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Area Forecast Discussion (AFD)

Issued by Charleston, SC (CHS)

                            
000
FXUS62 KCHS 240211
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1011 PM EDT Thu May 23 2019

.SYNOPSIS...
Unseasonably hot high pressure will dominate into late next
week. 

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Late this evening: IR satellite imagery shows thin cirrus
moving through the forecast area, rotating around the periphery
of the deep upper ridge that is centered just to the west. No 
changes needed to the forecast. A very quiet and mild night is 
on tap.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
High confidence this period that temperatures will remain much 
above normal with rain chances much below normal as deep-layer 
high pressure dominate the weather pattern. A backdoor cold 
front looks to approach from the north Friday night, possibly 
making it to around the Savannah River before dissipating and 
getting absorbed by an inland trough. This pattern will then 
persist through the rest of the weekend. 

The best chance for any rain should be across SC on Saturday 
with the front in the area and increased low-level moisture. 
Isolated thunderstorms will be possible, mainly in the 
afternoon, possibly becoming marginally severe with damaging 
winds due to the high amount (1000+ J/kg) of downdraft CAPE 
according to model soundings. 

Temperatures will definitely be the big story however with 
highs peaking well above normal near record levels (see Climate 
section below), especially by Sunday when lower 100s will be 
possible inland. Heat indices are forecast to peak around 100 
degrees inland Friday and then closer to 105 degrees by Sunday 
when our first Heat Advisories of the season may be needed. 
Interestingly, Saturday could end up being a bit warmer than 
forecast depending on the potential for some frontal 
compression. Unfortunately overnight lows will also be well 
above normal which means not much relief is expected.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
There does not appear to be any relief in the dangerous and 
prolonged heat wave through at least Thursday. Continued sinking
motion, a dry atmosphere above the boundary layer which will 
result in nearly full sun, a dry ground, and 850 mb temperatures
generally within a degree or two of 20 Celsius all point to 
high temperatures from 97 to 103 degrees away from the coast. 
Heat indices at or above 105 which would prompt a heat advisory 
may occur on any of the days. The need for a heat advisory seems
mostly likely to be needed on Monday and/or Tuesday. Air 
quality issues may develop at any point during this period due 
to the excessive heat and generally stagnant air pattern. Even 
though winds will be on the lighter side, hot conditions and dry
fuels could aid in the development of wild fires.

&&

.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
VFR.

Extended Aviation Outlook: VFR.

&&

.MARINE...
Tonight: The center of sfc high pressure will slide south 
across the local waters. Winds are forecast to shift from the 
southeast to south during the overnight hours, speeds remaining 
around 10 kts. Wave heights between 2-3 ft should remain common 
across the waters.

Friday through Tuesday: Summer-like pattern will prevail with 
Atlantic high pressure to the east. This will lead to increasing
winds during the afternoon as the sea breeze develops near the 
coast which will then subside a bit overnight but not much. 
Overall wind gust should stay 20 knots or less and with seas 
about 3-4 ft or less we don't anticipate any Small Craft 
Advisories will be required.

&&

.CLIMATE...
A very significant, hazardous and prolonged heat wave will 
challenge or break many of these records.

RECORDS FOR FRI 05/24...

Station     Record High       Year(s)
-------     -----------       -------
KCHS            97            1953
KSAV            98            2011, 1953

RECORDS FOR SAT 05/25...

Station     Record High       Year(s)
-------     -----------       -------
KCHS            97            2000, 1953
KSAV           100            1953

Station     Record High Min   Year(s)
-------     ---------------   -------
KCHS            75            1953
KSAV            76            1878
KCXM            79            1998

RECORDS FOR SUN 05/26...

Station     Record High       Year(s)
-------     -----------       -------
KCHS            98            1953
KSAV           100            1953

Station     Record High Min   Year(s)
-------     ---------------   -------
KCHS            75            1998
KCXM            79            1998

RECORDS FOR MON 05/27...

Station     Record High       Year(s)
-------     -----------       -------
KCHS            98            1989
KSAV            98            1989, 1962
KCXM            95            1962, 1926

Station     Record High Min   Year(s)
-------     ---------------   -------
KCHS            76            1991
KSAV            77            1878
KCXM            78            1991

RECORDS FOR TUE 05/28...

Station     Record High       Year(s)
-------     -----------       -------
KCHS            97            1967, 1964
KSAV            96            1964, 1898
KCXM            93            2000

Station     Record High Min   Year(s)
-------     ---------------   -------
KCHS            76            2000
KSAV            76            1885
KCXM            80            2000

RECORDS FOR WED 05/29...

Station     Record High       Year(s)
-------     -----------       -------
KCHS            95            1945
KSAV            98            1945, 1898

Station     Record High Min   Year(s)
-------     ---------------   -------
KCHS            76            2018
KSAV            75            1885
KCXM            77            1998

RECORDS FOR THU 05/30...

Station     Record High       Year(s)
-------     -----------       -------
KCHS            95            2004
KSAV           101            1898

Station     Record High Min   Year(s)
-------     ---------------   -------
KCHS            75            1982
KSAV            75            1924
KCXM            78            1998

&&

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

&&

$$

NEAR TERM...BSH
SHORT TERM...RJB
LONG TERM...MTE
AVIATION...BSH
MARINE...NED/RJB
CLIMATE...