Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 191506
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1006 AM EST Mon Feb 19 2018

.SYNOPSIS...
High pressure off the East Coast will provide a southerly flow of
air going into mid week with temperatures climbing well above
normal. Another cold front arrives from Tennessee by Thursday. This
front will stall out and linger just north of our area next weekend.
Chances for rain remain in the forecast each day.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM EST Monday: Minor tweaks made to temperatures and
PoPs with this update to account for latest trends as the rest
of the near term forecast remains on track. Will also note, have
added verbiage to HWO to highlight the potential for patchy
areas of dense fog across the area tonight through into Tuesday
morning.

With temperatures in the upper 40s/lower 50s across the area,
conditions remain fairly quiet this morning. Latest radar imagery
depicts a few areas of light rain/drizzle moving across the area as
latest obs continue to highlight patchy areas of fog as well, down
to around 1SM in some locations. While areas of fog will continue
through today, given latest fcst soundings, do anticipate widespread
fog to develop tonight, with areas of dense fog possible.

Otherwise, the upper level flow across the CONUS continues to
amplify, with a deep trough over the west and a ridge building over
the East Coast. At the surface, high pressure continues to slowly
drift off the Mid-Atlantic coast, while an area of low pressure
organizes over the Central Plains. The flow between the high and low
atop the CWFA is bringing moisture and upglide, producing areas of
light rain and drizzle. The precip is falling into some dry air,
causing an in situ CAD wedge to develop over the CWFA. Guidance
still shows this wedge holding on thru the day, at least near the
Blue Ridge escarpment. Temps will be held down under the wedge, but
some erosion around the fringes is expected as precip coverage
decreases, which may allow temps to warm into the 60s. In any case,
it should be cloudy today with near normal temps in the wedge and
above normal elsewhere.

Tonight, whatever wedge still in place will likely persist into
tonight. Guidance shows a slight uptick in moisture and areas of fog
looks likely. Confidence on dense fog is still low, but there may be
patches of it out there late tonight. Temps will drop little
overnight staying well above normal lows thru daybreak Tuesday.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 315 AM Monday: Upper pattern dominated by a strong high just
off the Southeast coast and a deep trough over the western CONUS.
These features remain in place through the period keeping southwest
flow over our area. A few weak short waves move through the flow and
near our area. A weak upper jet max moves near the area by the end
of the period as well. The combination does bring some weak synoptic
scale forcing into the area by the end of the period. At the
surface, high pressure centered over the Atlantic remains ridged
into the through the period. A weakening cold front approaches from
the west by Wednesday night. This keep deep southwesterly flow over
the area through the period. Moisture slowly increases as well. The
main forcing for precip Tuesday will be mechanical upslope flow into
the southern Blue Ridge. Expect mainly a slight chance of showers
with scattered showers possible over the upslope areas along the
NC/SC/GA border area. Weak instability develops Wednesday to go
along with the weak synoptic scale forcing. This will increase
precip chances into the likely range along and near the southern
Blue Ridge into the southwestern NC mountains, with chance PoP
elsewhere. Isolated thunderstorms cannot be ruled out over NE GA,
the western Upstate and along and west of the French Broad Valley.

With this pattern in place, very warm temps are expected during the
day and at night. In response, have trended toward the higher range
of guidance. This puts record highs at CLT and GSP in jeopardy both
days. AVL will be a few degrees below record but still nearly 20
degrees above normal. Lows will be 15 to 20 degrees above normal
which is above the normal highs. This also puts record warm lows in
jeopardy both days as well.

As previous shifts noted, with a saturated low-level inversion and
support from MOS guidance, areas of fog are a reasonably good bet
early Wednesday morning.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 120 AM EST Monday:  The medium range forecast period starts
Thursday morning with the 500mb pattern having the center of high
pressure near Bermuda and a broad trough over the western two thirds
of the nation. The cold front over Tennessee will stall and result
in highest rain chances over the mountains on Thursday. The average
of instability between the GFS and ECMWF is 500 to 600 CAPE along
and south of I-85 late Thursday. The high is expected to be strong
enough to push the band of rain associated with the front further
west over Tennessee going into Friday. The pattern will be stuck
into the weekend with waves of low pressure passing along the front
from Louisiana to Kentucky until Sunday night. A strong northern
flow shortwave passing across the Great Lakes will take the stalled
out surface front eastward. Rain chances will increase over the
mountains Sunday night. Frontal rain fades on Monday as it crosses
the piedmont which being after the end of the current forecast
period. Instability each day is rather low in the current models
from Friday through Sunday. Temperatures over ten degrees above
normal through the period.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: Patches of -ra and dz continue to develop and
ripple across the area early this morning, helping reinforce a weak
wedge. The areas of ra and dz should decrease in coverage as dry air
works in from the west atop the low cloud deck. Guidance generally
holds onto the wedge thru the day, with some erosion from the south
and east into the lower piedmont, approaching the Upstate and KCLT
sites by late aftn. If enough breaks in the clouds can form, this
could allow cigs to briefly improve to MVFR by the end of the
daylight hours. For now, I only have small improvement in cigs, with
the most improvement at KCLT. KAVL is the usual exception, which
should be MVFR for most of the day, and possibly even VFR at times
with a downslope, cross-valley flow. Sfc winds will be light,
generally ENE, except SE at KAVL and KCLT. Tonight, guidance shows
some increase in moisture allowing a return of at least a slight CHC
of rain and drizzle. The main concern that guidance is trending
toward is widespread fog across the piedmont developing late evening
thru the overnight, possibly dense in spots.

Confidence Table...

            15-21Z        21-03Z        03-09Z        09-12Z
KCLT       Med   79%     High  80%     Med   69%     High  83%
KGSP       Med   69%     Med   60%     Low   37%     High 100%
KAVL       Med   69%     High  87%     Med   64%     Low   36%
KHKY       Low   50%     Low   51%     Low   59%     High  83%
KGMU       Med   61%     Low   56%     Low   37%     High  83%
KAND       Low   59%     High  93%     Med   68%     Med   73%

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...
RECORDS FOR 02-20

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      75 1939     26 1908     50 1951      4 2015
                                        1939
   KCLT      77 2014     31 2015     59 1939      7 2015
                                        1890
   KGSP      75 2014     33 2015     57 1939      9 2015
                1986



RECORDS FOR 02-21

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      77 1986     12 1896     54 1997      8 1896
   KCLT      75 2011     32 1896     56 1997      6 1896
                1986
   KGSP      75 1917     35 1978     55 1997      9 1896
                            1902



RECORDS FOR 02-22

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      72 1897     27 1939     54 1897      2 1963
   KCLT      74 1990     33 1963     62 1897     12 1963
                1897
   KGSP      76 2011     35 1969     55 1980     10 1963
                            1963



RECORDS FOR 02-23

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      76 1982     29 1989     54 1922     10 1939
   KCLT      76 2012     29 1901     56 1944     19 2009
                1980                                1978
                1962                                1963
   KGSP      76 2012     36 1966     57 1922     15 1963
                1996        1939
                1980



RECORDS FOR 02-24

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      77 1930     26 1947     50 1985      6 1967
                                        1979
   KCLT      80 1982     26 1889     56 1992     16 1967
                1930
   KGSP      79 1982     33 1901     57 1909     15 1967
                                                    1901



RECORDS FOR 02-25

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      78 1930     17 1967     51 1985     -2 1967
   KCLT      82 1930     27 1967     58 1890      7 1967
                            1914
   KGSP      79 1930     30 1967     57 1985      8 1967

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...ARK/SGL
SHORT TERM...RWH
LONG TERM...DEO
AVIATION...ARK
CLIMATE...GSP



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