Area Forecast Discussion
Issued by NWS Columbia, SC

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059
FXUS62 KCAE 172055
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
355 PM EST Tue Jan 17 2017

.SYNOPSIS...
A weak cold front will move through the region on Wednesday
with widely scattered showers. A weak area of high pressure will
move into the Carolinas on Thursday. A trof of low pressure
will move through the region on Friday. A large storm system in
the southern plains Saturday night will move gradually toward
the southeast Sunday and Monday, providing mild but unsettled
weather.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
A cold front west of the region will approach the area towards
sunrise on Wednesday. Most of the night will remain dry across
the forecast area, but towards morning there may be some light
rain moving in just northwest of the cwa ahead of the
approaching front. Rain chances mainly in the isolated category,
and confined to the northern counties. With the front north of
the area overnight, and low-level moisture still remaining, can
not rule out the return of some fog. Inhibiting factor will be
stronger low-level winds and mixing through the night. Have
elected to only go with patchy fog wording. Lows will moderate
upwards to the upper 50s.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
Wednesday: The strong upper ridge that has been in place over
the southeast will only temporarily and slightly weaken. A low
moving south of New England will drag a cool front through the
region Wednesday, but upper support will be very minimal, so
only some isolated showers are expected. Temps will remain mild,
with afternoon max values again in the 70s.

Wednesday night: A modest high pressure wedge will build in
behind the front, allowing for slight cooling as a greatly modified
polar air mass moves into the southeast. We should generally get
down into the 40s for the midlands and Pee Dee with mins around
50 in the CSRA. It`s a little too early to call right now, but
there could be another round of patchy dense fog.

Thursday: With the weak wedge in place, temps will be about 10
degrees cooler than Wednesday, although still a little above
normal. As a jet streak moves in from the west, high clouds
will be on the increase, but I think most of the rain will hold
off until the evening as the mid levels will still be on the dry
side until night time.

Thursday night: Showers are likely as a deep layered trof moves
toward the area. While the ridge will weaken, the best energy
will still be forced well to the north, so the line of showers
and thunderstorms that should be approaching from the west will
weaken with time. I don`t think there will be enough instability
remaining overnight to support thunder, so I just went with
showers for now.

Friday: The trof will move into the area and pretty much stall
out on Friday as the upper support moves rapidly to the
northeast and heights start to build again in advance of the
next system. There will still be enough moisture and instability
around to support some showers, and I did add in some thunder
for the CSRA where temps will warm up to the lower 70s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
A very mild and unsettled weekend is in store as a highly
amplified pattern hold on over the U.S. An unusually strong
ridge will be in place early in the weekend along the eastern
seaboard, while strong jet disturbances move through northern
Mexico and the Gulf of Mexico. The first will move through the
eastern Gulf on Saturday with reasonably strong dynamics as a
tongue of PW greater than 1.5 inches, causing a lot of
convection along the Gulf Coast. SC and GA will be in a
favorable location of the jet for convection as well, but the
expected MCS along the Florida panhandle could rob some of the
moisture, making the forecast tricky. For now I am going with no
more than chance in the CSRA and midlands and slight chance
near the NC border.

A stronger jet will be moving through the southeast on Sunday.
Timing becomes increasingly difficult this far in advance, but
I think everyone in the area will see some rain Sunday or Sunday
night. There are hints that we may have to watch out for a
severe weather threat late Sunday as well with nicely curved
hodographs and the potential for some modest instability to
develop.

Early next week conditions will cool down again as a deep low
moves away from the area and high pressure builds back in for
Tuesday. It still does not look like there will be any arctic
air masses invading the region, though, as mid level heights
quickly rebuild again.

&&

.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
VFR conditions expected through the afternoon and early tonight
at all sites. Winds southwest between around 10 knots this
afternoon decreasing to around 5 knots tonight.

Models indicating a return of restrictions late tonight and
towards 12z Wednesday. MVFR visibilities and IFR/LIFR ceilings
possible by morning at all sites. Conditions should improve to
VFR by 15z. Winds will increase out of the west/southwest
during the day Wednesday, with gusts 15 to 20 knots ahead of
the front.

EXTENDED AVIATION OUTLOOK...Late night/early morning fog
possible through Saturday. Showers and associated restrictions
possible Thursday through Saturday.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.

&&

$$



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