Alert archive / Virginia / Mesoscale Discussions in 2012

Mesoscale Discussion 357

March 24, 201214 counties in North Carolina; 21 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Mar 24, 2012, 10:23 PM EDT for 14 counties in North Carolina; 21 counties in Virginia. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued: Mar 24, 2012, 10:23 PM EDT (02:23 UTC)
Expired: Mar 25, 2012, 12:00 AM EDT
In force: 97 min
Issued by: the Storm Prediction Center

All 35 counties

Bertie County, NC, Edgecombe County, NC, Franklin County, NC, Greene County, NC, Halifax County, NC, Hertford County, NC, Johnston County, NC, Martin County, NC, Nash County, NC, Northampton County, NC, Pitt County, NC, Warren County, NC, Wayne County, NC, Wilson County, NC, Amelia County, VA, Brunswick County, VA, Charles City County, VA, Chesterfield County, VA, City of Colonial Heights, VA, City of Emporia, VA, City of Hopewell, VA, City of Petersburg, VA, City of Richmond, VA, Dinwiddie County, VA, Goochland County, VA, Greensville County, VA, Hanover County, VA, Henrico County, VA, King William County, VA, New Kent County, VA, Nottoway County, VA, Powhatan County, VA, Prince George County, VA, Southampton County, VA, Sussex County, VA

The radar

The Norfolk radar (KAKQ), 72 km from the middle of the area, began a volume at 02:26 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 00:00Z, 2.4 hours before the alert went out and 174 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: 47 J/kg
Mixed-layer CIN: -46 J/kg
Mixed-layer LCL: 741 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: -2 m²/s²
0-3 km storm-relative helicity: 71 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.

545 
ACUS11 KWNS 250223
SWOMCD
SPC MCD 250223 
NCZ000-VAZ000-250400-

MESOSCALE DISCUSSION 0357
NWS STORM PREDICTION CENTER NORMAN OK
0923 PM CDT SAT MAR 24 2012

AREAS AFFECTED...PORTIONS CENTRAL/ERN NC...CENTRAL/SRN VA.

CONCERNING...TORNADO WATCH 108...109...

VALID 250223Z - 250400Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 108...109...CONTINUES.

WWS CAN CONTINUE TO BE CLEARED BEHIND WEAKENING MCS ACROSS REGION. 
ACTIVITY HAS SHOWN DECREASING TREND AS IT ENCOUNTERS BOUNDARY-LAYER
AIR STABILIZED PROGRESSIVELY MORE STRONGLY WITH TIME BY COMBINATION
OF
1. SFC DIABATIC COOLING NEAR SFC AND
2. OUTFLOW-STABILIZED AIR FROM EARLIER CONVECTION.
AS SUCH...INFLOW-LAYER PARCELS EXHIBIT MEAGER MLCAPE -- AOB 300 J/KG
MOST AREAS -- AND MAY NOT BE ROOTED AT SFC ANYMORE...BASED ON
MODIFIED RAOBS AND RUC FCST SOUNDINGS.  THOUGH ISOLATED SVR CANNOT
BE RULED OUT...OVERALL THREAT HAS DIMINISHED SUCH THAT EITHER OR
BOTH WWS MAY BE CANCELED BEFORE THEIR SCHEDULED EXPIRATION TIMES.

THREAT FOR LOCALIZED HEAVY RAIN RATES NEAR 2 INCHES/HOUR WILL
PERSIST FOR ANOTHER HOUR OR TWO WITH STRONGEST PORTION OF
COMPLEX...LOCATED OVER PORTIONS AMELIA/POWHATAN COUNTIES VA AS OF
215Z AND MOVING NEWD TOWARD RIC AREA.

..EDWARDS.. 03/25/2012

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

ATTN...WFO...AKQ...MHX...LWX...RAH...

LAT...LON   35677850 36787819 37537812 37907823 38097752 37657691
            36677696 36207658 35567685 35127809 35677850

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 24, 8:43 PM EDT	Severe Thunderstorm Watch	SPC	Bladen, Columbus, Robeson	5 hr
Mar 24, 10:20 PM EDT	Mesoscale Discussion	SPC	Brunswick, Columbus, Robeson	115 min
Mar 25, 12:33 AM EDT	Mesoscale Discussion	SPC	Bladen, Brunswick, Columbus, Robeson	57 min
Mar 25, 12:31 PM EDT	Mesoscale Discussion	SPC	Beaufort, Bertie, Bladen, Brunswick, Carteret, Chowan and 26 more	2 hr
Mar 25, 5:56 PM EDT	Mesoscale Discussion	SPC	Bladen, Brunswick, Carteret, Columbus, Craven, Dare and 7 more	94 min

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.