Alert archive / Delaware / Flash Flood Warnings in 2015

Flash Flood Warning 40, NWS Philadelphia/Mount Holly

July 21, 2015Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 21, 2015, 3:01 PM EDT for Sussex County, Delaware. It was in force for 4 hr. 3 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Jul 21, 2015, 3:01 PM EDT (19:01 UTC)
Expired: Jul 21, 2015, 7:00 PM EDT
In force: 4 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

County Sussex County, DE

The radar

The Dover AFB radar (KDOX), 23 km from the middle of the area, began a volume at 19:02 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.

What was reported inside it

Time	Report	Where
Jul 21, 3:25 PM EDT	HEAVY RAIN 2.01	Nassau, DE
Jul 21, 3:39 PM EDT	HEAVY RAIN 2.22	Lewes, DE
Jul 21, 3:44 PM EDT	HEAVY RAIN 2.37	Lewes, DE

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Wallops Is Stn, VA (KWAL), launched 12:00Z, 7.0 hours before the alert went out and 96 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: 899 J/kg
Mixed-layer CIN: -39 J/kg
Mixed-layer LCL: 1187 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: -12 m²/s²
0-3 km storm-relative helicity: 28 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.3

Open this sounding in Storm Lab

The text

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

504 
WGUS51 KPHI 211901
FFWPHI
DEC005-212300-
/O.NEW.KPHI.FF.W.0040.150721T1901Z-150721T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
301 PM EDT TUE JUL 21 2015

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ  HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  NORTHEASTERN SUSSEX COUNTY IN SOUTHERN DELAWARE...

* UNTIL 700 PM EDT
    
* AT 259 PM EDT...DOPPLER RADAR INDICATED A THUNDERSTORM PRODUCING 
  HEAVY RAIN ACROSS THE WARNED AREA. UP TO TWO INCHES OF RAIN HAS 
  ALREADY FALLEN. FLASH FLOODING IS EXPECTED TO BEGIN SHORTLY.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
  LEWES...MILTON AND HENLOPEN ACRES. 

ADDITIONAL RAINFALL AMOUNTS OF AROUND AN INCH ARE POSSIBLE IN THE 
WARNED AREA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

MOVE TO HIGHER GROUND NOW. ACT QUICKLY TO PROTECT YOUR LIFE.

TURN AROUND...DON'T DROWN WHEN ENCOUNTERING FLOODED ROADS. MOST FLOOD
DEATHS OCCUR IN VEHICLES.

&&

LAT...LON 3867 7527 3886 7538 3886 7524 3879 7516
      3879 7515 3878 7512 3878 7511 3880 7510
      3878 7508 3871 7508

$$

MWG

2 follow-up statements

262 
WGUS71 KPHI 211952
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
352 PM EDT TUE JUL 21 2015

DEC005-212300-
/O.CON.KPHI.FF.W.0040.000000T0000Z-150721T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
SUSSEX DE-
352 PM EDT TUE JUL 21 2015

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 700 PM EDT FOR
NORTHEASTERN SUSSEX COUNTY...

AT 350 PM EDT...TRAINED WEATHER SPOTTERS REPORTED THUNDERSTORMS THAT 
PRODUCED HEAVY RAIN OF AROUND TWO INCHES OF RAIN ACROSS THE WARNING 
AREA. FLASH FLOODING IS EXPECTED TO BEGIN SHORTLY. SOME LOCATIONS 
THAT WILL EXPERIENCE FLOODING INCLUDE... LEWES...MILTON AND HENLOPEN 
ACRES. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

MOVE TO HIGHER GROUND NOW. ACT QUICKLY TO PROTECT YOUR LIFE.

TURN AROUND...DON'T DROWN WHEN ENCOUNTERING FLOODED ROADS. MOST FLOOD
DEATHS OCCUR IN VEHICLES.

PLEASE REPORT FLOODING TO YOUR LOCAL LAW ENFORCEMENT AGENCY WHEN YOU
CAN DO SO SAFELY.

&&

LAT...LON 3867 7527 3886 7538 3886 7524 3879 7516
      3879 7515 3878 7512 3878 7511 3880 7510
      3878 7508 3871 7508

$$

MWG

487 
WGUS71 KPHI 212138
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
538 PM EDT TUE JUL 21 2015

DEC005-212148-
/O.CAN.KPHI.FF.W.0040.000000T0000Z-150721T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
SUSSEX DE-
538 PM EDT TUE JUL 21 2015

...THE FLASH FLOOD WARNING FOR NORTHEASTERN SUSSEX COUNTY IS
CANCELLED...

THE HEAVY RAIN HAS ENDED...AND FLOODING IS NO LONGER EXPECTED TO POSE
A THREAT.

LAT...LON 3867 7527 3886 7538 3886 7524 3879 7516
      3879 7515 3878 7512 3878 7511 3880 7510
      3878 7508 3871 7508

$$

MWG

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 21, 12:50 PM EDT	Special Weather Statement	PHI	Sussex	25 min
Jul 21, 1:01 PM EDT	Areal Flood Advisory	PHI	Sussex	3 hr
Jul 21, 1:54 PM EDT	Special Weather Statement	PHI	Sussex	36 min
Jul 21, 2:22 PM EDT	Areal Flood Advisory	PHI	Sussex	3 hr
Jul 21, 2:31 PM EDT	Special Weather Statement	PHI	Sussex	44 min

Nearby

Flash Flood Warnings in Delaware, 2015 Every flash flood warning in 2015

Sources

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