Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 211359

Area Forecast Discussion
National Weather Service Charleston SC
959 AM EDT Sun Apr 21 2019

High pressure will build across the region today, then dominate
the weather through Thursday. A cold front is expected to cross
through the region on Friday.


Mid/upper level low pressure and its attendant trough will
gradually lessen their influence on the region today as
elongated high pressure centered across the north-central Gulf
of Mexico propagates to the east. A weak surface trough across
the South Carolina Pee Dee and Midlands will shift southeast
and exit off the coast by late in the afternoon.

Scattered to broken stratocumulus associated with the low aloft
will develop and move through parts of the region through mid
afternoon. Cloud cover will be a little more prevalent across
the Charleston quad-county district, where skies for a couple of
hours could become partly sunny. Otherwise, mostly sunny to
sunny skies will dominate.

We`re already starting to see winds increase due to deepening
mixing of the modest winds within the boundary layer. This will
equate to westerly wind gusts as high as 15 or 20 kt at times.
Of course this is nothing compared to the past two days.

Temps are somewhat of a challenge, already running behind the
hourly LAV values. Plus the SREF, HRRR and RAP all hold temps
several degrees cooler than the MOS consensus and the ongoing
forecast. However, given downsloping trajectories, the strong
spring sunshine and H85 temps warming to 3C to 6C north to
south, we have left max temps as before, mainly 70-75F. Instead
we slowed the hourly climb, and will adjust later if necessary.


Tonight: A strong radiational night is expected as high pressure
dominates and skies clear as any linger stratocumulus dissipates
with the loss of insolation. The boundary layer looks to
decouple by mid-evening with calm to light/variable winds
prevailing. Sided with the cooler side of guidance once again with
lows ranging from the upper 40s inland to the upper 50s/near 60
at the beaches with mid 40s in some of the normally colder

Monday: The mid-levels will consist of a trough to our northeast in
the morning. This trough is forecasted to move away with time,
allowing ridging to build over the Southeast. At the surface, high
pressure will prevail over the Southeast. Expect dry weather and
sunny skies. The rising heights will allow temperatures to rise a
few degrees above normal. Though, they will be cooler at the beaches
with the afternoon sea breeze.

Tuesday: The mid-levels will consist of riding over the Southeast.
It may dampen and move a bit offshore overnight. At the surface, the
center of broad high pressure initially over the Southeast in the
morning will start to trend offshore in the evening and overnight.
Dry weather and mostly sunny skies are forecasted. Though, a warming
airmass will allow temperatures to rise into the mid 80s, cooler at
the beaches with the afternoon sea breeze. Lows will be mild,
generally around 60 degrees.

Wednesday: Mid-level ridging may dampen a bit with time, leading to
semi-zonal flow over our area. At the surface, high pressure will be
moving offshore. A cold front will approach from the distant north
while a storm system develops over the Southern Plains. Neither
feature will reach our area, meaning another dry day. Though, high
clouds should increase with time. We may see our highest
temperatures in a so far this year. Highs may make a run for the 90
degree mark in some locations, assuming the clouds don`t get to
thick too quick. Once again, relief in the form of cooler
temperatures will be at the beaches.


High pressure will shift further offshore Wednesday night into
Thursday as a cold front approaches from the north and a storm
system approaches from the west. The storm system with its
associated cold front is expected to move through the region on
Friday, bringing showers and cooler temperatures. Saturday, the
models differ on whether it will be dry or remnant showers will
persist. Since most of the models lean towards it being dry, we
trended our forecast in that direction.



Extended Aviation Outlook: VFR.


Through Tonight: West winds will veer to the northwest this
afternoon in the wake of a surface trough then becoming north
overnight. Speeds will remain 15 kt or less through the period
with seas seas 2-4 ft this morning subsiding to 1-3 ft by
daybreak Monday.

Monday through Thursday: High pressure will prevail over the
Southeast Monday. The center of the high will trend offshore
Tuesday night, continuing further offshore through Thursday. A
weak pressure gradient will bring fairly good marine conditions
through midweek along with a sea breeze each afternoon.




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