Alert archive / Virginia / Mesoscale Discussions in 2003

Mesoscale Discussion 1649

July 6, 20035 states

The Storm Prediction Center issued this mesoscale discussion at Jul 6, 2003, 1:04 PM EDT for 5 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jul 6, 2003, 1:04 PM EDT (17:04 UTC)
Expired: Jul 6, 2003, 3:30 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 88 counties

Kent County, DE, Sussex County, DE, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Caroline County, MD, Charles County, MD, City of Baltimore, MD, Dorchester 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, Somerset County, MD, Talbot County, MD, Wicomico County, MD, Worcester County, MD, Caswell County, NC, Granville County, NC, Person County, NC, Rockingham County, NC, Stokes County, NC, Cape May County, NJ, Cumberland County, NJ, Albemarle County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Arlington County, VA, Bedford County, VA, Buckingham County, VA, Campbell County, VA, Caroline County, VA, Charlotte County, VA, Chesterfield County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Colonial Heights, VA, City of Danville, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Hopewell, VA, City of Lynchburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Martinsville, VA, City of Petersburg, VA, City of Richmond, VA, City of Waynesboro, VA, Culpeper County, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Franklin County, VA, Goochland County, VA, Greene County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Henry County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Louisa County, VA, Lunenburg County, VA, Madison County, VA, Mecklenburg County, VA, Nelson County, VA, New Kent County, VA, Northumberland County, VA, Nottoway County, VA, Orange County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince William County, VA, Rappahannock County, VA, Richmond County, VA, Spotsylvania County, VA, Stafford County, VA, Westmoreland County, VA

The radar

The Sterling radar (KLWX), 102 km from the middle of the area, began a volume at 17:06 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, 5.1 hours before the alert went out and 98 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: 487 J/kg
Mixed-layer CIN: -143 J/kg
Mixed-layer LCL: 1310 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 32 m²/s²
0-3 km storm-relative helicity: 44 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.

577 
ACUS11 KWNS 061705
SWOMCD
SPC MCD 061704 
NJZ000-DEZ000-MDZ000-VAZ000-DCZ000-NCZ000-061930-

MESOSCALE DISCUSSION 1649
NWS STORM PREDICTION CENTER NORMAN OK
1204 PM CDT SUN JUL 06 2003

AREAS AFFECTED...PARTS OF CNTRL/NRN VA...MD...DE..NJ

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 061704Z - 061930Z

A FEW STRONG THUNDERSTORMS APPEAR LIKELY THIS AFTERNOON...AND MAY BE
ACCOMPANIED BY DAMAGING WIND GUSTS...BUT A WW IS NOT CURRENTLY
ANTICIPATED.

SURFACE TEMPERATURES HAVE ALREADY WARMED TO AROUND 90F IN THE LEE OF
THE CENTRAL APPALACHIANS WITH STRONG DAYTIME HEATING...SOUTH OF
PRE-FRONTAL WIND SHIFT/CONFLUENT ZONE EXTENDING FROM THE EASTERN
WEST VIRGINIA PANHANDLE INTO THE VICINITY OF THE PENNSYLVANIA/
MARYLAND BORDER AND SOUTHERN NEW JERSEY.  WITH ADDITIONAL HEATING...
CONVECTIVE INHIBITION WILL CONTINUE TO WEAKEN...LIKELY SUPPORTING AT
LEAST SCATTERED STRONG CONVECTIVE DEVELOPMENT DESPITE LACK OF MORE
READILY APPARENT LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION. 
WEAK CONVERGENCE NEAR BOUNDARY AND LEE SURFACE TROUGH ACROSS WEST
CENTRAL VIRGINIA LIKELY WILL PROVIDE FOCUS FOR THUNDERSTORM ACTIVITY
...A FEW OF WHICH WILL BECOME VIGOROUS IN MOIST BOUNDARY LAYER WITH
LOWER/MID 70S DEW POINTS AND MEAN MIXED LAYER CAPE OF 1000 TO 2000
J/KG.

THERMODYNAMIC PROFILES ARE WARM...AND SHEAR WEAK...BUT PRESENCE OF
SUFFICIENTLY LOW RELATIVE HUMIDITIES MAY ENHANCE POTENTIAL FOR
ISOLATED DOWNBURSTS IN STRONGEST CELLS.  GUSTY WINDS ALSO APPEAR
LIKELY ALONG LEADING EDGE OF WEAK COLD POOLS EVOLVING IN 20 TO 25 KT
WESTERLY MEAN FLOW REGIME.

..KERR.. 07/06/2003

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...PHI...AKQ...LWX...RAH...RNK...

37907548 37797654 37077747 36117889 36158058 36668014
37937919 38827823 39037740 39507676 39587608 39327490
39297456

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 6, 12:28 AM EDT	Mesoscale Discussion	SPC	Kent, New Castle	2 hr
Jul 6, 7:23 PM EDT	Mesoscale Discussion	SPC	Kent, New Castle	67 min
Jul 6, 5:46 PM EDT	Mesoscale Discussion	SPC	Anne Arundel, Calvert, Charles, Montgomery, Prince George's, Saint Mary's	59 min

Nearby

Mesoscale Discussions in Virginia, 2003 Mesoscale Discussions in Maryland, 2003 Mesoscale Discussions in North Carolina, 2003 Every mesoscale discussion in 2003

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.