Notable un-named hybrid storms?

[Dean_175]

I am creating this thread to create discussion of notable or interesting hybrids that did not quite meet the definition of a tropical or subtropical cyclone , but still had some characteristics of such (ie. storms with fairly weak frontal boundaries that derive much of their energy from latent heat release ). All "medicanes" are obvious examples- as they are "tropical like" but not considered such due to their region of formation.

Here are some that come to mind for me.

October 2011 Florida storm:
This was an unnamed storm that many thought would be included in re-analysis. This storm was a non-tropical frontal system that moved off the east coast of the US ,and had acquired some (transient) tropical or subtropical characteristics by the time it made landfall in east Florida. The fronts associated with this storm were fairly weak - only slightly evident when looking at 850 mb chart and not very discernible at the surface--very weak temperature gradients and horizontal shear axis. It developed a tight pressure gradient associated with a very compact cluster of thunderstorms wrapping around the center--which was a somewhat isolated feature. The rotation of this region of convection was very evident on radar. It hit Florida with tropical storm force winds of 50+ mph- which were much stronger than the winds found outside of the compact circulation near the center. NHC issued a statement post-season as to why they would not classify this storm- citing the small nature of the convective region--which really wasn't large enough to be considered a truly synoptic scale feature, and the weak frontal nature of the storm (when considered with the fact that it could not really be diagnosed as to whether the small convective region was truly separate).

Before crossing Florida:


After crossing Florida (had begun to lose some of the tropical characteristics as this point):



September 2008 Carolinas storm:
This originated from a purely non-tropical low that had cut-off. It moved to the south , occluded, and became situated under its associated upper level low. Convection began to wrap around the center and the storm developed a shallow warm core--with warm air at the center in the low to mid levels of the atmosphere. The storm began to intensify and developed tighter pressure gradients close to the center-and then weakened fairly rapidly at its landfall between North and South Carolina. It also developed the type of "quasi-eye" you often see with subtropical storms--but there were signs that it still was frontal- GFS analysed 850 mb and surface charts indicate that it still had very weak temperature gradients extending to the center -and the convective spiral around the center had only partially separated from the main frontal comma cloud feature. This storm was very close to becoming fully subtropical.

[EquusStorm]

I closely remember following the September 2008 storm. I watched the coastal radar sites all day. In fact, when I noticed that advisories on Tropical Storm Kyle had been initiated via the header on the NHC site that day, I first thought that the classification was for the coastal storm. If only it had 12-24 more hours offshore. In retrospect, and on satellite loops, it is not too hard to see the frontal structure still hanging on just a little as it came ashore.