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Area Forecast Discussion (AFD)

Issued by Charleston, SC (CHS)

                            
000
FXUS62 KCHS 241956
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
356 PM EDT Fri May 24 2019

.SYNOPSIS...
High pressure and unseasonably hot conditions will dominate
into late next week. 

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 350 PM: Surface observations and satellite images 
indicate that a sea breeze could be forming along the coast. 
HRRR shows a weak sea breeze drifting slowly inland very late 
this afternoon into this evening. The passage of the sea breeze 
would cool temperatures along and east of the boundary. 
Otherwise, temperatures will remain in the mid 90s with the heat
index 105 or less. Conditions under the H5 ridge will remain 
dry, with only shallow fair weather cumulus until sunset. Using 
a blend of MOS, I will forecast low temperatures from near 70 
inland to the mid 70s along the coast.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
A deep layer ridge is expected to be locked in over the southeast 
U.S., centered near the northern Gulf coast through the period. With 
rising mid and upper level heights and west-southwest low level 
flow, high temperatures are expected to approach or exceed record 
values. Overall, models generally showing highs in the mid to upper 
90s most areas away from the immediate coast. Even could see 
temperatures around 100, especially by Sunday and Monday. Late 
afternoon sea breezes are expected to be weak and not penetrate very 
far inland each day, which will hold relatively cooler afternoon 
highs close to the immediate coast.  Models indicate afternoon 
dewpoint temperatures will mix down a bit each day, possibly down 
around 60 well west of I-95, and mid to upper 60s close to the 
coast. If this pans out, afternoon max heat indices should hold in 
the 100 to 103 range. There could be a few spots that get closer to 
105, which is minimal Heat Advisory levels. 

No significant rain chances expected through the period. Kept 
low/slight chance PoPs on Saturday in the presence of a weak 
backdoor front over the northern Charleston Tri-county region, but 
confidence not very high. GFS showing another weak backdoor type 
front Sunday night and Monday, but with a lack of deep layer 
moisture and forcing, have kept out mention of rain chances for
now.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
The mid-level ridge will remain in place while surface high pressure 
persists. Temperatures may trend downward a few degrees each day. 
However, they are still forecasted to remain well above normal 
throughout the long term. Additionally, no rainfall is in the 
forecast. Heat advisories, poor air quality, and dry fuels that 
could increase the risk of wildfires are all concerns. But the 
details will need to be better defined as this time period gets 
closer.

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
VFR.

Extended Aviation Outlook: VFR conditions are expected to prevail 
for both CHS and SAV terminals through the middle of next week.

&&

.MARINE...
A brief window of gusty south winds are possible early this evening 
as a sea breeze pushes west. Otherwise, very quiet conditions across 
the marine zones tonight. South winds are forecast to remain between 
10-15 kts. Wave heights should range between 1-3 ft.

No highlights expected through the period. The axis of high pressure 
is expected to remain just south of the waters, keeping west-
southwest winds of mainly 15 knots or less and seas 3 feet or less 
through mid week. Winds could increase more toward 15 knots Sunday 
night and the first part of Monday over SC waters as a weak front 
potentially stalls and then dissipates over the northern waters. 

&&

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

ALL TIME RECORD HIGHS FOR MAY:
KCHS: 99 set May 21, 1938.
KSAV: 101 set May 30, 1898 and May 31, 1945.
KCXM: 99 set May 21, 1938 and May 26, 1953.

RECORDS FOR FRI 05/24...

Station     Record High       Year(s)
-------     -----------       -------
KCHS            97            1953
KSAV            98            2011, 1953
KCXM            98            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...NED
SHORT TERM...RFM
LONG TERM...
AVIATION...NED/RFM
MARINE...NED/RFM
CLIMATE...