979 
fxus62 kilm 210819 
afdilm 


Area forecast discussion 
National Weather Service Wilmington NC 
319 am EST Sat Nov 21 2009 


Synopsis... 
Gulf of Mexico moisture will overrun a wedge of high pressure through 
Sunday. A brief warmup is expected Tuesday and Wednesday. A strong 
cold front Thursday will usher in some colder air for next weekend. 


&& 


Near term /through tonight/... 
as of 3 am Saturday...weak wave of low pressure will move NE this 
morning along a stalled front located across the offshore waters. 
This will keep thickest cloud cover along the coast. A broad area of 
high pressure centered across the Ohio Valley will move to New 
England and Quebec province. This area of high pressure will begin 
to wedge across the Carolinas this period. This will set the stage 
for increasing isentropic upglide...mainly late in the period. 
At this time...it looks like although clouds will be plentiful this 
period...and thickest along the coast...rainfall will be slow to 
develop given the dryness if the column below 4 kft. However...we do 
expect light rain to begin to move in from the SW/develop across the 
area by daybreak on sun as column saturates from the top down. 


Weak wave of low pressure offshore will aid in reinforcing cool NE 
flow across the area. Couple this with clouds and we expect maximums 
this period will be held to the cooler side of model consensus. 
Coolest temperatures should be across the Cape Fear region...but still all 
areas should be at or just a degree or two below normal. Tonight... 
as wedge intensifies across the area...and with cool NE flow 
continuing...temperatures should again be down in the middle 40s to near 50 
degrees. 




&& 


Short term/Sunday through Monday night/... 
as of 3 am Saturday... 
moisture overrunning northeasterly surface flow associated with 
wedge of high pressure will bring plenty of cloudiness to start the 
period. Increasing isentropic upglide will also ramp up rain 
chances...ending up in the categorical range by evening. Quantitative precipitation forecast 
forecast is still a little uncertain as guidance has really backed 
off with rainfall when compared to previous days. Rain chances 
remain fairly high Sunday night as the weakening low jumps to the 
eastern side of The Wedge and ends up offshore. Soon thereafter rain 
chances should taper off from west to east early Monday. Clouds and 
possibly drizzle could linger into the morning hours. Might even see 
a trend towards overall slower progression which could mean drizzle 
and clouds linger most of the day. Have undercut guidance on Monday 
high temperatures. 


&& 


Long term/Tuesday through Friday/... 
as of 3 PM Saturday... 
a weak upper ridge manages to build on Tuesday and this should bring 
a mild afternoon. Wednesday may also bring highs in the low 70s 
ahead of what will end up being a pretty strong cold front on 
Thursday. Little to moisture flow ahead of the front so its passage 
should be dry. The ecwmf has indicated otherwise for a few runs now 
but this model has been displaying a very wet bias for some time 
locally in such setups. Dry and cool weather for the rest of the period 
with highs struggling to low 60s by day and upper 30s at night. 


&& 


Aviation /06z Saturday through Wednesday/... 
MVFR stratocumulus ceilings will continue to affect the coastal 
taf sites overnight. Further inland...stratocumulus deck should be 
more scattered below a cirrostratus ceiling. May be some MVFR br at 
klbt and kflo...but dewpoint depressions are still pretty high so 
any br should be patchy in nature. NAM model has a coastal surface 
trough that could produce precipitation along the immediate coast 
around 12z...however the feature is so small...will not include it 
the ilm taf. Continued northeast flow Saturday with thickening middle 
and high clouds in advance of the next system. Precipitation will 
approach the region at the end of the forecast period. 


Extended outlook...showers and low ceilings move back in Saturday 
night through Monday. 


&& 


Marine... 
near term /through tonight/... 
as of 3 am Saturday...will hoist a Small Craft Advisory for all 
zones except amz254 where a small craft should exercise caution 
headline will remain in place. Pinched gradient has developed across 
the waters early this morning...the result of pressure differences 
between weak low pressure moving NE along a stalled front offshore 
of the Carolinas and high pressure centered across the Ohio Valley. 
This pinched gradient should relax later in the day as weak wave of 
low pressure moves further away. Gradient will tighten up again this 
evening and especially overnight as wedge of high pressure intensifies 
across the area while low pressure reaches the northeastern Gulf 
Coast. Persistent NE winds will reach marginal Small Craft Advisory 
levels across the majority of the area. Seas will not change much 
through the period...and will be as high as 5 to 7 feet across the 
outer waters. Near shore seas will be lower in areas where fetch is 
greatly reduced in NE flow. 


Short term/Sunday through Monday night/... 
as of 3 am Saturday... 
surface high pressure wedge in control on Sunday to bring a moderate 
gradient wind. Small Craft Advisory from near term has been extended 
through Sunday for northern two zones as 6 feet seas affect the outer 
reaches along Frying Pan Shoals. Wave shadowing will probably 
preclude this over southern waters. A flat wave of low pressure will 
ride up the east side of The Wedge Sunday night into Monday. This 
will slightly taper the gradient and could lower the seas enough to 
drop any advisories. Wedge weakens but remains in place for the 
remainder of Monday and Monday night keeping winds with a northerly 
component. 


&& 


Long term/Tuesday through Wednesday/... 
as of 3 PM Saturday... 
looks like a fairly quiet pattern for most of the period. High 
pressure remains to the north Tuesday bringing a light northerly 
wind and seas in the 2 to 3 feet range. Changes may be underway come 
Wednesday as the high begins to lift out ahead of an approaching 
cold front. The timing of this front and the evolution of surface 
features associated with it is highly uncertain. 


&& 


Ilm watches/warnings/advisories... 
SC...none. 
NC...none. 
Marine...Small Craft Advisory until 7 am EST Sunday for amz256. 


Small Craft Advisory until 7 PM EST Sunday for amz250-252. 


&& 


$$ 
Synopsis...mbb 
near term...rjd 
short term...mbb 
long term...mbb 
aviation...rjd/dl 

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