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FXUS62 KGSP 211501
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1001 AM EST Wed Feb 21 2018

.SYNOPSIS...
High pressure off the East Coast will provide a warm and
moist southerly flow of air throughout the week as a cold front
stalls and lingers west of the mountains. This front is not expected
to pass through the region until Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM EST Wednesday: Minor tweaks made to going temperatures
to coincide with current trends as the rest of the near term
forecast remains on track.

Temperatures have been on a warming trend since the overnight hours,
with current temperatures well in the upper 60s/around 70 degrees.
Already a few degrees warmer than previously anticipated for this
hour, have increased temperatures slightly to coincide with
trends with this update. Otherwise, plenty of clouds continue
to stream in overhead attm as light showers move northwest up
the escarpment.

Otherwise, little change in the synoptic pattern thru the near term,
with the CWFA remaining between a large upper high to the east and
deep trough to the west. Moist LLVL SWLY flow will persist thru the
period, keeping skies cloudy to mostly cloudy. Cloud cover should
scatter out somewhat like it did yesterday, leaving a low-based cu
deck thru the aftn. Temps will be a category or two warmer than
yesterday, and this combined with dewpts in the 60s will result in
some sfc-based instability. CAPE is forecast to range from 500 to
1000 J/kg. But forecast soundings show a mid-level inversion that
should cap convection to under 700 mb (where temps are still above 0
C). So I think thunder chances will remain low. Cannot rule out an
isolated rumble of thunder in the NC mountains, where upslope might
help break the mid-lvl cap, but will not mention thunder for now. In
any case, scattered showers will be possible, with greatest coverage
in the SWLY upslope areas of the NC/GA mountains. Temps will
approach or break record highs at KCLT and KGSP (See climate section
below).

Tonight looks like it will be a lot like the current night, with
plenty of low clouds, patchy fog, isolated to scattered light
showers, and min temps way above normal. Lows look to be in the
upper 50s to lower 60s, which would tie or break high minimums for
Thursday, the 22nd.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 325 AM EST Wednesday: A persistent pattern remains in place
Thursday through Friday night with strong high pressure lingering
off the southeast coast, and a deep moisture fetch continuing west
of the MS Valley. Over our area, light south to southwest upslope
flow and continued sub-800 mb moisture will produce scattered
showers Diurnal instability will affect mainly the NC mountains on
Thursday afternoon, with thunder chances best in the extreme
southern Appalachians.

Marginal 850 mb drying is expected late Thursday night through
Friday; however, boundary layer moisture will persist. A back door
cold front will flirt with the northwest NC piedmont Friday, but
model consensus keeps the wedge front just north of the region
through Friday. In fact, the GFS which was bullish on southward
frontal movement has backed off significantly leaving the NAM the
sole model moving the front this far south. That said, even the NAM
keeps the front and the bulk of the colder air north of the area
just brushing Davie County. Precip chances will be limited to the NW
Piedmont Friday morning and the Northern Mountains during the
afternoon. Isolated showers increase across the Mountains into the
NC Foothills and Piedmont Friday night as deeper moisture returns.
Highs will be near records both days. Lows will be above normal
highs and near record high mins as well.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 1205 AM EST Wednesday: Circulating around the periphery of
deep layered hipres offshore, the very mild airmass will linger atop
the SE CONUS into the upcoming weekend. Saturday maxes are close to
persistence, 15 deg f or more above climo. Deeper layer moisture
should continue it's eastward creep with the associated upward
ramping of pops into solid chance range by later in the day. The
recently posted 21/00 utc op GFS supports the current thinking of a
questionably forced, decently sheared cold fropa Sunday within a
weak instability regime. Sensible wx will continue to feature
shower coverage becoming numerous west to east acrs the cwfa
beginning Sunday morning. Based on the timing of shower chances,
piedmont max temps are slated to be equally as warm as Saturday,
solidly middle 70s. With the orientation of the llvl boundary
expected to become parallel to the upper flow, and additional energy
progged to ripple up the boundary on Monday, it is probable that an
additional round of numerous showers will redevelop across the
region. Tuesday continues to look dry with encroaching upper ridging
and sfc hi pressure. Max temps should be less mild but still two to
three categories above climo.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: Mainly MVFR cigs are across the area, with
LIFR/dense fog conditions staying to the east. There is also some
IFR cigs near the Blue Ridge escarpment, which may briefly expand
and affect KGMU/KGSP and KHKY and KAVL. The moist southwesterly
low-level flow will continue today thru tonight, keeping low clouds
and periods of scattered showers across the mountains and adjacent
foothills. The low cigs should lift to VFR across the area with a
few shallow showers possible across the piedmont. Forecast soundings
show a bit shallower moisture depth tonight, which may allow more
low stratus and fog than what we had this morning. Winds will be out
of the south at all sites thru the period, generally 5-10 kts.

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

Confidence Table...

15-21Z 21-03Z 03-09Z 09-12Z
KCLT Med 74% High 81% High 89% Med 75%
KGSP High 92% Med 79% High 83% High 90%
KAVL High 82% Med 79% High 92% High 93%
KHKY High 85% High 83% Med 66% High 100%
KGMU High 86% High 83% High 87% High 90%
KAND High 85% High 85% High 94% High 82%

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 02-21

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