Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Columbia SC
1115 am EST Monday Nov 24 2014
an approaching cold front will cross the area tonight and stall
near the coast. A wave of low pressure is expected to develop
along the front adding sufficient moisture for significant
rainfall Tuesday into Wednesday. Dry high pressure will spread
across the region Thursday through Sunday.
Near term /through tonight/...
scattered showers will linger across the the central and eastern
midlands and lower Savannah River area for the remainder of this
morning and into the early afternoon.
A cold front crossing the MS River Valley this morning will
continue moving east to cross the midlands and csra tonight and
stall near the coast. Moisture surging northward ahead of the
front will spread showers back into the area today. The best
chance for showers will be across the eastern half of the forecast
area...where instability and moisture is highest. Isolated
thunderstorms are also possible with lifted index values near
minus 3. Widespread clouds this morning will decrease from west
to east later this afternoon. Should see daytime highs in the 70s
given our warm start this morning.
Mainly dry weather is expected tonight as the cold front moves
off the coast. Clouds and mixing will hold overnight lows in the
upper 40s west to upper 50s east.
Short term /Tuesday through Wednesday night/...
the main upper trough axis shifts eastward on Tuesday as energy
digs into the base of the trough across the Southern Plains. Main
surface cold front will push just to the east of the County Warning Area early in
the morning. The best chance for any rainfall should still be along
the coast through the day...with some inland progression possible
by the afternoon across the east as a surface low begins to
develop along the coast. Colder air will be filtering back into
the region...and with the rainfall and clouds
increasing...temperatures will cool back down for afternoon
highs...with readings mainly in the upper 50s to lower 60s.
Tuesday night...the models continue moving the upper trough
eastward through the southern Mississippi Valley region...and in
response to the approaching trough...the surface low off the
coast will deepen along the old cold front. As this low
deepens...moisture and precipitation will spread inland during the
overnight hours. Have increased the chance of rain to near 100
percent Tuesday night with lows in the 40s.
On Wednesday...the upper trough will push towards and through the
region...while the surface low begins moving northward along the
coast in response to the upper trough. Wrap around moisture and
precipitation behind the surface low will continue across the region
early in the day...then by the afternoon hours the bulk of the
precipitation should be pulling away from the forecast area. Continued
with cool temperatures on Wednesday because of clouds and expected
precipitation and surface winds from the north/northwest.
By Wednesday night...models show the surface low moving along the
middle-Atlantic and up into New England. A second piece of upper
energy will move across the southeast overnight...with with limited
moisture the best precipitation chances will mainly be across the central
Appalachian Mountains. Central SC and eastern Georgia will be dry. Colder
air will once again settle into the area. Overnight lows back down
to around freezing.
Long term /Thursday through Sunday/...
not much change in the thinking for the longer term. Once we get
into Thanksgiving and into the weekend...conditions quiet down
and dry out as high pressure settles over the area...and the upper
pattern flattens out. Expect temperatures to remain below normal
through the period.
Aviation /16z Monday through Friday/...
expect MVFR ceilings with possible IFR ceilings for much of the taf
period. Satellite loop and observation indicate some breaks in the low
clouds across portions of northern Georgia into portions of the upstate of
SC. However...all of the taf sites currently reporting IFR/MVFR
conditions for ceilings. Along the I-95 corridor and
eastward...scattered showers continue to move northeast...with
more showers beginning to develop over the csra. WV loop
continues to try and back the middle/upper flow and expect this
activity to continue through much of the forecast period. At this
time...will carry a vcsh ags/dnl/ogb through the morning/early
afternoon period. BUFKIT time sections and guidance not very
optimistic with conditions at taf sites today. Expect conditions
to improve to VFR by late in the day. This may happen sooner...but
not confident enough at this point to bring up conditions faster.
Models indicate a strong 800 mb/500 mb winds moving across the area today
and expect breezy conditions developing at all taf sites by later
this morning and continuing through much of the day from the
southwest. By this evening/tonight...guidance tries to once again
lower ceilings across the area. With a 20 to 30 knots low level
jet...would expect less of a fog threat...which guidance does not
show...but more of a stratus threat which guidance does indicate.
Lowered ceilings back to MVFR around 06z tonight and continued
through the remainder of the period.
Extended aviation outlook...widespread MVFR or IFR conditions may
occur Tuesday night and Wednesday associated with low pressure
tracking northward along the Carolina coast. Improving conditions
for Thursday and Friday.
SC...Flash Flood Watch until 7 PM EST this evening for scz030.