032 
fxus62 kilm 231731 
afdilm 


Area forecast discussion 
National Weather Service Wilmington NC 
1231 PM EST Monday Nov 23 2009 


Synopsis... 
low pressure will move slowly northeast along the Carolina coast 
today. Although the widespread rain will end early...areas of 
drizzle and fog will develop and persist into Tuesday. Wednesday and 
Thursday will feature a brief warm-up...but a cold front late 
Thursday will bring much colder conditions and the possibility of 
frost or a freeze for the weekend. 


&& 


Near term /through tonight/... 
as of 10 am Monday...forecast is behaving across most of the 
forecast area. Only issues are along the NC coast...which was 
expected to be a problem. Some clearing has developed over the 
coastal counties and has allowed temperatures to jump a few degrees. 
Tweaked highs up a couple degrees for the NC coast but with more 
clearing temperatures could top out around 70. Elongated surface low off 
the South Carolina coast is slowly working its way northeast and 
will keep surface winds out of the northeast. 


Radar echos have taken on look more characteristic of convective 
showers as opposed to stratiform rain. Forecast soundings suggest 
there may be a layer of weak instability from 925 to 700 mb which 
is allowing some elevated convection to develop. Above this there 
is a strong subsidence inversion...so cannot see any thunder from 
these but could see little pockets of enhanced precipitation for a few 
minutes. Forecast soundings also show the subsidence inversion 
becoming stronger during the afternoon hours which should shut off 
any elevated convection by the afternoon hours. Most of the 
stratiform precipitation has ended and is shifting to pockets of light 
drizzle. Saturated layer is pretty shallow...which should keep 
drizzle confined to small patches. 


&& 


Short term /Tuesday through Tuesday night/... 
as of 3 am Monday...large difference in high temperature guidance 
continues to be seen for Tuesday. Cool air wedge prognosticated to keep 
clouds in the forecast and even some morning fog and/or drizzle. The 
layer of moisture associated with The Wedge is very thin with very 
dry air above. The difference in temperature guidance is associated with whether 
or not that shallow layer of moisture can mix out. If so...then the 
afternoon could turn out nice with sunshine and highs in the middle 
60s. If not...as currently forecasted...then temperatures will stay mired 
in the 50s. Prefrontal middle level moisture looks a little faster than 
previous forecasted for Wednesday...possibly not allowing any break from 
tuesdays middle level cloudiness and keeping Wednesday cooler than climatology 
again. Weak low induced off the coast on the old frontal boundary to 
bring some slight chances for measurable rainfall as well that will 
persist into Wednesday night. 


&& 


Long term /Wednesday through Sunday/... 
as of 3 am Monday...guidance getting a little more aggressive with 
the cold temperatures to follow thursdays cold front. Frontal passage itself will 
bring only low end chance probability of precipitation as moisture will be limited despite 
some pretty strong dynamics. Friday highs should struggle to reach 
60 and low to middle 30s across the board Friday night. Moderation 
will be minimal for the remainder of the weekend so highs and lows 
will both be a few degrees below climatology. 


&& 


Aviation /18z Monday through Saturday/... 
low pressure off the southeast North Carolina coast will slide up 
the coast today and provide an abundance of wrap around moisture to 
sustain IFR ceilings for the taf sites. 


Only ilm will maintain MVFR with ceilings for the next few 
hours...otherwise IFR/LIFR will be the rule today and tonight 
throughout the terminals. Low ceilings from the persistent onshore 
flow will extend from the coast to the inland stations. Visibilities 
will hold at VFR to MVFR until 05z time frame...then start dropping 
to MVFR then to IFR by 07z. Wind to be northerly 6 to 14 knots today 
and diminish to 3 to 8 knots this evening. 


Extended outlook...IFR ceilings continue through Tuesday. IFR 
visibilities in fog possible each morning. 


&& 


Marine... 
near term /through tonight/... 
as of 10 am Monday...ended Small Craft Advisory for SC waters but raised an scec 
with seas continuing a slow decrease through the morning hours. 
Northeast flow will continue as elongated surface low passes just 
east of the waters. Approach of low will be close enough that 
winds may become light and highly variable later 
today...especially across NC waters. Overall did not make much 
change to previous forecast. 


Short term /Tuesday through Wednesday night/... 
as of 3 am Monday...weak cool wedge of high pressure up and down the 
East Coast will persist through the short term period. Look for a 
north to northeast wind generally capped at 10 kts as a result. A 
slight pinch in the gradient on Wednesday as weak low pressure develops to 
the east of the forecast waters. 2 to 3 feet seas will be lowest near 
shore and highest offshore...with the greatest range off the 
Brunswick coast where the flow will be most coast-perpendicular. 


Long term /Thursday through Friday/... 
as of 3 am Monday...pretty strong cold front slated for Thursday 
winds ahead of its passage pretty light and hard to pin down on 
account of presence of a surface trough. By later in the day though 
northwest winds start cranking up. Small Craft Advisory appears likely by 
Friday if not sooner on account of winds. The northwest fetch may keep seas 
from building into advisory realm. 


&& 


Ilm watches/warnings/advisories... 
SC...none. 
NC...none. 
Marine...Small Craft Advisory until 1 PM EST this afternoon for amz250- 
252. 


&& 


$$ 
Near term...iii 
short term...mbb 
long term...mbb 
aviation...mdc