594 
fxus62 kmhx 210030 
afdmhx 


Area forecast discussion 
National Weather Service Newport/Morehead City NC 
830 PM EDT Sat Mar 20 2010 


Synopsis... 
high pressure will continue to drift offshore tonight and Sunday. 
A wet cold front will approach eastern North Carolina late Sunday 
night and cross the region on Monday. An upper low low pressure 
area and secondary surface cold front will move across the area 
Tuesday. High pressure will build back into the area middle week. 


&& 


Near term /until 6 am Sunday morning/... 
as of 655 PM Saturday...although the surface high has drifted off 
the coast initiating light southerly flow late today...winds 
will be able to decouple after sunset in the still weak 
pressure gradient over the area. With clear skies expected to 
continue...radiational cooling again will be maximized tonight. 
Current forecast lows look to be too cold taking into account 
expected dewpoint recovery into the 40s due to the southerly 
boundary layer flow. Therefore I will need to raise minimum 
temperatures by 2-5 degrees in most locations. These adjusted 
minimum forecasts will still be at or below the coldest MOS 
temperatures over eastern NC...with values mainly in the middle 
40s. With a second full day of sunshine the atmosphere remains 
well mixed and dry so the prospects of widespread dense fog appear 
to be small with the main threat patchy shallow ground fog. 


&& 


Short term /6 am Sunday morning through Tuesday night/... 
as of 230 PM...ridge will slide offshore tonight and sun...so 
looking for temperatures to be a few degree cooler tomorrow. Near the 
beaches the onshore flow will pick up...and with water temperatures in 
the 50s will see temperatures along beaches/obx even cooler around the 
lower to middle 60s. Clouds will develop as Gulf moisture begins to 
stream in from the west. By sun nt there could be enough saturation 
for some light rain showers...which will transition into moderate 
to heavy showers by Monday morning. 


A deep S stream low pressure system responsible for snow over Texas/OK 
today will will move into the Gulf states region sun...with the 
surface low moving NE into the Ohio Valley by sun nt. The increase S low 
level jet and added Gulf moisture will increase precipitation water values 
to 1... the potential for moderate to heavy rainfall. 
The instability Monday looks weak despite marginal shear and 
dynamics...so confidence of widespread thunderstorms and rain low. Have schc to chance 
thunderstorms and rain with likely rain showers. Storm Prediction Center has the areas to our SW with potential 
for strong storms...but for now no mention of east NC. The best upper 
level divergence occurs as the precipitation is move east of Highway 17 Monday 
afternoon...so could see convection last into early evening hours. 
A dry slot will likely slide in behind the initial batch of 
showers Monday/Monday evening...but the presence of the upper level low 
will keep at least a minimal chance of showers through Tuesday. Drier 
air and cooler temperatures Tuesday will likely keep coverage 20% or less. 


&& 


Long term /Wednesday through Saturday/... 
as of 1120 am Saturday...high pressure builds in from the west 
for Wednesday and Thursday with mild and dry conditions. Middle-level trough 
moves east from the middle Mississippi Valley Friday into Saturday 
with surface reflection moving along the NC/Virginia border per the GFS 
with the European model (ecmwf) moving the surface low closer to the coast. Regardless 
of model solution...expect increasing rain chances Friday into 
Saturday with gusty north winds on the backside of the low on 
Saturday. Temperatures remain near normal into next weekend. 


&& 


Aviation /00z Sunday through Thursday/... 
as of 820 PM Sat...clear skies and VFR conditions to prevail 
tonight. Given the very low dewpoints this afternoon...temperatures should 
not come close to crossover temperatures...so expect very little in the way 
of fog development. But couldn't rule out a few spots of patchy 
shallow ground fog around sunrise Sunday morning. High clouds will 
begin to increase early Sunday morning...and continuing to lower 
throughout the day. 


Outlook Sunday through Thursday... 
onshore flow will increase with lowering ceilings by late Sunday 
and especially Sunday night into Monday with increasing precipitation 
chances. Expect periods of MVFR/IFR ceilings through Monday. Some 
MVFR ceilings will also be possible Tuesday as upper low crosses 
the region. VFR returns Wednesday through Thursday. 


&& 


Marine... 
as of 820 PM Sat...forecast is in good shape with no significant 
changes needed. Light S/SW winds overnight...generally 10 knots or less 
and seas 2-3 feet. 


Benign marine conditions to continue through Sunday but will 
deteriorate Sunday night as gradient tightens as a result of strong 
low pressure moving through the Ohio Valley toward the northeast. 
Will initiate a Small Craft Advisory for the waters south of Oregon 
Inlet starting at around midnight Sunday night as southeast winds gust to 
near 25 knots and seas build to 6 feet or greater. Small craft 
advisories may be required for the remaining coastal waters by 
Monday. Gusty winds will continue on the backside of the departing 
low with another good surge of northwest winds anticipated on Monday night 
into Tuesday. Per latest wavewatch guidance...rough seas will 
persist on the coastal waters through Tuesday night. 


&& 


Mhx watches/warnings/advisories... 
NC...none. 
Marine...Small Craft Advisory from midnight Sunday night to 5 am EDT 
Wednesday for amz152-154-156-158. 


&& 


$$ 
Synopsis...jme/sj 
near term...jme 
short term...sj 
long term...sj 
aviation...ctc/cqd 
marine...ctc/cqd