Area forecast discussion
National Weather Service Columbia SC
1000 PM EDT Sat may 18 2013
Synopsis...
an upper level trough will approach from the west through Sunday
bringing an increase in moisture as well as chances of showers and
thunderstorms. This trough will linger across the eastern US with
unsettled weather through much of the coming work week.
&&
Near term /until 6 am Sunday morning/...
another weak short wave in northeast Georgia triggering showers in
the csra. Another short wave further upstream in Tennessee. Instability
and low level convergence have weakened across the area but models
indicate continued lift overnight and moist air mass. Will keep
chance showers overnight with isolated thunderstorms. Temperatures
tonight falling into the middle 60s.
&&
Short term /6 am Sunday morning through Tuesday night/...
somewhat unsettled weather pattern the next several days. Surface
front will remain off to the north of the area through the period.
Aloft...the main upper trough will still be just off to the west
of the region Sunday morning...then it is prognosticated to very slowly
track eastward into Tuesday. Ridging behind the trough may be able
to take hold enough by Tuesday to bring lower rain chances. Until
that time...expecting high chance to likely probability of precipitation throughout the
short term period. Rain and thunderstorm chances will probably
come in waves...but did not try to pin down exact timing this far
out. Not expecting anything severe with the storms...just
occasional lightning and some heavier rainfall. Temperatures
Sunday and Monday will be Delaware pendant upon cloud cover and rainfall.
For now it appears as if most areas should be able to at least
climb into the lower 80s...but would not be surprised if some
areas that are in the heavier rainfall regions remain in the 70s
through the daytime hours both Sunday and Monday. Tuesday should
see a little more sunshine...so highs expected to be able to climb
into the middle and upper 80s once again. As for overnight
lows...readings mainly in the 60s.
&&
Long term /Wednesday through Saturday/...
moving into the long term...the region will be under the influence
of an upper ridge briefly on Wednesday...then the ridge slides
offshore as a deepening trough takes hole across the Mississippi
Valley region of the country. Rain chances low on Wednesday...then
increase slightly into Saturday as the main upper trough moves
eastward towards the forecast area. Expect mainly diurnal
showers and thunderstorms through the period though. Expect
temperatures close to or just above climatology through the
period.
&&
Aviation /02z Sunday through Thursday/...
showers associated with a weak shortwave continue across the area
late this evening and could impact terminals with MVFR/IFR visibilities if
moving directly overhead. Will continue prevailing VFR and handle
with amendments. Convection should diminish overnight with loss of
diurnal heating and passing shortwave.
All guidance except the hrrr suggesting IFR ceilings will develop
during the predawn hours Sunday. Am a little skeptical that IFR
conditions will develop but given many of the terminals received
rainfall today and the overwhelming agreement among guidance with
support from sref which also shows IFR ceilings...therefore
included a period of IFR ceilings early Sunday morning. Low clouds
should lift middle morning with VFR conditions returning by 16z. Winds
will generally be from the south less than 10 miles per hour.
Upper shortwave will approach from the west and scattered
convection is once again expected across the area. Timing and
location not certain enough to include in this forecast.
Extended aviation outlook...scattered showers and
thunderstorms...mainly afternoon and evening...possible through
Wednesday. Depending on cloud cover and rainfall...late night/early
morning fog/stratus may be possible as well.
&&
Cae watches/warnings/advisories...
SC...none.
Georgia...none.
&&
$$
