Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 181043
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
643 AM EDT Mon Jun 18 2018

.SYNOPSIS...
Weak surface trough will remain across the region, however a
building upper level ridge aloft through midweek will limit
afternoon thunderstorms and result in warmer than normal
temperatures through most of the week. Increasing moisture late
in the week along with the ridge weakening may result in an
increase in scattered afternoon thunderstorms late in the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Weak surface trough remains across the region. Upper level
ridge strengthening over the area today so the threat for
afternoon and evening thunderstorms appears to be lower than
past few days. Model soundings suggest a mid level cap will be
developing with weaker CAPE and a high LFC. Overall Mos pops
quite low. There is a short wave trough over Virginia this
morning that is associated with convection ongoing over north
central and eastern NC at the moment. The short wave will rotate
southeast around the ridge this afternoon and may trigger some
convection over eastern SC/Pee Dee this afternoon. This is
suggested by some high resolution models. Other convection may
be possible in the CSRA near old boundary and along a sea breeze
front. However with general subsidence across the area, believe
convection will be mostly isolated. Boundary layer temperatures
a couple degrees warmer so expect mainly mid to upper 90s this
afternoon for max temperatures. Above normal overnight
temperatures continue again tonight with min temps in the low to
mid 70s.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
Ridge aloft appears to be strongest on Tuesday although it
shifts a little south of the area Tuesday night and Wednesday.
So hot conditions expected during the period with temperatures
aloft about 2 standard deviations above normal. Temperature
guidance suggests max temperatures near 100 degrees both days.
The heat index will likely be above 105 degrees by Wednesday
afternoon despite some weak mixing in the afternoon resulting in
lower dew points. Afternoon thunderstorms appear unlikely
Tuesday due to mid level cap and subsidence. Mos pops very low
and will go with a dry afternoon/evening. With ridge shifting
south on Wednesday, a few weak short waves may rotate over ridge
resulting in a few widely scattered afternoon and evening
thunderstorms mainly in the north Midlands. Nam Model suggests
an inverted V and maybe large CAPE, so a few strong
thunderstorms possible.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Although the upper ridge should be south of the area Thursday,
warm advection and downslope flow may result in warmer
conditions. Temperatures near 100 again or a degree or two
higher resulting in near heat advisory conditions. CAPE appears
limited Thursday but a few afternoon thunderstorms possible with
higher low-level moisture.

An unseasonably strong upper trough is forecast to swing across
New England and push a backdoor cold front into Virginia/North
Carolina by Friday. Strong low pressure system over the
Midwest early in the period moving northeast. Models suggest
increasing moisture associated with warm advection ahead of
Midwest low and backdoor front near the region.  This should
result in an increase chance of diurnal convection and slightly
cooler temperatures for the weekend.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
Generally expecting VFR conditions through the forecast period.

Mostly clear skies this morning with some variable vsby
restrictions at AGS/OGB. Will include brief MVFR fog through 13z
then return to VFR conditions as heating and mixing take place.
Light and variable winds will increase to around 5 to 7 knots
from the southwest after 15z. Chance for convection will be
lower this afternoon given upper level ridging and subsidence
over the area, but few to scattered cumulus are again expected.

EXTENDED AVIATION OUTLOOK...Restrictions possible each day in
early morning fog and isolated afternoon and evening
thunderstorms.

&&

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

&&

$$



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