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Area forecast discussion 
National Weather Service Greenville-Spartanburg SC
334 am EDT sun Aug 30 2015

Synopsis...
an upper level disturbance will lift northeast across the region
today. Otherwise...weak surface high pressure will remain in place
over the area through the week. Moisture may spread northward from
the remnants of tropical system Erika...but with a great deal of
uncertainty over how much moisture may reach the area.

&&

Near term /through tonight/...
as of 325 am...a middle level low near the Florida Panhandle this morning
will lift northward today. As the low tracks north...it will weaken
into a short wave...expected to pass over the County Warning Area tonight. As the middle level
feature approaches the western Carolinas...clouds across the region
will thicken and lower along with the development of scattered showers.
Latest radar images and surface observations indicated a few patches of
sprinkles drifting over the lake lands. Latest runs of the NAM and 4
km WRF show sprinkles remaining across the region this
morning...with showers this afternoon and evening. Forecast
soundings show cape values remain quite low across the region this
afternoon...I will forecast primarily showers. The GFS indicates that
the period of greatest synoptic scale forcing will likely occur
between 0z to 6z Monday. During this period...the closed low or short wave
will slide across the region...resulting in a belt of q-vector
convergence across the Carolinas. I will forecast 30 to 50 probability of precipitation
during the late afternoon and evening. The combination of thick
cloud cover and showers should keep highs across the upper Savannah
River valley limited to the u70s...with middle 80s expected across the
clt metropolitan.

Tonight...the middle level trough will track NE...followed be weak height
rises during the late night hours. I will trend probability of precipitation lower after
midnight...but remaining in the schc to lchc range. Low temperatures
are forecast to range from the l60s across the mountains to the upper 60s
east.

&&

Short term /Monday through Tuesday night/...
as of 245 am EDT Sunday...a weak upper level closed low/trough will
remain orphaned over East Texas through the short term period...while a
broader upper ridge builds over the eastern Continental U.S. Through Tuesday. Under
this upper ridge...weak surface high pressure will linger along the
Appalachians. There appears to be improving consensus in the
numerical models on keeping the deeper tropical moisture associated
with the Erika remnants shunted south of this surface ridge...with
the greatest moisture confined mainly from Florida to the coastal
Carolinas Monday through Tuesday. For our region...this means continued
weak instability in vertical profiles under the ridge...but with
precipitable water values gradually increasing. Will continue to
feature mainly diurnal scattered convection with maximum temperatures slowly
rebounding to near climatology despite the cloud cover.

&&

Long term /Wednesday through Saturday/...
as of 245 am EDT Sunday...a very weak upper level flow pattern will
exist Wednesday through Sat as the persistent Gulf Coast trough slowly
migrates east under the broad flat eastern ridge. Any remnant Erika
circulation appears to make little northward progress through the medium
range...with the ecm/NAM Camp keeping the remnant low center near
coastal Georgia/NE Florida while the GFS Camp is farther SW near the Florida
Panhandle. This will make for highly uncertain moisture profiles
over the region...with a sharp gradient in precipitable water likely
from the drier northern mountains to the more moist lower southeast Piedmont.
Any predecessor rain event potential for early in the period now
appears quite nebulous given the current weak state of the Erika
remnants and possibility of some drier air reinforcing from north
middle to late week in the surface ridge. Will continue the current
forecast thinking of slightly above climatology/mainly diurnal probability of precipitation Wednesday
through Sat...with gradually climbing temperatures in the absence of
any strong signal for heavy rainfall.

&&

Aviation /08z Sunday through Thursday/...
at kclt...a middle level low near the Florida Panhandle this morning will
lift northward today. As the low tracks north...it will weaken into
a short wave...expected to pass over the County Warning Area Sunday night. As the middle level
feature approaches the western Carolinas...clouds across the region
will thicken and lower along with the development of scattered showers.
Sky should remain broken to overcast with middle level clouds through the
daylight hours. Forecast soundings indicate MVFR ceilings developing
one to two hours after sunset. I will include a vcsh between 2z to
4z. Light winds from the south are forecast to continue through the
taf period.

Elsewhere...conditions will remain VFR through the daylight hours
today. However...an approaching middle level feature will result in
widespread restrictive ceilings around sunset...along with scattered
showers. I will include at least a vcsh mention for each terminal
this evening. Light winds...favoring the south...are forecast to
continue through the taf period.

Outlook...the southeast region is forecast to remain under a plume
of Gulf and Atlantic moisture through the middle of next week. In
addition...moisture associated with the remnants of Erika could
reach the southern Appalachians during the middle week. Restrictions
are possible during periods of rain and with the Mountain Valley fog
around dawn.

Confidence table...

07-13z 13-19z 19-01z 01-06z
kclt high 100% high 100% high 100% high 80%
kgsp high 100% high 100% high 100% medium 78%
kavl high 100% high 100% high 100% high 83%
khky high 100% high 100% high 100% high 91%
kgmu high 100% high 100% high 100% high 81%
kand high 100% high 100% high 95% high 93%

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)

Www.Weather.Gov/gsp/aviation

&&

Gsp watches/warnings/advisories...
Georgia...none.
NC...none.
SC...none.

&&

$$
Synopsis...hg
near term...Ned
short term...hg
long term...hg
aviation...Ned

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