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fxus62 kilm 071722 
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Area forecast discussion 
National Weather Service Wilmington NC 
1220 PM EST Wednesday Jan 7 2009 


Synopsis... 
a strong cold front will move offshore through early afternoon. 
Behind the front...strong winds will continue through Thursday. High 
pressure will build into the area Thursday night through early 
Saturday. Another cold front will move southeast across the 
Carolinas Saturday night...but is not expected to produce any 
significant precipitation. Chilly high pressure will follow Sunday 
and persist into early next week. 


&& 


Near term /through tonight/... 
as of 10 am Wednesday...a strong cold front is currently moving 
across the forecast area and as of late morning was roughly along a 
line from cre to Riegelwood to Watha. This front will sweep off the 
coast through early this afternoon. Instability maximizes just ahead 
of the front and some of the showers could produce small hail and a 
rumble of thunder across coastal NC through early afternoon. Biggest 
concern is the strong synoptic winds. Winds from the SW are expected 
to shift to the west during the afternoon. At the top of the mixed 
layer...winds of up to 65 knots were noted on morning soundings. These 
winds will continue to be tapped and so the National Weather Service 
will leave the Wind Advisory in effect. The strongest winds this 
morning will wane and then as dry and cold advection increase 
through the afternoon and lapse rates steepen...winds are expected 
to again increase and persist into this evening. Will include mention of 
wind gusts to 45 and 50 miles per hour. 


Showers are expected to end across west portions of forecast area by 
midday and across coastal areas by middle/late afternoon. 


High temperatures will be reached across the area this morning/early 
afternoon. Temperatures will stabilize and then drop through the 60s middle to 
late afternoon...and into the 50s across far inland areas. 


Winds will begin to drop to more manageable levels by midnight as 
temperatures slide into the upper 30s inland to lower 40s at the coast. 


&& 


Short term /Thursday through Friday/... 
as of 3 am Wednesday...Thursday will be dominated by a deep East 
Coast upper trough and strong cold air advection behind an intense surface low lifting 
through the Canadian Maritimes. Here in the eastern Carolinas we can 
expect a dry but breezy day. Well-mixed boundary layer to start 
the day suggests that diurnal temperature recovery will be limited...and 
low-level thickness forecasts and 850mb temperatures only support highs in 
the middle 50s. Therefore have gone well under guidance maximum temperatures. 
Sustained winds will average 15-20mph...with some gusts touching 
30mph especially in the late morning/early afternoon. 


Upper trough moves offshore Thursday evening...and with high pressure 
building from the deep south we should see clear skies and winds 
going nearly calm. Favorable radiational cooling conditions will 
allow most locations to drop to freezing or below. 


Friday actually looks like the coolest day with the surface high 
settling over the Carolinas. Thermal trough at 850mb exits to the 
east but mixing will be too shallow to realize that. Have gone in 
line with MOS consensus of Lower/Middle 50s. 


&& 


Long term /Friday night through Tuesday/... 
as of 3 am Wednesday...main player over the weekend is a moisture- 
starved cold front with a few questions about timing. GFS is 
6-12 hours faster than the European model (ecmwf)...which HPC favors and is the 
preferred solution here. Based on that timing the best shot for 
precipitation is Sat night...but even then the lack of moisture limits US 
to a slight chance pop which is not mention-worthy this far out. 


Broad upper trough and cool and dry high pressure will hold sway 
Sunday through Tuesday...bringing temperatures at least slightly below 
climatology both day and night. GFS and European model (ecmwf) both suggest that we could 
tap into some Arctic air heading into mid-week...but that still 
appears to be beyond day 7. 


&& 


Aviation /18z Wednesday through Sunday/... 
a cold front cleared all of the terminals earlier this morning. A 
strong pressure gradient will produce strong wind gusts to 35 knots 
this afternoon from the southwest to west southwest. Patchy light 
rain will continue to decrease in coverage through the afternoon. 
Ceilings and visibilities will remain VFR through Thursday 18z. 


Extended...a strong pressure gradient will continue to produce windy 
conditions before high pressure builds in from the west late Friday. 
VFR expected through Sunday. 


&& 


Marine... 
near term /through tonight/... 
as of 10 am Wednesday...a strong cold front will move across the 
coastal waters early to middle afternoon. Environment will be well 
mixed and we will continue to forecast gale conditions north of 
Little River Inlet and strong Small Craft Advisory conditions across 
the remainder of the area as we tap winds near 65 knots at the top of 
the mixed layer. Very stable thermal conditions brought about by the 
cool shelf waters will insulate the ocean surface from the full 
force of these winds. Seas have already reached up to 7 to 10 feet and 
these wave heights will persist into this evening. SW winds will veer to 
west late day and this evening and this will quickly lay down seas near 
shore. 


Cold advection behind the front tonight will lead to a second period 
of strong gusty winds during the evening hours. Gale-force winds are 
expected over the NC coastal waters...but conditions should begin to 
improve after midnight. 


Short term /Thursday through Friday/... 
as of 3 am Wednesday...solid Small Craft Advisory winds are expected to persist 
through the day on Thursday...as low-level winds remain quite 
frisky through a deeply mixed boundary layer. Wind direction 
almost due west...which is not a pure offshore trajectory and even 
20 nm offshore...seas will vary widely due to the shape of the 
coastline. Look for seas up to 6 or 7 feet continuing in the 
vicinity of Frying Pan Shoals...while the more blocked SC waters 
will see no more than 5 feet. Have made no changes to going 
headlines...which carry the Small Craft Advisory through the end of Thursday afternoon for 
the SC waters. At this time will not try to step down from the 
Gale Warning that is flying for the NC waters. 


Winds will shift northwest and diminish Thursday night once the upper trough 
axis moves offshore and surface high pressure builds from the deep 
south. Seas will subside accordingly. Could see light and 
variable winds on Friday with the high overhead. 


Long term /Friday night through Sunday/... 
as of 3 am Wednesday...return flow develops late Friday night into 
Saturday ahead of the next cold front. Modest low-level jetting 
advertised by the GFS...but in warm air advection it will not be enough to breach 
advisory thresholds. Seas build to around 4 feet ahead of the 
front. Still not very confident in the frontal timing and have 
leaned toward the slower HPC/European model (ecmwf) solution which calls for frontal passage 
Sat night...and not much of a cold air advection surge behind the front. Even if 
the GFS is right any Post-frontal surge will be short-lived. 


&& 


Ilm watches/warnings/advisories... 
SC...Wind Advisory from 9 am this morning to midnight EST tonight 
for scz017-023-024-032>034-039-046. 


NC...Wind Advisory from 9 am this morning to midnight EST tonight 
for ncz087-096-097-099>101. 


Marine...Small Craft Advisory until 6 PM EST Thursday for amz254-256. 


Gale Warning until 2 am EST Thursday for amz250-252. 


&& 


$$ 


Near term...rjd 
short term...Ras 
long term...Ras 
aviation...mrr 

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