Area Forecast Discussion
Issued by NWS Greer, SC
FXUS62 KGSP 300557
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
157 AM EDT MON MAY 30 2016
Abundant moisture will persist over the region as tropical system
Bonnie stalls near the South Carolina coast. The remnants of Bonnie
will drift northeast along the Carolina Coast through the first half
of the week. A weak cold front will then push into the southern
Appalachians from the northwest and stall later in the week.
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
As of 145 AM EDT...A thin band of light to moderate showers has
developed within an area of LLVL convergence associated with the
remnant circulation of Bonnie within the last hour or so. This band
looks nearly stationary...extending from Statesville NC to near
Laurens SC. The latest HRRR shows this band dissipating during the
next couple hours...with new bands developing further west. Not sure
how this evolve...so will forecast mainly SLGT CHC to low-end CHC
pops and mainly east of I-26. Otherwise...only minor tweaks to the
sky and temps were needed.
Widespread cloud cover will continue as TD Bonnie meanders slowly
northeast up the SC coast, pushed slowly by a high-wavelength
shortwave passes through the Great Lakes and Appalachians, but
should see some scattering toward daybreak which will allow lows to
drop a few degrees cooler than last night. Very weak flow aloft is
expected during the day with again a minimum of instability across
the foothills and western Piedmont but with increasing instability
through the day mainly along the I-77 corridor. Temperatures will be
highly dependent on cloud cover but should climb back in to the mid
80s across a good chunk of the Upstate, and upper 80s in the Upper
Savannah Valley, but in general pretty close (within a degree or
two) to seasonal normals.
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/...
At 230 PM Sunday: On Monday evening weak nearly zonal upper level
flow will extend across the southeast USA, and will persist into
Wednesday, even as modest upper troughing eventually sets up along
he southern portion of eastern seaboard. A very weak upper impulse
appears to slowly cross the western Carolinas and northeast Georgia
on Tuesday and Wednesday.
At the surface, on Monday evening what`s left of tropical storm
Bonnie will be moving slowly northeast along the SC coast toward the
NC coast. Moisture associated with this system will will still be
impacting our area, but the models disagree on whether the moisture
will extend as far east as the mountains, or just to the Interstate
As Bonnie`s remains move along the NC coast on Tuesday, moisture is
expected to decrease over our area, but not enough to preclude
modest precipitation, and this trend continues into Wednesday.
Precipitation amounts are expected to be quite limited, as
isentropic downglide will be present in the west side of Bonnie`s
remains, however instability will be present both Tuesday and
Wednesday, perhaps supporting a few stronger showers. Temperatures
will run slightly above normal.
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
At 230 PM Sunday: On Wednesday night an upper trough will be
crossing the upper MS River Valley and and Southern Plains, while
weak upper troughing remains along the southern eastern seaboard.
The northern portion upper trough reaches the Great Lakes by
Thursday, where it remains into Sunday, while the southern portion
reaches the southern MS River Valley. Weak mid level vorticity
appears to reach our area late in the period, though the models
disagree on when and how much.
At the surface, on Wednesday night, moisture associated with tropical
system Bonnie will remain over our area, while a cold front crosses
the MS River Valley. The front reaches the Southern Appalachians
late Thursday, and slowly crosses the foothills and piedmont on
Friday, stalling near the southeastern portion of our are on
Saturday. There is some disagreement between the models on how far
north moisture will linger as a surface wave moves along the stalled
boundary on Sunday. Precipitation amounts are expected to peak with
the arrival of the cold front late in the forecast period, but at
this point do not appear to be excessive. Temperatures are expected
to cool from slightly above normal to near normal.
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
At KCLT...Moisture spiraling around the remnants of Bonnie have
produced a spoke of MVFR clouds extending from the CAE area north
thru the CLT area. This cloud deck is expected to expand and persist
thru the overnight...eventually lifting to VFR around midday. So
will go with prevailing 2500 ft CIGS thru 17z. Then 4500 ft
thereafter. There is also a band of -RA breaking out within this
cloud band...but is mainly west of the terminal. I will go with
VCSH...but cannot rule out a few -SHRA thru the morning. In the
AFTN...guidance shows some modest INSTBY which may be ENUF for a few
scattered TSRA. Will highlight with a PROB30. NE winds around 5-8
kts thru the period.
Elsewhere...As with KCLT above...HKY may see a few brief -SHRA or
sprinkles thru the morning associated with generally MVFR CIGS. To
the west...the Upstate sites and AVL should stay VFR as mid clouds
linger thru late morning. In the AFTN...a few SHRA/TSRA may develop
in the MTNS...but not ENUF coverage to warrant a PROB30 at any of
the sites. Winds will continue to be N to NE and generally under 10
kts thru the period.
Outlook: Bonnie is expected to move very slowly up the coastal
Carolinas over the next several days. Lingering shower chances into
the early part of the week would be greatest at KCLT. Otherwise,
patchy fog chances continue at KAVL each morning, with scattered
afternoon/evening SHRA/TSRA increasing throughout during the week.
06-12Z 12-18Z 18-24Z 00-06Z
KCLT Med 76% High 81% High 100% High 100%
KGSP High 100% High 100% High 100% High 100%
KAVL High 100% High 100% High 100% High 100%
KHKY High 98% 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 schedule TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link: