Alert archive / Virginia / Mesoscale Discussions in 2012
Mesoscale Discussion 2240
The Storm Prediction Center issued this mesoscale discussion at Dec 26, 2012, 6:11 PM EST for 18 counties in North Carolina; 19 counties in Virginia. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Dec 26, 2012, 6:11 PM EST (23:11 UTC)
- Expired
- Dec 26, 2012, 8:15 PM EST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 40%
All 37 counties
Beaufort County, NC, Bertie County, NC, Camden County, NC, Chowan County, NC, Currituck County, NC, Dare County, NC, Edgecombe County, NC, Gates County, NC, Greene County, NC, Hertford County, NC, Hyde County, NC, Martin County, NC, Northampton County, NC, Pasquotank County, NC, Perquimans County, NC, Pitt County, NC, Tyrrell County, NC, Washington County, NC, City of Chesapeake, VA, City of Franklin, VA, City of Hampton, VA, City of Newport News, VA, City of Norfolk, VA, City of Poquoson, VA, City of Portsmouth, VA, City of Suffolk, VA, City of Virginia Beach, VA, City of Williamsburg, VA, Gloucester County, VA, Isle of Wight County, VA, James City County, VA, Mathews County, VA, Middlesex County, VA, Northampton County, VA, Southampton County, VA, Surry County, VA, York County, VA
The radar
The Norfolk radar (KAKQ), 92 km from the middle of the area, began a volume at 23:14 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
Newport, NC (KMHX), launched 12:00Z, 11.2 hours before the alert went out and 166 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 438 m above ground
- 0-6 km bulk shear
- 51 kt
- 0-1 km storm-relative helicity
- 540 m²/s²
- 0-3 km storm-relative helicity
- 770 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
638
ACUS11 KWNS 262311
SWOMCD
SPC MCD 262311
VAZ000-NCZ000-270115-
MESOSCALE DISCUSSION 2240
NWS STORM PREDICTION CENTER NORMAN OK
0511 PM CST WED DEC 26 2012
AREAS AFFECTED...NORTHEAST NORTH CAROLINA AND SOUTHEAST VIRGINIA
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 262311Z - 270115Z
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...A BROKEN BAND OF LOW-TOPPED CONVECTION/TSTMS HAS FORMED IN
THE PAST HOUR ALONG COLD FRONT IN NORTHEAST NC. WERE THIS ACTIVITY
TO CONTINUE TO STRENGTHEN...THE STORMS COULD POSE A RISK FOR
MARGINALLY SVR HAIL...ISOLD DMGG WIND GUSTS...AND/OR A TORNADO
THROUGH EARLY TNGT.
DISCUSSION...A BROKEN BAND OF LOW-TOPPED SHOWERS AND STORMS HAS
FORMED IN THE PAST HOUR ALONG AND AHEAD OF SHALLOW COLD FRONT
PROGRESSING E ACROSS SE VA AND ERN NC. THE CONVECTION SHOULD
CONTINUE TO MOVE E WITH THE FRONT AS THE BOUNDARY ADVANCES EWD IN
ASSOCIATION WITH DEVELOPING SECONDARY CYCLONE NOW FORMING OVER THE
LWR CHESAPEAKE BAY /PER AREA SFC WIND AND PRESSURE CHANGE DATA/.
CONVECTIVE DEVELOPMENT ALSO LIKELY IS BEING ASSISTED BY THE LEADING
EDGE OF STRONGER MID-LVL COLD ADVECTION JUST NOW MOVING INTO REGION
IN ASSOCIATION WITH VORT LOBE ROTATING THROUGH BASE OF LARGER-SCALE
CNTRL APPALACHIANS TROUGH.
AREA WIND PROFILES SHOW STRONG...LARGELY UNIDIRECTIONAL DEEP SWLY
FLOW...WITH 700 MB SPEEDS ATTM AROUND 50 KTS. WIND PROFILES SHOULD
REMAIN FAVORABLE FOR SUSTAINED STORMS/SUPERCELLS OVER SE VA/NE NC
THROUGH MID EVE...ALTHOUGH SPEEDS SHOULD SOMEWHAT SLACKEN WITH THE
APPROACH OF THE TROUGH.
AT ANY RATE...IF THE UPDRAFTS NOW PRESENT ARE ABLE TO CONSOLIDATE
INTO SUSTAINED STORMS...SOME POTENTIAL WILL EXIST FOR MARGINALLY SVR
HAIL...LOCALLY DMGG WIND...AND PERHAPS A TORNADO. AREAL AND TEMPORAL
EXTENT OF THIS RISK WILL...HOWEVER...BE TEMPERED BY STRENGTH OF
SHEAR /ENTRAINMENT EFFECTS/...TIME OF DAY...AND FACT THAT AREA OVER
WHICH STORMS WILL BE MOVING HAS BEEN SOMEWHAT STABILIZED IN THE
LWR-LVLS BY PREVIOUS STORMS.
THE CONVECTION/STORMS WILL CONTINUE TO BE MONITORED. PARTS OF NE NC
AND SE VA MAY REQUIRE A SMALL WW IF THE ACTIVITY SHOWS CONTINUOUS
SIGNS OF STRENGTHENING/ORGANIZATION.
..CORFIDI/GOSS.. 12/26/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...AKQ...MHX...RAH...
LAT...LON 36217764 37167712 37627657 37477562 36877580 36187555
35817544 35547554 35217618 35287742 35397798 36217764SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 26, 6:20 AM EST | Mesoscale Discussion | SPC | Brunswick, Columbus, New Hanover | 85 min |
| Dec 26, 8:07 AM EST | Mesoscale Discussion | SPC | Anson, Beaufort, Bladen, Brunswick, Carteret, Columbus and 24 more | 83 min |
| Dec 26, 10:08 AM EST | Tornado Watch | SPC | Beaufort, Bladen, Brunswick, Carteret, Columbus, Craven and 23 more | 6 hr |
| Dec 26, 2:20 PM EST | Mesoscale Discussion | SPC | Beaufort, Bladen, Brunswick, Carteret, Columbus, Craven and 19 more | 85 min |
| Dec 26, 12:48 PM EST | Mesoscale Discussion | SPC | Albemarle, Amherst, Augusta, Bath, Clarke, Culpeper and 21 more | 6 hr |
Nearby
Mesoscale Discussions in Virginia, 2012Mesoscale Discussions in North Carolina, 2012Every 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.