Alert archive / Maryland / Flash Flood Watches in 2021

Flash Flood Watch 7, NWS Philadelphia/Mount Holly

August 19, 20214 counties in Maryland; Kent County, Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this flash flood watch at Aug 19, 2021, 3:22 PM EDT for 4 counties in Maryland; Kent County, Sussex County, Delaware. It took effect at Aug 20, 2021, 2:00 AM EDT. It was in force for 12 hr.

The area

The counties it named.

The facts

Issued: Aug 19, 2021, 3:22 PM EDT (19:22 UTC)
In effect from: Aug 20, 2021, 2:00 AM EDT
Expired: Aug 20, 2021, 2:00 PM EDT
In force: 12 hr
Issued by: NWS Philadelphia/Mount Holly
Flood severity: None

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

The radar

The Dover AFB radar (KDOX), 37 km from the middle of the area, began a volume at 19:24 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, 7.4 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: 1006 J/kg
Mixed-layer CIN: -47 J/kg
Mixed-layer LCL: 881 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: 64 m²/s²
0-3 km storm-relative helicity: 71 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

184 
WGUS61 KPHI 191922
FFAPHI

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Mount Holly NJ
322 PM EDT Thu Aug 19 2021

DEZ002-003-MDZ012-015-019-020-200730-
/O.NEW.KPHI.FF.A.0007.210820T0600Z-210820T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kent-Inland Sussex-Kent MD-Queen Annes-Talbot-Caroline-
Including the cities of Georgetown, Denton, Chestertown, 
Centreville, Easton, and Dover
322 PM EDT Thu Aug 19 2021

...FLASH FLOOD WATCH IN EFFECT FROM 2 AM EDT FRIDAY THROUGH FRIDAY 
AFTERNOON...

The National Weather Service in Mount Holly has issued a

* Flash Flood Watch for portions of Delaware...and northeast 
  Maryland...including the following areas...in Delaware...Inland 
  Sussex and Kent. In northeast Maryland...Caroline, Kent MD, Queen 
  Annes, and Talbot.

* From 2 AM EDT Friday through Friday afternoon.

* An approaching upper level disturbace will cause multiple rounds 
  of showers and thunderstorms to develop tonight into Friday 
  morning.  Widespread 1 to 3 inches of rainfall will be possible 
  with localized higher totals. This could result in flash flooding.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

BAH

2 follow-up statements

678 
WGUS61 KPHI 200702
FFAPHI

Flood Watch
National Weather Service Mount Holly NJ
302 AM EDT Fri Aug 20 2021

DEZ002-003-MDZ012-015-019-020-201800-
/O.CON.KPHI.FF.A.0007.000000T0000Z-210820T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kent-Inland Sussex-Kent MD-Queen Annes-Talbot-Caroline-
Including the cities of Georgetown, Denton, Chestertown, 
Centreville, Easton, and Dover
302 AM EDT Fri Aug 20 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL 2 PM EDT THIS 
AFTERNOON...

The Flash Flood Watch continues for

* Portions of Delaware...and northeast Maryland...including the 
  following areas...in Delaware...Inland Sussex and Kent. In 
  northeast Maryland...Caroline, Kent MD, Queen Annes, and Talbot.

* Until 2 PM EDT this afternoon.

* An approaching upper level disturbace will cause multiple rounds 
  of showers and thunderstorms to continue through early this 
  afternoon.  Widespread 1 to 3 inches of rainfall will be possible
  with localized higher totals. This could result in flash flooding.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

JEO

332 
WGUS61 KPHI 201738
FFAPHI

Flood Watch
National Weather Service Mount Holly NJ
138 PM EDT Fri Aug 20 2021


DEZ002-003-MDZ012-015-019-020-201845-
/O.EXP.KPHI.FF.A.0007.000000T0000Z-210820T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kent-Inland Sussex-Kent MD-Queen Annes-Talbot-Caroline-
Including the cities of Dover, Georgetown, Chestertown, 
Centreville, Easton, and Denton
138 PM EDT Fri Aug 20 2021

...FLASH FLOOD WATCH WILL EXPIRE AT 2 PM EDT THIS AFTERNOON...

The Flash Flood Watch for portions of Delaware and northeast
Maryland will be allowed to expire at 2 PM EDT as the heaviest
rain has diminished in the area. 

$$

Nearby

Flash Flood Watches in Maryland, 2021 Flash Flood Watches in Delaware, 2021 Every flash flood watch 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.