Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 241806

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
206 PM EDT SUN JUL 24 2016

Broad high pressure will linger over the region through mid
week. During the late week, a mid level disturbance is expected to
slowly ripple over the forecast area. Moisture levels will gradually
increase across the western Carolinas and northeast Georgia by the
middle of the week as the region will remain on the warm side of a
stalled mid Atlantic front.


As of 150 pm EDT, very warm profiles across the region are making
conditions a bit more inhospitable to convection than in previous
days. The MSAS SBCAPE analysis does show afternoon values of 2000 to
3000 J/kg across th southern piedmont and NE Georgia - with lesser
values farther north. Additionally, DCAPEs are a robust 1000 to 1400
J/kg across the region so isolated severe still has a chance if
better coverage can materialize. However, all the recent HRRR runs
are relegating afternoon and early evening coverage to the southwest
mountains and extreme lower piedmont.

Otherwise, A zonally-oriented 594 dm 500 mb ridge will remain over
the region through Monday. Any lingering late evening convection
will quickly diminish and we will see another night of mild min
temps 4 to 8 degrees above climo along with mountain valley stratus
and fog. Scattered convection will develop in the mountains again on
Monday afternoon - with similar coverage to today. A persistent
surface lee trough will keep winds light S to SW through the period
except a bit more westerly across the mountains. Expect plenty of
mid 90s maxes Monday afternoon, but with heat index values likely
peaking at 101 to 103 again in the lower piedmont.


As of 230 AM Sunday: On Monday, H5 ridge centered over the western
Atlantic as a mid level disturbance tracks west across the northern
Gulf coast. Mostly clear morning sky conditions should result in
steady warming, expected to reach the lower 90s east of the mtns by
lunch. Temperatures are forecast to peak in the upper 80s within the
mtn valleys to mid 90s along and east of I-85. Steady SE winds
should keep dewpoints in the upper 60s to around 70 through the
afternoon hours. The combination of the hot temperatures and RH
around 50 percent should result in Heat Index values around 100
degrees east of the mtns. In addition, the hot and humid llvl
conditions has resulted in interesting forecast soundings Monday
afternoon. NAM soundings across the upstate of SC indicate CAPE
values between 2500-2700 J/kg, LFC a little less that 5 kft, little
to no late afternoon CIN, and around 2000 j/kg of DCAPE. I will
forecast TSRAs to develop over the mtn ridges during the mid
afternoon, then start to slide SE during the late afternoon to early
evening. Areas along and east of I-77 should see the least coverage.
Several of these storms will become quite tall, reaching to around
45 kft. Given the DCAPE and low shear, I would expect several
damaging wet microburst with pulse thunderstorms.

On Tuesday, the center of broad sfc high pressure will shift over AL
as a lee trough develops across the Piedmont. The sfc pattern will
result in light and steady downslope winds from the WSW. Forecast
highs may peak around degree warmer than forecast for Monday.
Dewpoints should range 2 to 3 degrees lower than values from Monday.
Forecast soundings indicate moderate instability with weak capping
east of the mtns. The forecast will continue to highlight high chc
to likely across the TN border counties, fading to chc against the
foothills. Foothill and Piedmont should verify well with schc pops
for SHRAs and TSRAs.


As of 245 AM Sunday...A broad H5 ridge on Wednesday will give way to
a broad trough by Friday and Saturday. I will forecast diurnal chc
PoPs across the CWA on Wednesday. However, the arrival of the trough
would support greater coverage with less diurnal swings in coverage.
I will gradually increase PoPs to high chc to low likely by Sat,
keeping schc pops generally across the mtns during the overnight
hours. High temperatures are forecast to range for 3 to 4 degrees
above normal from Wednesday through the rest of the work week. On
Saturday, high temperatures are forecast to range 2 to 3 degrees
above normal.


At KCLT and elsewhere, the dominant upper ridge is producing very
warm profiles that are making convection less widespread today. KCLT
and KHKY should see nothing nearby. KGSP and KGMU will have slightly
better late day convection chances, but still unmentionable in the
TAF, while KAVL and KAND will need a VCTS in the higher terrain and
nearer the better dewpoint gradient, respectively. Expect light SW
winds through the period, except for more NW flow most hours at KAVL
west of the surface lee trough. Will feature another round of LIFR
to IFR conditions toward daybreak in the mountain river valleys -
including KAVL.

Outlook: Isolated/scattered afternoon/evening showers and
thunderstorms will continue across the mountains/piedmont through
much of the week - with coverage increasing a bit each day. Morning
fog and low stratus will continue in the mountain valleys around
daybreak each day, and also be possible in locations that receive
heavy rainfall the preceding afternoon/evening.

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%     Low   55%     Med   71%
KHKY       High 100%     High 100%     High  94%     High  94%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High 100%     High 100%     High  97%     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:



  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      96 1983     68 1985     71 1934     52 1966
   KCLT     100 1983     73 1938     78 2010     59 1947
                1952                    1883
   KGSP     101 1952     70 1985     79 2010     59 1904


  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      92 2010     68 2000     70 2012     51 1895
                2005                    2011
                1987                    2010
   KCLT     101 2010     69 2000     79 2010     62 1947
   KGSP     100 1995     72 2000     77 2010     57 1911




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