Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 250615
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
215 AM EDT MON JUL 25 2016

.SYNOPSIS...
Broad high pressure will linger over the region through the week
before a mid level disturbance crosses the forecast area on Friday.
Moisture levels will gradually increase across the western Carolinas
and northeast Georgia by the middle of the week while a stationary
front remains across the mid Atlantic region.

&&

.NEAR TERM /THROUGH TODAY/...
As of 210 AM: The western Carolinas will remain on the western edge
of a H5 ridge through tonight. The sfc pattern will feature a high
over the Atlantic and a shallow trough over the Piedmont. This
pattern should support a light SSW across the region, with periods
of calm this morning and late this evening. Temperatures will begin
the day around 5 to 7 degrees above normal. The warm start and
strong insolation should result in temps in the low 90s around noon,
peaking in the mid 90s by mid afternoon. Hot temperatures and
dewpoints near 70 degrees will yield moderate instability and steep
llvl lapse rates. However, LFC are forecast to range from 6.5 to 6.8
kft and mid level lapse rates generally run at a shallow 5 C/km. NAM
dewpoints appear too high and convection coverage is likely
overdone. Using the SPC SSEO and 4 km WRF, I will limit PoPs east of
the mtns.

As of 1040 PM EDT:  Once again the previous lowering pop trend was
favored as convection has cleared out across the region leading
into a partly cloudy, becoming mostly clear evening as mid/high
clouds advect downstream.  That combined with ample bl moisture and
calm winds will lead to patchy fog once again, with the most dense
fog being in the mountain valleys where visbs could fall to less
than a 1/2sm at times.  Other than that, expecting a rather quiet
evening, thus no sig changes were needed/made with this update.

Previous Discussion:  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. Southern Elbert County and Eastern Union County
NC will be the closest to approach 105.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
At 210 PM Sunday: On Monday night and upper ridge will centered off
the coast of the Carolinas, extending west and inland to the
southern Appalachians. Although the ridge remains in place off the
coast through Wednesday, there are some indications that falling
heights to our north may reach as far south as northern NC.

At the surface, weak troughing will be in place Monday night along
the eastern seaboard, while a weak cold front drops south over the
OH River Valley. The front slows to our north on Tuesday, while
moisture ahead of the boundary increases over the southern
Appalachians. By Wednesday there is some discrepancy in the models
on the position of the front, with some indications it will reach NC
or even northern SC, brining even more moisture to the area.

Instability will be sufficient to support convection through the
period, perhaps lingering overnight depending on models sources, but
shear appears to be limited and not supportive of organized
convection. Steering flow appears weakest during daylight hours, at
least at lower levels, perhaps supporting slow moving cells and
locally heavy rainfall. Temperatures will run three to five degrees
above normal. Apparent temperatures do not appear to exceed 100
degrees.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 210 PM Sunday...Good confidence is had in the ext range as the
op models continue in agreement with the ulvl pattern and to some
extent the lower levels. The ECMWF builds the subtrop ridge farther
west than the GFS across the nrn GOM...however moisture flux
differences will not appreciably affect the sensible wx. Broad flat
ridging will dominate the srn CONUS Thu with gradually lowering
heights across the east through the period as a broad H5 trof swings
across the Glakes region. This trof will push a weak cold front
toward the area by Fri and the airmass ahead of the front will
remain seasonably warm and moist. Likely pop coverage will favor the
NC mtns through the period with pulse stg/svr tstms developing each
afternoon. Slight to sct mention will be maintained non/mtns. The
persistent synoptic pattern will maintain max/min temps a few
degrees F above normal each day.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere east of the mtns: VFR through the period.
Rainfall coverage was outside of the foothill and Piedmont TAF
sites, potential for fog this morning is low. The
western Carolinas will remain on the western edge of a H5 ridge
through tonight. The sfc pattern will feature a high over the
Atlantic and a shallow trough over the Piedmont. This pattern should
support a light SSW across the region, with periods of calm this
morning and late this evening. Temperatures will begin the day
around 5 to 7 degrees above normal. The warm start and strong
insolation should result in temps in the low 90s around noon,
peaking in the mid 90s by mid afternoon. Hot temperatures and
dewpoints near 70 degrees will yield moderate instability and steep
llvl lapse rates. However, LFC are forecast to range from 6.5 to 6.8
kft and mid level lapse rates generally run at a shallow 5 C/km. NAM
dewpoints appear too high and convection coverage is likely
overdone. Using the SPC SSEO and 4 km WRF, I will limit PoPs east of
the mtns and keep convection out of the TAF.

KAVL: The terminal did not receive measurable rainfall on Sunday.
At 6Z, dewpoint depression was only 2 C. Based on the forecast rate
of cooling through sunrise, it appears that the crossover
temperature will be reached during the predawn hours. I will
indicate a TEMPO from 8z to 12z for mvfr fog and SCT005. Ridgetop
convection should trigger during the mid morning, drifting over the
valleys between 20z to 24z. I will highlight the potential for TSRA
with a PROB30 during expected period. Otherwise, winds will vary
from calm early this morning to NW during the morning daylight, SW
expected during the afternoon.

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...

            06-12Z        12-18Z        18-24Z        00-06Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High  94%     High  88%
KAVL       High  97%     High 100%     High  86%     High 100%
KHKY       High  97%     High 100%     High 100%     High  92%
KGMU       High 100%     High 100%     High  94%     High  88%
KAND       High 100%     High  97%     High 100%     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:

www.weather.gov/gsp/aviation

&&

.CLIMATE...
ERATURE         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



RECORDS FOR 07-29

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      98 1952     67 1984     74 1877     55 1911
                                                    1895
   KCLT     103 1952     72 1984     77 1993     59 1920
   KGSP     104 1952     70 1984     76 1949     59 1911
                                        1936



RECORDS FOR 07-30

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      93 1954     68 1936     72 2011     54 2014
                                        1878        1897
                                                    1895
   KCLT     101 2011     71 1981     77 1953     58 1914
                                        1941
   KGSP     101 1999     73 1981     77 2011     60 1914
                                                    1911
                                                    1884



RECORDS FOR 07-31

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      95 1999     65 1936     71 2011     53 1986
                                                    1914
   KCLT     100 1999     69 1936     77 1941     56 1914
                1931                    1931
                1915
   KGSP     104 1999     71 2014     78 1999     56 1936
                                        1931

&&

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

&&

$$
SYNOPSIS...SBK
NEAR TERM...NED
SHORT TERM...JAT
LONG TERM...SBK
AVIATION...NED
CLIMATE...


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