Models over the last few days have hinted at this for the past
few days, although the track of this feature is still a bit
uncertain. There is a pretty apparent split in outcomes between
the global models and the convective-allowing models; the global
models (GFS, ECMWF, NAM- 12) all take this feature across far
northern New England or adjacent Quebec late tonight with little
to no impact to SNE. On the other hand, the majority of the
CAMs have trended further SW, essentially backbuilding the
southern end of the MCS into the considerably more unstable air,
with a potential MCS moving over parts of or all of SNE during
the pre-dawn to early Sunday morning hours (approx 3 to 8 AM).
Although surface based instability progs at that time of day are
essentially nil, steepening lapse rates aloft support nearly
1500 J/kg of MUCAPE with increasing effective shear to around
40-45 kt, a shear/instability space which could support embedded
elevated supercells above more stable sfc layer.
There still is quite a bit of uncertainty regarding this feature`s
track and how strong it may become, were it to affect our area. The
outcomes here range from passing us by to the north, to an overnight
to early-day MCS capable of hail, wind damage and torrential rain. I
ended up following the trends in the CAMs, which increase PoPs into
the 15-25% range for the southern coast, and increasing to around 30-
50% for northern MA. After coordinating with the neighboring WFOs,
also included enhanced wording for gusty winds, hail and heavy
downpours. While not set in stone, there has been an uptrend in at
least some overnight/early-Sunday impact from this convective
complex. Stay tuned on this situation.