547
FXUS62 KCHS 030205
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1005 PM EDT Sun Jun 2 2024

.SYNOPSIS...
High pressure will extend across the area through Wednesday. A
cold front will slowly move through on Friday, followed by high
pressure.

&&

.NEAR TERM /THROUGH MONDAY/...
The axis of a broad mid-level trough will remain over the
forecast area tonight. Deep moisture associated with the trough
should remain just west of the region. Late this evening, KCLX
detected a few weak showers over the Midlands of SC, dry across
SE GA and SC. Recent runs of the HRRR indicates generally dry
conditions across the land and water zones tonight. The updated
forecast will remove SCHC PoPs over the marine zones. Otherwise,
conditions should remain dry with plenty of mid and high
clouds. Low temperatures are forecast to range from the mid 60s
inland to the around 70 along the coast.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
Monday: Weak ridging will be situated aloft, with a subtle short
wave to pass near the Santee River in the afternoon. At the surface,
high pressure is the main feature, although there might be the
development of a weak lee side trough. There isn`t as much of a cap
per sounding data, so we will be able to some convection across the
region. Lapse rates are only so-so, and MUCAPE is forecast to reach
1000-1500 J/kg. But given the sea breeze becoming more active, and
upstream convection due to diurnal heating and the lee trough will
produce scattered showers and t-storms. The greatest chances (50%
PoPs) are near and west of I-95 in the afternoon when buoyancy is
the best. Since DCAPE is in excess of 1000 J/kg and sounding do show
an inverted-V trace, there would be a risk for some strong wind
gusts where boundary interactions occur. Thus the severe risk is non-
zero. The HREF does show a 50% potential for more than 1 inch of
rain late in the afternoon near and west of I-95. But other guidance
has much less probabilities of that happening. 850 mb temperatures
reach 15-16C, and will support max temperatures prior to convection
hitting the mid and upper 80s. Evening convection quickly diminishes
far inland, and the rest of Monday night looks to be rainfree.
Although winds do decouple, a south-southwest synoptic flow and
higher dew points will limit lows to just 66-70F inland, several
degrees warmer at and closer to the coast.

Tuesday: Ridging prevails aloft and the capping is better than on
Monday. As a result we hold PoPs down to just 20/30%, driven mainly
by the sea breeze and any mesoscale boundary interactions. DCAPE is
again favorable for strong wind gusts in a few storms, but given
poor lapse rates, the potential is less than on Monday. 850 mb
temperatures climb about another 1C, leading to highs making it to
the upper 80s and near 90F.

Wednesday: Surface ridging is a bit weaker, while aloft the flow
becomes more zonal. There is also a short wave that is progged to
move through, and with greater MUCAPE and slightly better lapse
rates, this will lead to a higher chance of convection, as we show
up to 50% probabilities. Temperatures aren`t much different than
Tuesday, with the slightly higher 850 mb temperatures negated by the
higher rain chances.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
An anomalous upper low digs through the Great Lakes region Thursday
and Friday, then into the Northeast and Mid-Atlantic vicinity during
the weekend. That upper air pattern will likely send a cold front
toward us late in the week, with model consensus showing that the
cold front does indeed make it through for the weekend. That`s
difficult to do this time of year, but guidance has been consistent
on that happening, so we maintain that forecast. There is a decent
short wave that passes through Thursday, leading to at least
scattered coverage, then less activity with the approaching front
Friday due to better capping, and then little to no chance for
Saturday and Sunday if there actually is the passage of the cold
front prior to then. Every day will be well above climo, mainly in
the lower to perhaps mid 90s, the combination of warm advection and
compressional heating in advance of the cold front, the due to an
offshore flow in its wake. Some heat indices will be near or above
100F Thursday and Friday, but not enough for any Heat
Advisories.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
VFR conditions will prevail at KCHS, KJZI, and KSAV through 0z
Tuesday. Showers may develop near KSAV Monday afternoon. The
KSAV TAF will feature the mention of VCSH starting at 19Z.

Extended Aviation Outlook: Outside of any convection, conditions
will be VFR through the period.

&&

.MARINE...
Tonight: SE to SSE flow will prevail across the local waters,
with speeds mostly in the 10-15 knot range. The strongest winds
will likely be along the land/sea interface through early
evening and gusts up to around 20 knots will be possible. Seas
will average 2-3 feet.

Monday through Friday night: High pressure is the main weather
feature through the week, until a cold front approaches late in the
period. Winds will be mainly S or SW at 15 kt or less the entire
time, with seas no more than 2 or 3 feet. Of course in any
convection the winds and seas can be briefly higher. We`re into the
early part of our local waterspout season, so this will be something
that we`ll need to starting watching for.

&&

.TIDES/COASTAL FLOODING...
Due to tides running as much as 0.3 to 0.5 ft MLLW above
predicted astro tide levels, and increasing astronomical
influences, there is the risk for minor coastal flooding
starting Monday evening. The risk is greatest over coastal
sections of Charleston and Colleton County through the week. The
latest TWL forecast for Charleston Harbor shows 7.0 ft MLLW
Monday evening, 7.1 ft MLLW Tuesday evening, and 7.3 ft MLLW
Wednesday evening. As a result, Coastal Flood Advisories are
likely. The highest during that time at Fort Pulaski is 9.3 ft
MLLW Wednesday evening.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.

&&

$$

NEAR TERM...NED
SHORT TERM...
LONG TERM...
AVIATION...NED
MARINE...Adam