Comparison of November 15, 2008 Killer Tornado Outbreak with the December 2, 2009 Non Tornado Event The two events featured similar patterns but with much different results in central NC. The slides on the following pages are designed to serve as a reference for discussion. In many aspects, the events were very similar with the synoptic upper air and surface pattern. One obvious difference between the two events is a much greater amount of surface based CAPE in the 11/15 case then the 12/02 event which would obviously support more surface based convection and allow a storm to utilize the surface instability and drive a circulation to the surface. A review of the radar imagery shows that at the time of the tornadoes in central NC, the convection during the 11/15 event was not embedded in a large convective rain shield as was the case with the 12/02 event. In addition, the 11/15 tornadic supercells were long lived, originating in SC in a region of similar instability to that over eastern NC where they eventually produced tornadoes. I believe the 1988 Raleigh Tornado was spawned by a long lived supercell originating in SC. More recently, on March 28, 2010, a long lived supercell produced 4 tornadoes in the western Piedmont of North Carolina with the first tornado touching down just north of the South Carolina state line. Jonathan Blaes NOAA/NWS Raleigh, NC
On 2009/12/09 there were several reports of wind damage in the southern and central Coastal Plain of NC. Other severe weather was observed during the afternoon across GA/SC. Most of the severe weather on was reported as tornadoes and related to one or two long lived supercells.
No tornadoes were confirmed during the evening or early morning hours of 12/03/09 Most of the tornadoes on 11/15/08 occurred between 07 and 09 UTC
2009/12/03
2009/12/02
MESOSCALE DISCUSSION 2191 NWS STORM PREDICTION CENTER NORMAN OK 0731 PM CST WED DEC 02 2009 AREAS AFFECTED...ERN SC...ERN NC CONCERNING...TORNADO WATCH 789... VALID 030131Z - 030300Z THE SEVERE WEATHER THREAT FOR TORNADO WATCH 789 CONTINUES. THE TORNADO THREAT ACROSS WW 791 WILL CONTINUE TO INCREASE ACROSS NC OVER THE NEXT 1-2 HOURS. A NEW TORNADO WATCH WILL LIKELY BE NEEDED WITHIN THE HOUR ACROSS CNTRL NC INTO SERN VA. THE AIRMASS ACROSS WW 791 IS RAPIDLY DESTABILIZING DUE TO STRONG MOISTURE ADVECTION AS A WARM FRONT MOVES QUICKLY NWD ACROSS NC. SFC DEWPOINTS ARE ALREADY IN THE UPPER 60S F IN GREENVILLE NC AND THIS MOISTURE SHOULD REACH THE NC-VA STATE-LINE DURING THE 02Z TO 03 TIMEFRAME. THE MOISTURE COMBINED WITH A STRONG SHEAR ENVIRONMENT ALREADY IN PLACE IS INCREASING THE POTENTIAL FOR ROTATING STORMS AND TORNADOES. TORNADOES WILL BE POSSIBLE WITH DISCRETE CELLS AHEAD OF A BAND OF RAIN CURRENTLY WEST OF THE RALEIGH/DURHAM VICINITY. ROTATING CELLS WILL ALSO BE POSSIBLE EMBEDDED IN THE RAIN BAND ESPECIALLY SWD TOWARD THE SC STATE-LINE WHERE SFC DEWPOINTS ARE APPROACHING 70 F. AS LARGE-SCALE ASCENT SPREADS ACROSS NC...THE LOW-LCL HEIGHTS AND 0-1 KM SHEAR OF 35-45 KT SHOULD SUPPORT SUPERCELL DEVELOPMENT WITH A STRONG TORNADO POSSIBLE AS THE LOW-LEVEL JET SHIFTS NNEWD INTO THE CNTRL PART OF WW 791...BROYLES.. 12/03/2009
MESOSCALE DISCUSSION 2386 NWS STORM PREDICTION CENTER NORMAN OK 0210 AM CST SAT NOV 15 2008 CONCERNING...TORNADO WATCH 932...933... VALID 150810Z - 150945Z THE SEVERE WEATHER THREAT FOR TORNADO WATCH 932...933...CONTINUES. TORNADO WATCHES 932/933 CONTINUE ACROSS EASTERN SC AND CENTRAL/EASTERN NC UNTIL 11Z/13Z RESPECTIVELY...WITH A RECENTLY ISSUED WFO EXTENSION ACROSS FAR SOUTHEAST VA. A DISTINCT RISK FOR ISOLATED TORNADOES AND WIND DAMAGE WILL CONTINUE OVERNIGHT. LATEST SUBJECTIVE SURFACE ANALYSIS FEATURES A GENERAL SW-NE ORIENTED WARM FRONT FROM NORTHERN GA INTO UPSTATE SC/EAST CENTRAL NC AND SOUTHEAST VA...WITH UPPER 60S/LOWER 70S F SURFACE DEWPOINTS PREVALENT EAST OF THIS BOUNDARY. A NORTHEAST-ADVANCING EMBEDDED SPEED MAXIMA AND A FAVORABLE KINEMATIC/HIGHLY SHEARED ENVIRONMENT WILL CONTINUE TO CONTRIBUTE TO WELL-ORGANIZED TSTMS INCLUDING SUPERCELLS/BOWS ALONG AND EAST OF THIS WARM FRONT ACROSS EASTERN SC AND ESPECIALLY EASTERN NC...AND INTO SOUTHEAST VA WITHIN THE NEXT FEW HOURS. TORNADO DAMAGE WAS RECENTLY REPORTED SOUTHEAST OF THE RALEIGH AREA IN JOHNSTON COUNTY. REGIONAL WSR-88D DERIVED WIND PROFILES REFLECT A STRONG LOW LEVEL JET WITH 40-50 KT SOUTH-SOUTHWESTERLY FLOW AROUND 1 KM...WHICH IS CONTRIBUTING TO 250-350 MS/S2 0-1 KM SRH...GUYER.. 11/15/2008
300 hpa
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Surface Theta-E
SBCAPE
MLCAPE
0-1km SRH
0-6km shear
SPC Sig Tor effective layer
RUC profiles