Alert archive / Virginia / Mesoscale Discussions in 2016

Mesoscale Discussion 813

June 4, 2016Allegany County, Washington County, Maryland; 49 counties in Virginia; 7 counties in West Virginia

The Storm Prediction Center issued this mesoscale discussion at Jun 4, 2016, 1:33 PM EDT for Allegany County, Washington County, Maryland; 49 counties in Virginia; 7 counties in West Virginia. It was in force for 117 min.

The area

The outline as issued.

The facts

Issued: Jun 4, 2016, 1:33 PM EDT (17:33 UTC)
Expired: Jun 4, 2016, 3:30 PM EDT
In force: 117 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 58 counties

Allegany County, MD, Washington County, MD, Albemarle County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Augusta County, VA, Bath County, VA, Bedford County, VA, Botetourt County, VA, Buckingham County, VA, Campbell County, VA, Charlotte County, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Fredericksburg, VA, City of Harrisonburg, VA, City of Lexington, VA, City of Lynchburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Roanoke, VA, City of Salem, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Cumberland County, VA, Fauquier County, VA, Fluvanna County, VA, Franklin County, VA, Frederick County, VA, Goochland County, VA, Greene County, VA, Loudoun County, VA, Louisa County, VA, Madison County, VA, Nelson County, VA, Orange County, VA, Page County, VA, Powhatan County, VA, Prince Edward 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, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Mineral County, WV, Morgan County, WV, Pendleton County, WV

The radar

The Sterling radar (KLWX), 121 km from the middle of the area, began a volume at 17:35 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, 5.6 hours before the alert went out and 126 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: 225 J/kg
Mixed-layer CIN: -7 J/kg
Mixed-layer LCL: 591 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 13 m²/s²
0-3 km storm-relative helicity: 63 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted.

162 
ACUS11 KWNS 041734
SWOMCD
SPC MCD 041733 
MDZ000-VAZ000-WVZ000-041930-

MESOSCALE DISCUSSION 0813
NWS STORM PREDICTION CENTER NORMAN OK
1233 PM CDT SAT JUN 04 2016

AREAS AFFECTED...PORTIONS OF WRN/CENTRAL VA...WRN MD...WV PANHANDLE

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 041733Z - 041930Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...AN INCREASE IN THUNDERSTORM COVERAGE IS EXPECTED THIS
AFTERNOON WITH THE STRONGEST STORMS CAPABLE OF DAMAGING WINDS AND
HAIL. TRENDS IN EXPECTED THUNDERSTORM COVERAGE WILL BE MONITORED FOR
THE POSSIBILITY OF A SEVERE THUNDERSTORM WATCH.

DISCUSSION...A FEW THUNDERSTORMS HAVE DEVELOPED OVER THE BLUE RIDGE
MOUNTAINS EARLY THIS AFTERNOON AS DIURNAL HEATING OF A VERY MOIST
AND UNCAPPED LOW-LEVEL AIR MASS /UPPER 60S-LOWER 70S SURFACE DEW
POINTS/ CONTINUES. FARTHER EAST...LOW CLOUDS CONTINUE TO ERODE OVER
CENTRAL VIRGINIA WITH TEMPERATURES WARMING INTO THE UPPER 70S. 

CONTINUED INSOLATION AND EROSION OF LOW CLOUDS WILL RESULT IN A
WEAK-MODERATELY BUOYANT ENVIRONMENT BY MID AFTERNOON. THE DISCUSSION
AREA IS ON THE SOUTHERN FRINGE OF STRONGER MID-LEVEL FLOW WHICH WILL
RESULT IN AROUND 30-35 KTS OF VERTICAL SHEAR...SUFFICIENT FOR
ORGANIZED THUNDERSTORMS CAPABLE OF DAMAGING WINDS AND PERHAPS HAIL.
OVERALL STORM COVERAGE SHOULD INCREASE WITH EASTWARD EXTENT THIS
AFTERNOON WITH ONE OR MORE CLUSTERS OF STORMS MOVING TOWARDS THE
I-95 CORRIDOR. 

THE PRIMARY LIMITING FACTOR FOR WATCH ISSUANCE IS THE ANTICIPATED
SEVERE STORM COVERAGE. CONVECTIVE AND SHORT-TERM GUIDANCE TRENDS
WILL CONTINUE TO BE MONITORED FOR THE POSSIBILITY OF A WATCH BY
MID-AFTERNOON.

..BUNTING/WEISS.. 06/04/2016

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

ATTN...WFO...AKQ...LWX...RNK...

LAT...LON   37388019 37877988 38677935 39387899 39637879 39697855
            39677835 39627781 39377741 39047730 38607734 38097752
            37337794 36877841 36807900 36927998 37388019

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 4, 12:44 PM EDT	Mesoscale Discussion	SPC	Buchanan, Dickenson, Lee, Russell, Scott, Tazewell and 4 more	2 hr
Jun 4, 3:49 PM EDT	Mesoscale Discussion	SPC	Cabell, Jackson, Lincoln, Mason, Pleasants, Putnam and 3 more	116 min

Nearby

Mesoscale Discussions in Virginia, 2016 Mesoscale Discussions in West Virginia, 2016 Mesoscale Discussions in Maryland, 2016 Every mesoscale discussion in 2016

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.