Area Forecast Discussion
Issued by NWS Greer, SC

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585
FXUS62 KGSP 181522
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1022 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 1015 am: Fog and low stratus has burned off across all but a
section of the upper Savannah River Valley (where it`s also burning
off pretty quickly), giving way to sunny skies across the vast
majority of the forecast area. No worse than mostly sunny skies are
expected across the area through at least mid-afternoon. Yet another
high pressure area builds in from the NE in a cold air damming
configuration through the day. Moisture and clouds begin returning
from the SW by the end of 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 /16Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: IFR to VLIFR across much of the area this
morning. KAVL and KHKY have cleared out and should remain VFR. Where
restrictions are in place, expect VFR by 14z. High clouds return
through the day with low clouds returning this evening falling to
IFR overnight. Precip moves in as well with MVFR to possibly IFR
vsby. N to NE wind becomes easterly this afternoon then back to NE
overnight. KAVL the exception where gusty NNW wind becomes lighter
SSE for the afternoon.

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

Confidence Table...

            15-21Z        21-03Z        03-09Z        09-12Z
KCLT       High 100%     High 100%     High  98%     High  82%
KGSP       High  94%     High 100%     High  90%     High  85%
KAVL       High 100%     High 100%     High  90%     High  97%
KHKY       High 100%     High 100%     High 100%     High  82%
KGMU       High  98%     High 100%     High  90%     High  91%
KAND       High  94%     High  98%     Med   70%     High  91%

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...None.
NC...None.
SC...None.

&&

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



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