957
FXUS62 KCAE 080238
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
1038 PM EDT Tue May 7 2024

.SYNOPSIS...
A brief lull in thunderstorm activity is anticipated through
early Wednesday, with increasing chances of showers and storms
towards the end of the week. Potential for strong to severe
storms will exist on Thursday and 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 /UNTIL 7 AM WEDNESDAY MORNING/...
A weak shortwave aloft continues to move through the primary
mid-level ridge axis which is triggering some scattered strong
thunderstorms across western and central NC. A broad cirrus
shield aloft continues to push over our area, south of the deep
convection and as of 00z, our cumulus deck has completed
dissipated; instability across SC is generally limited and will
only continue to drop more over the next few hours. So based on
the current water vapor imagery, radar, and hi- res guidance,
the best forcing from this shortwave should continue to remain
north of our area, across NC, with broad height rises thanks to
the ridge positioning. So PoP`s are falling off quickly and
confidence in any showers-storms in our area is low. The only
question of note is the deeper convection-MCS back across GA,
which is not being handled well by the hi-res guidance. The
general steering flow aloft is turning more northwesterly on the
back-edge of the shortwave around the ridge axis which may
allow this MCS to move into eastern GA. But CIN rapidly
increases and instability drops off quickly across eastern GA,
so even if the complex does sustain eastward, severe potential
is low overall.


&&

.SHORT TERM /7 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
Active short term period is on tap, with multiple chances for
potential severe weather. This threat is primarily centered on
Thursday, where damaging winds and large hail are possible with
strong thunderstorm development.

09z RAP forecasts a fairly complex, expansive 500 hPa trough
centered across the central Plains with a shortwave trough exiting
into the northeastern US followed by another emerging into the
central Plains south of the center of the low. Ridge axis is
forecast to be atop the Carolinas, shifting eastward through the
day. Recent CAM guidance has begun to show a leftover MCS
progressing eastward across the TN Valley towards the Appalachians
by 12z. There is quite a bit of uncertainty surrounding this, but we
will address that momentarily. As the ridge axis shifts eastward it
will be followed by a strong, zonal southern stream 250 hPa jet
streak with the left exit region emerging over the central Carolinas
by 00z Thursday. As southwesterly flow increases, an EML with 7-7.5C
500-700 hPa lapse rates will push over northern SC and southern NC,
yielding 2000+ j/kg of MLCAPE across the northern FA as early as
18z. Soundings are quite impressive, with EML and deep layer shear
supportive of potential severe convection.

Large scale forcing is primarily going to be focused to our
northwest across the OH Valley, leaving some question marks as to
whether or not we actually are able to see convection initiate in
the northern FA. The severe risk is definitely conditional, which is
why it is important to note the spread amongst guidance as to
whether or not a convective system makes it to the Appalachians
tomorrow morning. Forecaster confidence will increase in potential
severe convection tomorrow afternoon if an outflow boundary from
decaying convection makes it into western NC. This would be able to
focus low-level forcing to initiate convection into the favorable
thermo environment across the northern FA. But until details become
more concrete, it is hard to say whether or not we`ll certainty see
convection tomorrow up there. Low-end Chance PoPs seem appropriate
at this point. Highs will be quite warm given nice southwesterly
flow at the surface, so look for highs in the lower 90s.

Wednesday night through Thursday night looks very active, with
higher confidence in at least a couple rounds of potentially severe
convection. MLCIN will likely settle in across much of the forecast
area after 11p Wednesday, allowing much of the convective threat to
shift north of the forecast area. Then we turn our attention to the
northwest. Boundary layer moisture is expected to remain rich, with
steep mid-level lapse rates helping maintain easily accessible
instability ahead of an expected line of convection approaching from
the west. Most pieces of guidance show this crossing the
appalachians Thursday morning and decaying in western NC. Ahead of
this, it is likely that capping over our forecast area should help
to keep any prior convection at bay and allow for significant
destabilization to develop - potentially on the order of 2000+ j/kg
of MLCAPE again. The question is again whether or not convection
initiates during the afternoon hours. Cold front will slowly
approach the region through the afternoon. While there doesn`t look
to be significant synoptic support across the area, both the GFS and
NAM are showing a 700 hPa shortwave pushing across the Carolinas.
Combine that with moderate instability with the surface cold
front/remnant outflow boundary and the thinking is that convection
will be more widespread than either model is currently showing
during the afternoon hours. Temps should get into the mid 80s ahead
of the convection.

Another round of convection is possible on Thursday night, which may
be the highest confidence this forecaster has in any of these
rounds. The cold front looks as if it will continue to slowly move
southward and almost stall across the area by Thursday night, with a
strong shortwave pushing atop this with high MUCAPE values along and
south of the front as the shortwave pushes eastward. This should
yield at least widespread, elevated convection that will likely push
into the area late Thursday night and early Friday. Uncertainty
abounds about this given the uncertainty during the day on Thursday,
so it is hard to comment on the potential severity of the
convection. However, a severe risk certainly looks to continue
into the overnight hours on Thursday as elevated instability
will likely remain in place. So to summarize: forecaster
confidence in several rounds of convection is moderate, with
overall confidence increasing with each time step from Wednesday
to Thursday to Thursday night. SPC has a Marginal Risk in place
tomorrow and a Slight Risk on Thursday, which makes sense given
uncertainty regarding both days. Given the widespread
instability expected across the area, severe convection is
definitely possible in each of these rounds. Clarity will be
added over the next 24-36 hours as more model guidance takes
what actually happens into account.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Won`t spend a ton of time focused on this considering the
threat for convection on Wednesday and Thursday. It does look
like the front will slowly push through the area on Friday, with
drier air and high pressure filtering into the region over the
weekend. Showers and thunderstorms are likely to to push
eastward and out of the area during the day on Friday. Really
tough to discern whether or not this convection will be severe
given the uncertainty preceding it, but it is possible that more
strong storms occur on Friday. Temps will likely return back
towards normal, with highs in the low to mid 80s through much of
this period. Guidance shows dry weather through early next week
before moisture and southwesterly flow return early next week
and offer up more substantial rain chances by Tuesday or
Wednesday.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
High confidence in VFR conditions through the forecast period.

No convection to worry about this evening with cumulus
dissipating with the loss of heating, although cirrus shield
continues to slowly move overhead through the early overnight
hours. A 25 knot low level jet should help keep the boundary
layer mixed and surface winds in the 3 to 5 knot range overnight
which should help preclude fog concerns.

Winds should pick up to around 10 knots by 15z from the
southwest as deep southwesterly flow develops with low pressure
moving into the Ohio Valley with afternoon convection expected
to remain mainly north of the terminals.

EXTENDED AVIATION OUTLOOK...Active weather with mainly diurnal
convection each day through Friday. There`s potential for more
widespread severe storms on Thursday. Brief CIG/VSBY restrictions
and gusty winds may accompany any thunderstorms that affect the
terminals.

&&

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

&&

$$

SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...