Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 270650
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
250 AM EDT Tue Jun 27 2017

.SYNOPSIS...
A front lingering near the coast will shift farther offshore
tonight. A pressure ridge extending through the Ohio River
Valley today will be in the Mid-Atlantic Region Wednesday and
off the East Coast Thursday. Diminished relative humidity
will be associated with this pattern through Wednesday but
moisture will be on the increase late in the week as the
offshore ridge directs an onshore flow into the forecast area.
This trend will lead to increasing chances of thunderstorms.

&&

.NEAR TERM /THROUGH TONIGHT/...
Drying has occurred behind the cold front. However, there may be
enough recovery of moisture and instability associated with a
mid-level shortwave trough to support a few showers or
thunderstorms this afternoon into the evening mainly in the
east section closer to deeper moisture. The HRRR suggested
isolated coverage in east section. The NAM and GFS depicted the
greatest instability in the east section of the forecast area
with surface-based LI values -4 to -6. The GFS had the greater
instability. Forecast soundings indicated a generally dry
atmospheric column and an inverted-V signature. If thunderstorms
do develop with the limited moisture then strong gusty winds
may occur. The thunderstorm chance should further diminish
overnight with the loss of heating and drying behind the mid-
level shortwave trough.

Followed the guidance consensus for the temperature forecast.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
The models have been consistent with dry high pressure
dominating Wednesday and Wednesday night. Moisture should be on
the increase Thursday especially in the south part of the
forecast area in an onshore flow associated with the ridge off
the East Coast and a mid-level shortwave trough moving into the
region. Followed the guidance consensus and forecasted slight
chance pops in the south part. Also used the guidance consensus
for the temperature forecast.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
The GFS and ECWMF display moisture in a southerly flow
associated with offshore high pressure and broad upper
troughing during much of the medium-range period. The pattern
supports scattered mainly diurnal thunderstorms. The GFS and
ECWMF MOS plus GFS ensemble mean indicate chance pops with
temperatures near climatology.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
A dry atmosphere is expected to ensure VFR conditions through
the morning. Some guidance indicating MVFR fog at OGB. However,
with previous day dewpoints in the upper 50s there, think it is
too dry. Some mid-level cloudiness may stream across the region.
Upper energy and a surface trough is expected to traverse the
region in the afternoon. Moisture will be limited. However,
some guidance is indicating a few showers and isolated
thunderstorms possible with these features in the afternoon. For
now, will handle with VCSH and a BKN cloud deck above VFR
level.

EXTENDED AVIATION OUTLOOK...No significant impacts to aviation
expected through Wednesday. A return flow and increasing low-level
moisture may provide a late night/early morning stratus threat
Thu/Fri. Scattered thunderstorms expected Fri/Sat.

&&

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

&&

$$
SYNOPSIS...99
NEAR TERM...99
SHORT TERM...99
LONG TERM...99
AVIATION...99



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