FFC
LONG TERM /Monday Night through Saturday/...
A complicated forecast period is in store for the extended period as
Hudson Bay
vortex continues to dump arctic air into the US within
associated broad cyclonic
flow extending from the Northern Rockies
to the East Coast.
The beginning of the extended period /Mon night/ will feature a
broad area of
sfc high pressure with center migrating from the
eastern TN Valley into the Mid Atlantic. Nearly
zonal flow will
exist in the mid and upper levels across the Southeast at the base
of the deep Hudson Bay
trough. Despite weak impulses in the mid
level
flow skirting north Georgia Monday night...high pressure
will keep conditions dry and chilly.
Moisture transport will commence Tuesday night into Wednesday as
sfc
high slides off the
NC/VA coastline. Very broad lower level
anticyclonic
flow around this high will push an area of Gulf
influenced
moisture along old frontal boundary into TX/LA which is
expected to collide with an incoming arctic
front. Subtle impulses
within the mid level
trough may allow for the spread of
moisture
along this boundary into a portion of the
CWA on Wednesday. At this
time all rain is expected on Wednesday...tho degree of
moisture
content is questionable. By Wednesday night into early Thursday the
parent arctic high associated with the frontal passage will quickly
move into the Great Lakes region...which will set up the beginning
of what looks like a fairly significant wedge as the
sfc high is
expected to have a central pressure of over 1040mb...
As the wedge sets up early Thursday...forecast becomes incredibly
complicated. This forecast is guaranteed to change over the coming
days as discrepancies abound this far out. Peeking at ensemble
guidance...there is evidence that weak troughing southwest of Baja
California will be able to send a surge of Pacific moisture into the
Southeast while the wedge is in place. As lower level WAA increases
in response to this set up...a warm nose is expected to develop atop
of the cold sfc wedge. This will lead to the possibility of a mix of
rain and freezing rain in the Thursday-Friday timeframe.
However...cannot get too cute with this right now given uncertainty
of moisture transport...presence or degree of WAA/warm nose
temp...or actual temps and wet bulb temps within the wedge.
Therefore...have kept mention of a chance of a mix for now. This
will really need to be monitored over the coming days as a wedge
with such a strong parent sfc high would undoutedbly bring in cold
and dry air should it be able to ridge down the mtns
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