Alert archive / Virginia / Mesoscale Discussions in 2004

Mesoscale Discussion 613

May 9, 20044 states

The Storm Prediction Center issued this mesoscale discussion at May 9, 2004, 12:12 PM EDT for 4 states. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: May 9, 2004, 12:12 PM EDT (16:12 UTC)
Expired: May 9, 2004, 2:45 PM EDT
In force: 3 hr
Issued by: the Storm Prediction Center

All 67 counties

Allegany County, MD, Carroll County, MD, Frederick County, MD, Garrett County, MD, Montgomery County, MD, Washington County, MD, Adams County, PA, Bedford County, PA, Franklin County, PA, Fulton County, PA, Albemarle County, VA, Alleghany County, VA, Amherst County, VA, Arlington County, VA, Augusta County, VA, Bath County, VA, Buckingham County, VA, City of Alexandria, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Covington, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Harrisonburg, VA, City of Lexington, VA, City of Manassas, VA, City of Manassas Park, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Cumberland County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Frederick County, VA, Goochland County, VA, Greene County, VA, Highland County, VA, King George County, VA, Loudoun County, VA, Louisa County, VA, Madison County, VA, Nelson County, VA, Orange County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Rockbridge County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Berkeley County, WV, Grant County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Mineral County, WV, Morgan County, WV, Pendleton County, WV, Pocahontas County, WV, Randolph County, WV, Tucker County, WV

The radar

The Sterling radar (KLWX), 84 km from the middle of the area, began a volume at 16:16 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

Roanoke, VA (KRNK), launched 12:00Z, 4.2 hours before the alert went out and 195 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: 53 J/kg
Mixed-layer CIN: -197 J/kg
Mixed-layer LCL: 1419 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: -10 m²/s²
0-3 km storm-relative helicity: -2 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 
ACUS11 KWNS 091612
SWOMCD
SPC MCD 091612 
MDZ000-PAZ000-DCZ000-VAZ000-WVZ000-091845-

MESOSCALE DISCUSSION 0613
NWS STORM PREDICTION CENTER NORMAN OK
1112 AM CDT SUN MAY 09 2004

AREAS AFFECTED...FAR ERN WV...S-CENTRAL PA...CENTRAL/NRN
VA...WRN/CENTRAL MD...WASHINGTON D.C. METRO

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 091612Z - 091845Z

THUNDERSTORM DEVELOPMENT IS POSSIBLE ACROSS THE HIGHER TERRAIN OF
SRN PA/WRN MD/ERN WV DURING THE NEXT 1-2 HOURS. STORMS DEVELOPING IN
THIS REGION WILL MOVE GENERALLY 280/20 KT. THREAT OF HAIL AND
DAMAGING WINDS MAY NECESSITATE A SEVERE THUNDERSTORM WATCH THIS
AFTERNOON ACROSS PORTIONS OF THE AREA.

AT 16Z...CIN HAS RAPIDLY DIMINISHED ACROSS ERN WV NWD INTO S-CENTRAL
PA IN RESPONSE TO CONTINUED SURFACE HEATING /TEMPERATURES IN THE LOW
TO MID 80S NEAR THE BLUE RIDGE/. VISIBLE SATELLITE IMAGERY SHOWS
INCREASING BOUNDARY LAYER CU ACROSS THE MOUNTAINOUS TERRAIN AND
THUNDERSTORM DEVELOPMENT IS POSSIBLE DURING THE NEXT 1-2 HOURS.

DISCUSSION AREA IS ON THE SRN FRINGE OF THE WESTERLIES...WITH ETA
AND RUC MODEL SOUNDINGS INDICATING AROUND 30 KT OF SFC-6KM SHEAR
ACROSS THE REGION THIS AFTERNOON. THIS SHOULD BE SUFFICIENT FOR A
FEW LONGER LIVED STORMS AND SHORT CONVECTIVE LINE SEGMENTS CAPABLE
OF PRODUCING SEVERE HAIL AND WIND. SURFACE DEWPOINTS IN THE 60S WILL
LEAD TO 100MB MLCAPE VALUES OF 1000-1500 J/KG THIS AFTERNOON.
ALTHOUGH LARGE-SCALE FORCING IS WEAK...ISOLATED STORMS FORMING OVER
THE MTNS SHOULD MOVE EWD INTO THE COASTAL PLAIN OF CENTRAL/NRN
VA...CENTRAL MD...AND S-CENTRAL PA TOWARD MID-LATE AFTERNOON
SUSTAINED BY SUFFICIENT CAPE AND SHEAR.

..BANACOS.. 05/09/2004

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

ATTN...WFO...AKQ...CTP...LWX...RNK...PBZ...RLX...

38917983 40097891 40147786 40037708 38937687 38387706
37827753 37537812 37417894 37878042

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 9, 1:43 PM EDT	Mesoscale Discussion	SPC	Armstrong, Berks, Blair, Cambria, Cameron, Carbon and 24 more	2 hr
May 9, 11:20 AM EDT	Mesoscale Discussion	SPC	Carroll, Floyd, Franklin, Grayson, Henry, Patrick and 6 more	2 hr

Nearby

Mesoscale Discussions in Virginia, 2004 Mesoscale Discussions in West Virginia, 2004 Mesoscale Discussions in Maryland, 2004 Every mesoscale discussion in 2004

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.