Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Greenville-Spartanburg SC
734 PM EDT sun Mar 9 2014
dry and warm high pressure will continue to prevail through Tuesday.
A low pressure system will approach the western Carolinas and
northeast Georgia from the west by Wednesday...with temperatures
turning colder late week following an associated cold front passage.
Near term /through Monday/...
as of 730 PM...a quiet and pleasant evening across the region. Forecast is
on track...with no significant changes needed with this update.
clear/mostly clear skies will persist through much of the period.
Some lower clouds may approach western sections of the forecast area
around daybreak Monday...in association with a region of low level
warm air advection/warm frontogenesis responding to Southern Plains cyclogenesis...
so brief partly cloudy conditions will be possible across the
southwest NC mountains Monday morning. Otherwise...rising heights
aloft/deep west/SW flow will allow the warm weather to persist...with
Monday maxes expected to top out 10-15 degrees above climatology...and
portions of the Piedmont likely reaching the mid-70s.
Short term /Monday night through Wednesday night/...
at 230 PM EDT Sunday...the short term period initializes Monday
evening with short wave ridging across the southeast leading to well
above normal temperatures. Meanwhile...a southern stream upper wave
will deepen across the western Gulf while a northern stream upper
trough amplifies over The Rockies. In response...a surface low will
form/deepen across the Central Plains overnight into Tuesday morning
while warm advection regime prevails across the southeast out ahead
of above mentioned Gulf disturbance. Temperatures across the
southern Appalachians and NC/SC Piedmont regions will remain
generally 6-10 degrees above normal. Deep layer moisture is
expected to increase across northeast Georgia...the western upstate...and
the southwest NC mountain into Tuesday evening in response to above
mention warm air advection leading to increased sky cover and above normal
overnight lows as radiational cooling is limited.
Likewise...expecting increasing low level flow to promote upslope
induced showers across the southwest NC and northeast Georgia mountains
by early morning Wednesday. Therefore probability of precipitation begin to ramp up to
likely levels through the early/middle morning hours.
Meanwhile...the above mentioned surface cyclone and its associated
surface cold front will be crossing through the midsouth and into
the Cumberland Plateau region by daybreak Wednesday. At this point
the operational models have the frontal boundary intruding into the
high terrain of western NC by midday with scattered prefrontal
showers likely with a slight chance of thunderstorms...thus kept
probability of precipitation elevated to likely levels through the late afternoon. Lapse
rates will steepen during the late morning hours ahead of the
approaching boundary as heating occurs despite widespread cumulus thereby
warranting mention of thunder as MUCAPE will exceed 600j/kg across
most of the warm sector region. At this time...think thunderstorms
will remain below severe limits as updrafts will be weak/shallow
thus heavy rainfall and frequent lightning will be the primary
threats with any thunderstorms.
The frontal boundary will push east of the region late on Wednesday
evening with probability of precipitation decreasing rapidly from the west.
However...strong low level northwest flow will warrant at least high
end chance level probability of precipitation through early Thursday morning across the
northern mountains of western NC. By that time cold advection will
have lowered snow levels enough such that at least a few hours of
snow showers cannot be ruled out. Accumulations should remain below
advisory criteria with generally around an inch or less expected.
Long term /Thursday through Sunday/...
as of 145 PM EDT Sunday...a full latitude trough will pull away off
the eastern Seaboard on Thursday...leaving dry profiles in place across our
forecast area as cold high pressure builds in from the west. Any lingering
low level northwest flow moisture in the cold air Thursday morning should be
quite shallow and brief across the northern mountains...with only very slight
chances of any lingering light snow showers...and no additional
accumulations. 850 mb temperatures will likely drop some 20 degree c
below Wednesday values across the region to lead to unseasonably cold maximum
temperatures Thursday afternoon despite the sunshine and downslope warming east of the
Relatively zonal flow will develop over the region Friday through
Sat...with occasional weak impulses S of a Great Lakes low rippling
through our area. Some transient middle level moisture cloud briefly
contribute to sky cover at times through this period. At the
surface...high pressure will gradually migrate offshore and permit a
steady warming trend back toward climatology under returning SW flow.
Energy will start digging southward through the Southern Plains on
Sunday...with middle level moisture streaming eastward into the southern
Appalachians ahead of this feature for the latter half of the
weekend. A warm front ahead of a developing surface low over the
Lower/Middle MS River Valley on Sunday will activate eastward toward the western
Carolinas. The developing moist upglide should remain mainly west of
the forecast area until just beyond the current forecast
period...with just slight chances of light rain over the mountains late
Aviation /00z Monday through Friday/...
at kclt and elsewhere...VFR conditions expected through the
period...with a few cirrus and dissipating fair weather cumulus early this
evening. So mainly a wind forecast. Winds should diminish within the next
hour or two...then pick up again out of the SW (except northwest at kavl)
Monday afternoon. A few low-end gusts (15-20 kts) cannot be ruled
out...but are not expected to be frequent. West/northwest winds at 6-9 kts
(slightly higher with some gusts possible at kavl) will continue
through the afternoon hours.
Outlook...dry high pressure will persist through Tuesday. Rain and
associated restrictions are expected to spread back into the area
Tuesday night into Wednesday...with dry high pressure returning for late week.
23-05z 05-11z 11-17z 17-23z
kclt high 100% high 100% high 100% high 100%
kgsp high 100% high 100% high 100% high 100%
kavl high 100% high 100% high 100% high 100%
khky high 100% high 100% high 100% high 100%
kgmu high 100% high 100% high 100% high 100%
kand high 100% high 100% high 100% high 100%
The percentage reflects the number of guidance members agreeing
with the scheduled taf issuance flight rule category. Complete
hourly experimental aviation forecast consistency tables and ensemble
forecasts are available at the following link: (must be lower case)