Alert archive / Virginia / Mesoscale Discussions in 2009

Mesoscale Discussion 889

May 29, 20096 states

The Storm Prediction Center issued this mesoscale discussion at May 29, 2009, 12:20 PM EDT for 6 states. It was in force for 55 min.

The area

The outline as issued.

The facts

Issued: May 29, 2009, 12:20 PM EDT (16:20 UTC)
Expired: May 29, 2009, 1:15 PM EDT
In force: 55 min
Issued by: the Storm Prediction Center

All 73 counties

Kent County, DE, New Castle County, DE, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Caroline County, MD, Carroll County, MD, Cecil County, MD, Charles County, MD, City of Baltimore, MD, Dorchester County, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Prince George's County, MD, Queen Anne's County, MD, Saint Mary's County, MD, Talbot County, MD, Washington County, MD, Atlantic County, NJ, Camden County, NJ, Cumberland County, NJ, Gloucester County, NJ, Salem County, NJ, Adams County, PA, Berks County, PA, Chester County, PA, Cumberland County, PA, Delaware County, PA, Franklin County, PA, Fulton County, PA, Lancaster County, PA, Lebanon County, PA, Montgomery County, PA, Philadelphia County, PA, York County, PA, Albemarle County, VA, Arlington County, VA, Caroline County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, Greene County, VA, King George County, VA, Loudoun County, VA, Louisa County, VA, Madison County, VA, Orange County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Richmond County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Westmoreland County, VA, Berkeley County, WV, Jefferson County, WV, Morgan County, WV

The radar

The Sterling radar (KLWX), 30 km from the middle of the area, began a volume at 16:23 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 314May 29, 1:25 PM EDT

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 4.3 hours before the alert went out and 103 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: 4 J/kg
Mixed-layer CIN: -283 J/kg
Mixed-layer LCL: 620 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 58 m²/s²
0-3 km storm-relative helicity: 139 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.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 29, 1:26 PM EDT	Severe Thunderstorm Watch	SPC	Kent, New Castle, Sussex	8 hr
May 29, 4:30 PM EDT	Mesoscale Discussion	SPC	Kent, New Castle, Sussex	60 min
May 29, 6:20 PM EDT	Mesoscale Discussion	SPC	Kent, New Castle, Sussex	55 min
May 29, 2:22 PM EDT	Mesoscale Discussion	SPC	Brunswick, Charlotte, Greensville, Halifax, Lunenburg, Mecklenburg and 6 more	23 min
May 29, 2:41 PM EDT	Severe Thunderstorm Watch	SPC	Amelia, Appomattox, Brunswick, Campbell, Charles City, Charlotte and 37 more	8 hr
May 29, 6:01 PM EDT	Mesoscale Discussion	SPC	Amelia, Appomattox, Brunswick, Campbell, Charles City, Charlotte and 37 more	59 min

Nearby

Mesoscale Discussions in Virginia, 2009 Mesoscale Discussions in Maryland, 2009 Mesoscale Discussions in Pennsylvania, 2009 Every mesoscale discussion 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.