Alert archive / Delaware / Areal Flood Advisories in 2021

Areal Flood Advisory 101, NWS Philadelphia/Mount Holly

August 7, 2021Caroline County, Maryland; Kent County, Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this areal flood advisory at Aug 7, 2021, 9:49 PM EDT for Caroline County, Maryland; Kent County, Sussex County, Delaware. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued
Aug 7, 2021, 9:49 PM EDT (01:49 UTC)
Expired
Aug 8, 2021, 2:20 AM EDT
In force
5 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Kent County, DE, Sussex County, DE, Caroline County, MD

The radar

The Dover AFB radar (KDOX), 14 km from the middle of the area, began a volume at 01:52 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

Wallops Is Stn, VA (KWAL), launched 00:00Z, 1.8 hours before the alert went out and 86 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, Wallops Is Stn, VA at 00:00Z on 2021-08-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 86 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, Wallops Is Stn, VA at 00:00Z on 2021-08-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 173 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
86 J/kg
Mixed-layer CIN
-4 J/kg
Mixed-layer LCL
512 m above ground
0-6 km bulk shear
50 kt
0-1 km storm-relative helicity
173 m²/s²
0-3 km storm-relative helicity
241 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

The text

As transmitted.

835 
WGUS81 KPHI 080149
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
949 PM EDT Sat Aug 7 2021

DEC001-005-MDC011-080645-
/O.NEW.KPHI.FA.Y.0101.210808T0149Z-210808T0645Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kent DE-Sussex DE-Caroline MD-
949 PM EDT Sat Aug 7 2021

The National Weather Service in Mount Holly has issued a

* Urban and Small Stream Flood Advisory for...
  South Central Kent County in central Delaware...
  Sussex County in southern Delaware...
  Eastern Caroline County in eastern Maryland...

* Until 245 AM EDT.

* At 949 PM EDT, Doppler radar indicated heavy rain. This will cause 
  urban and small stream flooding. Between 1 and 2 inches of rain 
  have already fallen with reports of street flooding near Dewy 
  Beach. Another 1 to 2 inches of rain will be possible in spots.

* Some locations that will experience flooding include...
  Georgetown, Milford, Seaford, Millsboro, Laurel, Lewes, Milton, 
  Bridgeville, Dagsboro, Millville, Ellendale, and Henlopen Acres.

LAT...LON 3865 7572 3882 7573 3895 7533 3888 7516
      3881 7506 3846 7504 3846 7569 3864 7571

$$

Fitzsimmons
1 follow-up statement
441 
WGUS81 KPHI 080620
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
220 AM EDT Sun Aug 8 2021

DEC001-005-MDC011-080630-
/O.CAN.KPHI.FA.Y.0101.000000T0000Z-210808T0645Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kent DE-Sussex DE-Caroline MD-
220 AM EDT Sun Aug 8 2021

...THE URBAN AND SMALL STREAM FLOOD ADVISORY IS CANCELLED FOR SOUTH 
CENTRAL KENT, SUSSEX, AND EASTERN CAROLINE COUNTIES...

The heavy rain has ended. Urban and small stream flooding is no 
longer expected to pose a threat. Please continue to heed remaining 
road closures.

LAT...LON 3865 7572 3882 7573 3895 7533 3888 7516
      3881 7506 3846 7504 3846 7569 3864 7571

$$

Deal

Nearby

Areal Flood Advisories in Delaware, 2021Areal Flood Advisories in Maryland, 2021Every areal flood advisory 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.