Alert archive / Virginia / Mesoscale Discussions in 2012

Mesoscale Discussion 351

March 24, 201230 counties in North Carolina; 48 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Mar 24, 2012, 6:03 PM EDT for 30 counties in North Carolina; 48 counties in Virginia. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Mar 24, 2012, 6:03 PM EDT (22:03 UTC)
Expired: Mar 24, 2012, 8:30 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 78 counties

Beaufort County, NC, Bertie County, NC, Bladen County, NC, Brunswick County, NC, Camden County, NC, Carteret County, NC, Chowan County, NC, Columbus County, NC, Craven County, NC, Currituck County, NC, Dare County, NC, Duplin County, NC, Gates County, NC, Greene County, NC, Hertford County, NC, Hyde County, NC, Jones County, NC, Lenoir County, NC, Martin County, NC, New Hanover County, NC, Northampton County, NC, Onslow County, NC, Pamlico County, NC, Pasquotank County, NC, Pender County, NC, Perquimans County, NC, Pitt County, NC, Robeson County, NC, Tyrrell County, NC, Washington County, NC, Amelia County, VA, Brunswick County, VA, Caroline County, VA, Charles City County, VA, Chesterfield County, 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 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 Williamsburg, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Fluvanna County, VA, Gloucester County, VA, Goochland County, VA, Greensville County, VA, Hanover County, VA, Henrico County, VA, Isle of Wight County, VA, James City County, VA, King and Queen County, VA, King William County, VA, Louisa County, VA, Lunenburg County, VA, Mecklenburg County, VA, Middlesex County, VA, New Kent County, VA, Nottoway County, VA, Orange County, VA, Powhatan County, VA, Prince George County, VA, Richmond County, VA, Southampton County, VA, Spotsylvania County, VA, Surry County, VA, Sussex County, VA, York County, VA

The radar

The Raleigh/Durham radar (KRAX), 94 km from the middle of the area, began a volume at 22:05 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.

The nearest sounding before it

Newport, NC (KMHX), launched 12:00Z, 10.1 hours before the alert went out and 106 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: 441 J/kg
Mixed-layer CIN: -6 J/kg
Mixed-layer LCL: 531 m above ground
0-6 km bulk shear: 17 kt
0-1 km storm-relative helicity: -57 m²/s²
0-3 km storm-relative helicity: -59 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.

534 
ACUS11 KWNS 242204
SWOMCD
SPC MCD 242203
NCZ000-VAZ000-250030-

MESOSCALE DISCUSSION 0351
NWS STORM PREDICTION CENTER NORMAN OK
0503 PM CDT SAT MAR 24 2012

AREAS AFFECTED...PORTIONS CENTRAL/S-CENTRAL/SERN VA...ERN NC.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 242203Z - 250030Z

SVR TSTM POTENTIAL MAY SPREAD ACROSS THIS REGION FROM W-E OVER NEXT
FEW HOURS...IN ASSOCIATION WITH TWO PRIMARY REGIMES...

1. LOOSELY ORGANIZED BELT OF SCATTERED TO NUMEROUS TSTMS EVIDENT AT
2145Z FROM ERN PORTIONS SC/NC BORDER NEWD ACROSS ERN PORTIONS WW 108
INTO NERN NC NE OF WW.  AIR MASS E OF THIS ACTIVITY APPEARS MRGLLY
FAVORABLE...THANKS TO COMBINATION OF
A. EARLIER/PERSISTENT CLOUDS AND PRECIP AND
B. INLAND PENETRATION OF SEA BREEZE AIR
...EACH OF WHICH SUBSTANTIALLY HAS LIMITED BOUNDARY-LAYER LAPSE
RATES AND DESTABILIZATION.  STILL...MODIFIED FCST SOUNDINGS SUGGEST
LOW-LEVEL THETAE WILL BE SUFFICIENT TO OFFSET WEAK MIDLEVEL LAPSE
RATES AND SUPPORT MLCAPE 200-800 J/KG AHEAD OF THIS ACTIVITY.
DEEP-LAYER SHEAR WILL CONTINUE TO WEAKEN WITH EWD EXTENT...SO
PRIMARY MODE WILL REMAIN MULTICELLULAR AND CLUSTERED WITH THIS
ACTIVITY.  SOME POTENTIAL EXISTS FOR AGGREGATE COLD-POOL GENERATION
RELATED TO CLUSTER MOVING NEWD OUT OF SC INTO SERN NC...WHICH MAY
PRODUCE FORCED ASCENT OF MRGLLY FAVORABLE AREA ACROSS COASTAL
PLAIN/TIDEWATER OF NC.  OTHERWISE...ISOLATED DOWNBURSTS WITH MOST
INTENSE/EMBEDDED CELLS WILL POSE PRIMARY DAMAGING GUST POTENTIAL.

2. BETTER-ORGANIZED ARC OF CONVECTION NOW TRANSLATING EWD ACROSS ERN
WV...WRN VA...AND WRN CAROLINAS IN WWS 105-108.  MORE FAVORABLE
PARAMETERS ARE EVIDENT FOR BOTH DEEP-LAYER SHEAR AND BOUNDARY-LAYER
INSTABILITY.  OUTFLOW BOUNDARY FROM EARLIER CONVECTION WAS ANALYZED
OVER MADISON/BUCKINGHAM/CAMPBELL/BEDFORD COUNTIES VA.  RELATED
ENHANCEMENTS TO LOW-LEVEL LIFT/SHEAR/VORTICITY APPEAR TO BE AIDING
MESOCYCLONE PRODUCTION/MAINTENANCE WITH SWRN VA CONVECTION
INTERACTING WITH IT.  ONE OFFSETTING FACTOR IS THAT STORM MOTIONS
MAY OUTPACE EWD TRANSLATION OF FAVORABLE SHEAR.  ANOTHER IS THAT
LOW-LEVEL LAPSE RATES PROBABLY ARE PAST PEAK GIVEN COMBINATION OF
A. LOSS OF INSOLATION/DIABATIC SFC HEATING AND
B. INCREASING ANTECEDENT MLCINH WITH NEWD EXTENT OVER NERN NC AND
SERN VA RELATED TO STABILIZATION BY EARLIER CONVECTION.
STILL...NARROW SWATH OF CENTRAL/SRN VA AND NERN NC AHEAD OF ONGOING
WWS MAY BECOME FAVORABLE FOR A FEW HOURS BEFORE ACTIVITY WEAKENS.

..EDWARDS.. 03/24/2012

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

ATTN...WFO...AKQ...MHX...LWX...RAH...ILM...RNK...

LAT...LON   36877835 38267828 38277693 36817596 36117574 35647547
            35137552 35247560 35077597 34507657 34637654 34677699
            34417755 34027787 33747797 33927810 33897856 34627930
            34907883 34687821 36117727 36557796 36617876 37107840
            37287869 36877835

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 24, 12:03 PM EDT	Mesoscale Discussion	SPC	Alamance, Alexander, Alleghany, Anson, Cabarrus, Caswell and 20 more	117 min
Mar 24, 12:46 PM EDT	Severe Thunderstorm Watch	SPC	Alamance, Alexander, Alleghany, Anson, Ashe, Avery and 33 more	7 hr
Mar 24, 2:31 PM EDT	Mesoscale Discussion	SPC	Alexander, Alleghany, Ashe, Avery, Burke, Caldwell and 4 more	59 min
Mar 24, 2:54 PM EDT	Mesoscale Discussion	SPC	Caswell, Forsyth, Guilford, Rockingham, Stokes, Surry and 1 more	66 min
Mar 24, 3:38 PM EDT	Tornado Watch	SPC	Alamance, Anson, Caswell, Chatham, Cumberland, Davidson and 30 more	7 hr
Mar 24, 4:16 PM EDT	Mesoscale Discussion	SPC	Cabarrus, Davidson, Davie, Forsyth, Iredell, Mecklenburg and 6 more	59 min
Mar 24, 6:43 PM EDT	Tornado Watch	SPC	Caswell, Rockingham	4 hr
Mar 24, 6:58 PM EDT	Mesoscale Discussion	SPC	Alexander, Alleghany, Burke, Cabarrus, Caldwell, Catawba and 9 more	92 min
Mar 24, 7:34 PM EDT	Mesoscale Discussion	SPC	Alamance, Anson, Caswell, Chatham, Cumberland, Durham and 23 more	116 min
Mar 24, 3:02 PM EDT	Severe Thunderstorm Watch	SPC	Albemarle, Alleghany, Amherst, Appomattox, Augusta, Bath and 13 more	5 hr

Nearby

Mesoscale Discussions in Virginia, 2012 Mesoscale Discussions in North Carolina, 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.