Alert archive / Maryland / Flash Flood Warnings in 2011

Flash Flood Warning 49, NWS Philadelphia/Mount Holly

September 6, 20115 counties in Maryland; Kent County, Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this flash flood warning at Sep 6, 2011, 10:21 PM EDT for 5 counties in Maryland; Kent County, Sussex County, Delaware. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Sep 6, 2011, 10:21 PM EDT (02:21 UTC)
Expired: Sep 7, 2011, 1:15 AM EDT
In force: 3 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

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

The radar

The Dover AFB radar (KDOX), 53 km from the middle of the area, began a volume at 02:20 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.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 00:00Z, 2.4 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 458 m above ground
0-6 km bulk shear: 53 kt
0-1 km storm-relative helicity: 380 m²/s²
0-3 km storm-relative helicity: 581 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

473 
WGUS51 KPHI 070221
FFWPHI
DEC001-005-MDC011-015-029-035-041-070815-
/O.NEW.KPHI.FF.W.0049.110907T0221Z-110907T0815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1021 PM EDT TUE SEP 6 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  KENT COUNTY...
  CAROLINE COUNTY...
  CECIL COUNTY...
  QUEEN ANNE'S COUNTY...
  TALBOT COUNTY...
  SUSSEX COUNTY...

* UNTIL 415 AM EDT...

* AT 1016 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED  
  VERY HEAVY RAIN OVER THE EASTERN SHORE OF THE CHESAPEAKE BAY. THIS 
  RAIN WAS MOVING NORTH-NORTHEAST...AND HAS THE POTENTIAL TO DROP    
  ONE TO TWO INCHES OF RAIN OVER THE WARNED AREA INTO THE EARLY      
  OVERNIGHT HOURS. GIVEN THE ALREADY WET GROUND FROM EARLIER         
  RAIN...FLOODING OF LOW LYING AREAS CAN BE EXPECTED WHEREVER THE    
  HEAVIEST RAIN HAPPENS TO FALL.
 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLASH FLOODING IS OBSERVED ACT QUICKLY. MOVE
UP TO HIGHER GROUND TO ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS
SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

&&

LAT...LON 3846 7570 3869 7583 3856 7604 3867 7636
      3887 7625 3882 7621 3883 7620 3894 7624
      3884 7638 3885 7639 3905 7631 3900 7618
      3918 7628 3951 7599 3973 7623 3971 7579
      3930 7576 3932 7558 3845 7513

$$

FORECASTER:JJM

1 follow-up statement

921 
WGUS71 KPHI 070515
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
115 AM EDT WED SEP 7 2011

DEC001-005-MDC011-015-029-035-041-070523-
/O.CAN.KPHI.FF.W.0049.000000T0000Z-110907T0815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
KENT DE-CAROLINE MD-CECIL MD-KENT MD-QUEEN ANNE'S MD-TALBOT MD-
SUSSEX DE-
115 AM EDT WED SEP 7 2011

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR SUSSEX...TALBOT...
QUEEN ANNE'S...KENT...CECIL...CAROLINE AND KENT COUNTIES...

AT 115 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
THAT MOST OF THE HEAVY RAIN HAS MOVED OUT OF THE AREA. THE WATERS 
FROM EARLIER RAIN ARE RECEDING AND SO FLASH FLOODING NO 
LONGER POSES A THREAT TO LIFE OR PROPERTY. THEREFORE...THE FLASH 
FLOOD WARNING HAS BEEN CANCELLED.

LAT...LON 3846 7570 3869 7583 3856 7604 3867 7636
      3887 7625 3882 7621 3883 7620 3894 7624
      3884 7638 3885 7639 3905 7631 3900 7618
      3918 7628 3951 7599 3973 7623 3971 7579
      3930 7576 3932 7558 3845 7513

$$

JJM

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 7, 11:48 AM EDT	Coastal Flood Advisory	PHI	Caroline, Cecil, Kent, Queen Anne's, Talbot	18 hr
Sep 7, 1:34 PM EDT	Special Weather Statement	PHI	Cecil	56 min
Sep 7, 4:40 PM EDT	River Flood Warning	PHI	Cecil, Harford	4 days
Sep 7, 6:34 PM EDT	Special Weather Statement	PHI	Cecil, Kent, Queen Anne's	56 min
Sep 7, 7:52 PM EDT	Special Weather Statement	PHI	Harford	53 min
Sep 7, 6:12 AM EDT	Rip Current Statement	PHI	Sussex	65 hr
Sep 7, 7:32 AM EDT	River Flood Warning	PHI	New Castle	3 hr

Nearby

Flash Flood Warnings in Maryland, 2011 Flash Flood Warnings in Delaware, 2011 Every flash flood warning in 2011

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.