Weather

247 
fxus62 kilm 071723 
afdilm 


Area forecast discussion 
National Weather Service Wilmington NC 
123 PM EDT sun Sep 7 2008 


Synopsis... 
high pressure will gradually build into the area through Monday. A 
cold front will move into the area by Wednesday...and linger just 
to our south through the end of the week. 


&& 


Near term /through tonight/... 
as of 9 am Sunday...a very weak surface pressure pattern remains 
over the area this morning. Fog has all but dissipated and have 
removed any mention at least for this morning from the forecast. Any 
forcing for convection remains subtle at best for the afternoon 
hours and the trend for thermodynamic profiles is drier as water 
vapor imagery shows large swath of dry air making inroads to the 
western areas. There still remains enough moisture in the column to 
warrant isolated coverage and following the nam12 and the GFS to an 
extent...placed the probability of precipitation inland starting in the western parts of 
Columbus...Horry...Williamsburg and Pender counties. New Hanover and 
Brunswick counties should remain dry for the most part. Temperatures 
appear to be on track. 


&& 


Short term /Monday through Tuesday night/... 
as of 3 am Sunday...western Atlantic 500 mb ridge will be quite 
pronounced on Monday...as a surface high migrates quickly off the middle- 
Atlantic coast. This ridging will break down as we head into 
Tuesday...but a general easterly flow will persist as the 
peripheral circulation around Ike starts to become a player. 


Moisture profile is not that impressive for Monday...and with that 
and the strength of the upper ridge...will not go for any more 
than a slight chance of afternoon convection...mainly along the 
seabreeze. Better shot at precipitation on Tuesday with the breakdown in 
the upper ridge and precipitable water values recover to nearly 2 
inches. 


Temperatures above normal through the period...but Worth noting that GFS MOS 
once again advertises maximum temperatures several degrees warmer than the 
Eta model MOS. Have leaned toward the cooler Eta model MOS values for 
Monday...and basically split the difference for Tuesday. 


&& 


Long term /Wednesday through Saturday/... 
as of 3 am Sunday...looks like a rather unsettled pattern for most 
of the latter half of the week. Cold front will drop into the 
Carolinas on Wednesday but the upper pattern remains too flat to push it 
much farther south. Expect the front to stall just south of the 
ilm County Warning Area and linger there Thursday-Friday before returning north as a warm 
front on Saturday. GFS extended MOS is quite bullish on probability of precipitation and I 
will carry a solid chance Wednesday into Thursday. Not much confidence for 
Friday into Saturday but will carry a 30 pop for now given deep 
onshore flow continuing and the difficulty in timing any 
disturbance that may act as upper support with a boundary still in 
the area. 


Juicy airmass will limit diurnal temperature ranges...with readings near 
normal by day and above normal by night. 


&& 


Aviation /18z Sunday through Thursday/... 
the main concern for the aviation community will be the development 
of fog Monday morning. A weak pressure pattern with plenty of low 
level moisture and dry air aloft is a recipe for a significant 
event. Will use prevailing MVFR from about 0600 UTC with tempo IFR 
groups in ilm...lbt...and flow. Did not see development in The 
Myrtles this morning...probably due to the boundary winds being a 
little higher. Guidance is giving a strong signal there however and 
will hedge my bets with tempo MVFR groups to address the 
uncertainty. Any convection this afternoon will be too isolated to 
address in the forecast. 




Outlook through Thursday...chance IFR visibilities Monday and 
Tuesday mornings. Isolated thunderstorms Monday and Tuesday. 
Scattered thunderstorms Wednesday and Thursday. 


&& 


Marine... 
near term /through tonight/... 
as of 9 am Sunday...buoy observations show long period swell still 
prevalent over the waters with 4.6 feet at nine seconds at 41013. 
Little contribution from wind waves in the spectrum as winds are a 
paltry 5.8 knots. This trend will continue through the day and no 
changes are needed with the middle morning update. 


Short term /Sunday through Monday night/... 
as of 3 am Sunday...surface high pressure moving off the coast to our 
north will result in an easterly flow through the period. 
However...winds will remain relatively light with speeds holding 
at or below 10 knots. Bigger question mark is seas...which will be 
dictated by how much of a southeast swell can get in here from distant 
Hurricane Ike. Have gone between the wna and nah runs of the ww3 
model. Therefore will keep 3-4 feet in the coastal waters...while 
allowing for a few 5 footers out near The Frying Pan buoy and 
other points beyond 20nm. 


Long term /Wednesday through Thursday/... 
as of 3 am Sunday...expect benign conditions with a general 
easterly flow continuing. Lack of cold air behind the front means 
speeds will remain around 10 knots through most of the period...with the 
seas continuing a subsiding trend as Ike moves into the Gulf and 
stops generating swell on the Atlantic side. 


&& 


Rip currents... 
some leftover swell from Hanna along with an increasingly long 
period swell from Hurricane Ike will produce a high risk for rip 
currents on Sunday. The hurricane version of wavewatch shows two 
distinct swells from Hanna...both over 11 seconds for the period. 
While the threat for rip currents is high at all area beaches...the 
highest risk will be for the beaches of Pender and New Hanover 
counties in NC...and the beaches of Georgetown and southern Horry 
counties in SC due to the swell direction from the southeast. 


Swells from Ike will keep an increased threat for rip currents 
through early next week. 


&& 


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


&& 


$$ 


Synopsis...shk 
near term...shk 
short term...Ras 
long term...Ras 
aviation...shk 
rip currents...heden