FXUS62 KCHS 070545
Area Forecast Discussion
National Weather Service Charleston SC
145 AM EDT Sun Jun 7 2020
The area will remain between Atlantic high pressure and a
surface trough inland tonight. A cold front will stall over or
just north of our area early next week, then will gradually
dissipate through the middle of next week. Another weakening
cold front could approach the area late next week, then shift
offshore late next weekend.
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Main change on this update was to increase rain chances late in
the far south. Thought QPF was too high so lowered it a bit,
especially north of I-16.
Isentropic ascent will continue to produce widespread rains
associated with Tropical Storm Cristobal that will continue to
inch northward across the Altamaha River overnight. The rains
will only make it so far north, prevented from spreading much
further north than maybe I-16, if even that far north.
Lows will average several degrees above climo.
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/...
Sunday: Mid-level heights should remain consistent overhead as TC
Cristobal moves into a ridge of high pressure over the MS Valley. At
the surface, focus will be on TC Cristobal approaching the Gulf
Coast. Abundant moisture on the eastern side of the storm will be
ushered across the Southeast, with PWATs in the 1.5-2" range. At the
same time, a weak cold front will approach from the north, stalling
over or just north of our area. The combination of the abundant
moisture and increasing lift will lead to showers. The highest POPs
are over our GA counties where moisture is slightly higher. There is
not much instability, so the thunderstorm risk during the day is
low. Despite plenty of clouds, highs are still expected to reach the
mid to upper 80s. The showers are expected to dissipate in the
evening and overnight with the loss of daytime heating. Lows will
remain mild, ranging in the low to mid 70s, warmest at the beaches.
Monday and Tuesday: The mid-levels will consist of Cristobal moving
to the north towards the Great Lakes region, eventually becoming
absorbed in an approaching trough to the west. This will push a
ridge of high pressure to the east, over the East Coast. At the
surface, Cristobal will be moving inland far to our west while a
weak front will be dissipating over or just north of our area. Deep
moisture originating from the Gulf of Mexico will remain across the
Southeast, with PWATs still in the 1.5-2" range. Most of the
precipitation should be driven by the afternoon heating. We kept the
chance POPs each afternoon, with lower POPs at night. There is a
more instability both days, leading to greater probability of
thunderstorms. The main concern is locally heavy rainfall due to the
slow storm motions. Though, damaging wind gusts cannot be ruled out
if DCAPE values increase. Highs should be in the upper 80s to near
90 degrees each day. Lows will remain mild, ranging in the low to
mid 70s, warmest at the beaches.
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Sfc high pressure will gradually spread across the region from the
western Atlantic mid-week under a ridge of high pressure aloft. This
should shift the bulk of deeper tropical moisture inland while the
remnants of Tropical Cyclone Cristobal continues to lift north and
eventually becomes absorbed in a longwave trough of low pressure
advancing across the Central United States. Few to scattered showers
and thunderstorms remain in the forecast Tuesday night through
Wednesday, but the bulk of precip activity should be more diurnally
driven with peak coverage Wednesday afternoon. Latest guidance then
suggests a weakening cold front approaching inland areas Thursday
and potentially stalling over or near the area into Friday before a
reinforcing cold front approaches inland and shifts offshore during
the weekend. Given the setup, scattered showers and thunderstorms
are forecast each day, before the bulk of precip shifts offshore
with the front late Saturday. Afternoon highs should remain near
normal throughout the week given precip activity and some clouds in
place. In general, highs should range in the mid/upper 80s (warmest
away from the coast). Overnight lows will start off mild Wednesday
night, ranging in the low/mid 70s, then become cooler by the weekend
behind any fropa, ranging in the mid/upper 60s inland to lower 70s
along the coast.
.AVIATION /06Z SUNDAY THROUGH THURSDAY/... KSAV: VFR ceilings
as we begin the 06Z TAF cycle, but MVFR ceilings will be
possible towards sunrise. IFR ceilings possible, but really
think it will be either VFR or IFR ceilings. Any IFR or MVFR
ceilings should increase into the low-end VFR range after 15Z.
The bulk of the -RA should stay south of the terminal through
KCHS: VFR will prevail with the 06Z TAF. There could be some
scattered clouds near 1500 feet towards daybreak and shortly
there after, but not expecting any MVFR ceilings at this time.
Extended Aviation Outlook: Brief flight restrictions are possible
due to showers/thunderstorms, especially each afternoon/evening.
Overnight: Main change on this update was to significantly
reduce both seas and winds over the waters for the remainder of
the night given current conditions. Southwest winds of 10 to
perhaps 15 knots top with seas mainly near 2 feet expected.
A cold front will stall over or just north of our area on
Sunday, then gradually dissipate into the middle of the week.
Winds/seas are expected to remain below Small Craft Advisory
levels. High pressure should then pass offshore midweek before a
weakening cold front approaches inland areas Thursday.
Winds/seas are expected to remain well below Small Craft
Advisories during this time frame with onshore winds generally
remaining at or below 10-15 kt while seas build no higher than
Lingering affects of the recent lunar perigee and full moon will
continue to contribute to elevated tides into early next week. Minor
coastal flooding will be possible during the evening/nighttime high
tides along the South Carolina coast.
The KCLX radar will remain out of service for equipment upgrades
through June 11, and radar data will not be available during this
time. Neighboring radars include: Wilmington, NC (KLTX);
Jacksonville, FL (KJAX); Moody AFB, GA (KVAX); Warner Robins AFB, GA
(KJGX); and Columbia, SC (KCAE).
Supplemental weather balloon releases in support of Tropical
Cyclone Cristobal forecasts will end at 06Z tonight (6/7).
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