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Area forecast discussion 
National Weather Service Wilmington NC 
708 am 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 3 am Monday...a weak area of low pressure is elongated along 
the southeast coast early this morning. This area of low pressure is 
expected to consolidate as it slowly moves NE and should be in the 
process of lifting north of Cape Fear during the late afternoon and evening. 
At the same time...a strong area of high pressure is positioned 
across New England this morning and will reassert itself across the 
eastern Carolinas today and tonight. For the inland areas...any 
light rain will taper to a drizzle as subsidence inversion lowers 
and sharpens from 3 kft this morning to below 2 kft tonight. Above 
this...it will be dry as a Bone...but as you near the surface...low 
level moisture will be stubbornly trapped. The moisture will be too 
shallow to support rain...but we do expect areas of drizzle and fog 
to accompany the low stratus. Skies will be cloudy right through the 
period with little diurnal range. Maximums will be almost 10 degrees 
below normal as NE winds drain chilly air southward. Thick low 
hanging clouds and fog will aid in keeping temperatures above normal 
overnight. Most areas will be in the middle and upper 40s. 


For the coast...the forecast is complicated by the proximity of low 
pressure off the coast. This does complicate the forecast and there 
is more uncertainty for the daytime period. At this time...we will 
forecast low pressure to remain far enough offshore thus keeping 
significant rainfall and milder air over the waters. There is a 
very small chance that coastal North Carolina could see higher temperatures 
than we are forecasting should low pressure sneak up the coast in 
closer to proximity to what we are expecting. Keeping to our 
scenario...we are calling for clouds to hang in through the day as 
subsidence inversion lowers and sharpens. Left over patchy rain will 
transition to more of a drizzle and this drizzle will be more 
prevalent tonight as shallow moisture is squeezed out. Areas of fog 
will also develop. Temperatures while slightly higher on the coast as 
compared to inland will still be below normal by several degrees. 
Clouds and fog will keep temperatures from chilling down as low as they 
would otherwise given the chilly airmass that is advecting into the 
area. Minimums will be mainly in the upper 40s at the coast. 


&& 


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 /12z Monday through Friday/... 
high pressure...which is exiting New England...is ridging through 
the Atlantic coastal states. Low pressure has moved offshore of the 
Carolinas and will slide up the coast today. 


IFR will be the rule today 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 00z 
time frame...then start dropping to MVFR then to IFR by 02z. Wind to 
be northerly 6 to 14 knots today. 


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


&& 


Marine... 
near term /through tonight/... 
as of 3 am Monday...a Small Craft Advisory will expire from S to north 
middle morning through early afternoon. An elongated area of low 
pressure along the southeast coast is expected to consolidate and 
move slowly up the coast today. Weak low pressure should be in the 
process of lifting north of Cape Fear late day and this evening. Winds will 
be primarily NE this morning and may become light and variable for a 
time as low pressure migrates NE in close proximity. Winds will 
settle on northwest on the backside of weak low pressure as it moves slowly 
up the coast. The strongest winds will continue to diminish through 
sunrise. Seas will of course lag...but the trend is for seas to 
significantly subside through the period. 


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 9 am EST this morning for amz254- 
256. 


Small Craft Advisory until 1 PM EST this afternoon for amz250- 
252. 


&& 


$$ 
Synopsis...tra 
near term...iii 
short term...tra 
long term...rgz 
aviation...mdc 

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