Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Columbia SC
204 PM EDT Sat Aug 29 2015
expect increasing atmospheric moisture to drift slowly north into
our region Sunday...and remain in place into next week.
Near term /through tonight/...
Main upper pattern continues to be dominated by the western Atlantic
ridge...and cutoff low in the northern Gulf of Mexico. At the
surface...weak high pressure remains over the middle-Atlantic and
extending into the Carolinas...with a weak trough/dew point
discontinuity near the Savannah River. Dew points generally greater
than 70 degrees south of the boundary. Latest radar returns showing
scattered showers over portions of central and southeast Georgia as well as the
SC lowcountry. Storm Prediction Center sref keeps forecast area mainly dry for the rest
of the afternoon into this evening...with with generally slight
chance probability of precipitation in the csra into this evening. Probability of precipitation slowly increasing
from south to north overnight as the onshore flow continues to
increase. Daytime maximum temperatures will be in the middle to upper 80s.
Skies will remain mostly cloudy overnight with probability of precipitation increasing
especially for the southern and central counties. Overnight lows
generally in the middle to upper 60s.
Short term /Sunday through Monday night/...
models still trending slightly slower but still lifting upper
energy NE from the Gulf Coast into the southern Apps
Sunday...bringing increasing moisture with it into our region from
the S/SW. Surface high pressure and low level drier air will still
try to hang tough to the north. Some model guidance has been
inconsistent with probability of precipitation. Will lean towards blend of short range
ensemble mean and ongoing forecast for probability of precipitation...favoring best probability of precipitation
across southern and western forecast area Sunday. Monday...west atl upper ridge
to our southeast builds some towards the southeast coast as upper energy lifts
out to our north...with weak upper trough/closed low shifting west
some towards the lower miss Valley/West Gulf. Remnant circulation
from former tropopause cyclone Erika expected to drift northwest into the East
Gulf...with some uncertainties regarding whether it will
regenerate. For our region...appearance of sufficient atmospheric
moisture remaining in place given continued low level southerly
moisture transport...leading to expectations of scattered mainly
diurnally favored convection.
Long term /Tuesday through Saturday/...
models indicate weak upper trough to remain to our west...with
upper ridge centered to our east/southeast continuing to slowly build
westward some towards the southeast coast. Considerable uncertainties
with remnant circulation associated with former tropopause cyclone
Erika...as it could possibly regenerate over the East Gulf and drift
north. For now...due to uncertainty...will indicate chance probability of precipitation
and near climatology temperatures.
Aviation /18z Saturday through Thursday/...
Middle and high level clouds will continue into tonight. Some lower
clouds possible at ags and ogb late tonight with some MVFR visibilities.
Otherwise expecting VFR conditions for the most part for much of the
taf period. Scattered showers possible especially after sunrise
Sunday at the taf sites...but timing is still a bit uncertain this
far out...so will not mention in the tafs at this time.
Extended aviation outlook...restrictions possible in mainly early
morning fog and stratus plus afternoon and evening scattered