 092218
FFSPHI

Flash Flood Statement
National Weather Service Mount Holly NJ
618 PM EDT Mon Aug 9 2021

DEC001-MDC011-035-092228-
/O.CAN.KPHI.FF.W.0033.000000T0000Z-210810T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kent DE-Caroline MD-Queen Anne's MD-
618 PM EDT Mon Aug 9 2021

...FLASH FLOOD WARNING IS CANCELLED FOR WEST CENTRAL KENT, 
NORTHEASTERN CAROLINE, AND EASTERN QUEEN ANNE'S COUNTIES...

The heavy rain has ended and flood waters are recededing. Flooding 
is no longer expected to pose a threat. Please continue to heed 
remaining road closures.

LAT...LON 3909 7589 3913 7586 3913 7577 3911 7571
      3900 7560 3891 7571

$$

Robertson

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 9, 2:41 PM EDT	Areal Flood Advisory	PHI	Caroline, Kent, Queen Anne's	3 hr
Aug 9, 4:35 PM EDT	Severe Thunderstorm Warning	PHI	Caroline	40 min
Aug 9, 5:12 PM EDT	Severe Thunderstorm Warning	PHI	Caroline, Queen Anne's	20 min
Aug 9, 2:10 PM EDT	Special Weather Statement	PHI	Sussex	50 min
Aug 9, 3:01 PM EDT	Flash Flood Warning	PHI	Kent, Sussex	2 hr
Aug 9, 3:43 PM EDT	Excessive Heat Watch	PHI	New Castle	12 hr
Aug 9, 4:36 PM EDT	Areal Flood Advisory	PHI	New Castle	104 min

Nearby

Flash Flood Warnings in Maryland, 2021 Flash Flood Warnings in Delaware, 2021 Every flash flood warning in 2021

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.