Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 201716

Area Forecast Discussion
National Weather Service Columbia SC
116 PM EDT Thu Jun 20 2024

Dry weather and near normal temperatures will continue through
tonight as synoptic situation remains relatively unchanged.
Unsettled conditions are possible tomorrow and into the weekend
as moisture moves in from the Atlantic. Well above normal
temperatures are expected by Sunday into early next week.


With little change in the overall pattern and the surface high
remaining in control of the region another day of cumulus with
limited vertical development is upon us. The 12z CHS sounding
once again showed a strong subsidence inversion and based on
current clouds expect the inversion to persist through tonight.
This will result in cumulus developing through early this
evening then dissipating with the loss of heating. Temperatures
across the area are currently in the upper 80s and remain on
track for the low 90s at most locations. Easterly winds at 5 to
10 mph with gusts up to 20 mph will continue through the
afternoon then diminish this evening becoming light and
variable overnight. With good radiational cooling tonight
overnight lows will be in the mid to upper 60s.


Westerly moving wave/low pressure center is forecast to move ashore
northern Florida during the day on Friday, pushing westward by the
evening hours. Initially, our forecast area will have quite a bit of
subsidence north of this feature as we`ll still be stuck underneath
the mid and upper level ridge. As a result, the day is initially
expected to be dry and warm. By the afternoon hours, however, a
surge of PWs is forecast by all guidance, with HREF members
generally showing the highest PWs >1.5" approaching the I20 corridor
and points southward. This is the area most likely to see rain
between 2p and 8p, though it should remain generally scattered in
nature. Thunderstorms are possible but generally expecting things to
remain sub-severe. I do want to note that the well-performing HRRR
has been consistently showing no precip developing but it also is
mixing the boundary layer substantially more than its fellow CAMs
(even those that have had that bias in the past) so tend to think
that is the outlier. Highs will likely end up in the lower 90s,
maybe a touch cooler in the coastal plain where clouds are likely to
develop earlier in the day. Showers/storms will likely hang around
for a bit after sunset, diminishing as the night goes along. Look
for lows in the upper 60s.

Saturday looks fairly similar, as the plume of higher PWs is
expected to fully overspread the forecast area by this point. Given
hot temperatures and rich boundary layer moisture, we should see
scattered showers/thunderstorms develop across the forecast area
again on Saturday. Again, generally expecting these to remain
sub-severe but can`t rule out a strong storm here or there. Highs are
likely to be in the low to mid 90s, with overnight lows again in the
upper 60s or lower 70s.


Guidance continues to show fairly conflicting signals in terms of
heat in the long term. The ridge that has been parked across the OH
Valley and Mid Atlantic regions is expected to shift westward and
yield troughing as the next work week approaches. The first signs of
this are expected by Sunday as heights will begin falling across the
Carolinas. Heights should continue to remain at or below 588dm by
Monday and Tuesday as the western CONUS ridge builds and persistent
troughing looks like it may set up. LREF Members support the
operational models in showing, leading to higher confidence than
normal in the pattern evolution through early next week.

However, the sensible weather that results from this in the forecast
is conflicting to say the least. The trough is forecast and expected
to yield a surface low into the northeast CONUS by Monday, pushing a
weakening cold front towards the FA by Monday afternoon and the
overnight hours. PWs will still be near to slightly above normal
both Sunday and Monday, with scattered to potentially numerous
thunderstorms expected both days given the favorable setup. This
conflicts with models also showing high chances at temps in the
upper 90s to around 100F for highs by Monday. This is also shown on
Tuesday despite the cold front likely stalling near the area. Part
of this looks like it could be westerly or northwesterly flow that
develops in the base of this trough advecting warm (20-22C) 850 hPa
temps across the area Sun-Wed of next week. Given the expectation
that daily showers/thunderstorms will be a risk, and lowering 500
hPa heights, it is hard to believe NBM guidance that temps will make
it to near 100F any day next week, let alone multiple days. Have
capped forecast highs around 98F as that makes conceptual sense
given the forecast as it stands right now. Lows will likely be in
the 70s given surface moisture in place. Overall, it does look hot
but nothing too crazy for June in the southeast. By the middle of
next week, things still look to be active with a building western
CONUS ridge, so expect daily chances at rain to continue into
Wednesday and Thursday.


VFR conditions expected through the TAF period.

High pressure remains in control of the region with scattered
cumulus again across the area. Little will change is expected
through tonight which will result in the cumulus dissipating
toward sunset with the easterly winds also diminishing. Friday
morning the situation will begin changing as a weak tropical
wave moves toward the coast of eastern GA and NE FL. This will
spread moisture into AGS/DNL/OGB during the morning and CAE/CUB
during the early afternoon. Convection will be possible very
late in the period however confidence remains too low in timing
and coverage to include attm.

EXTENDED AVIATION OUTLOOK...Brief restrictions possible in
isolated to scattered afternoon and evening thunderstorms Friday
and Saturday with increasing chances Sunday through Tuesday.