Alert archive / Maryland / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 170, NWS Philadelphia/Mount Holly

August 18, 2017Kent County, Delaware; 4 counties in Maryland

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 18, 2017, 6:10 PM EDT for Kent County, Delaware; 4 counties in Maryland. It was in force for 65 min. 1 report 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: Aug 18, 2017, 6:10 PM EDT (22:10 UTC)
Expired: Aug 18, 2017, 7:15 PM EDT
In force: 65 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Tornado: Possible
Hail: 1.25 in
Wind: 60.0 mph

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

The radar

The Dover AFB radar (KDOX), 69 km from the middle of the area, began a volume at 22:11 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	Remark
Aug 18, 6:50 PM EDT	MARINE TSTM WIND 39	5 Ese Bay Ridge, MD

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

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Aug 18, 2:27 PM EDT	Severe Thunderstorm Watch	SPC	9 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 10.2 hours before the alert went out and 102 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: 746 J/kg
Mixed-layer CIN: -72 J/kg
Mixed-layer LCL: 651 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 12 m²/s²
0-3 km storm-relative helicity: 76 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

As transmitted.

160 
WUUS51 KPHI 182210
SVRPHI
DEC001-MDC011-029-035-041-182315-
/O.NEW.KPHI.SV.W.0170.170818T2210Z-170818T2315Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
610 PM EDT FRI AUG 18 2017

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  West central Kent County in central Delaware...
  Talbot County in eastern Maryland...
  Queen Anne's County in northeastern Maryland...
  Northern Caroline County in eastern Maryland...
  Kent County in northeastern Maryland...

* Until 715 PM EDT

* At 610 PM EDT, severe thunderstorms were located along a line
  extending from near Newtown to Crofton, moving southeast at 25 mph.

  HAZARD...60 mph wind gusts and half dollar size hail. 

  SOURCE...Radar indicated. 

  IMPACT...Minor damage to vehicles is possible. Expect damage to 
           trees and power lines. 

* Locations impacted include...
  Dover, Easton, Centerville, Talbot, Chestertown, Centreville,
  Camden, Greensboro, Oakland, Ridgely, Rock Hall, St. Michaels,
  Church Hill, Oxford, Millington, Sudlersville, Goldsboro, Queen
  Anne, Hartly and Old Town.

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.

In addition to large 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.

&&

LAT...LON 3894 7636 3904 7631 3898 7628 3900 7617
      3917 7628 3934 7616 3930 7573 3914 7552
      3864 7615 3876 7622 3871 7628 3878 7629
      3876 7632 3869 7632 3870 7634 3875 7637
      3897 7625 3895 7627 3885 7638 3886 7638
TIME...MOT...LOC 2210Z 306DEG 20KT 3926 7623 3902 7667 

TORNADO...POSSIBLE
HAIL...1.25IN
WIND...60MPH
 
$$

SFJ

1 follow-up statement

844 
WWUS51 KPHI 182255
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
655 PM EDT FRI AUG 18 2017

DEC001-MDC011-029-035-041-182315-
/O.CON.KPHI.SV.W.0170.000000T0000Z-170818T2315Z/
Kent DE-Talbot MD-Queen Anne's MD-Caroline MD-Kent MD-
655 PM EDT FRI AUG 18 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 715 PM EDT
FOR WEST CENTRAL KENT...TALBOT...QUEEN ANNE'S...NORTHERN CAROLINE AND
KENT COUNTIES...

At 655 PM EDT, severe thunderstorms were located along a line
extending from Church Hill to near Kent Point, moving southeast at 25
mph.

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

SOURCE...Radar indicated. 

IMPACT...Minor damage to vehicles is possible. Expect damage to 
         trees and power lines. 

Locations impacted include...
Dover, Easton, Centerville, Talbot, Chestertown, Centreville, Camden,
Greensboro, Oakland, Ridgely, Rock Hall, St. Michaels, Church Hill,
Oxford, Millington, Sudlersville, Goldsboro, Queen Anne, Hartly and
Old Town.

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.

In addition to large 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.

&&

LAT...LON 3894 7636 3904 7631 3898 7628 3900 7617
      3917 7628 3934 7616 3930 7573 3914 7552
      3864 7615 3876 7622 3871 7628 3878 7629
      3876 7632 3869 7632 3870 7634 3875 7637
      3897 7625 3895 7627 3885 7638 3886 7638
TIME...MOT...LOC 2255Z 306DEG 20KT 3912 7598 3888 7642 

TORNADO...POSSIBLE
HAIL...1.00IN
WIND...60MPH
 
$$

SFJ

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 18, 3:39 AM EDT	Flash Flood Watch	PHI	Kent, New Castle, Sussex	18 hr
Aug 18, 5:03 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	42 min
Aug 18, 5:20 PM EDT	Areal Flood Advisory	PHI	New Castle	3 hr
Aug 18, 5:39 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	66 min
Aug 18, 6:12 PM EDT	Areal Flood Advisory	PHI	Kent, New Castle	3 hr
Aug 18, 6:20 PM EDT	Special Weather Statement	PHI	Sussex	25 min
Aug 18, 6:38 PM EDT	Special Weather Statement	PHI	New Castle	37 min
Aug 18, 6:48 PM EDT	Special Weather Statement	PHI	New Castle	27 min
Aug 18, 7:07 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle, Sussex	53 min
Aug 18, 7:33 PM EDT	Areal Flood Advisory	PHI	Kent, Sussex	3 hr
Aug 18, 7:53 PM EDT	Severe Thunderstorm Warning	PHI	Kent, Sussex	48 min
Aug 18, 4:29 PM EDT	Severe Thunderstorm Warning	PHI	Cecil	61 min
Aug 18, 4:57 PM EDT	Areal Flood Advisory	PHI	Cecil	3 hr

Nearby

Severe Thunderstorm Warnings in Maryland, 2017 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.