Alert archive / Maryland / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 207, NWS Philadelphia/Mount Holly

August 18, 20094 counties in Maryland

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 18, 2009, 8:35 PM EDT for 4 counties in Maryland. It was in force for 55 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: Aug 18, 2009, 8:35 PM EDT (00:35 UTC)
Expired: Aug 18, 2009, 9:30 PM EDT
In force: 55 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

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

The radar

The Dover AFB radar (KDOX), 70 km from the middle of the area, began a volume at 00:37 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 00:00Z, 0.6 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: 1007 J/kg
Mixed-layer CIN: -48 J/kg
Mixed-layer LCL: 1498 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 53 m²/s²
0-3 km storm-relative helicity: 129 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 190035 RRA
SVRPHI
MDC011-029-035-041-190130-
/O.NEW.KPHI.SV.W.0207.090819T0035Z-090819T0130Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
835 PM EDT TUE AUG 18 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHERN CAROLINE COUNTY IN EASTERN MARYLAND...
  NORTHEASTERN TALBOT COUNTY IN EASTERN MARYLAND...
  SOUTHERN KENT COUNTY IN NORTHEAST MARYLAND...
  QUEEN ANNES COUNTY IN NORTHEAST MARYLAND...
  THIS INCLUDES THE CITY OF CENTERVILLE...

* UNTIL 930 PM EDT

* AT 833 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING PENNY SIZE HAIL...AND
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR
  CHESTER...OR 13 MILES WEST OF CENTERVILLE...AND MOVING EAST AT 20
  MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  GRASONVILLE AND OVERTON AROUND 845 PM EDT...
  WYE MILLS AROUND 905 PM EDT...
  CENTERVILLE AND CENTREVILLE AROUND 910 PM EDT...
  STARR AND CARVILLE AROUND 915 PM EDT...
  HOPE AROUND 920 PM EDT...
  OAKLAND AND JUMPTOWN AROUND 930 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY FOR DAMAGING WINDS...DESTRUCTIVE HAIL...AND DEADLY CLOUD
TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS.

&&

LAT...LON 3904 7631 3899 7624 3900 7618 3903 7625
      3910 7624 3915 7628 3930 7578 3890 7577
      3889 7620 3894 7624 3890 7624 3893 7628
      3890 7629 3891 7631 3889 7632 3889 7635
      3894 7637
TIME...MOT...LOC 0035Z 264DEG 18KT 3898 7627

$$

RNS

Nearby

Severe Thunderstorm Warnings in Maryland, 2009 Every severe thunderstorm warning in 2009

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.