Alert archive / Maryland / Areal Flood Advisories in 2021

Areal Flood Advisory 97, NWS Philadelphia/Mount Holly

July 29, 2021Caroline County, Talbot County, Maryland

NWS Philadelphia/Mount Holly issued this areal flood advisory at Jul 29, 2021, 12:12 PM EDT for Caroline County, Talbot County, Maryland. It was in force for 84 min.

The area

The outline as issued.

The facts

Issued
Jul 29, 2021, 12:12 PM EDT (16:12 UTC)
Expired
Jul 29, 2021, 1:36 PM EDT
In force
84 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Caroline County, MD, Talbot County, MD

The radar

The Dover AFB radar (KDOX), 56 km from the middle of the area, began a volume at 16:13 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.

The nearest sounding before it

Wallops Is Stn, VA (KWAL), launched 12:00Z, 4.2 hours before the alert went out and 99 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 12:00Z on 2021-07-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 581 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 12:00Z on 2021-07-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 44 square meters per square second.19395878Sfc1 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
581 J/kg
Mixed-layer CIN
-61 J/kg
Mixed-layer LCL
863 m above ground
0-6 km bulk shear
24 kt
0-1 km storm-relative helicity
44 m²/s²
0-3 km storm-relative helicity
112 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.6

Open this sounding in Storm Lab

The text

As transmitted.

445 
WGUS81 KPHI 291612
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
1212 PM EDT Thu Jul 29 2021

MDC011-041-291915-
/O.NEW.KPHI.FA.Y.0097.210729T1612Z-210729T1915Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Caroline MD-Talbot MD-
1212 PM EDT Thu Jul 29 2021

The National Weather Service in Mount Holly has issued a

* Flood Advisory for...
  Southwestern Caroline County in eastern Maryland...
  Southeastern Talbot County in eastern Maryland...

* Until 315 PM EDT.

* At 1212 PM EDT, Doppler radar indicated heavy rain due to 
  thunderstorms. Between 1 and 2 inches of rain have fallen for some 
  areas. Minor flooding is ongoing or expected to begin shortly in 
  the advisory area.

* Some locations that will experience flooding include...
  Trappe, Preston, Oxford, Hambleton, Windyhill, and Choptank.

LAT...LON 3871 7615 3872 7607 3873 7599 3871 7590
      3869 7590 3868 7593 3867 7595 3865 7596
      3863 7598 3860 7599 3861 7608 3863 7609
      3862 7611 3863 7612 3864 7613 3864 7615
      3866 7615 3867 7617

$$

Robertson
1 follow-up statement
886 
WGUS81 KPHI 291736
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
136 PM EDT Thu Jul 29 2021

MDC011-041-291746-
/O.CAN.KPHI.FA.Y.0097.000000T0000Z-210729T1915Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Caroline MD-Talbot MD-
136 PM EDT Thu Jul 29 2021

...FLOOD ADVISORY IS CANCELLED FOR SOUTHWESTERN CAROLINE AND 
SOUTHEASTERN TALBOT COUNTIES...

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

LAT...LON 3871 7615 3872 7607 3873 7599 3871 7590
      3869 7590 3868 7593 3867 7595 3865 7596
      3863 7598 3860 7599 3861 7608 3863 7609
      3862 7611 3863 7612 3864 7613 3864 7615
      3866 7615 3867 7617

$$

Robertson

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 29, 11:35 AM EDTSpecial Weather StatementPHITalbot55 min
Jul 29, 11:48 AM EDTSevere Thunderstorm WarningPHICaroline, Talbot45 min
Jul 29, 5:59 PM EDTSpecial Weather StatementPHIQueen Anne's31 min

Nearby

Areal 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.