Alert archive / Delaware / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 158, NWS Philadelphia/Mount Holly

August 7, 2017Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 7, 2017, 2:41 PM EDT for Sussex County, Delaware. It was in force for 34 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 7, 2017, 2:41 PM EDT (18:41 UTC)
Expired: Aug 7, 2017, 3:15 PM EDT
In force: 34 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Tornado: Possible
Hail: 0.75 in
Wind: 60.0 mph

County Sussex County, DE

The radar

The Dover AFB radar (KDOX), 34 km from the middle of the area, began a volume at 18:45 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, 6.7 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: 57 J/kg
Mixed-layer CIN: -91 J/kg
Mixed-layer LCL: 996 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: 176 m²/s²
0-3 km storm-relative helicity: 193 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.3

Open this sounding in Storm Lab

The text

As transmitted.

555 
WUUS51 KPHI 071841
SVRPHI
DEC005-071915-
/O.NEW.KPHI.SV.W.0158.170807T1841Z-170807T1915Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
241 PM EDT MON AUG 7 2017

The National Weather Service in Mount Holly NJ has issued a

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

* Until 315 PM EDT

* At 241 PM EDT, a severe thunderstorm was located near Selbyville,
  or 9 miles northwest of Ocean City, moving east at 40 mph.

  HAZARD...60 mph wind gusts. 

  SOURCE...Radar indicated. 

  IMPACT...Expect damage to trees and power lines. 

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.

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 3853 7528 3884 7519 3884 7517 3881 7514
      3881 7506 3854 7504 3846 7504 3845 7505
      3845 7525
TIME...MOT...LOC 1841Z 254DEG 36KT 3847 7515 

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

CMS

2 follow-up statements

328 
WWUS51 KPHI 071857
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
257 PM EDT MON AUG 7 2017

DEC005-071915-
/O.CON.KPHI.SV.W.0158.000000T0000Z-170807T1915Z/
Sussex DE-
257 PM EDT MON AUG 7 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 315 PM EDT
FOR SOUTHEASTERN SUSSEX COUNTY...

At 257 PM EDT, a severe thunderstorm was located 7 miles southeast of
Milton, or 7 miles east of Georgetown, moving northeast at 35 mph.

HAZARD...60 mph wind gusts. 

SOURCE...Radar indicated. 

IMPACT...Expect damage to trees and power lines. 

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.

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 3857 7527 3881 7520 3883 7519 3884 7517
      3881 7514 3881 7507 3880 7506 3854 7504
      3846 7504 3845 7505 3845 7507
TIME...MOT...LOC 1857Z 241DEG 31KT 3869 7524 

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

CMS

014 
WWUS51 KPHI 071910
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
310 PM EDT MON AUG 7 2017

DEC005-071920-
/O.EXP.KPHI.SV.W.0158.000000T0000Z-170807T1915Z/
Sussex DE-
310 PM EDT MON AUG 7 2017

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN SUSSEX COUNTY
WILL EXPIRE AT 315 PM EDT...
                
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 will be allowed to expire.  However gusty winds
and heavy rain are still possible with this thunderstorm.

LAT...LON 3857 7527 3881 7520 3883 7519 3884 7517
      3881 7514 3881 7507 3880 7506 3854 7504
      3846 7504 3845 7505 3845 7507
TIME...MOT...LOC 1910Z 254DEG 36KT 3872 7509 

$$

CMS

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 7, 9:59 AM EDT	Areal Flood Advisory	PHI	Kent, New Castle	3 hr
Aug 7, 10:44 AM EDT	Flash Flood Warning	PHI	Kent	4 hr
Aug 7, 11:41 AM EDT	Areal Flood Advisory	PHI	Kent, Sussex	3 hr
Aug 7, 12:36 PM EDT	Areal Flood Advisory	PHI	Kent	4 hr
Aug 7, 1:47 PM EDT	Special Weather Statement	PHI	Sussex	43 min
Aug 7, 1:58 PM EDT	Severe Thunderstorm Warning	PHI	Sussex	47 min
Aug 7, 2:06 PM EDT	Flash Flood Warning	PHI	Kent, Sussex	4 hr
Aug 7, 2:08 PM EDT	Tornado Warning	PHI	Sussex	37 min
Aug 7, 2:22 PM EDT	Areal Flood Advisory	PHI	Sussex	4 hr
Aug 7, 2:40 PM EDT	Areal Flood Warning	PHI	Kent	6 hr
Aug 7, 4:57 PM EDT	Areal Flood Warning	PHI	Sussex	4 hr
Aug 7, 5:25 PM EDT	Areal Flood Warning	PHI	Kent	4 hr

Nearby

Severe Thunderstorm Warnings in Delaware, 2017 Every severe thunderstorm warning in 2017

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.