Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Columbia SC
1004 am EDT Friday Aug 28 2015
a frontal boundary will remain stalled near the coast today. A
large area of surface high pressure centered over the Great Lakes
region will slide east to the Atlantic coast for the weekend.
Increasing atmospheric moisture will drift north into our region
this weekend. Tropical cyclone Erika is expected to approach
southern Florida on Sunday. Refer to the latest advisory on Erika
issued by the National Hurricane Center.
Near term /until 7 PM this evening/...
an upper level trough extending from the Ohio River valley to the
Gulf of Mexico will weaken and lift north today. The frontal
boundary is expected to remain stalled near the coast. Surface
high pressure will continue to ridge in from the north producing
northeasterly/easterly flow. Models show a strong gradient in
precipitable water from north to south across the area with the
best moisture south. Model soundings show weak instability. The
hrrr and 00z Storm Prediction Center WRF show isolated coverage. Slight chance probability of precipitation
mainly southern forecast area still seems appropriate. High
temperatures are forecast near normal...in the upper 80s.
Short term /7 PM this evening through Saturday night/...
may still have an isolated lingering shower/storm until
midnight...then dry for all areas the remainder of the night.
Moisture will begin to increase across the southern portions of
the County Warning Area Saturday. This moisture increase is expected to remain
confined to the south through the day...with northern counties
still having drier air in place. This would lead to the best rain
chances being across the south and south-central counties on
Saturday...with the northern counties dry or only having an
isolated shower/storm. Temperatures in the middle to upper 60s
tonight with the drier air. Saturday will see highs in the upper
80s. Lows Saturday night moderate slightly with the moisture
increase...with readings around 70.
Long term /Sunday through Thursday/...
upper trough will remain to our west with upper ridge remaining
centered to our east and southeast. This will continue to draw moisture
northward into our region Sunday. Expecting to have continued
diurnal convection Sunday into Tuesday with this pattern.
Early to middle next week...models maintain weak upper trough to our
west and upper ridge to our east and southeast. Main concern for this time
period continues to be the eventual track and strength of tropical
cyclone Erika as it approaches the Atlantic coastline. Latest
official forecast from NHC brings it northwest towards the Southeast
Florida coast...and then bringing it northward through the central
Florida penisula Monday into Tuesday...keeping it mainly a
tropical storm. There continues to be little run to run
consistence with the longer range models...especially with the
track...and with the large model spread...confidence is low out in
the long term. Please see the NHC forecast for latest discussion
and track of Erika. For now...due to uncertainties regarding
impact for our area...will continue to maintain chance probability of precipitation.
Aviation /14z Friday through Tuesday/...
most of the early morning stratus has dissipated by late this
morning. Otherwise mainly middle and high level clouds over the
area. Another slight chance of diurnal convection at the
terminals this afternoon/evening...although confidence remains too
low to include in current issuance. Winds will continue out of the
northeast/east today at 10 knots or less.
Extended aviation outlook...restrictions possible in mainly early
morning fog and stratus plus afternoon and evening scattered