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Area Forecast Discussion

733
FXUS62 KGSP 221508
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1108 AM EDT FRI JUL 22 2016

.SYNOPSIS...
Broad high pressure will remain across the region through early next
week. The high is expected to weaken on Monday, shifting west and
east of the region. Moisture is forecast to gradually increase
across the western Carolinas and northeast Georgia early next week
as a cold front becomes stationary across the mid Atlantic states.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1045 AM EDT, very little change to the forecast was needed,
with just a bit more high clouds into the early afternoon before
mainly scattered cumulus develops. Temps are off to a slow start
with the high clouds but insolation should improve by Noon

Otherwise, a massive upper ridge centered over western Kansas will
continue to compete with a trough along the East Coast for synoptic
supremacy across the forecast area through the period. Thickness
values today continue to support max temps a couple of degrees
higher than on Thu., somewhat augmented in the foothills and far
western Piedmont by more of a westerly low level flow. Warming temps
aloft and deeper mixing are yielding some rather uninspiring
forecast soundings in terms of the deep convective potential this
afternoon. Dewpoints may see enough mixing out west of a lee trough
this afternoon to severly limit SBCAPE values. There does still
appear to be plenty of buoyancy available across the high terrain,
and scattered cells should generate in the usual spots near the Blue
Ridge during mid-afternoon. Mean cloud-bearing winds and the
buoyancy gradient would tend to take any activity almost due south
into the western half of the Upstate and northeast GA Piedmont, so
30 pops will be carried in those areas. Elsewhere, pops will be
slight chance at best. A well-mixed boundary layer and dry air aloft
is resulting in some healthy dCAPE values in forecast soundings in a
weakly sheared environment. Would therefore expect a handful of
microbursts from pulse storms this afternoon and evening.

Expect diurnal convection to gradually wind down mid-to-late
evening. Will need to keep an eye upstream, as the possibility
remains that the remnants of organized convection could make a run
at the CWA, or mid-level vorticies originating from this activity
could initiate new convection in our area. This doesn`t appear to be
all that likely attm, and pops will taper off to less than slight
chance by daybreak Saturday. Min temps will be a category or so
above climo in most areas.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 2 AM Friday: On Saturday, h5 ridge will remain across the CWA,
heights around 592DM. NAM forecast soundings indicates the mixing
will deepen to around H8 during the heat of the afternoon. The llvl
thermal and dewpoint profile resembles an inverted V. Using a blend
of MOS guidance, I will indicate sfc dewpoints starting the day
around 70 degrees, then mixing into the upper 60s during the
afternoon. Convective inhibition may linger through the afternoon,
with values ranging as little as 5 to 10 J/kg around 21Z. Convection
appears favored across the mtn ridges and adjacent foothills.
However, weak steering flow and lingering capping may yield at most
isolated coverage. The main headline for Saturday will be the heat.
A blend of model guidance supports highs ranging from the upper 80s
within the mtn valleys to mid 90s across the Piedmont. The high
temperatures combined with afternoon RH around 40 percent should
result in Heat Index values to peak between 100 to 105.

Sunday, models begin to show differences within the mid level ridge.
The 0z GFS shows the ridge centered over the Four Corners with a 587
DM low over northern FL. The 12z ECMWF shows the center of a 594 DM
ridge shifting over the southern Appalachians. The 0z NAM appears to
be the compromise solution and I will favor it through the rest of
the short term. Overall, Sunday appear around one degree hotter than
high temperature and Heat Index values forecast for Saturday. In
addition, capping appears a little weaker for Sunday. I will
continue to favor the mtn ridge for high chc PoPs, spreading schc
PoPs east during the heat of the afternoon.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 215 AM Friday: I will favor the ECMWF through the extended
period, Monday through Thursday. Overall the pattern change little
through the period, with gradual lowering of H5 heights as rights
splits and develops a Bermuda ridge and desert SW ridge. Weak cold
fronts are expected to drop and stall across the mid Atlantic
states. This pattern should favor slightly elevated PWs across the
forecast area with slight to moderate instability each afternoon. I
will continue to feature likely PoPs across the ridges and chc PoPs
east Monday through Thursday. Hot conditions will remain across the
region on Monday, very close to Sat and Sun. However, lowering
heights and increase in moisture should favor highs around normal
through the remainder of the period.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Will feature a VFR forecast through the
period. That leaves afternoon/evening convection as the prime
concern. Convection is expected to develop across the high terrain
once again this afternoon, and to move almost due south. PROB30s for
TSRA are therefore carried first at KAVL (where VCTS is also
advertised after 18Z), then at the Upstate SC terminals during the
evening. Convection will continue to be omitted from the forecast at
KCLT/KHKY. Otherwise, light S/SW winds will persist through the
period at KCLT, but are expected to turn toward the W/NW at other
terminals to the west of a lee trough.

Outlook: Expect typical midsummer weather with scattered afternoon
and evening showers and thunderstorms through the early next
week. Morning fog and low stratus will be possible each day in
the mountain valleys and also in locations that receive heavy
rainfall the preceding afternoon/evening.

Confidence Table...

            15-21Z        21-03Z        03-09Z        09-12Z
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%     Med   66%
KHKY       High 100%     High 100%     High 100%     High  94%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High 100%     High 100%     High 100%     High  94%

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:

www.weather.gov/gsp/aviation

&&

.CLIMATE...
ERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      96 1926     67 1970     75 1983     52 1966
   KCLT     103 1926     71 1929     80 1881     58 2001
   KGSP     101 1983     70 1970     79 1940     58 1890
                1926



RECORDS FOR 07-23

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      95 1983     69 1974     71 2015     50 1966
                1952        1938        1999
                1934                    1983
   KCLT     101 1987     73 1880     78 1991     56 2007
                1952
   KGSP     102 1952     74 1974     79 1934     59 1966
                                                    1947



RECORDS FOR 07-24

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      96 1983     68 1985     71 1934     52 1966
                                                    1895
   KCLT     100 1983     73 1938     78 2010     59 1947
                1952                    1883
   KGSP     101 1952     70 1985     79 2010     59 1904



RECORDS FOR 07-25

               MAX 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
                            1890



RECORDS FOR 07-26

               MAX 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
                1987



RECORDS FOR 07-27

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      97 1952     70 1946     72 1936     48 1911
                                        1925
   KCLT     103 1940     74 1926     76 1944     57 1920
                                        1940
                                        1936
   KGSP     103 1940     70 1946     75 2012     54 1911
                                        1944



RECORDS FOR 07-28

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      98 1952     68 1890     70 2010     53 1895
                                        1878
                                        1877
   KCLT     102 1952     70 1890     77 1997     54 1962
                                        1993
   KGSP     103 1952     72 1926     76 1936     60 1911
                                                    1904

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

$$
SYNOPSIS...NED
NEAR TERM...HG/JDL
SHORT TERM...NED
LONG TERM...NED
AVIATION...HG/JDL
CLIMATE...



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