Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Columbia SC
656 PM EST sun Feb 1 2015
a cold front will move through the region early Monday. Widespread
showers expected ahead of the front tonight. It will become windy
tonight through Monday. Another weather system will move into the
region on Thursday into Friday.
Near term /through Monday/...
Lake Wind Advisory remains in effect from midnight tonight
through Monday evening 900 PM...potential for strong wind gusts...
WSR-88D network shows rain moving through the upstate and will
enter the western midlands and northern csra between 7 and
8pm. Rain will progress into the central midlands around 9pm and
eastern midlands by 11pm. With the system crossing the region
quickly expect quantitative precipitation forecast amounts to remain under one half inch through
daybreak. Have adjusted probability of precipitation according to current radar returns
across the area with categorical probability of precipitation at most locations overnight.
Probability of precipitation will decrease during the morning as cold front pushes
through the area by 15z...and offshore around 18z. Models also
indicate elevated instability...note showalter index around -1.
Will mention isolated thunderstorms mainly east. Quite a bit of
drying will occur by the afternoon resulting in decreasing clouds
and mostly sunny conditions by late afternoon.
Biggest issue tonight and Monday appears to be the strong wind
potential. BUFKIT time sections showing very strong low- level jet
moving through late tonight and Monday. With good mixing/cold
advection behind front...the momentum Transfer to the surface from
the jet will cause sustained winds of over 20 miles per hour...with wind
gusts to over 30 miles per hour...from late morning through the afternoon. As
such lake Wind Advisory remains in effect from midnight tonight
through 9pm Monday evening.
Moderately mild temperatures tonight with overnight lows in the
upper 40s to middle 50s. Temperatures on Monday will only warm
slightly from overnight lows...then begin falling in the afternoon
as cold air advection overtakes the region resulting in
temperatures falling into the upper 40s by late afternoon.
Short term /Monday night through Tuesday night/...
a lake Wind Advisory will continue through the evening hours and
expect winds to initially be quite breezy across the County Warning Area and
especially on the area lakes. As the pressure gradient decreases
Monday night...the winds will fall below lake Wind Advisory
conditions by midnight. Dry conditions expected to persist then
from Monday night through Wednesday as high pressure moves in and
settles across the region. After having temperatures around normal
tonight and for portions of Monday...temperatures will fall below
normal once again from Monday night through Wednesday. Moisture
and the rain chances will once again be on the increase Wednesday
night ahead of the next upper level system and surface front.
Chilly temperatures expected Monday night as the winds decrease
and also again Tuesday night with high pressure over the
Long term /Wednesday through Sunday/...
still quite a bit of uncertainty regarding the longer term
period...especially with the possible system moving through from
Thursday evening into Friday. Still seems to be little consistency
in regards to the overall rainfall pattern and timing from run to
run between the GFS/ECMWF/Canadian. 12z runs of all 3 models have
trended to speed up the system and not allowing the northern/southern
streams to phase and develop low pressure that intensifies along
the southeast coast. Have changed very little in the extended
period due to the run to run inconsistency. The models still try
to bring some precipitation through on Thursday...however the
latest trend is to keep most of the moisture south/east and any
precipitation would likely be associated with the middle/upper level
trough. As mentioned earlier...really not changes at this
time..will adjust as models come into better agreement. At this
time the precipitation for the day and early evening hours on Thursday
will be rainfall. Then for late Thursday night into early Friday
morning...there will be a potential for a mixture of rain/snow
beginning across the northern counties...then working its way
southward. This is in associating with surface temperatures
falling to around freezing...and with very cold core of
temperatures aloft moving through the region. Model soundings at
this time indicate much of the column below freezing...with some
moisture in the best snow growth region...so as the column cools
overnight...rain could chance to rain/snow...then all snow. It is
Worth mentioning that the chance for any precipitation overnight is only
around 20 percent at this time...and quantitative precipitation forecast amounts would be light.
The ensemble MOS guidance has a large spread in both probability of precipitation and
temperatures that far out...which is one of the reasons for the low
confidence forecast. Also this system is 5 days out...so much can
change between now and then. Temperatures generally below normal
through the extended period.
Aviation /00z Monday through Friday/...
VFR conditions through 06z then diminishing to MVFR ahead of an
approaching cold front. Very strong winds also expected late
tonight through the day Monday.
Strong southerly moisture transport is resulting in widespread
rain across Georgia into upstate South Carolina. This rain will
shift eastward overnight and rain should impact the terminals
beginning after 03z...with MVFR ceilings/visibilities expected after 06z.
Some brief IFR ceilings possible but confidence is low so will not
include in the forecast at this time.
Southerly winds around 10 miles per hour or less to start the period will
increase after 03z as low pressure deepens in the Ohio
Valley...increasing to 15-20 knots with gusts to 25 knots. Winds
shift more southwesterly ahead of a cold front which pushes
through the forecast area around 15z...then westerly behind the
front and increasing to 20-25 knots with gusts as high as 35
knots. Ceilings return to VFR behind the front with skies clearing by
late in the period.
Extended aviation outlook...no significant issues to aviation.
SC...lake Wind Advisory from midnight tonight to 9 PM EST Monday
Georgia...Lake Wind Advisory from midnight tonight to 9 PM EST Monday