Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 180847
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
347 AM EST Sun Feb 18 2018

.SYNOPSIS...
Dry high pressure will bring a break from rain today.
Temperatures will climb through the middle of the week as
another cold front arrives from Tennessee by Thursday. This front
stalls out and lingers just north of our area next weekend. Chances
for rain remain in the forecast each day.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 345 AM: Areas of low clouds and fog will continue across the
area early this morning. Areas of dense fog have developed along the
I-40 corridor and south along and near the Blue Ridge. Expect the
dense fog will expand through daybreak, so issuing a dense fog
advisory for these areas. Locations south of I-85 may not quite
reach the widespread dense category, but there will be patchy dense
fog. Given that areas will be nearby, think it is better to err on
the side of caution.

The bulk of the day today will mostly sunny and mild as skies clear
and fog burns off. Yet another high pressure area builds in from the
NE in a cold air damming configuration through the day. Moisture
returns from the SW late today so clouds will begin to move in late
in the day. Winds will generally be light outside of the mountains.
However, gusty NW winds this morning across the mountains will
diminish and turn southeasterly for the afternoon. Highs will be 5
to 10 degrees above normal.

A warm front will pass by to our west as the damming high weakens
but remains in place across the area. Deep moisture and low level
isentropic lift increase through the evening and slowly move north
overnight. This will create increasing precip chances from SW to NE
across the area. Best precip chances will be generally along and
north of I-85 with good chance PoP south of there. Temps and
thicknesses will be too warm for anything other than liquid rain and
will be non-diurnal in nature, especially across the mountains. Lows
will end up around 15 degrees above normal.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 300 AM Sunday: The upper pattern will amplify thru the short
term, with a large anticyclone setting up over the North
Atlantic. At the sfc, guidance still shows a weak in-situ wedge
trying to hold on thru the day on Monday, breaking down at some
point late in the day or overnight Monday night. This makes for a
tricky temp forecast on Monday, as a retreating wedge may produce a
tight temp gradient. For now, will go a little warmer than
SuperBlend across the southern and eastern fringes of the CWFA, and
keep temps cooler near the Blue Ridge. PoPs look overdone in the
guidance, given only shallow moisture within the southwesterly
upglide flow. Depending on how much mixing can remain overnight,
areas of fog may develop Monday night, as MOS and SREF vsby probs
indicate. Min temps will be well above normal.

On Tuesday, the forecast area should be completely in the warm
sector of a low pressure system over the Plains, with a strong high
over the Atlantic. The models spit out some light QPF, which looks
overdone, given lack of deep moisture and little forcing. I kept a
token slight chc in the southerly to southwesterly upslope areas;
otherwise, it should be dry with a mix of sun and clouds. Temps will
be way above normal in the 60s to lower 70s, close to records.
Moisture does increase a little Tuesday night, as a cold front
nudges closer to the area, still in the Mississippi Valley. So I
have PoPs ramp up into the chance range, but again, I think guidance
may still be overdone. Overnight temps will be very warm for late
February, struggling to fall into the upper 50s to lower 60s, which
would break record high minimums for Wednesday (see climate section
below).

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 130 AM EST Sunday: This period begins 12Z Wednesday with the
500mb pattern having high pressure centered near Bermuda and a broad
trough over the western two thirds of the nation. This pattern seems
somewhat stuck through next weekend with a ridge over the East Coast
and trough over the west.

At the surface, a cold front approaches from the NW Wednesday then
stalls out before reaching the mountains with waves of low pressure
moving NE along the front.  The result will be best chances of rain
in the mountains and less out over the piedmont which will be more
distant away from the front. Initially, on Wednesday low level wind
will be upslope against NE GA to along the SC Mtns. These low level
wind become more parallel to the mountains late Wednesday into
Thursday. The front remains just NW and north of our area Friday and
may drift north to align over KY to Maryland. If the front is that
far NW and north of our region next weekend, chances for rain will
be less as waves of low pressure passing along the front affect TN,
KY and the Virginias more. Instability bring best Wed and Thurs
afternoon with CAPE values 500 to 600 across the piedmont of GA and
SC. Instability much less according to the models into the weekend.
Temperatures well above normal. Another larger low pressure will
pass from the Plains to the Great Lakes at the end of the forecast
which may enhance chances for showers late Saturday and Saturday
night.

&&

.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: IFR outside of the mountains will briefly
scatter out early this morning before fog returns before daybreak.
Expect MVFR tempo LIFR. KAVL will see low VFR with some MVFR through
daybreak. Expect conditions to improve quickly after daybreak with
mainly cirrus until evening when low VFR then MVFR moves in from the
SW. Precip will be possible overnight. Light NE to E winds continue
through the period. KAVL the exception where gusty NNW wind becomes
light after daybreak. Wind turns SSE for the afternoon and evening.

Outlook: The weather will remain periodically unsettled, with
occasional restrictions likely through much of next week.

Confidence Table...

            08-14Z        14-20Z        20-02Z        02-06Z
KCLT       Med   65%     High 100%     High 100%     High 100%
KGSP       Med   64%     High 100%     High 100%     High  95%
KAVL       High  89%     High 100%     High 100%     High  95%
KHKY       Med   64%     High 100%     High 100%     High 100%
KGMU       Low   56%     High 100%     High 100%     High  94%
KAND       Med   68%     High  97%     High 100%     High  86%

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

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Dense Fog Advisory until 9 AM EST this morning for GAZ010-017-
     018-026-028-029.
NC...Dense Fog Advisory until 9 AM EST this morning for NCZ035>037-
     056-057-068>072-082-501>510.
SC...Dense Fog Advisory until 9 AM EST this morning for SCZ001>014-
     019.

&&

$$
SYNOPSIS...DEO
NEAR TERM...RWH
SHORT TERM...ARK
LONG TERM...DEO
AVIATION...RWH
CLIMATE...



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