Scientific Forecaster Discussion
area forecast discussion
National Weather Service Columbia SC
1041 PM EDT Wednesday Oct 1 2014
high pressure will remain over the forecast area through Thursday
night. A cold front will move through the area Friday night and
early Saturday morning. Scattered to numerous showers and
thunderstorms will occur ahead of the front. The coolest
temperatures of the season so far will follow the front.
Near term /until 6 am Thursday morning/...
zonal flow aloft will become more northwesterly toward daybreak as
a closed upper low over the New England coast shifts eastward and a
weak upper ridge builds over the southeastern states. At the
surface...weak high pressure will continue over the area. Skies
will be mostly clear and winds will generally be light and
variable or calm. There will likely be some patchy fog towards
morning...especially in low lying normally colder areas.
Nearly ideal radiational cooling conditions will support lows
overnight around 60.
Short term /6 am Thursday morning through Saturday/...
dry weather pattern will continue through the day on
Thursday...lasting into the early part of Thursday night. Models
continue to show a strong upper trough and associated surface cold
front moving towards the region late Thursday night. Rain chances
will be on the increase late Thursday night across much of the
upstate...but expecting the County Warning Area to remain dry during the Thursday
night time period. As for Friday...rain chances increase from west
to east through the morning as the front approaches and moisture
increases in advance of the passage. Showers...with some
thunderstorm activity...are expected at some point through the day
and evening hours Friday. Can not rule out a strong storm later in
the afternoon due to some stronger shear and instability during
that time. As for the actual frontal passage...timing still a
little bit of an issue...with the GFS being a little faster with
the movement than the NAM. Frontal passage will likely not occur
until Friday night...with the rain chances then diminishing
rapidly on the backside of the front. Saturday should be dry as
the front moves east of the region. Winds through the day may be
rather strong and gusty.
Long term /Saturday night through Wednesday/...
at this point it appears as if the dry air behind the cold front
will be able to dominate the weather through much of the longer
term period. Upper troughing over the eastern part of the nation
should maintain below normal temperatures. Guidance indicating
that we should experience coolest temperatures Saturday night and
Sunday night with lows mainly in the middle 40s to around 50.
These temperatures will be the coolest so far this season.
Readings will begin to warm back up during the early part of next
Aviation /03z Thursday through Monday/...
high pressure will be over the area through the taf period.
Mostly clear skies and near calm wind will aid the development of
fog overnight...particularly at kags and kogb. Already seeing a
decline in visibility at kags. The rap and NAM models indicated a low
level jet overnight...thereby limiting fog. The hrrr showed MVFR fog
Should see at least patchy MVFR fog develop before sunrise as the
nocturnal jet weakens. Have indicated MVFR/IFR fog at kags/kogb
through 13z. Forecasted MVFR fog at kcae/kcub/dnl around sunrise.
Conditions should improve to VFR around 13z. Winds will be south to
southwest during the afternoon with scattered clouds 4 kft to 6 kft.
Extended aviation outlook...fog and low clouds could bring
restrictions early Friday morning. Restrictions possible in showers
and thunderstorms Friday afternoon and Friday night as a cold front
crosses the region. Post frontal gusty winds could develop Saturday.