Alert archive / Maryland / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 48, NWS Philadelphia/Mount Holly

July 3, 2018Cecil County, Maryland; Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 3, 2018, 7:39 PM EDT for Cecil County, Maryland; Chester County, Pennsylvania. It was in force for 51 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 3, 2018, 7:39 PM EDT (23:39 UTC)
Expired
Jul 3, 2018, 8:30 PM EDT
In force
51 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), 122 km from the middle of the area, began a volume at 23:38 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

Washington/Dulle, VA (KIAD), launched 12:00Z, 11.7 hours before the alert went out and 158 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, Washington/Dulle, VA at 12:00Z on 2018-07-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 574 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, Washington/Dulle, VA at 12:00Z on 2018-07-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 14 square meters per square second.1939Sfc1 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
574 J/kg
Mixed-layer CIN
-189 J/kg
Mixed-layer LCL
1257 m above ground
0-6 km bulk shear
7 kt
0-1 km storm-relative helicity
14 m²/s²
0-3 km storm-relative helicity
55 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

685 
WUUS51 KPHI 032339
SVRPHI
MDC015-PAC029-040030-
/O.NEW.KPHI.SV.W.0048.180703T2339Z-180704T0030Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
739 PM EDT TUE JUL 3 2018

The National Weather Service in Mount Holly NJ has issued a

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

* Until 830 PM EDT.

* At 738 PM EDT, severe thunderstorms were located along a line
  extending from Cochranville to Oxford, moving south at 15 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...
  Calvert, Oxford, Parkesburg, North East, West Grove, Homeville,
  Zion, Blake, Cochranville, Lombard, Andora, Pleasant Hill, Mount
  Vernon, Cherry Hill, Ladenberg, Kemblesville, Fair Hill, Glen
  Westover, Bay View and Appleton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3982 7603 3986 7601 3987 7599 3992 7600
      3994 7598 3995 7600 4001 7596 3979 7573
      3956 7591 3973 7605
TIME...MOT...LOC 2338Z 342DEG 11KT 3992 7594 3976 7598 

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

SFJ
2 follow-up statements
340 
WWUS51 KPHI 040011
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
811 PM EDT TUE JUL 3 2018

MDC015-PAC029-040030-
/O.CON.KPHI.SV.W.0048.000000T0000Z-180704T0030Z/
Cecil MD-Chester PA-
811 PM EDT TUE JUL 3 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 830 PM EDT
FOR NORTHEASTERN CECIL AND SOUTHWESTERN CHESTER COUNTIES...

At 811 PM EDT, severe thunderstorms were located along a line
extending from near West Grove to Farmington, moving south at 10 mph.

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

SOURCE...Radar indicated.

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

Locations impacted include...
Calvert, Oxford, Parkesburg, North East, West Grove, Homeville, Zion,
Blake, Cochranville, Lombard, Andora, Pleasant Hill, Mount Vernon,
Cherry Hill, Ladenberg, Kemblesville, Fair Hill, Glen Westover, Bay
View and Appleton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 3982 7603 3986 7601 3987 7599 3992 7600
      3994 7598 3995 7600 4001 7596 3979 7573
      3956 7591 3973 7605
TIME...MOT...LOC 0011Z 349DEG 11KT 3983 7590 3967 7602 

HAIL...0.88IN
WIND...60MPH
 
$$

SFJ
060 
WWUS51 KPHI 040020
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
820 PM EDT TUE JUL 3 2018

MDC015-PAC029-040030-
/O.EXP.KPHI.SV.W.0048.000000T0000Z-180704T0030Z/
Cecil MD-Chester PA-
820 PM EDT TUE JUL 3 2018

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN CECIL AND
SOUTHWESTERN CHESTER COUNTIES WILL EXPIRE AT 830 PM EDT...
            
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 will be allowed to expire.  However heavy rain
is still possible with these thunderstorms.

LAT...LON 3982 7603 3986 7601 3987 7599 3992 7600
      3994 7598 3995 7600 4001 7596 3979 7573
      3956 7591 3973 7605
TIME...MOT...LOC 0020Z 342DEG 11KT 3981 7589 3965 7601 

$$

SFJ

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 3, 7:54 PM EDTFlash Flood WarningPHICecil4 hr
Jul 3, 2:15 PM EDTSpecial Weather StatementPHIDelaware30 min
Jul 3, 3:00 PM EDTSpecial Weather StatementPHIPhiladelphia60 min
Jul 3, 3:11 PM EDTFlash Flood WarningPHIMontgomery, Philadelphia50 min
Jul 3, 4:06 PM EDTSpecial Weather StatementPHIMontgomery54 min
Jul 3, 4:30 PM EDTSpecial Weather StatementPHIBucks60 min
Jul 3, 5:24 PM EDTAreal Flood AdvisoryPHIDelaware, Montgomery, Philadelphia4 hr
Jul 3, 5:29 PM EDTAreal Flood AdvisoryPHIBucks, Montgomery, Philadelphia4 hr
Jul 3, 5:30 PM EDTSpecial Weather StatementPHIPhiladelphia30 min
Jul 3, 5:45 PM EDTFlash Flood WarningPHIDelaware, Montgomery, Philadelphia4 hr
Jul 3, 6:03 PM EDTSpecial Weather StatementPHIMonroe57 min
Jul 3, 6:15 PM EDTSpecial Weather StatementPHIChester60 min
Jul 3, 6:18 PM EDTSevere Thunderstorm WarningPHIDelaware, Philadelphia42 min
Jul 3, 6:21 PM EDTSpecial Weather StatementPHIDelaware24 min
Jul 3, 6:25 PM EDTSevere Thunderstorm WarningPHIBucks, Philadelphia50 min
Jul 3, 6:37 PM EDTFlash Flood WarningPHIBucks, Philadelphia3 hr
Jul 3, 6:40 PM EDTAreal Flood AdvisoryPHIChester, Delaware4 hr
Jul 3, 6:50 PM EDTSpecial Weather StatementPHIDelaware55 min
Jul 3, 6:54 PM EDTSevere Thunderstorm WarningPHIChester, Delaware51 min
Jul 3, 6:58 PM EDTFlash Flood WarningPHIChester, Delaware4 hr
Jul 3, 7:03 PM EDTSpecial Weather StatementPHINorthampton57 min
Jul 3, 7:06 PM EDTFlash Flood WarningPHIBucks, Chester, Delaware, Montgomery, Philadelphia2 hr
Jul 3, 7:22 PM EDTSevere Thunderstorm WarningPHIChester, Delaware, Montgomery, Philadelphia21 min
Jul 3, 7:35 PM EDTSpecial Weather StatementPHIChester25 min

Nearby

Severe Thunderstorm Warnings in Maryland, 2018Severe Thunderstorm Warnings in Pennsylvania, 2018Every 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.