473
FXUS62 KGSP 051836
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
236 PM EDT Wed Jun 5 2024

.SYNOPSIS...
Scattered showers and thunderstorms will develop again on Thursday.
Dry Canadian air will mix across the area Friday and persist into
the weekend. A chance of thunderstorms returns to the region Sunday
and continues into the first half of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 234 PM EDT Wednesday: Widespread cloud cover still exists
across the forecast area, but the bulk of it has finally lifted and
taken on a more cumuliform appearance on satellite.  Convection
west of I-26 has somewhat sapped the environment there of good
instability, and has now shifted east into the NC Foothills and
central SC Upstate.  None of the CAMs have a great handle on an
additional round of convective initiation stretching from the
Midlands up into GSP`s forecast area.  All this is supported by a
robust shortwave whose central axis is now located just southwest
of the forecast area...which will provide the forcing over the
coming hours for further convection.

The latest hi-res guidance supports the development of some
1500-2000 J/kg sbCAPE across much of the forecast area -
even those zones over the western Upstate that have received
on-and-off rainfall for hours, which seems a little dubious -
but the environment remains very shear-deficient.  Wind risk is
typically subdued by the type of moist, well-saturated profiles
depicted in the morning RAOBs and today`s ACARS data, and lapse
rates will be poor enough that even should instability exceed
the current forecast, updrafts may be too weak to accomplish
anything other than small hail.  A very weak 850mb LLJ will skirt
the area late this afternoon...and although it`s not entirely
out of the question that this could enhance low-level SRH enough
to support a weak tornado...the reality is that this environment
isn`t a good one for severe weather, and such an occurrence would
require more than a little serendipity.  An additional problem is
that the ongoing convection has already been far more extensive
than earlier forecasts suggested, and it`s unclear if this will
further inhibit robust updrafts from developing into the evening,
or if the atmosphere will have time to recover by then.

At any rate, convection will subside after sundown as whatever
instability we end up with vanishes, and the shortwave translates
east, taking synoptic support with it.  The overnight hours will
feature mostly dry conditions (although yet again, recent HRRR and
RAP runs are hinting at a wave of isolated morning showers for the
Upstate around daybreak) and the development of another deck of low
stratus and patchy fog incited by a still-moist boundary layer.
Guidance depicts this scattering out more quickly than it did
today, as stronger WAA picks up ahead of an advancing cold front.
The leading edge of this circulation should arrive by evening,
and ahead of it, another round of afternoon convection is depicted
by virtually all the guidance.  Severe risk still looks hampered by
weak shear...but 0-6km shear, particularly over the NC Piedmont out
to the I-77 corridor, approach 20kts, enough that some strong to
severe storms cannot be completely ruled out.  And, with the front
slowed in the latest 12z cycle of operational guidance, it arrives
late enough for 1700-2300 J/kg sbCAPE to develop.  Therefore, an
isolated damaging wind risk can`t be ruled out with any segments
that manage to get organized Thursday afternoon and evening.

&&

.SHORT TERM /THURSDAY THROUGH SUNDAY/...
As of 100 PM Wednesday...An amplified system over the Great Lakes
states will push a cold front through the area by Thursday evening.
This will lead to drier and thus more comfortable conditions for
Friday and Saturday. With surface high pressure in place, lows
Friday night will drop into the 55-60 range in the Piedmont and to
the upper 40s to lower 50s in the mountains. Highs both Friday and
Saturday will be near climo, but with low relative humidity.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
As of 110 PM Wednesday...The mid level system over the Great Lakes
will further amplify creating a little more active northwest flow
pattern on Sunday and Monday. This will lead to the return of pops
for these days and nights, but there is a lot of uncertainty as to
where and when any storms might occur. Drier conditions will return
for the middle of next week as the system pushes through the area.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
At KCLT and elsewhere: A challenging TAF forecast for the 18z
issuance.  Widespread MVFR to even isolated IFR ceilings remain
in place circa 1715z, which is somewhat inhibiting the instability
needed for more a more robust convective environment.  That said,
the majority of recent hi-res model runs suggest that we`ll scatter
out in the next hour or so, permitting destabilization followed by a
round of afternoon convection as a supporting upper feature passes
overhead.  So, we still expect TSRA at all the terminals later
this afternoon.  Timing has been tweaked for TEMPOs.  Showers may
linger into the late evening before drying up overnight; another
round of MVFR to IFR low ceilings is expected toward morning,
and visibilities may be reduced at any locations receiving ample
rainfall today.  Tomorrow, restrictions are depicted lifting much
more quickly than they have today, and the consensus is for another
round of thunder in the mid afternoon, associated with an advancing
frontal circulation.

Outlook: Drier air will move into the area Thursday night into
Friday morning with improving restrictions into the weekend.
High pressure will linger through Saturday before another system
approaches on Sunday or Monday.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...MPR
SHORT TERM...SCW
LONG TERM...SCW
AVIATION...MPR