Alert archive / Virginia / Mesoscale Discussions in 2006

Mesoscale Discussion 421

April 3, 200643 counties in North Carolina; 48 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Apr 3, 2006, 2:36 PM EDT for 43 counties in North Carolina; 48 counties in Virginia. It was in force for 114 min.

The area

The outline as issued.

The facts

Issued
Apr 3, 2006, 2:36 PM EDT (18:36 UTC)
Expired
Apr 3, 2006, 4:30 PM EDT
In force
114 min
Issued by
the Storm Prediction Center
All 91 counties

Alamance County, NC, Beaufort County, NC, Bertie County, NC, Camden County, NC, Caswell County, NC, Chatham County, NC, Chowan County, NC, Davidson County, NC, Davie County, NC, Durham County, NC, Edgecombe County, NC, Forsyth County, NC, Franklin County, NC, Gates County, NC, Granville County, NC, Greene County, NC, Guilford County, NC, Halifax County, NC, Harnett County, NC, Hertford County, NC, Johnston County, NC, Lee County, NC, Lenoir County, NC, Martin County, NC, Montgomery County, NC, Moore County, NC, Nash County, NC, Northampton County, NC, Orange County, NC, Pasquotank County, NC, Perquimans County, NC, Person County, NC, Pitt County, NC, Randolph County, NC, Rockingham County, NC, Stokes County, NC, Tyrrell County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Washington County, NC, Wayne County, NC, Wilson County, NC, Amelia County, VA, Appomattox County, VA, Bedford County, VA, Brunswick County, VA, Campbell County, VA, Charles City County, VA, Charlotte County, VA, Chesterfield County, VA, City of Chesapeake, VA, City of Colonial Heights, VA, City of Danville, VA, City of Emporia, VA, City of Franklin, VA, City of Hampton, VA, City of Hopewell, VA, City of Lynchburg, VA, City of Martinsville, 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 Roanoke, VA, City of Suffolk, VA, City of Williamsburg, VA, Cumberland County, VA, Dinwiddie County, VA, Floyd County, VA, Franklin County, VA, Greensville County, VA, Halifax County, VA, Henrico County, VA, Henry County, VA, Isle of Wight County, VA, James City County, VA, Lunenburg County, VA, Mecklenburg County, VA, Nottoway County, VA, Patrick County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Southampton County, VA, Surry County, VA, Sussex County, VA, York County, VA

The radar

The Raleigh/Durham radar (KRAX), 73 km from the middle of the area, began a volume at 18:37 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

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 6.6 hours before the alert went out and 150 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-pSkew-T log-p diagram, Greensboro/Hi Pt, NC at 12:00Z on 2006-04-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Greensboro/Hi Pt, NC at 12:00Z on 2006-04-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 23 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1332 m above ground
0-6 km bulk shear
45 kt
0-1 km storm-relative helicity
23 m²/s²
0-3 km storm-relative helicity
57 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 031836
SWOMCD
SPC MCD 031836 
NCZ000-VAZ000-032030-

MESOSCALE DISCUSSION 0421
NWS STORM PREDICTION CENTER NORMAN OK
0136 PM CDT MON APR 03 2006

AREAS AFFECTED...SRN VA...NRN NC

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 031836Z - 032030Z

STORM INITIATION WILL BECOME INCREASINGLY LIKELY FROM NRN NC INTO
SRN VA AS DESTABILIZATION OCCURS THIS AFTERNOON. THE ENVIRONMENT
WILL BECOME FAVORABLE FOR SUPERCELLS WITH A POTENTIAL FOR
TORNADOES...LARGE HAIL AND WIND DAMAGE. A WW MAY BE NEEDED BY MID TO
LATE AFTERNOON ACROSS THE REGION.

WATER VAPOR IMAGERY CURRENTLY SHOWS A STRONG UPPER-LEVEL TROUGH
ENTERING THE APPALACHIAN MTNS. LARGE-SCALE ASCENT WILL MARKEDLY
INCREASE AS THE TROUGH BEGINS TO AFFECT THE FOOTHILLS OF VA AND NC
THIS AFTERNOON. IN ADDITION...VISIBLE IMAGERY SHOWS CUMULUS
BEGINNING TO FORM ALONG A MESOSCALE THERMAL AXIS EXTENDING NWD FROM
GREENSBORO NC TO ROANOKE VA. ALTHOUGH THE AREA REMAINS CAPPED AND
WEAKLY UNSTABLE...DESTABILIZATION WILL CONTINUE DUE TO SFC HEATING.
IN ADDITION...LOW-LEVEL CONVERGENCE SHOULD BECOME ENHANCED LATE THIS
AFTERNOON WHICH COMBINED INCREASING ASCENT FROM THE WEST SHOULD
SUPPORT STORM INITIATION. INITIATION WOULD BE MOST LIKELY ALONG THE
THERMAL AXIS IN THE 20Z TO 22Z TIMEFRAME.

CLEARING ON VISIBLE IMAGERY SHOULD ALLOW MODERATE INSTABILITY TO
DEVELOP BY LATE AFTERNOON WHICH COMBINED WITH 50 KT OF VERTICAL
SHEAR WILL BE FAVORABLE FOR SUPERCELLS. IN ADDITION...A 40 KT
LOW-LEVEL JET CURRENTLY FORMING OVER NRN NC EVIDENT ON OBJECTIVE
ANALYSIS COMBINED WITH BACKED SFC WINDS ALONG THE NC-VA STATE-LINE
WILL BE INCREASINGLY FAVORABLE FOR TORNADOES AS SUPERCELLS DEVELOP
AND TRACK EWD INTO SE VA AND NE NC BY EARLY THIS EVENING. LARGE HAIL
AND WIND DAMAGE WILL ALSO BE LIKELY WITH SUPERCELLS AS LAPSE RATES
STEEPEN DUE TO THE APPROACH OF THE UPPER-LEVEL TROUGH.

..BROYLES.. 04/03/2006

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

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

35347698 35117848 35227996 35768049 36148061 36778064
37198032 37557918 37557731 37377641 36837607 36217602
35727610

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 3, 3:16 AM EDTMesoscale DiscussionSPCBuncombe, Burke, Cherokee, Clay, Graham, Haywood and 10 more89 min
Apr 3, 3:47 AM EDTTornado WatchSPCAlexander, Avery, Buncombe, Burke, Caldwell, Catawba and 18 more5 hr
Apr 3, 6:10 AM EDTMesoscale DiscussionSPCBurke, Catawba, Clay, Cleveland, Gaston, Henderson and 8 more2 hr
Apr 3, 9:34 AM EDTMesoscale DiscussionSPCAnson, Bladen, Chatham, Cumberland, Duplin, Edgecombe and 19 more86 min
Apr 3, 12:54 PM EDTTornado WatchSPCAlexander, Buncombe, Burke, Cabarrus, Caldwell, Catawba and 20 more7 hr
Apr 3, 4:15 PM EDTTornado WatchSPCAlamance, Anson, Beaufort, Bertie, Bladen, Brunswick and 56 more7 hr
Apr 3, 4:59 PM EDTMesoscale DiscussionSPCAlamance, Anson, Cabarrus, Catawba, Chatham, Cleveland and 19 more91 min
Apr 3, 12:01 AM EDTSevere Thunderstorm WatchSPCBuchanan, Dickenson3 hr
Apr 3, 2:14 PM EDTMesoscale DiscussionSPCClarke, Frederick, Highland, Page, Rockingham, Shenandoah and 3 more2 hr

Nearby

Mesoscale Discussions in Virginia, 2006Mesoscale Discussions in North Carolina, 2006Every mesoscale discussion in 2006

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.