Alert archive / Virginia / Mesoscale Discussions in 2012

Mesoscale Discussion 1273

June 25, 20124 counties in Maryland; 66 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Jun 25, 2012, 3:57 PM EDT for 4 counties in Maryland; 66 counties in Virginia. It was in force for 63 min.

The area

The outline as issued.

The facts

Issued: Jun 25, 2012, 3:57 PM EDT (19:57 UTC)
Expired: Jun 25, 2012, 5:00 PM EDT
In force: 63 min
Issued by: the Storm Prediction Center

All 70 counties

Saint Mary's County, MD, Somerset County, MD, Wicomico County, MD, Worcester County, MD, Accomack County, VA, Albemarle County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Brunswick County, VA, Buckingham County, VA, Campbell County, VA, Caroline County, VA, Charles City County, VA, Charlotte County, VA, Chesterfield County, VA, City of Charlottesville, VA, City of Chesapeake, VA, City of Colonial Heights, VA, City of Emporia, VA, City of Franklin, VA, City of Hampton, VA, City of Hopewell, VA, City of Lynchburg, VA, City of Newport News, VA, City of Norfolk, VA, City of Petersburg, VA, City of Poquoson, VA, City of Portsmouth, VA, City of Richmond, VA, City of Suffolk, VA, City of Virginia Beach, VA, City of Waynesboro, VA, City of Williamsburg, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Fluvanna County, VA, Gloucester County, VA, Goochland County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Isle of Wight County, VA, James City County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Lancaster County, VA, Louisa County, VA, Lunenburg County, VA, Mathews County, VA, Mecklenburg County, VA, Middlesex County, VA, Nelson County, VA, New Kent County, VA, Northampton County, VA, Northumberland County, VA, Nottoway County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Richmond County, VA, Southampton County, VA, Spotsylvania County, VA, Surry County, VA, Sussex County, VA, Westmoreland County, VA, York County, VA

The radar

The Norfolk radar (KAKQ), 86 km from the middle of the area, began a volume at 19:59 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, 8.0 hours before the alert went out and 156 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: 1176 J/kg
Mixed-layer CIN: -98 J/kg
Mixed-layer LCL: 1268 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 84 m²/s²
0-3 km storm-relative helicity: 95 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 2.8

Open this sounding in Storm Lab

The text

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

282 
ACUS11 KWNS 251958
SWOMCD
SPC MCD 251957
DEZ000-MDZ000-VAZ000-NCZ000-252100-

MESOSCALE DISCUSSION 1273
NWS STORM PREDICTION CENTER NORMAN OK
0257 PM CDT MON JUN 25 2012

AREAS AFFECTED...SERN MD...VA

CONCERNING...SEVERE THUNDERSTORM WATCH 426...

VALID 251957Z - 252100Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 426
CONTINUES.

SUMMARY...DAMAGING WINDS AND LARGE HAIL WILL ACCOMPANY THUNDERSTORMS
AS THEY SPREAD TOWARD COASTAL SERN VA.

DISCUSSION...SOMEWHAT VEERED LOW LEVEL FLOW HAS ALLOWED LOW LEVEL
LAPSE RATES TO STEEPEN SIGNIFICANTLY ACROSS SRN VA WHERE SFC-3KM
VALUES ARE NOW ON THE ORDER OF 9 C/KM.  THIS APPEARS PARTLY
RESPONSIBLE FOR ROBUST UPDRAFTS AND SEVERE DOWNBURSTS THAT HAVE BEEN
NOTED WITH PRE-FRONTAL CONVECTION.  UNTIL THIS AIR MASS STABILIZES
DUE TO FRONTAL PASSAGE OR DIURNAL COOLING THERE IS MORE THAN
ADEQUATE INSTABILITY ACROSS THIS REGION FOR SEVERE THUNDERSTORMS
CAPABLE OF PRODUCING DAMAGING WIND GUSTS AND LARGE HAIL.  GREATEST
CONCENTRATION OF STORMS WILL SOON CONGREGATE OVER SERN VA.

..DARROW.. 06/25/2012

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

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

LAT...LON   38137923 38457529 36727529 36387921 38137923

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 25, 10:44 AM EDT	Mesoscale Discussion	SPC	Anne Arundel, Calvert, Caroline, Charles, Dorchester, Kent and 6 more	61 min
Jun 25, 12:55 PM EDT	Severe Thunderstorm Watch	SPC	Dorchester, Saint Mary's, Somerset, Wicomico, Worcester	6 hr

Nearby

Mesoscale Discussions in Virginia, 2012 Mesoscale Discussions in Maryland, 2012 Every mesoscale discussion in 2012

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.