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Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
246 PM EDT MON AUG 29 2016

A weak tropical system will approach the North Carolina Outer Banks 
tonight and tomorrow before moving back out to sea on Wednesday. 
A cold front will approach the region from the north Wednesday night 
with another tropical system emerging from the Gulf of Mexico on 
Thursday. This system is expected to remain just to our south and
move offshore over the weekend.


As of 2:30 PM: Water vapor imagery shows several tropical features
in the western Atlantic and Gulf of Mexico. The GSP forecast area
appears to sit between all of them. A break in the large ridge of
high pressure, from Missouri to Bermuda, was noted off the North
Carolina coast - via aforementioned water vapor imagery.

An easterly flow was pushing bands of mid and high level cloudiness
west/southwest, into our region, which should continue for the rest
of the afternoon and tonight. Meanwhile an upper low was spinning
off the SC/GA coast, sending moisture to the northwest. Perhaps it
is this feature which has slowed the overall drop in dewpoints,
especially in our southern areas. SB capes are running higher than
model guide, as a result we have moved the slight chance to chance
POPS of thunderstorms north into early evening. 

The second area of potential precipitation for the rest of the day
would be the high terrain of NE Georgia and North Carolina. We have
maintained continuity with small chances those locations into early
evening. DCAPES meanwhile are running on the low side, which should
keep a bit of a lid on strong convection.

Valley fog and some stratus should once again be noted in those
locations of western NC late tonight.

On Tuesday, as lower theta e air continues to advect into our
forecast area, any precipitation prospects should be minimal. We
will go ahead with below climatology POP values in the NC mountains
during the late afternoon hours.

Despite the clouds, temperatures continue to edge up. We plan to
follow the suite of temperature guide tonight, and then perhaps a
degree or two (above the coolest high temperatures Tuesday).


As of 200 pm EDT Monday:  By Tuesday evening, tropical depression 8 
will be moving northeast of the Outer Banks and well outside of 
having any direct impacts on the GSP CWA.  Meanwhile, tropical 
depression 9 will gradually organize over the Gulf before tracking 
across northern Florida late on Thursday.  9 is also not expected to 
have direct impacts on the CWA, being too far south and eventually 
southeast of the area; at least through Thursday.  POPs, though, 
will increase Wednesday and Thursday as deep upper trough over the 
northeast CONUS with a surface cold front approaches the area on 
Wednesday and Thursday with a FROPA expected around 18Z on 
Thursday.  FROPA will bring a significant chance for showers 
Thursday afternoon through Friday morning, with some showers 
possible Wednesday afternoon over higher terrain in advance of the 
system.  Airmass is dryer than recent weeks and we will see CAPE 
below 1000 j/kg at most Tuesday and Wednesday afternoons, and precip. amounts 
are not expected to be particularly generous.  Front is followed by 
significantly cooler and dryer conditions leading into the end of 
the week.


As of 210 PM EDT Monday, the medium range fcst picks up at 00Z on
Friday with a positively tilted upper trof axis passing to our 
north and a very steep upper ridge spreading over the central 
CONUS. In addition, a tropical disturbance that is currently 
located north of Western Cuba is expected to be moving across 
Northern Florida by early Friday. As we move into the weekend,
the trof axis will translate offshore while the upper ridge 
spreads farther east eventually encompassing the eastern half 
of the CONUS. 

At the sfc, a tropical low associated with the upper lvl disturbance
mentioned above is expected to be moving over North Central Florida 
and then off the southeast coast on Saturday. The long range models 
appear more consistent with the system overall, however the ECMWF is
still quite a bit faster moving the low off the southeast coast over 
the weekend compared to the GFS. The Canadian model remains the farthest
west and slowest wrt the storm track. Regardless, by early Sunday all 
the models agree that the low will be moving well offshore and Canadian
high pressure will spread back over the region and persist into early 
next week. As for the sensible fcst, the guidance has been trending 
drier overall with most of the precip associated with the tropical 
system likely remaining to our south and east. The best chances for 
widespread precip will be early Friday over the SE zones with only 
scattered slight chance POPs for Saturday. The rest of the period 
should be dry. Flooding should not be a concern over the CWFA with 
total QPF on Friday expected to be less than 0.5 inches. Temps will 
start out near or slightly below climatology on Friday and remain 
in that range for the rest of the period.


At KCLT: Mid and high level cloudiness will continue to advect
west/southwest across the site right through Tuesday. This is all
tied into the tropical feature off the North Carolina coast.
Meanwhile, dewpoints have been slower to drop which has allowed a
fair amount of cumulus clouds today. They should linger through the
afternoon before dissipating this evening.

VFR conditions should persist Tuesday, with waves of clouds moving
through from time to time. NE surface winds ( on average ) should be
the rule into Tuesday.

Elsewhere: Mostly VFR conditions this afternoon and tonight with a
few exceptions. Model bias of lowering dewpoints appears fast. As a
result brief periods of MVFR CIGS will be possible (mainly at our
southern TAF sites) until loss of heating.

Most of the convection however should remain south of all sites,
although we will have to keep and eye on Anderson We have beefed up
the late night fog at AVL with nearly calm winds, and will follow

Outlook: We will remain in-between many systems surrounding the
sites Wednesday, with convection tied into mostly higher terrain. A
cold front will enter the region Thursday and Thursday night, with a
potential uptick in showers and thunderstorms. Depending on the
track of any of the various tropical features, we might be favoring
a drier weekend forecast.

Confidence Table...

            18-24Z        00-06Z        06-12Z        12-18Z 
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  97%     
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:





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