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682
FXUS62 KCAE 190804
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
404 AM EDT Thu Sep 19 2024

.SYNOPSIS...
Showers and thunderstorms will be possible today, favored in
the eastern Midlands. Moisture is expected to decrease Friday.
High pressure will build into the area from New England over the
weekend into early next week with dry and seasonable
temperatures expected.

&&

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

- Isolated to scattered showers and thunderstorms today

The upper low will open up into a trough as it shifts eastward
today. The axis of the trough will move offshore with drier air
moving into the region through light N winds. Despite lower PWAT
values than the previous day, atmospheric moisture remains
relatively high in the eastern Midlands and Lowcountry with PWAT
values from 1.6 to 1.7 inches. As convection develops in the
afternoon, aided by shortwave energy rounding the base of the
trough, development will be favored in the eastern Midlands.
Drier air to the west will work to inhibit showers. Overall, the
direr airmass will keep showers and thunderstorms isolated to
widely scattered. Convection will diminish in the evening with
loss of heating, although a weak shortwave could support an
isolated, lingering shower into the overnight period. Mean
sbCAPE values from the HREF are lower than 750 J/kg suggesting
instability may be too limited for any severe threat. Highs will
be in the low to mid 80s with lows overnight in the mid 60s.

&&

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

- Possible isolated showers Friday afternoon
- Upper ridge builds on Saturday with warming temps

The upper trough axis should be east of the forecast area on
Friday and slowly shifting eastward while 500mb heights
gradually rise as the upper ridge over the middle of the
country begins to build eastward. PWATs should decrease
slightly during the day but still remain near normal ranging
from 1.2 to 1.4 inches with forecast soundings showing this
moisture generally confined in the lower levels between
850mb-700mb. Deep northerly flow above 700mb results in
significant dry air in the mid levels also noted in the
forecast soundings. Instability appears weak but there could be
a weak vorticity max rotating through the back side of the
upper trough that may help support an isolated shower but will
continue to keep the forecast pops below 15 percent due to low
coverage.

The upper ridge should build eastward into the forecast area on
Saturday with rising upper heights. Forecast soundings show a
strong subsidence inversion and this combined with limited
moisture and no upper forcing should prevent any rain threat.
Temperatures during this period should show a warming trend and
expect highs in the lower to mid 80s on Friday and a bit warmer
on Saturday with highs in the mid to upper 80s. Overnight lows
both nights are expected to be near normal in the low to mid 60s
under mostly clear skies.
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&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
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Key Message(s):

- Generally benign weather with near to above normal temperatures

Global ensembles in good agreement with the upper level pattern
featuring an upper ridge over the OH/MS Valleys on Sunday
building eastward along the east coast through early next week.
At the surface, high pressure centered over New England will
ridge down the east coast through the period providing
northeasterly to easterly winds Sunday, shifting more
southeasterly to southerly early next week. The low level
southerly flow should support PWATs rising back slightly above
normal with values around 1.4-1.5 inches early to mid week.
However, with the strong upper ridge overhead and forecast
soundings showing a strong subsidence inversion with little
instability, will continue to carry a dry forecast through
Tuesday.

A bit more uncertainty exists by Wednesday as the GEFS shifts
the ridge axis east of the area with upper troughing over the
OH/MS valleys while the EC ensemble is much weaker and slower
with the upper trough approaching the region. Temperatures
during the extended forecast period are expected to be near to
above normal with Sunday being the warmest day with highs in the
mid 80s to around 90 degrees, otherwise highs in the 80s into
early next week. Overnight lows expected to be in the 60s.
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&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
Lingering low-level moisture over the region will promote
patchy low clouds and fog over the terminals this morning. Given
the patchy nature of the cloud decks it`s difficult to
determine how prolonged any IFR or possibly LIFR conditions
would last. With some drier air working into the area, fog could
develop as clouds break up but would be localized. It is
shaping up to be a messy forecast through the morning with low
confidence in restrictions and their duration.

Any possible restrictions would begin mixing out after sunrise
but MVFR conditions could persist into the mid to late morning
before all sites return to VFR. Winds will generally be light
and out of the north. Convective coverage today should be more
limited than the previous day, with highest rain chances in the
eastern Midlands near OGB. At this point, confidence is not high
enough to include in the TAFs but showers and thunderstorms
will be possible again. Any convection will diminish during the
evening hours. Drier air working into the region should reduce
the chances of stratus like we`ve seen the previous nights. But
shallow moisture lingering over the area could support patchy
fog around sunrise.

Extended Aviation Outlook...Drier air over the region will
limit the chance of restrictions through the weekend before
moisture begins to increase early next week.

&&

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

&&

$$