Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 231732
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1232 PM EST Fri Feb 23 2018

.SYNOPSIS...
Warm and moist conditions will continue into the weekend until a
cold front crosses east on Sunday. Showers will linger Sunday into
Monday before dry high pressure builds back in on Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1230 PM EST Friday:  Updated discussion for 18z taf issuance.
As for the public fcst, made a few minor tweaks to t/td and sky
trends to align with recent obs which favor ample heating across
much of the area where earlier low stratus has delayed such.  These
areas (generally along and north of I40 in association with the
back door front, as well as across the Lakelands region of SC/GA)
should see decreasing coverage of lower stratus as the afternoon
goes on, however enough moisture in the low levels will likely
keep llv cu in place regionwide through at least sunset tonight.
Otherwise, no sig changes needed/made at this time.

Previous Discussion:  Another persistence type fcst is in the works
over the near term. A strong ST high will dominate the pattern over
the SE CONUS thru the period. Soundings show a well developed subs
inversion holding GOM/Atl moisture limited generally within the sfc-
h85 layer. With daytime heating...the stcu/st will begin to lift
and dissipate thru noon and the early afternoon. With sw/ly llvl
flow and large scale subs warming...max temps shud have no problem
reaching record levels or about 20 degrees F abv normal. Low-level
instability will increase thru the afternoon...yet the atmos will
remain capped and shunt any deep convec threat. The main forcing
once again will be mech lift over the NC mtns where shallow -shra
will develop during the afternoon. Precip amnts will be low-end
and showers will dissipate with loss of daytime heating.

During the overnight period...expect low-level clouds and areas
of fg to develop over most of the FA with high levels of moisture
remaining underneath the strong ulvl high. Mins will be close
to record `high-min` values...however if clear skies begin the
period...temps will likely drop below record `high-min` levels.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
As of 330 AM EST Friday: The balance of the weekend continues to
look Spring-like and unsettled as the upper pattern featuring
a large upper ridge over the FL peninsula/nrn Bahamas remains
in place. A persistent moist S/SW flow awaits better mid/upper
forcing to act upon deep moisture to increase precip chances. That
is expected to happen gradually from the west Saturday afternoon and
night, thus precip chances slowly ramp up from the west. The model
guidance is in general agreement with bringing the frontal zone into
the region on Sunday, so a likely probability is warranted given the
upper divergence and short wave passage. The main concern for the
fcst period is the possibility of severe storms, mainly on Sunday
as the front moves in. The models have just enough instability
ahead of the front...CAPE on the order of 300-500 J/kg...and shear
on the order of 30-40 kt...to give some pause. Not exactly the
ideal setup for QLCS action as the front lays down, maybe more a
case of multicells with some supercell-like structures if we can
eke out CAPE above 500 J/kg with peak heating. Not too surprised
to see the new Day3 Outlook with the marginal creeping close
to the fcst area, and this will have to be monitored as Sunday
approaches. From late Sunday onward, though, the model guidance
diverges sharply with the op GFS taking the front well to our
east by Monday morning. Meanwhile, the NAM and ECMWF suggest the
front will make much less eastward progress against the stubborn
upper anticyclone strung out to the southeast. The new ECMWF also
develops a wave on the old front, which moves across the region
on Monday afternoon. At this point, it seems prudent to hold onto
at least a chance of precip through the day on Monday given the
low amplitude of the short wave moving over the OH Valley region,
with the expectation the old front will be in closer proximity per
the European model solution. This scenario means that temps will
be a bit warmer Sunday night and Monday as well, so the fcst was
trended in that direction.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
As of 1210 AM EST Friday: Confidence is increasing that deep layer
moisture coincident with elongated sfc bndry will be oriented atop
the region Sunday night into Monday morning, promoting numerous,
if not widespread showers. The latest medium range model consensus
translates forcing downstream of the cwfa Monday afternoon, followed
by a developing low amplitude ridge aloft and building sfc hipres
Monday night. Maximum Monday temps remain slated to be much less
mild than than our current warm wave, but still are expected to
be about 2 categories above climo.  Tuesday continues to look dry
with maxes similar to Monday`s readings. The ridging providing
Tuesday dry wx will quickly translate offshore by Tuesday night
giving way to a moistening return flow leading, a quick return to
rainy conditions Wednesday.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: A moist pattern continues across the region
this fcst cycle as a stalled front remains westward keeping the
fcst area in the warm sector.  With that, moist swly/sly flow
will prevail through the period with said moisture supportive of
varying cig heights.  With that, initialized MVFR at KAND/KHKY
given lingering stratus, while leading off with low VFR at all
other sites.  All sites should go VFR within the next hour/two.
Otherwise,  brief relief from the low cigs/visb into the overnight
before another round of said restrictions returns ahead of
sunrise Saturday.  Meanwhile, a weak wave looks to traverse
the aforementioned frontal boundary, sliding into the TN valley
overnight.  Thus, cannot rule out some stray showers across the
western tier of the fcst area to affect all sites aside for KCLT,
therefore prob30s were included.  Conditions will improve from
MVFR/IFR and possibly LIFR cigs and visb into the late morning
hours as has happened today, thus each site will experience
improvement late.  As stated, winds will remain swly/sly through the
period with some low end gusting possible at KAVL this afternoon.
Otherwise look for winds in the 6-10kts range at all sites this
afternoon, weakening overnight with loss of mixing, increasing
again on Saturday.

Outlook: Moist conditions will keep chances for restrictions
elevated through the period, with the best chances for low cigs/visb
to occur each morning.  Precipitation chances are also slightly
elevated, mainly across the high terrain.

Confidence Table...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       High 100%     High 100%     High 100%     High  85%
KGSP       High 100%     High 100%     High 100%     Med   68%
KAVL       High 100%     High 100%     High  94%     High  93%
KHKY       High 100%     High 100%     High 100%     Low   53%
KGMU       High  91%     High 100%     High 100%     Med   75%
KAND       Med   75%     High 100%     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      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



RECORDS FOR 02-26

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      78 1951     24 1920     55 1957      5 1967
   KCLT      81 1977     35 1993     57 1890      7 1967
                            1920
   KGSP      80 1996     28 1914     56 1985     12 1974



RECORDS FOR 02-27

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      78 1996     22 1935     58 1962      6 1934
   KCLT      82 2011     29 1934     59 1917      7 1963
   KGSP      81 1996     37 1987     58 1944     12 1963
                            1982



RECORDS FOR 02-28

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      77 1918     26 1941     58 1948     13 1935
                                        1896        1934
                                                    1906
   KCLT      78 2011     29 1934     61 1890     14 2002
                1962
                1948
   KGSP      77 1961     35 1934     59 1997     16 2002



RECORDS FOR 03-01

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      76 2006     31 1920     55 1997     10 1914
   KCLT      82 1918     36 1980     59 1997     15 1980
                            1969        1910
                            1927
   KGSP      80 1918     30 1934     60 2012     19 1906

&&

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

&&

$$
SYNOPSIS...SBK
NEAR TERM...CDG/SBK
SHORT TERM...PM
LONG TERM...CSH
AVIATION...CDG
CLIMATE...



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