Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 190541

Area Forecast Discussion
National Weather Service Charleston SC
141 AM EDT Mon Aug 19 2019

Weak low pressure over the Florida Panhandle will drift into
southeast Georgia late tonight. Atlantic high pressure and an
inland trough will then prevail into late week before a cold
front approaches but likely stalls before reaching the area.


As of 140 AM: IR satellite and sfc based observations
indicated a ragged patch of low clouds across SE GA. I will
update the forecast to increase sky cover across GA.

Previous Discussion: Late this evening: No changes to the
forecast thinking for the rest of the overnight. Previous
discussion continues below.

Early this evening: Shower and thunderstorm activity has become
confined to a small area across southeast Georgia, and even that
is steadily dwindling. We should be rain free in the next hour
or two, and should remain that way for most of the overnight.
The main forecast feature tonight will be the weak area of low
pressure located near the area where Alabama, Georgia, and
Florida all come together. This low will slowly drift toward our
southeast Georgia zones tonight and as day break approaches cold
help to kick off a few showers or thunderstorms for areas closer
to the Altamaha, or offshore over the nearshore coastal waters.
Model guidance also suggests some potential for fog and stratus,
mainly for interior portions of the forecast area. Overall, no
significant changes were made to the going forecast through


The large scale pattern will consist of Atlantic high pressure
offshore, with troughing inland. A weak area of low pressure
will meander over southern Georgia Monday into Tuesday before
possibly lifting into SC then dissipating. The most active day
of the set looks to be on Monday especially in southeast
Georgia, given forcing aid from shortwave energy and PWATs of
over 2 inches. More typical summertime rain chances are expected
thereafter. It is worth noting that there is some discrepancy
between model solutions regarding convective coverage Tuesday
and Wednesday. GFS seems to be the outlier indicating a wetter
forecast, so have opted to go with consensus. Overall severe
threat looks to be low with marginal instability, however cannot
rule out a stronger to marginally severe storm during this time
of year, especially where boundary interactions occur.

Temperatures will be fairly seasonable, with highs in the upper
80s/low 90s. Lows overnight will range from the low 70s inland
to mid/upper 70s at the immediate coast.


The pattern doesn`t change much until late week when a cold
front moves south toward the area this weekend. Deeper moisture
and the nearby front should promote better rain chances.
Otherwise, no significant impacts expected overall with the
severe weather risk remaining low. Temperatures should remain
near/above normal.


Prior to the 6Z TAFs, IR satellite and sfc based observations
indicated a ragged patch of IFR/MVFR ceilings across SE GA. I
will initialize the KSAV TAF with BKN011 and will TEMPO BKN009
between 6Z-10Z. KCHS is expected to remain north of the
restrictive ceilings, VFR conditions forecast for this morning.
The combination of deep moisture and steeper afternoon lapse
rates should support scattered to numerous thunderstorms today.
I will highlight the mid to late afternoon hours with a TEMPO
for TSRA at both sites. CAMs indicate that KSAV will see a
greater chance for thunderstorms that KCHS. Convection should
dissipate within an hour or two of sunset.

Extended Aviation Outlook: Flight restrictions are possible
mainly from afternoon/evening showers and thunderstorms through
late week.


Tonight: There are no concerns with south to southwest winds
prevailing. Speeds will average 10-15 kt, but gusts could
occasionally reach as high as 20 kt at times, mainly through
midnight. Seas will average 1-3 ft.

Monday through Friday: The marine zones will remain on the
backside of Atlantic high pressure, keeping winds out of the
south/southwest through the period. Wind speeds will remain
below small craft advisory criteria, generally 15 knots or less.
Seas will average 2 to 3 feet.




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