Weather

968 
fxus62 kilm 292311 
afdilm 


Area forecast discussion 
National Weather Service Wilmington NC 
710 PM EDT Friday Aug 29 2008 


Synopsis... 
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 /until 6 am Saturday morning/... 
as of 3 PM Friday...thunderstorms have kicked off along the sea 
breeze front over Georgetown County and are gradually spreading 
northeast...just inland from the coast. Convection slow to start 
over the remainder of the County Warning Area amend was probably suppressed by 
extensive cloud cover earlier. However still expect scattered 
convection will affect the coastal counties and a bit further 
inland...so have chance probability of precipitation in for those areas. Slight chance for 
the remainder of the County Warning Area. Convection will fade with loss of heating 
this evening and it should be dry overnight. Mins temperatures have been 
consistently above guidance so have added a few degrees to consensus 
MOS numbers. This will give US min temperatures in the middle 70s about 
everywhere. 


&& 


Short term /6 am Saturday morning through Sunday night/... 
as of 3pm Friday... 
main weather factors for Saturday seem to be three main factors. Onshore 
flow...a very slow moving upper low over SC...and a weak Piedmont 
trough. So far today the latter two have failed to produce much 
convection and looks like tomorrow may be similar. Small coverage 
along the seabreeze seems likely just as today. Temperatures pretty close 
to climatology. Cold front drops into the area late Sat night...making 
keeping a dry forecast overnight tough. Show Low chance dropping to shc 
over northern zones. Little more uncertainty come Sunday...mainly as to 
how quick drying is behind the boundary. GFS is quite a bit slower 
than WRF and actually depicts a better chance of rain as compared to 
Sat. For now this seems plausible. Temperatures a bit lower sun more a 
function of cloud cover as opposed to temperature advection. 


&& 


Long term /Monday through Friday/... 
as of 3 PM Friday...much of the period will be dominated by high 
pressure at the surface and ridging aloft. Hanna will play some role in 
the forecast...but still a lot of questions as to how the storm will 
affect the region. Tight surface gradient will result in strong gusty NE 
winds but with mostly clear skies and drier conditions as subsidence 
aloft keeps atmosphere capped. Temperatures near to slightly above climatology 
during the period. Only real threat of widespread precipitation may be at 
the end of the period...dependant on the track Hanna takes and where 
the associated moisture GOES. 






&& 


Aviation /00z Saturday through Wednesday/... 
fairly typical late Summer pattern. Another round of fog is in 
store...with coastal terminals likely seeing thicker fog due to 
higher dewpoints at the onset. Winds at the boundary layer will be 
light...so no hinder to fog formation. 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. Not enough 
coverage and some uncertainty will keep thunder out of the tafs at 
this time. Light winds overnight...becoming mainly southeast by 
midday Saturday. 


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


&& 


Marine... 
near term /through tonight/... 
as of 3 PM Friday...weak pressure gradient will keep winds light and 
southerly...around 10 knots or less...for the remainder of this 
afternoon and overnight. Seas will maintain at right around 2 feet 
mainly due to a persistent 2 feet east-southeast swell with a period of around 
11 seconds. 


As of 3pm Friday... 
light onshore winds on Saturday with seas 2 to 3 feet...overall a 
pretty nice day. Cold front moving into the northern zones early 
Sunday with a switch to northeast but no real increase in speeds. 
Northeast winds continue on Sunday with perhaps a category's Worth 
of speed increase and some increasing gustiness. Swells from Hanna 
also arrive on Sunday...not only increasing wave period but also 
adding to their heights. 


Long term /Monday through Wednesday/... 
as of 3 PM Friday...headlines may be needed during much if not all 
of the period as tight pressure gradient between high building S and 
Hanna in the vicinity of the Bahamas. Location of each feature 
remains in question...but gradient over the waters will be pinched. 
Based on latest guidance speeds will exceed 20 knots but may have 
trouble reaching 25 knots. However...extended period of strong NE flow 
will push seas over 6 feet away from the coast. 




&& 


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




&& 


$$