Area Forecast Discussion
Issued by NWS Columbia, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
164
FXUS62 KCAE 211902
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
202 PM EST Tue Nov 21 2017

.SYNOPSIS...
A weak wave of low pressure will shift NE from the Gulf of Mexico to
offshore the Carolinas, proving a slight chance of light rain through
early tonight. Another area of low pressure is expected to
shift northeast from the Gulf of Mexico to offshore the
Carolinas, providing a chance of rain Wednesday night and
Thursday. Fair this weekend, with cooler conditions early next
week as a dry cold front pushes through.

&&

.NEAR TERM /THROUGH TONIGHT/...
An upper trough extending from the Great Lakes region south into
the Gulf of Mexico will gradually shift eastward tonight.
Surface high pressure ridging into the forecast area from off
the Mid- Atlantic coast this afternoon will weaken and shift
northward tonight. A wave of low pressure along the Gulf of
Mexico will move toward the South Carolina coast and deepen and
shift northeastward overnight. Onshore flow and isentropic lift
will promote rain chances through the period. The deepest
moisture will be south and east of the area, so have continued
to indicate the best chance east. Mild overnight low
temperatures expected under mostly cloudy skies, in the upper
40s to near 50.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Upper troughiness will extend from the Midwest south into the Gulf
of Mexico, with a series of upper impulses shifting through our
region late Wednesday through Thursday night. Our region appears
will be generally in between systems early Wednesday, as first wave
will be departing off to the NE, while a dry frontal boundary will
attempt to shift into our region Wednesday, slowly getting over the
mountains while battling nearly parallel flow aloft.  In general,
models showing weak areas of low pressure developing in the Eastern
Gulf of Mexico and tracking towards FL and the Carolina coast, while
surface high pressure builds into the Mid Atlantic. Chances of
precipitation ramp up late Wednesday through late Thursday,
especially for the central and southern counties, diminishing
Thursday night. Highs on Wednesday a bit above normal in the
middle to upper 60s, lowering to the lower to middle 50s
Thursday. Lows Wednesday night ranging from the upper 30s north
to the middle 40s south.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Latest GFS keeps the second surface low and most of the associated
moisture offshore Friday/Friday night, with some drier air working
into our area Friday, though depending on how much rain we get
Wednesday night and Thursday and how good of a low level wedge gets
established, low cloudiness may be slow to erode and push out of the
region. As a result, some low confidence for Friday so for now will
stay close to model consensus.  Fair this weekend as system pushes
farther offshore and upper trough digging into the E CONUS provides
a drier NW flow aloft, with dry cool Canadian high pressure building
into the region Monday and Tuesday.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
VFR conditions this afternoon expected to deteriorate tonight.

A wave of low pressure along the eastern Gulf of Mexico will
shift toward the South Carolina coast tonight and deepen as it
shifts northeastward. Isentropic lift and an onshore flow will
provide a chance of rain at the terminals through tonight. The
chance of rain is too low to include in the terminals at this
time. The chance of rain will gradually diminish toward daybreak
as low pressure off the coast shift further northeastward and
the deeper moisture shifts east. Models show VFR ceilings this
afternoon deteriorating to MVFR/IFR overnight. Ceilings may
return to VFR around 15Z Wednesday, but confidence in
improvement timing is low.

EXTENDED AVIATION OUTLOOK...A front lingering near the coast
may help support MVFR or IFR conditions through Thursday.

&&

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

&&

$$



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.