If the Halloween cold front had arrived even a couple hours earlier I’d have headed east of the Blue Ridge to chase. As it was the convection that did happen was too near darkness – and moving at highway speeds – to convince me to do so. Thus my “chasing” was limited to observing from a couple of vantage points in the Roanoke valley.
This, of course, was the tempting part: an unusual Enhanced Risk on the last day of October.
An upper trough, a strong surface low moving up the Ohio valley, and a sharp cold front all contributed to the severe parameters. CAPE (instability) was a bit limited but shear values were incredible. The main concern was a cap in the 850-700 mb range that looked to limit convection ahead of the front itself.
The first observation point afforded me a great view to the north and west. This look at fog on Fort Lewis mountain was impressive:
But what was even more impressive was the view a bit later of low level scud moving right to left (south) in an apparent eddy behind the mountain until the cloud tags rose high enough to get caught by the low level jet and start scooting left to right:
This was visual evidence of the available shear that pervaded the region.
As the squall line associated with the cold front approached from the west I decided to relocate to another vantage point that gave me a better view to the southwest. From here I watched a small lowering under a rain-free base cross the southern Roanoke valley.
Rain filled in and obscured visibility not long after this. Meanwhile just enough weak sunshine had eroded the cap enough just east of the Blue Ridge for this pre-frontal cell to go up and rotate.
A couple of chasers who did brave the timing and conditions witnessed a couple of supercells near Lynchburg. And despite a plethora of tornado watches that blanketed the Old Dominion so far the only confirmed Virginia tornado occurred after dark not far from my son’s house.
Still glad I decided to stick close to home.