Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 070748

Area Forecast Discussion
National Weather Service Columbia SC
348 AM EDT Fri May 7 2021

An upper level trough and weak surface low will cross the area
today and shift east of the area tonight. Dry high pressure
will build across the area over the weekend. A cold front will
move into the region Monday and stall resulting in rain chances
through Thursday.


Surface low pressure is developing off the coast in response to
the approach of an upper trough moving across the southern
Appalachians this morning. Satellite imagery showing some higher
clouds arriving from the west associated with the trough axis
and some mid level clouds over the northern Midlands and Pee
Dee region associated with some weak isentropic lift in an area
where PWATs are elevated.

Regional radar shows some scattered showers just east of
Charlotte and as the upper trough moves east additional
convection may develop across central NC and move southeast
possibly clipping the Pee Dee region and Chesterfield county in
particular, so will keep a mention of slight chance pops there
through the day. Elsewhere, dry air and deep mixing should
prevent any rain chances with mostly sunny skies expected.
Downsloping northwesterly flow will develop by mid morning with
breezy conditions expected through the day with northwest winds
increasing to around 15 to 20 mph with gusts up to 25-30 mph
this afternoon. After coordination with CHS, we will go with a
Lake Wind Advisory from 14z-00z. Temperatures will slightly
below normal today but the downsloping flow combined with plenty
of sunshine, highs are expected to range from the lower 70s west
to mid 70s east.

Tonight...As the upper trough moves away from the region weak
high pressure will build in from the west. Despite mostly clear
skies overnight, radiational cooling conditions are not going to
be ideal as winds are expected to stay up and keep the boundary
layer mixed. Overnight lows expected to drop into the mid and
upper 40s.


The upper trough over the area will dampen Saturday with rising
500mb heights as the airmass moderates with highs a few degrees
warmer than Friday. Downsloping is expected early with NW low
level flow early but expect winds to turn westerly into the
afternoon and evening with a slight dew point recovery. Some
mid-level moisture advected from the west will lead to a bit
more cloud coverage as well Saturday but low levels remain dry.
Moderating lows also expected with temps Saturday night dropping
into the low to mid 50s.

Surface high pressure moves offshore Sunday with with low pressure
centered over the Midwest and a associated cold front moving towards
the area. Breezy SW winds will develop with a strengthening of the
upper ridge promoting much higher temperatures with highs in the mid
to upper 80s. Dew points will also recover into the upper 50s and
60s by Sunday night. With winds staying elevated overnight, lows
will remain in the mid 60s. A weak pre-frontal surface trough will
approach the area late Sunday night but showers should hold off
until Monday with a substantial layer of mid-level dry air still in


Moisture will continue to increase into Monday with PWATs
approaching the 90th percentile, around 1.5 inches in the CSRA and
slightly less north. A shortwave will pivot through the region
generating showers with thunderstorms also possible, although
instability looks weak at this point will most ensemble members
keeping CAPE less than 500 J/kg. Backdoor cold front looks to move
in for Tuesday with dry, cold advection at the surface and cool
Canadian high pressure settling over the area. Moisture will begin
to return with a bit of spread among ensembles as to how fast it
does. Kept at least a slight chance and chance pops Tuesday and
Wednesday to account for this uncertainty but do expect moisture to
return by Thursday at the latest with additional chances for
showers, although with the potential for wedge conditions to
develop, less confident in storms developing.


VFR throughout the 24 hr forecast TAF period, with winds being
the main focus on today.

An upper trough is approaching from the west and will cross the
region today. Satellite imagery showing some scattered high
clouds moving in from the west with some lower clouds associated
with isentropic lift over the Pee Dee region and northern
Midlands. Expect mostly clear skies at terminals through the
period with relatively dry air mass in place.

Winds will pick up to around 10 knots around dawn as the
pressure gradient increases related to a deepening surface low
off the coast. Winds increase further by 15z to around 15 knots
with gusts over 25 knots possible late morning through the
afternoon from the northwest as the upper trough passes. Winds
should subside with sunset this evening dropping below 10 knots.

EXTENDED AVIATION OUTLOOK...No restrictions expected Saturday
and Sunday. Restrictions possible as a low pressure system and
cold front moves through Monday and Tuesday.


There is an elevated fire danger today due to low relative
humidity, around or below 25%, and gusty winds to near 30 mph.


GA...Lake Wind Advisory from 10 AM this morning to 8 PM EDT this
     evening for GAZ040-063>065-077.
SC...Lake Wind Advisory from 10 AM this morning to 8 PM EDT this
     evening for SCZ016-018-020>022-025>031-035-037-038-041-


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