Sumter, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

517
FXUS62 KCAE 211609
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
1209 PM EDT Wed May 21 2025

.SYNOPSIS...
A cold front has moved east of the area, with above normal
temperatures and gusty winds expected today. Dry weather and
cooler temperatures then expected into the weekend. We return
to a more seasonable pattern for Sunday with temperatures rising
back to near or above normal and a chance of rain each day.

&&

.NEAR TERM /THROUGH TONIGHT/...
Key Message(s):

- Breezy conditions with above normal temperatures today.

Shortwave energy responsible for the early morning convection
has shifted offshore, with subsidence and drier air aloft in
its wake. A weak surface front continues to shift east of the
area, with a slight westerly wind shift noted in obs along with
a minor drop in dewpoints.

While dry overall, forecast soundings do show limited in
moisture in the low levels of the atmosphere, which may be
sufficient to support a few fair weather cumulus clouds through
the afternoon. A few of the HREF members do show very isolated
showers forming in NC and perhaps extending down into the
northern Midlands, but think probabilities are much too low to
include in the forecast.

Have adjusted forecast highs up a couple of degrees to show
upper 80s to lower 90s area-wide, given the expected sunshine,
and slight downslope component to the winds. Forecast soundings
show deep mixing this afternoon, and expect gusty winds as high
as 25-30 mph at times through peak heating. Held off on a Lake
Wind Advisory as mixing should be limited over the relatively
warm lake waters, with the strongest gusts likely along the lake
shores.

Mainly clear skies tonight will allow temperatures to fall into
the lower to mid 60s.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
Key Message(s):

- Gusty conditions Thursday behind a front
- Cool, dry weather in store for Friday and Saturday.

Thursday and Thursday night: Surface low pressure will deepen
offshore as it lifts north along the East Coast. A strong
pressure gradient in the wake of the cold front will lead to
deep mixing and gusty winds during the day. ECMWF EFI values for
wind gusts on Thursday range from 0.7 to 0.8 indicating
potential for stronger than normal gusts and forecast soundings
generally show winds around 40 kts at the top of the mixed
layer. Gusts above 30 mph will be possible and a Lake Wind
Advisory may be needed. Some HREF members suggest that isolated
showers or thunderstorms will be possible during the afternoon
but a dry airmass and downslope winds will work to hinder
convection. Even so we can`t rule out an isolated shower or
thunderstorm during the afternoon. With cold advection lagging
behind the front and downslope flow leading to diabatic heating
we expect highs on Thursday above normal with values in the low
to mid 80s. Lows overnight will be in the mid 50s to low 60s as
mixing prevents ideal radiational cooling.

Friday through Saturday night: With a cool, dry airmass firmly
in place over the region by Friday morning we will see
temperatures much cooler than the past week or so. Highs will be
in the upper 70s to low 80s. Lows will be coolest on Friday
night (low to mid 50s) with surface high pressure over the
region. No rain is expected with median PWAT values from the
LREF below 1 inch.

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
Key Message(s):

- Seasonable temps and moisture return

Global ensembles favor rising 500 mb heights late this weekend
through the end of the long term. With models also tending
towards deep SW flow over the Southeast we can expect to see a
return to near or above normal atmospheric moisture and
temperatures. Mean PWAT values from the GEFS rise up to 125
percent of normal. With this return to a more seasonable
synoptic pattern we can expect highs generally in the mid 80s to
low 90s and a chance of diurnal convection each day.

&&

.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions will prevail.

Scattered cumulus expected at the terminals this afternoon, then
mainly clear skies overnight. Gusty westerly winds through the
day, with peak gusts upwards of 27 kt possible, diminishing
this evening.

EXTENDED AVIATION OUTLOOK...VFR conditions are likely outside
of mainly diurnal convection and typical vsby issues at AGS.

&&

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

&&

$$

SYNOPSIS...
NEAR TERM...JAQ
SHORT TERM...
LONG TERM...
AVIATION...JAQ