Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 191454
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1054 AM EDT Thu May 19 2022

.SYNOPSIS...
Afternoon temperatures will remain well above normal through the
weekend. Scattered showers and thunderstorms are expected today and
Saturday. A cold front approaching the area Sunday and Monday will
bring better chances for showers and storms, with cooler weather
returning Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1050 AM EDT Thursday: Morning convection has moved east
leaving a PPINE radar scope at this time. Big question today remains
the potential for diurnal convection. Previous CAMs all had some
version of convection forming over the mountains or E TN associated
with a shortwave or MCV then tracking E or SE across the forecast
area. All of them had at least some convection for much of the area,
and all had the least chance over NE GA. The 12z HRRR has gone
almost completely dry save for possibly an isolated NW Piedmont
cell. The 12Z RAP shows some weak convection over NC early afternoon
then dry. 12Z ARW and Fv3 still show mountain convection spreading
across NC and far eastern Upstate, but a later start than usual.
12Z RAOBs show quite a bit of elevated instability with steep mid
level lapse rates. The soundings and mesoanalysis show CIN needs to
be overcome, but given the strong warming taking place, this should
occur, but is likely helping with the later start time. Moderate
effective shear is also seen in the soundings and analysis.
Therefore, storms that do form have the potential for organization
and producing large hail and damaging winds, but trends do show more
of an NC and eastern Upstate threat.

There is some mountain wave cirrus this morning which could keep
highs from reaching the full sun potential. Still given the warm
start and late convective initiation, hot temps look likely.
Therefore, have bumped up highs a degree or so making 90s outside of
the mountains likely.

Upper-level ridging builds into the Southeast tonight into daybreak
Friday leading to drier conditions. Lows tonight should be around 8
to 10 degrees above climo.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 100 AM Thu: Friday does still look like the warmest day of
the period, as upper ridge begins to build over the East Coast
and exceptionally warm air spreads across our region on southwest
flow. 850mb temps invof 20C are near daily records. A capping
inversion probably will preclude any diurnal convection. Certainly
seems appropriate to expect max temps will at least flirt with the
record; our usual first guess, the NBM, has proven to be a little
too warm in recent days, but given the strength of the low-level
ridge we feel comfortable saying records may be in jeopardy.

A shortwave will cross the Rockies and High Plains Saturday,
subsequently leading to Great Lakes cyclogenesis. The associated
cold front will reach the lower to mid Mississippi Valley Saturday
night. However, over our area, the ridge will just continue to
build during the same timeframe, although with the axis already
being off the Atlantic coast. A plume of mosture should advect
northward into the area during the day Saturday, introducing a
bit of midlevel cloud cover and increasing dewpoints. Slightly
cooler air also arrives in the midlevels, weakening or eroding the
inversion. Accordingly a seasonable chance for diurnal convection
returns to the forecast Saturday. Most guidance also suggests
slightly cooler max temps; records are higher that day anyway. In
short, prog soundings look typical for late spring, in terms of
CCLs, lapse rates, and fairly weak shear; a seasonable risk thus
will exist for isolated wet microbursts with marginally severe
wind/hail.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 200 AM Thu: Western Atlantic ridge will hold strong into
early next week. Low pressure and attendant shortwave will be
shunted off to the north Sunday into Monday, and accordingly the
trailing cold front will pivot or take on a more zonal orientation
in that timeframe. Global models have trended later in depicting
its arrival into our area, such that the front probably won`t
actually arrive Sunday as once suggested. PoPs have been lowered a
bit Sunday, although chances still will be higher than Saturday via
prefrontal convergence and slightly lower heights. Sfc front will
lay over across the Mid-Atlantic region Monday as high centers to
our north; front then looks to stall as cyclogenesis occurs in the
south-central CONUS. Global models show some spread in the location
thereof, and thus also disagree as to where the front actually
stalls. Operational GFS and a number of GEFS/GEPS members suggest
the front may actually settle as far south as GA/SC, and some of
the area may actually have a chance to dry out for a time. Most
solutions show the front remains in our general vicinity, such
that a small continuing PoP will be warranted, still with diurnal
enhancement. Likely PoPs are warranted again Monday with the arrival
of the front, but only peak at chance Tuesday and Wednesday. Temps
probably will remain above-normal for part of the area into Monday,
but most guidance does show below-normal temps Tuesday, probably
via weak CAD.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: Winds will be mainly W/WNW`ly at KAVL with
SW`ly/WSW`ly elsewhere today. Should be mostly VFR through the 12Z
TAF period with afternoon cumulus expected. However, we could see
another round of showers and thunderstorms develop this afternoon
into this evening so have TEMPOs for TSRA at all TAF sites, with the
exception of KAND, to account for potential convection. Confidence
is low regarding TSRA development today as model guidance is not in
good agreement regarding the exact coverage of TSRA or where TSRA
will initiate. Convection should wind down early evening leading to
drier conditions tonight into Friday. Winds this evening into
tonight will be generally SW`ly with some locations seeing light and
variable winds.

Outlook: Brief drying returns Friday leading to VFR conditions.
Summer-like pattern returns Saturday with a chance of diurnal
convection and nocturnal fog/stratus possible, especially where rain
has fallen. A cold front moves into the area on Sunday with more
widespread convection likely.

&&

.CLIMATE...
RECORDS FOR 05-19

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      93 1996     55 1894     65 2017     33 1894
                                        2015
   KCLT      95 1962     59 2003     71 1930     40 2009
                                        1896
   KGSP      99 1962     55 1932     68 2000     38 1976
                                        1987
                                        1930



RECORDS FOR 05-20

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      91 1941     50 1894     64 2018     36 2002
                                        1959
   KCLT      95 1964     51 1981     71 1938     40 2002
                                        1896
   KGSP      96 1962     57 1981     69 1927     41 1894



RECORDS FOR 05-21

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      93 1941     57 1993     64 2001     36 1993
                            1894
   KCLT      97 1941     57 1888     71 1998     41 1894
   KGSP      96 1941     56 1888     68 2001     40 1993
                                        1927

&&

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

&&

$$
SYNOPSIS...Wimberley
NEAR TERM...AP/RWH
SHORT TERM...Wimberley
LONG TERM...Wimberley
AVIATION...AP/RWH
CLIMATE...


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