Potential HSLC event Tuesday night / Wednesday morning (October 18/19)


Considerable uncertainty remains with regard to the evolution of the low pressure system in the GOMEX, including the eventual track of the surface low through the Carolinas Tuesday night into Wednesday. However, the ECMWF has changed little over the past several runs, and the 12Z  ECMWF shows a setup that is reminiscent of the one we had on March 28, 2010 – an HSLC event where several tornadic supercells tracked along the wedge front from Charlotte northeast to Greensboro.  I remember that event well because temperatures/dewpoints on the immediate warm side of the wedge front were no higher than the upper 50s to lower 60s, and the SPC mesoanalysis that evening indicated no instability along the wedge front in NC and actually indicated considerable CIN during the time that low-topped supercells were producing tornadoes, including one that was rated EF3 near High Point.  It’s important to remember that the SPC mesoanalysis page can often be in error with regard to CAPE/CIN, especially during HSLC events, and that paying close attention to convective trends on radar is necessary to help determine whether or not the SPC mesoanalysis may be failing to capture the thermodynamic environment, including the potential for surface-based storms/tornadoes.

Attached below are the tornado track map from 03/28/2010 and the 23Z 03/28/2010 MLCAPE/CIN analysis during the time that the tornadoes were occurring.

Also attached are MSLP and H85 data from the March 28, 2010 event. Since I cannot post ECMWF data here, you’ll need to view the data in AWIPS to compare the low-level pattern on 03/28/2010 to that advertised by the ECMWF Tuesday night.

While the 12Z ECMWF is reminiscent of the March 28, 2010 setup, there are certainly differences as well. It will be interesting to see how the system currently producing gale force winds in the Gulf of Mexico plays into the evolution of the baroclinic low Tuesday night/Wednesday – particularly with regard to the duration and location of the best theta-e advection from the Atlantic (in advance of the wave of low pressure tracking toward the area) and the location of the frontal zone over the Carolinas.

About bvincentnws

Meteorologist National Weather Service 2003 - Current
This entry was posted in High Shear Low Cape Severe Wx. Bookmark the permalink.

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