067 
fxus62 kchs 061913 
afdchs 


Area forecast discussion 
National Weather Service Charleston SC 
313 PM EDT Sat Sep 6 2008 


Synopsis... 
a weak surface trough will push into the region later tonight or 
Sunday...while high pressure builds aloft. Hurricane Ike is expected 
to pass S of the area early next week. A cold front will slip S 
over Georgia and the Carolinas toward middle week...then will stall over 
or near the region into next weekend. 


&& 


Near term /until 6 am Sunday morning/... 
expect a tranquil night across the forecast area. The only concern 
is that stratus/fog could develop where heavy rain fell across 
northern counties...and across inland counties if the upstream 
surface trough pushes into the region late tonight. However...with 
afternoon dewpoints in the 60s at most locations...crossover 
temperatures are too low to justify a mention of late night fog 
within the afternoon forecast package. 


&& 


Short term /6 am Sunday morning through Sunday night/... 
upstream surface trough and associated middle/upper level vorticity/ 
deformation axis producing clouds and scattered showers/ 
thunderstorms upstream Saturday afternoon will slide east and into 
the forecast area Sunday. These features will push into the building 
upper ridge over the area and will gradually weaken with time. 
However...pooling of low level moisture and instability...featuring 
precipitable waters  around 2 inches and sbcapes as high as 2000-2500 j/kg...will 
combine with low level convergence...enhanced as the sea breeze 
advances inland...and weak ascent to support isolated to scattered 
diurnal thunderstorms. While the threat for pulse severe 
thunderstorms will remain very low...weak wind fields and high precipitable waters  
may support slow moving thunderstorms and locally heavy rainfall. 


High temperatures Sunday will average in the lower to middle 90s away 
from the coast...slightly above normal for early September. 


Diurnal showers/thunderstorms should dissipate Sunday evening. 
Then...low level moisture and a weak pressure pattern/light winds 
will support at least patchy fog overnight...especially if skies 
become clear. 


&& 


Long term /Monday through Saturday/... 
tropical cyclone Ike is forecast to go into the Gulf of Mexico by 
midweek and we are continuing to monitor the track. GFS continues to 
indicate an unsettled soggy pattern this week due to a weak cold 
front passing through the area by middle to late week. Probability of precipitation increase 
from Tuesday on through the period as persistent southerly flow 
pumps moisture into the region. 


With increasing cloud cover and shower activity around...this will 
hold maximum temperatures down in the middle to upper 80s for most of the 
week. Lows will continue to be near normal. 


&& 


Aviation /20z Saturday through Thursday/... 
the sea breeze will struggle to push inland this afternoon...and 
may only push through kchs late. Otherwise...VFR conditions will 
prevail at both terminals through most of tonight. Low level 
moisture/light winds may support brief MVFR conditions around 
daybreak Sunday. At kchs...where Hanna produced significant 
rainfall...brief IFR or lower visibilities/ceilings cannot be 
ruled out during the 09z-13z time frame. Then...as the sea breeze 
pushes inland and a weak surface trough advances into the region 
from the west...isolated showers/thunderstorms may develop. 
However...the sea breeze and associated convection will most 
likely not become factors before 18z Sunday...thus did not include 
a wins shift/cumulonimbi within the latest tafs. 


Extended aviation outlook...VFR conditions will prevail into 
middle week. 


&& 


Marine... 
winds/seas are expected to remain below Small Craft Advisory 
thresholds tonight through Sunday night. Ahead of an approaching 
surface trough...SW winds may surge to around 15 knots outside 
Charleston Harbor tonight. Then...as the pressure pattern weakens 
west/variable winds will diminish to less than 10 knots late 
tonight into early Sunday...before the sea breeze circulation 
develops by Sunday afternoon...supporting S/southeast winds 10-15 knots 
during the afternoon. Long period swell produced by Hurricane Ike 
will contribute to 3 to 5 foot seas beyond 10 nm...highest toward 
the 60 nm benchmark of the outer Georgia waters. 


Rip currents...rip currents were reported at Tybee Island Saturday 
afternoon. Also...spectral density plots obtained from buoys off the 
southeast coast reveal a 14-16 second period swell produced by 
Hurricane Ike. This long period swell and persistence factors will 
contribute to a moderate risk of rip currents on area beaches 
Sunday. The elevated risk of rip currents...produced mainly by this 
long period swell...may then persist into early this week. 


Extended marine...high pressure looks to remain over the marine zones 
through middle week. Winds will stay below advisory criteria at this 
time but will enhance during the afternoon due to the seabreeze. 
Winds and seas will increase by late week as the high pressure 
builds in from the northeast. 


&& 


Chs watches/warnings/advisories... 
Georgia...none. 
SC...none. 
Marine...none. 


&& 


$$