Alert archive / Maryland / Severe Thunderstorm Warnings in 2013

Severe Thunderstorm Warning 83, NWS Philadelphia/Mount Holly

July 28, 2013Cecil County, Maryland; Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 28, 2013, 11:54 PM EDT for Cecil County, Maryland; Chester County, Pennsylvania. It was in force for 51 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: Jul 28, 2013, 11:54 PM EDT (03:54 UTC)
Expired: Jul 29, 2013, 12:45 AM EDT
In force: 51 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties Cecil County, MD, Chester County, PA

The radar

The Dover AFB radar (KDOX), 116 km from the middle of the area, began a volume at 03:56 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
Jul 29, 12:20 AM EDT	TSTM WND DMG	Farmington, MD	TREES DOWN IN NORTHERN PART OF COUNTY

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 00:00Z, 3.9 hours before the alert went out and 151 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: 957 J/kg
Mixed-layer CIN: -9 J/kg
Mixed-layer LCL: 1152 m above ground
0-6 km bulk shear: 43 kt
0-1 km storm-relative helicity: -11 m²/s²
0-3 km storm-relative helicity: 23 m²/s²
Significant tornado parameter: -0.1
Supercell composite: -1.4

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

635 
WUUS51 KPHI 290354
SVRPHI
MDC015-PAC029-290445-
/O.NEW.KPHI.SV.W.0083.130729T0354Z-130729T0445Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1154 PM EDT SUN JUL 28 2013

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHERN CECIL COUNTY IN NORTHEAST MARYLAND...
  SOUTHWESTERN CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 1245 AM EDT

* AT 1149 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  LINE OF SEVERE THUNDERSTORMS. THESE SEVERE STORMS EXTENDED FROM
  QUARRYVILLE TO WAKEFIELD TO SCARBORO...MOVING EAST AT 25 MPH. THESE
  STORMS ARE CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS OF 60 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  OCTORARO AND CONOWINGO AROUND MIDNIGHT EDT...
  MOUNT VERNON AND RICHARDSMERE AROUND 1205 AM EDT...
  HOMEVILLE AND GLEN ROY AROUND 1210 AM EDT...
  WOODLAWN AND OXFORD AROUND 1215 AM EDT...
  COCHRANVILLE AND FARMINGTON AROUND 1220 AM EDT...
  ZION AND LOMBARD AROUND 1225 AM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE WINDS OF MORE THAN 57 MPH...OR HAIL ONE
INCH OR LARGER.

VERY HEAVY RAIN WILL ALSO OCCUR WITH THIS LINE OF SEVERE
THUNDERSTORMS...WHICH COULD FLOOD LOW LYING AREAS QUICKLY AND COVER
ROADS WITH WATER. DO NOT DRIVE INTO AREAS WHERE WATER COVERS THE
ROAD.

FREQUENT CLOUD TO GROUND LIGHTNING IS OCCURRING WITH THIS LINE OF
SEVERE THUNDERSTORMS. WHEN THUNDER ROARS...MOVE INDOORS! REMEMBER...
IF YOU CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH TO BE STRUCK BY
LIGHTNING.

&&

LAT...LON 3973 7614 3977 7607 3985 7603 3988 7599
      3994 7599 4000 7571 3985 7571 3981 7575
      3963 7581 3961 7612 3964 7616 3966 7616
      3972 7623
TIME...MOT...LOC 0354Z 258DEG 22KT 3985 7613 3977 7612
          3974 7617 3962 7622

$$

FORECASTER:  DRAG

2 follow-up statements

170 
WWUS51 KPHI 290416
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1216 AM EDT MON JUL 29 2013

MDC015-PAC029-290445-
/O.CON.KPHI.SV.W.0083.000000T0000Z-130729T0445Z/
CECIL MD-CHESTER PA-
1216 AM EDT MON JUL 29 2013

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1245 AM EDT
FOR SOUTHWESTERN CHESTER AND NORTHERN CECIL COUNTIES...

AT 1212 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING
WINDS IN EXCESS OF 60 MPH. THESE STORMS WERE LOCATED ALONG A LINE
EXTENDING FROM HOMEVILLE TO OXFORD TO GLEN ROY TO WEST NOTTINGHAM...
MOVING EAST AT 25 MPH.

SEVERE THUNDERSTORMS WILL BE NEAR...
COCHRANVILLE AND ZION AROUND 1225 AM EDT...
WEST GROVE AND PLEASANT HILL AROUND 1230 AM EDT...
FAIR HILL AND CHERRY HILL AROUND 1235 AM EDT...
MODENA AND TOUGHKENAMON AROUND 1240 AM EDT...
LADENBERG AND GLEN WESTOVER AROUND 1245 AM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU ARE IN THE PATH OF THIS STORM...PREPARE FOR DAMAGING 
WINDS...AND DEADLY CLOUD TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD 
MOVE TO A SHELTER...PREFERABLY INSIDE A STRONG BUILDING...AWAY FROM 
WINDOWS OR EVEN BELOW GROUND LEVEL.

&&

LAT...LON 3974 7612 3977 7607 3984 7601 3988 7599
      4000 7571 3985 7571 3981 7575 3963 7581
      3965 7610 3969 7614
TIME...MOT...LOC 0416Z 258DEG 22KT 3984 7597 3980 7595
          3977 7600 3968 7603

$$

FORECASTER:  DRAG

342 
WWUS51 KPHI 290431
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1231 AM EDT MON JUL 29 2013

MDC015-PAC029-290445-
/O.CON.KPHI.SV.W.0083.000000T0000Z-130729T0445Z/
CECIL MD-CHESTER PA-
1231 AM EDT MON JUL 29 2013

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1245 AM EDT
FOR SOUTHWESTERN CHESTER AND NORTHEASTERN CECIL COUNTIES...

AT 1226 AM EDT...A LINE OF SEVERE THUNDERSTORMS WAS REPORTED CAPABLE
OF PRODUCING DAMAGING WINDS IN EXCESS OF 60 MPH. THESE STORMS WERE
LOCATED ALONG A LINE EXTENDING FROM WEST GROVE TO BLAKE TO ZION...
MOVING EAST AT 25 MPH.

SEVERE THUNDERSTORMS WILL BE NEAR...
WEST GROVE AND FAIR HILL AROUND 1235 AM EDT...
AVONDALE AND KEMBLESVILLE AROUND 1240 AM EDT...
LADENBERG AND GLEN WESTOVER AROUND 1245 AM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU ARE IN THE PATH OF THIS STORM...PREPARE FOR DAMAGING 
WINDS...AND DEADLY CLOUD TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD 
MOVE TO A SHELTER...PREFERABLY INSIDE A STRONG BUILDING...AWAY FROM 
WINDOWS OR EVEN BELOW GROUND LEVEL.


&&

LAT...LON 3975 7603 3977 7599 3982 7594 3995 7577
      3985 7573 3979 7576 3963 7581 3965 7599
      3972 7603
TIME...MOT...LOC 0430Z 258DEG 22KT 3982 7588 3979 7587
          3976 7589 3968 7592

$$

FORECASTER:  DRAG

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 28, 8:00 PM EDT	Special Weather Statement	PHI	Caroline	45 min
Jul 28, 8:06 PM EDT	Areal Flood Advisory	PHI	Caroline, Kent, Queen Anne's, Talbot	4 hr
Jul 28, 9:04 PM EDT	Flash Flood Warning	PHI	Kent, Queen Anne's	4 hr
Jul 28, 10:52 PM EDT	Special Weather Statement	PHI	Cecil	53 min
Jul 28, 11:33 PM EDT	Special Weather Statement	PHI	Cecil	42 min
Jul 28, 11:46 PM EDT	Areal Flood Advisory	PHI	Cecil	4 hr
Jul 28, 11:59 PM EDT	Special Weather Statement	PHI	Cecil	46 min
Jul 29, 12:39 AM EDT	Special Weather Statement	PHI	Cecil	66 min
Jul 28, 8:17 PM EDT	Areal Flood Advisory	PHI	Carbon, Monroe	118 min
Jul 28, 8:39 PM EDT	Areal Flood Warning	PHI	Chester	4 hr
Jul 28, 9:12 PM EDT	Areal Flood Advisory	PHI	Bucks, Philadelphia	4 hr
Jul 28, 9:45 PM EDT	Areal Flood Advisory	PHI	Carbon, Monroe	6 hr
Jul 29, 12:24 AM EDT	Areal Flood Advisory	PHI	Chester, Delaware	4 hr
Jul 29, 12:28 AM EDT	Special Weather Statement	PHI	Carbon, Lehigh	62 min
Jul 29, 12:45 AM EDT	Areal Flood Advisory	PHI	Berks, Lehigh, Northampton	4 hr
Jul 29, 1:05 AM EDT	Special Weather Statement	PHI	Lehigh, Monroe, Northampton	55 min
Jul 29, 1:18 AM EDT	Severe Thunderstorm Warning	PHI	Delaware	42 min
Jul 29, 1:45 AM EDT	Special Weather Statement	PHI	Monroe, Northampton	60 min

Nearby

Severe Thunderstorm Warnings in Maryland, 2013 Severe Thunderstorm Warnings in Pennsylvania, 2013 Every severe thunderstorm warning in 2013

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.