573 
fxus62 kilm 301148 
afdilm 


Area forecast discussion 
National Weather Service Wilmington NC 
749 am EDT Sat Aug 30 2008 


Synopsis... 
area beaches will see an increased threat of rip currents this 
upcoming week as swells from Hanna arrive. Otherwise...a weak trough 
of low pressure will linger over the eastern Carolinas through 
Saturday. A cold front will push southeast across the region Sunday 
into early Monday. High pressure will build in from the north Monday 
through the middle of next week. 


&& 


Near term /through tonight/... 
as of 3 am Saturday...will have to deal with some fog through 
sunrise...possibly locally dense at times inland areas. The fog 
will burn off an hour or so after sunrise...yielding partly cloudy 
skies. A weak upper low...noted on water vapor imagery across SC 
will continue to direct a Narrow Channel of moisture into the 
Carolinas. The upper low...along with lift provided by the sea 
breeze should be enough to spark scattered rain showers/thunderstorms and rain during the 
day...persisting into the evening before dissipating. Think 
coverage will be largest across the Lumberton zone area. Mav/met 
numbers are very similar to maximum temperatures today...and saw no reason to 
stray too far. For mins... favored a blend toward the slightly 
cooler mav numbers. Also... potential will exist for additional 
fog late tonight into early Sunday morning. 




&& 


Short term /Sunday through Monday night/... 
as of 3 am Saturday...the big story will be the change in air mass 
as the front will be well to the south of the area Sunday 
morning...at least from the wind fields. The change will be more 
gradual from a moisture and temperature standpoint. 


Enough moisture lingers Sunday to warrant chance probability of precipitation with an east 
to northeasterly flow and speed convergence the main forcing 
mechanisms. The GFS appears a little to aggressive with the probability of precipitation or 
quantitative precipitation forecast fields probably the result of a vorticity maximum that is present over 
The Sand Hills from early Saturday through Sunday. 


Monday is a repeat of Sunday although the probability of precipitation will be more 
suppressed to the south as very dry middle level air slowly creeps into 
the North Carolina counties during the day. 


High temperatures along the coast will remain very close to adjacent 
water temperatures while inland values will have the opportunity to 
modify a bit. Still like the cooler met numbers throughout. 


&& 


Long term /Tuesday through Friday/... 
as of 3 am Saturday...latest gridded MOS guidance has trended a bit 
cooler and drier so nudged temperatures down across the board 
slightly...otherwise no changes to the extended forecast this 
morning. The latter part of the extended depends heavily on the 
evolution of Hanna. The latest operational GFS has shifted 
dramatically with the northern turn now occurring on the east side 
of the Florida Peninsula bringing it up the coast. I suspect we will 
see this bounce back and forth for the next several days. 


&& 


Aviation /12z Saturday through Thursday/... 
LIFR to IFR visibility and ceiling restrictions due to fog will 
continue at the inland terminals until 1330z. Along the coast brief 
MVFR is possible for the next hour or so before the fog lifts. Look 
for stations to rise to VFR from 13-14z...with cumulus building along the 
sea breeze boundary. Should be enough moisture and instability to 
kick off isolated/scattered convection along the resultant. Light 
winds through the early morning hours...becoming mainly southeast by 
midday Saturday. 


Light winds and leftover moisture will again provide ideal 
conditions for fog tonight. LIFR restrictions likely at the inland 
terminals after 09z with MVFR along the coast. 


Outlook through Thursday...isolated/scattered thunderstorms 
through Sunday...mainly afternoon and early evening hours. High 
pressure builds in Monday through Thursday. 


&& 


Marine... 
near term /through tonight/... 
as of 3 am Saturday...a weak pressure gradient will prevail across 
the coastal waters today leading to light flow. Seas will be no more 
than 2-3 feet...primarily comprised of an easterly swell. The latest 
wavewatch iii output indicates swells from Hanna showing up in 
earnest during the short term period. Otherwise...speeds around 10 
knots...enhanced slightly by the sea breeze circulation during the day. 


Short term /Sunday through Monday night/... 
as of 3 am Saturday...reflecting the public section...the deep east 
to northeasterly flow will be the main focus for the coastal waters 
with the swell generated from Hannah the wild-card. Strong high 
pressure building in will generate winds from the NE of 15-20 knots 
with the ranges possibly increasing to 20-25 knots late Monday. 


The eventual strength of Hanna will modulate the long period swell 
affecting the waters. The GFS appears to have a decent handle on 
initializing the cyclone and therefor cant argue with the magnitude 
and timing of the wavewatch guidance. This brings in the significant 
swell late Sunday and increasing it throughout Monday. 


Long term /Tuesday through Wednesday/... 
as of 3 am Saturday...no changes to the extended coastal waters 
forecast this morning. The NE flow is expected to continue along 
with the swells from Hanna. 


&& 


Rip currents...latest wavewatch output from the nah version shows 
swells from Hanna arriving Sunday night...and building through 
Monday. Given the tail end of a Holiday weekend with many people 
expected to be at the beaches Monday this could be a potentially 
hazardous event setting up along the coast. Further compounding 
the problem is that there will likely be some tidal modulations in 
rip current intensity given the tidal cycle will be near the end 
of the new moon. Ultimately the degree of the rip current threat 
will depend on how strong Hanna and subsequently how large the 
swells will be that affect the coast. Plan to highlight this 
threat in the hazardous weather outlook for the upcoming week. 




&& 


Ilm watches/warnings/advisories... 
SC...none. 
NC...none. 
Marine...none. 


&& 


$$ 
Synopsis...srp 
near term...srp 
short term...shk 
long term...shk 
aviation...srp/heden 
rip currents...srp