858
FXUS62 KCAE 081944
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
344 PM EDT Wed May 8 2024

.SYNOPSIS...
Potential for strong to severe storms Wednesday through
Thursday night ahead of an approaching cold front. Drier
conditions return for the weekend. Expect generally above
average temperatures through the latter half of the week before
transitioning to near or slightly below average during the
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Convection associated with a shortwave is progged to move
through the northern forecast area this afternoon into this
evening. Storms have already initiated well to our northwest,
and continue to be stronger than initial guidance suggested.
Strong heating with temperatures in the upper 80s and low 90s
combined with dewpoints in the upper 60s and low 70s have
yielded SBCAPE values over 3000 J/kg. CAMs are in decent
agreement that the storms across the Upstate and western NC will
continue east/southeastward over the next several hours with a
very favorable environment (0-6 km shear increasing to 30-40
kts) helping to sustain organization. Main threat will be for
strong winds (DCAPE >1000 J/kg) across the northern half of the
forecast area, but large hail is also possible with many of the
storms to our west/northwest producing hail between 1 and 2
inches in diameter given low WBZ heights. The tornado threat is
low given the lack of helicity and weaker 0-1km shear, but can`t
be ruled out.

Additional convection is likely late tonight into early
Thursday, primarily after about 09/08z. A MCS is expected to
develop across portions of TN and push through the area with the
severe threat continuing. However, there is lower confidence in
the evolution of this system and it will depend on how things
evolve with this first go around. Overnight lows mild in the
70s.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Very complex forecast expected to unfold in this time period,
with multiple rounds of severe thunderstorms (some severe)
possible. Much of what actually occurs tomorrow is actually
dependent on how much convection gets going tonight and
subsequently pushes into and through the FA. HREF members are
quite confident in convection initiating upstream in the TN
Valley and pushing the doorstep of the FA between midnight and
8a Thursday...which is a large time period. Confidence has
increased in this scenario but the primary question is where the
convection tracks and how widespread it will be. Some guidance
shows an initial wave developing and pushing into the northern
FA overnight with a secondary line of storms developing over
northern AL/MS by early Thursday morning and progressing into
the western and southern FA by late morning or early afternoon.
To be honest, this is one of the tougher forecast periods I can
remember simply due to the amount of model spread that remains.
Looking at current radar, HRRR/ARW/NSSL CAMs are doing well and
will be leaned upon with early Thursday morning`s forecast...and
each of these have different solutions. Bottom line is that the
thermodynamic and shear environments present across the area
and to our southwest will be favorable for severe convection,
even early in the morning hours Thursday. I think the most
likely outcome is that a line of storms pushes along a weak
boundary that is laid up across the northern FA right now (the
focus for potentially severe convection this afternoon), with
another line of storms across the southern TN valley pushing
southeastward into the CSRA. Primary threat is for wind with all
of this activity, but an isolated tornado cannot be ruled out.
SPC has placed the entire area in a Slight Risk with an Enhanced
Risk across the southern FA. It is important not to get hung up
on exactly where the risk lines run as the majority of the area
is under the threat of severe weather at some point over the
next 24 hours.

Confidence is fairly high that we will see a break in convection
tomorrow afternoon as the complex of thunderstorms moves
southeastward and leaves the atmosphere worked over by the
afternoon hours. Highs should be somewhere in the 80s across the
FA, with confidence low and dependent on morning convective
evolution. A stronger and more substantial shortwave trough is
expected to rotate around the large scale trough and approach
the FA from the west by Thursday night, with another complex of
thunderstorms likely pushing through by Friday morning. Not
quite as confident that this will produce severe weather as
there will be little time for the atmosphere to recover. So (for
now) just expecting rain and thunderstorms to arrive across the
FA from west to east after midnight Friday, progressing through
the area by early Friday afternoon. The front should finally
push through thereafter and decrease our threat for severe
weather altogether.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Operational and ensemble guidance is in good agreement with
respect  to the overall synoptic evolution in this period. 500
hPa troughing is expected to finally swing eastward by Saturday,
setting the area up within convergence aloft as a 250 hPa jet
streak pushes eastward and across the area. High pressure is
forecast to begin settling into the southern plains, and will
likely push eastward as upper level convergence shifts eastward.
A 500 hPa vort max is likely to shift into the Mid-Atlantic,
shifting another reinforcing cold front through during the
afternoon hours. Probabilities are low, but wouldn`t be
surprised to see a stray shower along and ahead of that feature
Saturday afternoon. Aside from that, things looks quite nice
Sat/Sun/Mon as the progressive pattern keeps high pressure
translating towards and through the FA. Temps look much more
seasonal - in the upper 70s and lower 80s. As we get into early
next week, shortwave ridging shifts over the region by Monday
night. This will be ahead of a slow moving, closed mid/upper
level low progged to push into the eastern CONUS by the middle
of next week. Confidence is low on the details of this as
operational models and LREF members diverge on speed and
amplitude of this feature. But moisture return ahead of it and
southwesterly flow aloft favor the potential for showers and
thunderstorms Mon Night through Wednesday, and that will be
reflected in the grids.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
Mainly VFR conditions this evening. SCT-BKN clouds AOA 4k ft
MSL. SW winds 10-12 knots with gusts up to 20 kts through the
afternoon. Gusts diminish overnight but speeds remain around 4-7
kts. Strong thunderstorms may develop this afternoon but should
remain north of the terminals. Tonight, thunderstorms may move
through the terminals mainly after 09/08z with gusty winds and
brief CIG/VSBY restrictions. There continues to be more
uncertainty Thursday regarding the exact timing and location,
but multiple rounds of showers and thunderstorms are possible
through at least the morning hours. Storms will continue to be
capable of gusty winds in excess of 40 kts.

EXTENDED AVIATION OUTLOOK...Then expect another day of convection
and associated restrictions on Friday. Drier weather with no
restrictions likely for this weekend.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
SC...None.
GA...None.

&&

$$