Alert archive / Maryland / Areal Flood Advisories in 2021

Areal Flood Advisory 95, NWS Philadelphia/Mount Holly

July 17, 2021Caroline County, Maryland; Kent County, Delaware

NWS Philadelphia/Mount Holly issued this areal flood advisory at Jul 17, 2021, 10:54 PM EDT for Caroline County, Maryland; Kent County, Delaware. It was in force for 48 min.

The area

The outline as issued.

The facts

Issued
Jul 17, 2021, 10:54 PM EDT (02:54 UTC)
Expired
Jul 17, 2021, 11:42 PM EDT
In force
48 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Kent County, DE, Caroline County, MD

The radar

The Dover AFB radar (KDOX), 26 km from the middle of the area, began a volume at 02:56 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, 2.9 hours before the alert went out and 122 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 2021-07-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1997 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 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 2021-07-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 59 square meters per square second.1939Sfc1 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
1997 J/kg
Mixed-layer CIN
-29 J/kg
Mixed-layer LCL
1118 m above ground
0-6 km bulk shear
18 kt
0-1 km storm-relative helicity
59 m²/s²
0-3 km storm-relative helicity
74 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

391 
WGUS81 KPHI 180254
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
1054 PM EDT Sat Jul 17 2021

DEC001-MDC011-180600-
/O.NEW.KPHI.FA.Y.0095.210718T0254Z-210718T0600Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kent DE-Caroline MD-
1054 PM EDT Sat Jul 17 2021

The National Weather Service in Mount Holly has issued a

* Flood Advisory for...
  Kent County in central Delaware...
  Central Caroline County in eastern Maryland...

* Until 200 AM EDT.

* At 1054 PM EDT, Doppler radar indicated heavy rain due to 
  thunderstorms. Minor flooding is ongoing or expected to begin 
  shortly in the advisory area. Between 1 and 1.5 inches of rain 
  have already fallen in spots. An additional inch is possible.

* Some locations that may experience flooding include...
  Dover, Smyrna, Milford, Denton, Harrington, Camden, Greensboro, 
  Oakland, Ridgely, Cheswold, Bowers, and Goldsboro.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3921 7575 3935 7546 3926 7539 3909 7538
      3900 7529 3895 7529 3893 7531 3895 7532
      3896 7538 3893 7541 3890 7549 3884 7556
      3882 7590 3888 7595 3888 7594 3894 7595
      3897 7594 3907 7585 3911 7584 3914 7575

$$

Iovino
1 follow-up statement
866 
WGUS81 KPHI 180342 RRA
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
1142 PM EDT Sat Jul 17 2021

DEC001-MDC011-180352-
/O.CAN.KPHI.FA.Y.0095.000000T0000Z-210718T0600Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kent DE-Caroline MD-
1142 PM EDT Sat Jul 17 2021

...FLOOD ADVISORY IS CANCELLED FOR KENT AND CENTRAL CAROLINE 
COUNTIES...

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

LAT...LON 3921 7575 3935 7546 3926 7539 3909 7538
      3900 7529 3895 7529 3893 7531 3895 7532
      3896 7538 3893 7541 3890 7549 3884 7556
      3882 7590 3888 7595 3888 7594 3894 7595
      3897 7594 3907 7585 3911 7584 3914 7575

$$

Iovino

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 17, 10:36 PM EDTSpecial Weather StatementPHICaroline24 min
Jul 17, 8:40 PM EDTSpecial Weather StatementPHIKent35 min
Jul 17, 9:25 PM EDTAreal Flood AdvisoryPHINew Castle2 hr
Jul 17, 9:27 PM EDTSevere Thunderstorm WarningPHINew Castle48 min
Jul 17, 9:36 PM EDTFlash Flood WarningPHINew Castle2 hr
Jul 17, 10:55 PM EDTSevere Thunderstorm WarningPHIKent50 min

Nearby

Areal Flood Advisories in Maryland, 2021Areal Flood Advisories in Delaware, 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.