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Area Forecast Discussion (AFD)

Issued by Charleston, SC (CHS)

                            
000
FXUS62 KCHS 252336
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
736 PM EDT Sat May 25 2019

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

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
No significant changes were made for this evening. Satellite and
radar loops clearly show the sea breeze is now well inland, and
is continuing to move westward. Expect a clear/mostly clear,
warm night tonight. Lows will range from the lower 70s to mid
70s inland to near 80 close to the coast.

Climate Note: Record high temperatures were tied this afternoon
at both North Charleston and Savannah climate sites.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
The so-called "Heat Dome" will remain in place across the southeast 
early this upcoming week, with both H5 heights and H85 temps about 
as high as they have been on record for May in this part of the 
country. With the jet stream displaced far to the north, a strong 
deep layered ridge will remain to the south, resulting in 
considerable sinking air. The sinking air is compressed, and as this 
occurs it warms the air further. Combined this with the lack of 
rainfall, and the area generally in a D1 or "Moderate Drought" 
conditions will be near or at record levels the next few days. 

There are hints that maybe a couple of stray showers could form 
along the sea breeze that reaches near and inland from I-95 Sunday, 
probably not much further inland than US-17 Monday, and again inland 
from I-95 Tuesday. Plus there is a pronounced lee side trough not 
far away. However, with so much subsidence in place, warm mid levels 
and the lack of moisture outside of the H85-H7 layer, we have no 
mentionable PoP. 

With deep offshore trajectories and the resulting downslope flow, we 
stayed close to the pure low level thickness forecast scheme. This 
will support max temps hitting the century mark (100F) all three 
afternoon across a large portion of the area. There will be some 
minor relief at the beaches due to the developing sea breeze, as 
temps reach "only" the upper 80s to lower 90s.

Dew points will mix out each afternoon down into the lower and 
middle 60s, but will pool back into the lower or lower to middle 70s 
along the coastal corridor as the sea breeze moves inland. This will 
put conditions very close to our criteria of issuing the pre-July 
1st Heat Advisory as heat indices approach 105F over the coastal 
counties.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The mid-level ridge will remain in place Tuesday night through 
Thursday, then finally flatten out Thursday night followed by zonal 
flow on Friday. Surface high pressure will continue to dominate our 
weather pattern. Models hint at a cold front approaching towards 
Friday. But they also show it dissipating as it runs into our 
persistently dry airmass. Temperatures should 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 
there remain too many variables this far out to get to deep into the 
details.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
VFR at KCHS/KSAV through 00Z Monday. 

Extended Aviation Outlook: VFR.

&&

.MARINE...
Tonight: No significant changes were made to the previous
forecast. Winds generally 15 knots or less and seas 2 feet or
less all waters. South-southeast winds this evening will likely
veer to south-southwest after midnight. For now, have averaged
the winds to be southerly all night, given the speeds are less
than 15 knots. 

Sunday through Thursday: The Bermuda-Azores High will remain 
the dominate weather feature during this time, resulting in a 
general SW flow that backs some during the day and veers some at
night. Even with sea breeze influences and the nocturnal low 
level jet, winds will be mainly at or below 15 kt, with seas no 
more than 2 or 3 ft.

&&

.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 SAT 05/25...

Station     Record High       Year(s)
-------     -----------       -------
KCHS            97            2000, 1953
KSAV           100            1953
KCXM            95            1962, 1953, 1912

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

RECORDS FOR FRI 05/31...

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


Station     Record High Min   Year(s)
-------     ---------------   -------
KCHS            77            2004 
KSAV            75            2004

&&

.EQUIPMENT...
WFO Charleston will only conduct upper-air soundings at 12Z until
further notice due to a shortage of helium.

&&

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

&&

$$
NEAR TERM...RFM/RJB
SHORT TERM...33
LONG TERM...
AVIATION...33/RJB
MARINE...33/RJB
CLIMATE...
EQUIPMENT...