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Area forecast discussion...updated 
National Weather Service Greenville-Spartanburg SC
202 PM EDT Monday Jul 25 2016

broad high pressure will linger over the southeast through the
remainder of the week, supporting plenty of heat and humidity. A
front is expected to remain more or less stationary from the mid
Atlantic through the Ohio Valley.


Near term /through Tuesday/...
as of 145 PM...convective temps have been reached per visible and
radar trends. However, showers have struggled to become deep enough
for thunder so far. It seems the upper ridge is in a position to
keep things somewhat suppressed. The latest Storm Prediction Center mesoanalysis shows
SBCAPE around 2000 j/kg, with some higher amounts along a Lee trough
in western NC. This instability may be enough for at least a few
thunderstorms to develop. And with dcape between 1000-1400 j/kg, any storms
that can get an icy core may produce wet microbursts. Another
concern this afternoon is heat indices, which are running a little
higher than this time yesterday. Dew points are remaining in the
lower 70s across much of the Piedmont, as temps reach the mid 90s.
So far heat indices are generally between 96-104 across the Piedmont.

Tonight...convection should wane with loss of heating this evening,
leaving some debris cloudiness around. Patchy fog will likely
develop again in the mountain valleys. Lows will remain a couple
categories above normal (upper 60s mountains to mid 70s piedmont).

Tuesday...little change in the overall set up and air mass from
Monday. Model guidance has slightly higher pops, perhaps due to a
frontal boundary approaching from the north. In fact, most of the
guidance keeps dew points more elevated across the area, with
widespread lower to mid 70s even during peak heating. This should
result in a little more cape. Temps are forecast to be a degree or
two cooler, but with the increased humidity, heat indices will again
range in the upper 90s to 104.


Short term /Tuesday night through Wednesday night/...
as of 310 am Monday, the subtropical ridge will remain the dominant
synoptic scale feature across the southeast during the short term.
Surface reflection/Bermuda high will support plenty of heat and
humidity across our area for the foreseeable future. A Lee trough and
the usual terrain effects will provide the primary source of lift
for initiating deep convection Tue afternoon. Buoyancy profiles are
quite impressive across the mountains during this time, and 50-60
pops appear warranted. There are some hints that surface dewpoints
could mix out outside the mtns in response to westerly flow, but at
least scattered activity should push off the high terrain by as
dewpoints begin to recover by evening.

Instability profiles continues to improve over a larger area on Wed,
while a surface boundary associated with Midwest height falls will
approach the area from the northwest. Thus, while more convection is likely
to initiate across the forecast area Wed afternoon, there will also
be an increasing chance for frontal activity to push into the
mountains during the late afternoon/evening. Another round of 50-60
pops will be forecast for the mtns, with 30-40 percent chances
across much of the foothills and Piedmont. Wind shear profiles will
remain weak through the period, thus chances for organized
convection will be small. However, increasing coverage of
convection, along with healthy downdraft cape forecasts will likely
result in increasing chances for microbursts into mid-week. Temps
will remain a good 5 degrees above climo through the period.


Long term /Thursday through Monday/...
as of 210 PM Sunday...little to no change in the pattern or sensible
weather is anticipated late week into the weekend, as Bermuda high
pressure continues to support at least seasonal levels of heat/
humidity/instability, while weak synoptic scale boundary is expected
to remain draped in the vicinity of the Ohio Valley. The only
potential break in the monotony would be a weak disturbance that
global model guidance is trying to develop within a weakness in the
subtropical ridge across the northwest Gulf of Mexico later this
week. Moisture associated with this feature could get advected north
toward the end of the week, as a weak mid-level wave moves out of
the plains. However, even the more aggressive guidance keeps the
deeper moisture west of our forecast area through day 7. Overall,
near to slightly above climo pops and near to slightly above climo
temps look to be the most likely scenario for days 4-7.


Aviation /18z Monday through Saturday/...
at kclt and elsewhere...convection beginning to become a little
deeper around the mountains and along a Piedmont trough, but still
limited to rain showers at time of 18z taf issuance. Expect a few of these
cells to become tsra, but mainly in the mountains. Only kavl will
mention ts, but will keep vcsh at kand as it is surrounded by small
rain showers. Confidence is too low elsewhere, but timely amendments will be
made, if any ts manage to develop near the other sites. Otherwise,
expect VFR conditions with cumulus bases around 6000 ft and a light
SW wind, becoming somewhat vrb tonight. The one exception being
possible fog and/or stratus at kavl late tonight due to valley fog
potential. Tuesday looks similar to today, with isolated convection
in the Piedmont and scattered to numerous in the mountains.

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% Med 72% high 91%
khky high 100% high 99% high 97% high 97%
kgmu high 100% high 100% high 100% high 100%
kand high 100% high 100% high 97% high 97%

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:



records for 07-25

Maximum temperature min temperature
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

Records for 07-26

Maximum temperature min temperature
station high low high low
------- ---------- ---------- ---------- ----------
kavl 94 1949 72 1911 71 2012 49 1911
1940 2010
kclt 100 2005 74 1920 76 1992 60 1904
1940 1940
1914 1936
kgsp 99 2010 76 1920 76 2005 53 1911
1995 1940


Gsp watches/warnings/advisories...


near term...Arkansas
short term...jdl
long term...jdl

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