Area Forecast Discussion
Issued by NWS Columbia, SC
FXUS62 KCAE 271726
Area Forecast Discussion
National Weather Service Columbia SC
126 PM EDT TUE SEP 27 2016
A cold front will slowly push into the area later today into
Wednesday and cross the area Wednesday night. Cooler and drier
more seasonable temperatures expected late in the week and over
the weekend with little rain chances.
.NEAR TERM /THROUGH TONIGHT/...
Latest analysis depicts the cold front extending from eastern
West Virginia southwestward along the spine of the Appalachians
into northern Georgia. Weak surface low remains off the Southeast
coast. Precipitable water values remain around 1.6 to 1.8 inches with
abundant low level moisture present with dewpoints in the upper
60s to lower 70s. Surface CAPEs are around 1500-2000 J/kg and 500
mb temps about -7 to -8 degrees C. Lifted indices are currently
around -2 to -4. Regional radar currently showing only a few
light showers across the area early this afternoon.
Latest SPC HRRR continues to indicate that convection will
develop over the Upstate by late afternoon and move eastward into
the evening hours. There should be enough instability to support
isolate to scattered convection late afternoon into the evening
mainly across the northern and western parts of the forecast area
so will continue to carry highest pops there with lower pops
elsewhere. SPC has placed the western Carolinas in a Marginal risk
for severe storms, so an isolated severe storm cannot be ruled out.
Weak surface low offshore will also lift northward through tonight
and limit convergence along the seabreeze. The threat of any
possible severe storms should lessen by mid-evening with loss of
daytime heating. The high moisture content and possible training
of convection may lead to a limited isolated flood threat
especially in the northern Midlands where recent rain has fallen.
Will keep mention of chance pops mainly over the northern and
western counties for late afternoon into tonight.
Temperatures will remain well above normal with afternoon highs
once again expected in the mid to upper 80s. Debris clouds and
abundant boundary layer moisture will limit overnight lows tonight
as temperatures are expected to be in the upper 60s to lower 70s.
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
Models are a fairly good agreement on the movement of the Great
Lakes upper low the next few days. The center of the low will
slowly push southward towards Kentucky through Friday. This will
help to finally drive a cold front through the cwa Wednesday night
into Thursday. Some instability will exist on Wednesday ahead of
the front, and can not rule out some stronger winds in the
convection. SPC does have the northeastern portions of the cwa in
a marginal risk for Wednesday. Expecting chance pops through the
day Wednesday, lingering into the early portions of Wednesday
evening. Activity should be east of the cwa by Thursday morning,
with drier air pushing into the area. Dry forecast for Thursday
through Friday night. As for temperatures, with the region in the
warm sector for Wednesday, expect readings slightly above normal
in the mid to upper 80s. Temperatures drop for Thursday and
Friday, with readings around 80 on Thursday, and then highs in the
mid to upper 70s for Friday. Overnight lows will range from the
upper 50s west to mid 60s east Wednesday night, then cooler
overnight readings in the 50s the remainder of the short term.
.LONG TERM /SATURDAY THROUGH MONDAY/...
Dry and fair conditions will prevail through the weekend and into
the early portions of next week. The closed upper low will lift
back north by Monday, bringing a more zonal pattern to the region
to start off the work week. As previously mentioned, the models
indicate a tropical low in the Caribbean Monday and Tuesday.
Models diverge Monday evening into Tuesday though, with the GFS
bringing the system due north but keeping it in the western
Atlantic. The ECMWF takes the low more towards Cuba. This low is
currently over the Atlantic, well east of Barbados, and is being
monitored by the National Hurricane Center. Temperatures will be
near normal with highs around 80 to the lower 80s and lows in the
50s and 60s.
.AVIATION /17Z TUESDAY THROUGH SATURDAY/...
VFR conditions have returned across the area this afternoon. VFR
will continue this afternoon into this evening, except for the
possibility of restrictions in scattered late afternoon/evening
showers and thunderstorms. The latest hi-res models indicating
that a line of convection may develop in the Upstate and move
eastward late this afternoon into this evening. Given lack of
confidence of actual timing and strength of the convection, for
now will mention VCSH at all TAF sites from around 00Z until 06Z
Wednesday. Some MVFR restrictions possible across the area during
the early morning hours on Wednesday. More convection may develop
ahead of a slow-moving cold front near the end of the TAF period
by early Wednesday, but not enough confidence to mention in the
TAFS at this time.
EXTENDED AVIATION OUTLOOK...Chance of showers and possible
thunderstorms, and associated restrictions, Wednesday afternoon.
No impacts to aviation expected Thursday through Saturday.