551
FXUS62 KCAE 171033
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
633 AM EDT Wed Jul 17 2024

.SYNOPSIS...
Shower and thunderstorm chances increase over the next few days,
leading to a wetter than normal 7-day period. After Thursday,
temperatures are expected to drop to near or slightly below normal
levels into early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Key Message(s):

- Scattered showers and thunderstorms with locally heavy
  rainfall develop this afternoon, with some gusty to damaging
  winds in stronger thunderstorms.
- Slightly cooler, but still hot with heat index values nearing
  105 this afternoon.

An upper large scale trough continues to sag southward across
the eastern half of the CONUS in response to a building ridge
over the western portions of the country. This trough is
expected to dig further south through the day, pushing a surface
cold front closer to the area. As it approaches, gusty
southwest winds are expected to develop, keeping moisture levels
quite high across the forecast area. As a result, PWAT values
are likely to remain around the 2" mark today. Shower and
thunderstorm activity is expected to develop once again today,
with overall coverage anticipated to be greater than the past
couple of days. Due to the high PWAT values, locally heavy rain
is possible with the activity. Forecast soundings aren`t all
that different than the past couple of days, so there is
potential for some strong to potentially severe storms, with
strong winds being the main threat.

With the increased coverage and attendant cloud cover,
temperatures are forecast to be slightly cooler overall (mid
90s). The temps combined with the moisture will cause heat index
values of around 105 this afternoon, a bit shy of Heat Advisory
criteria, so will not issue one at this time. Despite the lack
of an advisory today, still take breaks and hydrate if you`re
spending time outdoors. Overnight lows are forecast to generally
be in the mid 70s.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Key Message(s):

- Scattered to numerous afternoon and evening showers and
  thunderstorms with the potential for gusty winds and flash
  flooding
- Daytime temperatures expected to be near normal by Friday
  behind the passage of a cold front

A cold front approaches the region from the northwest Thursday, with
upper troughing building south from the Great Lakes region. The
front will provide a source of instability supported aloft by
passing short waves, and this is expected to promote the development
of showers and thunderstorms. GEFS mean SBCAPE values are
between 750-1000 J/kg, with the ECENS mean a bit more bullish,
and showing greater than 1000 J/kg. With the added dynamics,
CSU severe probabilities for damaging winds are 30%+ for much
of the forecast area. In addition, copious moisture will remain
in place with PW around 2"- 2.25" and the threat for flash
flooding to accompany training or slow moving storms. This will
carry over into Friday as the boundary remains a source of
convective initiation. WPC ERO guidance is Marginal for much of
the area on Thursday, with the eastern half of the CWA extending
northeast into the Pee Dee under a Slight Risk.

Temperatures will be hot again Thursday, but heat indices are
expected to remain below heat advisory criteria, though still in the
100-105 range. Behind the front, the airmass will be a little
cooler, though not much drier. At any rate, highs Friday will seem
markedly improved, aided by increased cloud cover, with temperatures
in the upper 80s west to low 90s east and heat indices remaining in
the double digits.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Key Message(s):

-Moisture and a series of passing disturbances expected to lead
 to daily chances of showers and thunderstorms.

Moisture remains anchored over the area, with southwest flow
providing a continuous stream of moisture into the region this
weekend into early next week. The surface front should finally pass
to our south, while the flow around the upper trough over the TN
Valley will continue to move shortwaves through the region. Expect
scattered to numerous showers and thunderstorms each day, with
the threat for some gusty winds and flash flooding continuing as
well. Lower heights along with cloud cover will keep
temperatures below or near normal, with highs in the upper 80s
to low 90s and overnight lows in the mid 70s. One or two days
will likely stand out with an elevated severe and/or flooding
threat as we get closer to the valid period, but right now
details are too inconsistent to make a definite distinction.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
Generally VFR conditions expected through the TAF period.

Only a few pockets of mid-level clouds being noted to start the
TAF period. Scattered thunderstorm activity is expected to
develop again this afternoon. Confidence remains high enough to
include VCTS at all terminals during the 19z-01z timeframe.
However, confidence in when or if convection affects the
terminals is rather low, so some fine tuning of the TAFs will
likely be needed over the next several hours. Activity then
wanes for the remainder of the period. Southwest winds expected
to increase to around 10 kts, gusting to around 20 kts this
afternoon as well before diminishing overnight. With elevated winds
in the boundary layer through the TAF period, restrictions
outside of the thunderstorm activity are not anticipated.

EXTENDED AVIATION OUTLOOK...Typical summertime afternoon
showers and thunderstorms may cause periodic restrictions each
day with abundant moisture causing possible, brief early morning
restrictions around sunrise.

&&

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

&&

$$