695 
fxus62 kmhx 211921 
afdmhx 


Area forecast discussion 
National Weather Service Newport/Morehead City NC 
221 PM EST Sat Nov 21 2009 


Synopsis... 
high pressure will build in from the north today...then slide 
offshore tonight. Low pressure will develop just offshore late 
Sunday and Sunday night...then lift NE on Monday. High pressure 
will rebuild over the area Tuesday and Wednesday. A cold front 
will approach from the west on Thursday and move offshore 
Friday. 


&& 


Near term /until 6 PM this evening/... 
despite the cool NE flow regime...partial sunshine and weak 
thickness ridging aloft will allow temperatures to rise anthr 5-10 degrees 
this afternoon. NAM forecast sounding continue to show a nearly saturated layer 
near 5000 feet this afternoon so expect will see decent amount of strato- 
cumulus...will also have some high clouds today but expect enough peaks 
of sun to get highs in the 60 to 65 dgr range. 


&& 


Short term /6 PM this evening through Monday/... 
as of 2 am Sat...clouds will thicken tonight as begin to see low 
level moisture increase plus will have some middle/high clouds well 
ahead of approaching srt wave. Continue previous forecast of slight pop late 
tonight southern tier. Lows mainly upper 40s to lower 50s. Rain will be 
increasing from SW to NE Sunday as insent lift increases over the 
area as coastal front takes shape just offshore ahead of approaching 
srt wave. Continue likely probability of precipitation inland to chance NE CST later Sunday. Sun 
night looks wet as isent lift continues with increasing middle/upper 
support with srt wave passing by to the northwest. Have categorical probability of precipitation 
all areas Sun night. Rain will gradient diminish from SW to NE Monday 
however will still have good covering early and continue categorical NE 
CST to likely probability of precipitation elsewhere with probability of precipitation decreasing to chance late. 
Total quantitative precipitation forecast from this event looks to average out in 0.5 to 1 inch range and 
despite very wet ground many areas shld not cause significant 
problems. Highs both sun and Monday with clouds...precipitation and NE winds 
will be mainly in the upper 50s to lower 60s. 


&& 


Long term /Monday night through Friday/... 
as of 2 am Sat...any lingering light rain/drizzle will end Monday 
night. With high pressure building in Tuesday and Wednesday expect dry 
conditions. Impressive srt wave/cold front will approach Thursday and 
move offshore Friday. Models differ with GFS showing limited moisture 
and bulk of precipitation offshore. Emcwf is wetter...espcly CST with 
moisture coming in off Atlantic. Currently have chance probability of precipitation Thursday and will 
not change until get more clarity from models. Cooler and dry Friday in 
wake of front/srt wave. 


&& 


Aviation /19z Saturday through Thursday/... 
as of 2 PM Sat...GFS lamp and NAM guidance continues to slow down 
the progression of the moisture into the region...and general lack 
of support for much cloud development. Have gone a bit faster 
bringing in the middle deck overnight with clouds dropping into sun 
as the rain advances on the region. The rain will move in late sun 
into Monday...with low clouds experimental to linger potentially into Tuesday. 
High pressure will build over the region thereafter...with clearing 
and predominant VFR conditions. However higher dew point could lead to 
overnight fog or stratus development Tuesday nt and Wednesday nt. 




&& 


Marine... 
as of 2 PM Sat...the weak low offshore and high pressure to our north 
is producing winds 20-25kt winds mainly S of Oregon Inlet. Seas 
have bounced around 5 to 8 feet this after...with conditions experimental to 
change little this evening. Later tonight as the low moves east we will 
see an improvement in winds...though seas will remain up especially 
south. Meanwhile...satellite shows a clearly defined low over the 
Gulf states which will move east sun and over the Carolinas by Monday. 
The low is experimental to remain poorly organized as upper level support 
weakens. The track of this weak system will move near or over 
Hatteras...which will keep the lightest winds over this region. 
However the southeast winds ahead and behind the low could briefly gust 
to small craft. The north waters will likely remain around 20kt as the 
low passes to the S. The seas will remain above Small Craft Advisory through out Monday 
nt. 


By Monday the strong high over New England will slide east offshore. 
Meanwhile an area of low pressure near 50w will pinch the gradient and 
combined with some higher seas over the North Atlantic will produce 
some double digit seas. The east-northeast fetch around the high will steer a 
lot of this energy towards the East Coast...and though it will 
diminish greatly before it reaches the coast it could add some 
swell to the sea heights to the local waters early to middle week. 
The high pressure sliding over the region will aid in dropping wind 
speeds so combined seas could drop below 6ft during this 
time...however north waters could remain up through the rest of the 
forecast if wavewatch seas were accurate. Due to limited observations 
over that part of the Atlantic can't verify the initial conditions 
of wavewatch...so have shaved about a foot off the output by 
Tuesday/Wednesday until there is more support of this long period swell. A 
closed upper low digging out of the Great Lakes region could lead 
to cyclogenesis off the middle Atlantic coast by Thursday. Most models 
support a weak low passing obx and strengthening at is moves 
towards New England...with the Canadian being the strongest 
solutions of a coastal low skirting NC. With the upper support 
being much further north than our last coastal low...feel the weaker 
solutions here are more likely. However...the cold air advection on the backside 
of the low Thursday nt into Friday will increase to Small Craft Advisory in strong northwest 
winds. 




&& 


Mhx watches/warnings/advisories... 
NC...none. 
Marine...Small Craft Advisory until 9 PM EST this evening for amz135. 
Small Craft Advisory until 4 am EST Tuesday for amz150-152-154. 
Small Craft Advisory until 5 am EST Monday for amz156-158. 


&& 


$$ 
Synopsis...rf 
near term...btc/rf 
short term...rf 
long term...rf 
aviation...sj 
marine...sj 

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