Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Greenville-Spartanburg SC
734 am EDT Monday Aug 3 2015
dry high pressure will remain in place across the area today. Low
level moisture will gradually return through the work week as a cold
front approaches from the area from the northwest.
Near term /through tonight/...
as of 650 am...low clouds moving north across the upstate and NE Georgia
will move into the NC southern Piedmont this morning...then slowly lift
through the day. Otherwise...forecast generally on track with updates
mainly for current conditions.
As of 240 am...upper trough remains over the eastern Continental U.S. Today...then
begins to lift tonight as a weak shortwave moves east of the area.
At the surface...weak high pressure remains over the area as a low
pressure center rides up the East Coast along a leftover frontal
boundary. Finally a cold front will drop south toward the area late
tonight. Dew points are much higher across the area this morning as
a seabreeze boundary has moved north across the County warning forecast area bringing in the
better low level moisture. Despite the higher start...still expect
dew points to mix out...although not to the extreme of the past few
days. The NAM and cam guidance show convection developing across the
area today. However...the GFS and European model (ecmwf) continue to show a dry forecast.
Given the recent trends with the wetter guidance showing a strong
wet bias...and some dew point mixing...will keep with the current
dry forecast for now. Cannot rule out some lingering convection moving
into the northern tier from mesoscale convective system activity ahead of the front. However...
will keep pop dry then as well. Temperatures will be up to 5 degrees above
normal today and tonight.
Short term /Tuesday through Wednesday night/...
at 230 am EDT Monday...on Tuesday morning zonal upper level flow
will exist across the southern tier of states...to the south of an
upper low over James Bay and a ridge over the northern rockies. This
pattern persists into Wednesday night.
At the surface...a weakening stationary front will be near the
Carolina and Georgia coasts on Tuesday morning...while a cold front moves
south of the Ohio River valley. The cold front reaches the NC
mountains Tuesday evening....moving into the upstate SC on
Wednesday. The boundary then returns north as a warm front on
Wednesday night and reaches Virginia by Thursday morning.
Precipitation chances will increase as moisture spreads east along
the front through Wednesday night. Instability will actually be
greater on Tuesday before the front arrives and moisture increases.
Temperatures will run above normal as cold advection never really
sets up with front retreating.
Long term /Thursday through Sunday/...
at 230 am EDT Monday...on Thursday nearly zonal upper level flow
will be over the Continental USA...with shortwave energy crossing
the MS River Valley. The shortwave will cross the southern
Appalachians on Friday. The upper patter amplifies by Saturday...
with a trough over the plains...and a trough over the east. By
Sunday the pattern starts to deamplify...and the ridge expands
eastward across the Gulf states. Meanwhile...a weak upper trough
remains along the East Coast.
At the surface...on Thursday a stationary front will extend from the
Virginia convective available potential energy to the Ohio River valley...while Atlantic surface ridging
extend across Florida to the Gulf of Mexico. The boundary drops south as a
cold front on Friday...reaching western NC on Friday night...and
crossing upstate SC and NE Georgia on Saturday. This front reaches S Georgia
and the SC coast on Sunday cool high pressure noses down the eastern
Seaboard behind this front.
Only modest instability will be present ahead of the front.
Precipitation chances and amounts should diminish as the front drops
south of the area. Temperatures wil experience a downward trend as
the front moves through and heights fall aloft.
Aviation /12z Monday through Friday/...
at kclt...Sat pictures and regional observation show IFR/MVFR stratus making a
northward run at the airfield. If these trends continue...then
restrictions will develop and slowly rise to VFR through the morning.
If not...at least scattered low clouds will only slowly rise to VFR through
the morning. Otherwise...expect VFR cumulus to develop for the afternoon
and continue into the evening before dissipating. It is currently
unclear whether stratus will develop tomorrow morning. Light winds
this morning will turn southerly and continue there through the period. That
said...a brief period of northeasterly winds cannot be ruled out this
Elsewhere...ceiling restrictions look likely at the SC sties...but not
at the NC sites...with similar trends to kclt. The rest of the
period trends look similar as well...except for winds. Winds look to
remain NE or east for the SC sites with southerly wind for khky. North-northwest wind
continues through the period at kavl.
Outlook...gradually increasing precipitation/restriction chances
through middle week as moist southerly flow returns ahead of the next
11-17z 17-23z 23-05z 05-06z
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 87% 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)