Alert archive / Delaware / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 139, NWS Philadelphia/Mount Holly

July 25, 2017Caroline County, Maryland; Kent County, Sussex County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 25, 2017, 12:34 AM EDT for Caroline County, Maryland; Kent County, Sussex County, Delaware. It was in force for 41 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
Jul 25, 2017, 12:34 AM EDT (04:34 UTC)
Expired
Jul 25, 2017, 1:15 AM EDT
In force
41 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Kent County, DE, Sussex County, DE, Caroline County, MD

The radar

The Dover AFB radar (KDOX), 24 km from the middle of the area, began a volume at 04:33 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 00:00Z, 4.6 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-pSkew-T log-p diagram, Wallops Is Stn, VA at 00:00Z on 2017-07-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 161 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 00:00Z on 2017-07-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 40 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
161 J/kg
Mixed-layer CIN
-82 J/kg
Mixed-layer LCL
1504 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
40 m²/s²
0-3 km storm-relative helicity
51 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

The text

As transmitted.

644 
WUUS51 KPHI 250434
SVRPHI
DEC001-005-MDC011-250515-
/O.NEW.KPHI.SV.W.0139.170725T0434Z-170725T0515Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
1234 AM EDT TUE JUL 25 2017

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Sussex County in southern Delaware...
  Southern Kent County in central Delaware...
  Southeastern Caroline County in eastern Maryland...

* Until 115 AM EDT

* At 1234 AM EDT, a severe thunderstorm was located near Bridgeville,
  or 13 miles northeast of Hurlock, moving east at 30 mph.

  HAZARD...60 mph wind gusts and penny size hail. 

  SOURCE...Radar indicated. 

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

* Locations impacted include...
  Georgetown, Seaford, Millsboro, Laurel, Lewes, Federalsburg,
  Milton, Selbyville, Bridgeville, Dagsboro, Preston, Millville,
  Ellendale, Henlopen Acres, Smithville, Gumboro, Agner, Sycamore,
  Harmony and Long Neck.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In addition to hail and damaging winds...frequent cloud to ground 
lightning is occurring with this storm. Move indoors immediately. 
Remember...if you can hear thunder...you are close enough to be 
struck by lightning.

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

&&

LAT...LON 3845 7550 3851 7570 3864 7571 3869 7577
      3868 7580 3870 7580 3871 7584 3868 7593
      3870 7594 3887 7581 3879 7521 3873 7505
      3846 7504 3845 7505
TIME...MOT...LOC 0434Z 281DEG 25KT 3872 7566 

HAIL...0.75IN
WIND...60MPH
 
$$

JRK
2 follow-up statements
962 
WWUS51 KPHI 250454
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
1254 AM EDT TUE JUL 25 2017

DEC001-MDC011-250503-
/O.CAN.KPHI.SV.W.0139.000000T0000Z-170725T0515Z/
Kent DE-Caroline MD-
1254 AM EDT TUE JUL 25 2017

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHERN KENT AND SOUTHEASTERN
CAROLINE COUNTIES IS CANCELLED...

The storms which prompted the warning have moved out of the warned 
area. Therefore, the warning has been cancelled.

LAT...LON 3845 7552 3851 7570 3865 7571 3883 7548
      3879 7521 3873 7505 3846 7504 3845 7505
TIME...MOT...LOC 0453Z 295DEG 22KT 3878 7543 3859 7558 3853 7575 

$$

DEC005-250515-
/O.CON.KPHI.SV.W.0139.000000T0000Z-170725T0515Z/
Sussex DE-
1254 AM EDT TUE JUL 25 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 115 AM EDT
FOR SUSSEX COUNTY...

At 1253 AM EDT, severe thunderstorms were located along a line
extending from near Ellendale to near Laurel to Sharptown, moving
southeast at 25 mph.

HAZARD...60 mph wind gusts. 

SOURCE...Radar indicated. 

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

Locations impacted include...
Georgetown, Seaford, Millsboro, Laurel, Lewes, Milton, Selbyville,
Bridgeville, Dagsboro, Millville, Ellendale, Henlopen Acres, Gumboro,
Sycamore, Long Neck, Ocean View, Blades, Frankford, South Bethany and
Dewey Beach.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In addition to damaging winds...frequent cloud to ground lightning 
is occurring with this storm. Move indoors immediately. 
Remember...if you can hear thunder...you are close enough to be 
struck by lightning.

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

&&

LAT...LON 3845 7552 3851 7570 3865 7571 3883 7548
      3879 7521 3873 7505 3846 7504 3845 7505
TIME...MOT...LOC 0453Z 295DEG 22KT 3878 7543 3859 7558 3853 7575 

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

JRK
051 
WWUS51 KPHI 250516
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
116 AM EDT TUE JUL 25 2017

DEC005-250525-
/O.EXP.KPHI.SV.W.0139.000000T0000Z-170725T0515Z/
Sussex DE-
116 AM EDT TUE JUL 25 2017

...THE SEVERE THUNDERSTORM WARNING FOR SUSSEX COUNTY HAS EXPIRED...
            
The storms which prompted the warning have weakened below severe
limits, and no longer pose an immediate threat to life or property.
Therefore the warning has been allowed to expire. However, these 
storms may try to re-intensify in far southeastern Delaware before 
moving off the coast by 2 AM so be certain to monitor local radio 
stations and available television stations for additional 
information and possible warnings from the National Weather Service.

LAT...LON 3845 7552 3851 7570 3865 7571 3883 7548
      3879 7521 3873 7505 3846 7504 3845 7505
TIME...MOT...LOC 0515Z 281DEG 25KT 3875 7525 3856 7540 3850 7557 

$$

JRK

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 24, 8:08 PM EDTSevere Thunderstorm WarningPHICecil52 min
Jul 24, 8:59 PM EDTAreal Flood AdvisoryPHICecil2 hr
Jul 24, 9:52 PM EDTSevere Thunderstorm WarningPHICaroline, Kent, Queen Anne's38 min
Jul 24, 10:02 PM EDTSpecial Weather StatementPHICecil43 min
Jul 24, 10:06 PM EDTSevere Thunderstorm WarningPHICaroline, Cecil, Kent, Queen Anne's39 min
Jul 24, 10:50 PM EDTSevere Thunderstorm WarningPHICaroline, Queen Anne's40 min
Jul 24, 11:10 PM EDTSpecial Weather StatementPHITalbot35 min
Jul 24, 11:30 PM EDTSpecial Weather StatementPHICaroline45 min
Jul 24, 11:55 PM EDTAreal Flood AdvisoryPHICaroline, Queen Anne's2 hr
Jul 24, 9:01 PM EDTSpecial Weather StatementPHINew Castle59 min
Jul 24, 10:01 PM EDTAreal Flood AdvisoryPHINew Castle119 min
Jul 24, 10:38 PM EDTSevere Thunderstorm WarningPHIKent, New Castle52 min
Jul 25, 12:16 AM EDTSpecial Weather StatementPHISussex44 min
Jul 25, 1:15 AM EDTSpecial Weather StatementPHISussex45 min
Jul 25, 3:25 PM EDTCoastal Flood AdvisoryPHISussex11 hr

Nearby

Severe Thunderstorm Warnings in Delaware, 2017Severe Thunderstorm Warnings in Maryland, 2017Every 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.