Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Columbia SC
1200 am EDT Thursday may 28 2015
high pressure in the Atlantic will circulate a moist southerly
flow into the forecast area through Friday. This will create a
chance of mainly afternoon and evening showers and thunderstorms
through Thursday. Dry conditions are expected for Friday with
showers and thunderstorms returning to the forecast for the
weekend as the next frontal boundary moves into the region.
Near term /until 8 am Thursday morning/...
lingering showers across the csra expected to diminish through 2
am. Airmass remains moist with dewpoints in the middle 60s to around
70 degrees. Given light winds and ample low level moisture...could
see fog develop during the early morning hours as debris clouds
clear. Overnight lows expected to cool into the middle and upper 60s.
Short term /8 am Thursday morning through Saturday night/...
guidance continues to show the upper ridge remaining across the
southeastern coast...with upper troughing off to the west of the
region through the period. At lower levels...a moist onshore flow
will continue. Weak shortwaves moving across the western County Warning Area
through the period may be able to produce scattered afternoon
showers and storms each day. Will continue with generally 30-40
percent probability of precipitation across the west...with slightly lower probability of precipitation east each
afternoon. Generally went with a model blend through for
temperatures through the period.
Long term /Sunday through Wednesday/...
during the longer term...both the GFS and the European model (ecmwf) keep the upper
ridge along the southeast coast into early next week. Slight
differences appear Monday into Tuesday in regards to the handling
of a developing upper low along the lower Mississippi River and
Tennessee River regions. The GFS is a little deeper and more
cutoff with the low Monday...while the European model (ecmwf) is slightly further
east and does not cut the low off until the Tuesday time frame.
During the period at the surface...models try to bring a back
door cold front into the region. The GFS solution would bring a
deeper south to southwesterly flow...which would bring Gulf
moisture into the area as the front moves in. Winds with the European model (ecmwf)
would be more westerly and a little drier. For now will continue
to carry 30-50 percent probability of precipitation each afternoon. Temperatures near or a
little above normal through the period.
Aviation /04z Thursday through Monday/...
showers have ended across the tafs sites. Weak surface high
pressure ridge will remain in place overnight with light winds.
Depending on cloud cover...fog will be possible over some areas
due to light winds and rain cooled air. Item of uncertainty
involves extent of any lingering convective debris cloud cover.
If skies clear out...fog more likely. Will expect any late
night/early morning fog to gradually lift with diurnal heating
Thursday morning...with scattered to broken cumulus possible. VFR expected
Thursday afternoon...with scattered convection possible...but ts
chances Thursday afternoon do not appear high enough to include mention in
the tafs at this time.
Extended aviation outlook...early morning restrictions possible
through the end of the week. Afternoon showers and thunderstorms
may also bring restrictions Saturday through Monday.