Area Forecast Discussion
Issued by NWS Greer, SC

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874
FXUS62 KGSP 190821
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
321 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 300 AM: 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 will 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 /09Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: A weak wedge has already begun to set up and
will try to hold on across the area thru the day today. Persistent
moist flow atop this wedge will keep low clouds and areas of -shra
and -dz around thru at least midday. Some brief, slight improvement
in cigs/vsby is expected, especially at KCLT, furthest from the Blue
Ridge, but may barely get to MVFR before going back down into
IFR/LIFR. Low cigs and fog is expected to be widespread across the
area tonight. Winds will be light, generally out of the NE across
the foothill and piedmont sites, with periods of SE at KCLT. At
KAVL, winds should be SE thru the period.

Outlook: Unseasonably warm and humid conditions are expected to
develop by Tuesday, and persist through the end of the week. Shower
chances will be highest across the mtns, while periodic cig and
visby restrictions will be likely through the week, esp during the
late night and morning hours.

Confidence Table...

            08-14Z        14-20Z        20-02Z        02-06Z
KCLT       High  83%     Med   75%     Med   74%     Med   76%
KGSP       Med   69%     Med   69%     Med   76%     Med   70%
KAVL       Low   59%     Med   65%     Med   79%     High  90%
KHKY       Med   75%     Med   62%     Med   78%     Med   79%
KGMU       Low   59%     Med   70%     Med   78%     Med   78%
KAND       Med   61%     Med   70%     Med   61%     Med   72%

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
SHORT TERM...RWH
LONG TERM...DEO
AVIATION...ARK
CLIMATE...



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