Alert archive / Maryland / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 4, NWS Philadelphia/Mount Holly

May 10, 2018Cecil County, Maryland; Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at May 10, 2018, 6:51 PM EDT for Cecil County, Maryland; Chester County, Pennsylvania. It was in force for 39 min. 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: May 10, 2018, 6:51 PM EDT (22:51 UTC)
Expired: May 10, 2018, 7:30 PM EDT
In force: 39 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Cecil County, MD, Chester County, PA

The radar

The Dover AFB radar (KDOX), 112 km from the middle of the area, began a volume at 22:51 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
May 10, 6:53 PM EDT	HAIL 0.75	Rising Sun, MD
May 10, 6:54 PM EDT	HAIL 0.5	Nottingham, PA	HAIL SLIGHTLY SMALLER THAN DIMES IN NOTTINGHAM.
May 10, 6:54 PM EDT	HAIL 1	1 N Sylmar, PA	PHOTO INDICATES HAIL UP TO QUARTER SIZE FELL IN THE NOTTINGHAM AREA. TIME APPROXIMATED BY RADAR.

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

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 10.9 hours before the alert went out and 142 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1336 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 206 m²/s²
0-3 km storm-relative helicity: 171 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

882 
WUUS51 KPHI 102251
SVRPHI
MDC015-PAC029-102330-
/O.NEW.KPHI.SV.W.0004.180510T2251Z-180510T2330Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
651 PM EDT THU MAY 10 2018

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Northern Cecil County in northeastern Maryland...
  Southwestern Chester County in southeastern Pennsylvania...

* Until 730 PM EDT.

* At 651 PM EDT, a severe thunderstorm was located over Rising Sun,
  or 11 miles north of Havre De Grace, moving east at 30 mph.

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

  SOURCE...Radar indicated.

  IMPACT...Minor damage to vehicles is possible. Wind damage to 
           roofs, siding, trees, and power lines is possible.

* Locations impacted include...
  Elkton, Calvert, Oxford, North East, West Grove, Rising Sun,
  Charlestown, Glen Roy, Zion, Blake, Barksdale, West Nottingham,
  Octoraro, Mount Vernon, Fair Hill, Glen Westover, Bay View,
  Lombard, Richardsmere and Woodlawn.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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 3972 7614 3974 7612 3973 7610 3974 7610
      3976 7606 3981 7604 3984 7578 3953 7582
      3957 7610 3965 7616 3968 7621 3972 7623
TIME...MOT...LOC 2251Z 261DEG 26KT 3971 7604 

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

Gorse

2 follow-up statements

283 
WWUS51 KPHI 102308
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
708 PM EDT THU MAY 10 2018

MDC015-PAC029-102330-
/O.CON.KPHI.SV.W.0004.000000T0000Z-180510T2330Z/
Cecil MD-Chester PA-
708 PM EDT THU MAY 10 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 730 PM EDT
FOR NORTHERN CECIL AND SOUTHWESTERN CHESTER COUNTIES...

At 707 PM EDT, a severe thunderstorm was located over Blake, or 8
miles west of Newark, moving east at 25 mph.

HAZARD...60 mph wind gusts and quarter size hail. Hail up to the 
         size of pennies was reported in Rising Sun Maryland.

SOURCE...Radar indicated.

IMPACT...Minor damage to vehicles is possible. Wind damage to roofs, 
         siding, trees, and power lines is possible.

Locations impacted include...
Elkton, Calvert, Oxford, North East, West Grove, Rising Sun,
Charlestown, Glen Roy, Zion, Blake, Barksdale, West Nottingham,
Octoraro, Mount Vernon, Fair Hill, Glen Westover, Bay View, Lombard,
Richardsmere and Woodlawn.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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.

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

&&

LAT...LON 3972 7614 3974 7612 3973 7610 3974 7610
      3976 7606 3981 7604 3984 7578 3953 7582
      3957 7610 3965 7616 3968 7621 3972 7623
TIME...MOT...LOC 2307Z 265DEG 22KT 3971 7592 

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

Gorse

868 
WWUS51 KPHI 102324
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
724 PM EDT THU MAY 10 2018

MDC015-PAC029-102333-
/O.EXP.KPHI.SV.W.0004.000000T0000Z-180510T2330Z/
Cecil MD-Chester PA-
724 PM EDT THU MAY 10 2018

...THE SEVERE THUNDERSTORM WARNING FOR NORTHERN CECIL AND
SOUTHWESTERN CHESTER COUNTIES WILL EXPIRE AT 730 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 small hail
and heavy rain are still possible with this thunderstorm.

LAT...LON 3972 7614 3974 7612 3973 7610 3974 7610
      3976 7606 3981 7604 3984 7578 3953 7582
      3957 7610 3965 7616 3968 7621 3972 7623
TIME...MOT...LOC 2323Z 261DEG 26KT 3973 7578 

$$

Gorse

The office that day

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

Issued	Product	Office	Counties	Lasted
May 10, 5:50 PM EDT	Special Weather Statement	PHI	Carbon, Monroe	55 min
May 10, 6:17 PM EDT	Severe Thunderstorm Warning	PHI	Carbon, Monroe	43 min
May 10, 7:01 PM EDT	Special Weather Statement	PHI	Monroe	29 min
May 10, 7:54 PM EDT	Special Weather Statement	PHI	Chester	51 min

Nearby

Severe Thunderstorm Warnings in Maryland, 2018 Severe Thunderstorm Warnings in Pennsylvania, 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.