Alert archive / Delaware / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 69, NWS Philadelphia/Mount Holly

August 11, 2018Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 11, 2018, 1:23 PM EDT for Sussex County, Delaware. It was in force for 37 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 11, 2018, 1:23 PM EDT (17:23 UTC)
Expired: Aug 11, 2018, 2:00 PM EDT
In force: 37 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

County Sussex County, DE

The radar

The Dover AFB radar (KDOX), 29 km from the middle of the area, began a volume at 17:22 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, 5.4 hours before the alert went out and 80 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: 1571 J/kg
Mixed-layer CIN: -26 J/kg
Mixed-layer LCL: 1008 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 40 m²/s²
0-3 km storm-relative helicity: 50 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.7

Open this sounding in Storm Lab

The text

As transmitted.

942 
WUUS51 KPHI 111723
SVRPHI
DEC005-111815-
/O.NEW.KPHI.SV.W.0069.180811T1723Z-180811T1815Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
123 PM EDT SAT AUG 11 2018

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Eastern Sussex County in southern Delaware...

* Until 215 PM EDT.

* At 122 PM EDT, a severe thunderstorm was located over Millsboro, or
  10 miles southeast of Georgetown, moving northeast at 20 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Damage to roofs, siding, trees, and power lines is 
           possible.

* Locations impacted include...
  Millsboro, Lewes, Dagsboro, Millville, Henlopen Acres, Gumboro,
  Cape Henlopen State Park, Long Neck, Ocean View, Frankford, South
  Bethany and Dewey Beach.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3848 7550 3887 7521 3881 7514 3881 7506
      3851 7504 3846 7507
TIME...MOT...LOC 1722Z 217DEG 25KT 3855 7530 

HAIL...<.75IN
WIND...60MPH
 
$$

jjm

1 follow-up statement

330 
WWUS51 KPHI 111800
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
200 PM EDT SAT AUG 11 2018

DEC005-111810-
/O.CAN.KPHI.SV.W.0069.000000T0000Z-180811T1815Z/
Sussex DE-
200 PM EDT SAT AUG 11 2018

...THE SEVERE THUNDERSTORM WARNING FOR EASTERN SUSSEX COUNTY IS
CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning has been cancelled.  However gusty winds and
heavy rain are still possible with this thunderstorm.

LAT...LON 3848 7550 3887 7521 3881 7514 3881 7506
      3851 7504 3846 7507
TIME...MOT...LOC 1757Z 217DEG 25KT 3876 7509 

$$

JRK

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 11, 3:24 AM EDT	Flash Flood Watch	PHI	Kent, New Castle	20 hr
Aug 11, 4:26 AM EDT	Coastal Flood Advisory	PHI	Kent, New Castle, Sussex	24 hr
Aug 11, 4:19 PM EDT	Areal Flood Advisory	PHI	New Castle	3 hr
Aug 11, 4:19 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	29 min
Aug 11, 5:20 PM EDT	Areal Flood Advisory	PHI	Kent, New Castle	4 hr
Aug 11, 6:08 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	52 min
Aug 11, 6:12 PM EDT	Flash Flood Warning	PHI	Kent, New Castle	3 hr
Aug 11, 6:45 PM EDT	Flash Flood Warning	PHI	Kent	5 hr
Aug 11, 6:55 PM EDT	Severe Thunderstorm Warning	PHI	Kent	50 min
Aug 11, 7:42 PM EDT	Special Weather Statement	PHI	Kent	48 min

Nearby

Severe Thunderstorm Warnings in Delaware, 2018 Every severe thunderstorm warning in 2018

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.