The severe weather event that unfolded in central NC during the evening hours of March 29, 2014 was notable for several reasons. Although diurnal destabilization in central NC was severely limited by widespread cloud cover, intermittent showers, and weak mid-level lapse rates during peak heating, strong synoptic ascent /layer-lifting/ in the presence of a convectively unstable airmass (associated with a drier mid-level airmass advecting atop an unseasonably moist boundary layer) resulted in an atypical thermodynamic setup in which marginal to moderate destabilization (500-1000 J/kg mlcape) occurred after peak heating during the early evening hours. This in of itself is worth another post, as I think it highlights some of the inherent limitations in convective parameters and the necessity of performing a thorough environmental analysis using data from a variety of remote sensing platforms, observations, and short-term model guidance.
The animated GIF below shows a 4-panel loop of REF, SRM, VEL and CC from 0.5 to 2.4 degrees of the 0111Z volume scan from KRAX. This is an excellent example of a subtle tornadic debris signature associated with a supercell observed within several miles of an 88D. Note that the ‘hole’ in CC (values 0.60 to 0.90) is co-located precisely with both the velocity couplet and the reflectivity ‘ball’ within the hook. Vertical continuity (including a down-shear tilt) of this feature from 0.5-0.9-1.3-2.4 degrees and the lack of such a feature prior to when the supercell arrived or after it departed provide compelling evidence for a tornadic debris signature. A weak (EF-0) tornado was indeed confirmed at this precise location/time in southeastern Wake county (see damage survey PNS below).
In case the aforementioned radar loop did not attach properly, you can also find it at:
...TORNADO CONFIRMED NEAR GARNER IN WAKE COUNTY NORTH CAROLINA... LOCATION...GARNER IN WAKE COUNTY NORTH CAROLINA DATE...03/29/2014 ESTIMATED TIME...0908 PM EDT MAXIMUM EF-SCALE RATING...EF0 ESTIMATED MAXIMUM WIND SPEED...80 MPH MAXIMUM PATH WIDTH...75 YDS PATH LENGTH...1/8TH OF A MILE * FATALITIES...0 * INJURIES...0 * THE INFORMATION IN THIS STATEMENT IS PRELIMINARY AND SUBJECT TO CHANGE PENDING FINAL REVIEW OF THE EVENT(S) AND PUBLICATION IN NWS STORM DATA. ...SUMMARY... THE NATIONAL WEATHER SERVICE IN RALEIGH NC HAS CONFIRMED A TORNADO NEAR GARNER IN WAKE COUNTY NORTH CAROLINA ON 03/29/2014. PER EYEWITNESS AND A DAMAGE SURVEY...A WEAK EF0 TORNADO OCCURRED SHORTLY AFTER 9 PM AT THE INTERSECTION OF TREBOR DRIVE AND CROSS POINTE LANE. A RESIDENCE SUSTAINED PARTIAL ROOF DAMAGE WITH A COUPLE OF WINDOWS BROKEN AND A COUPLE OF TREES DOWN.