Area Forecast Discussion
Issued by NWS Wilmington, NC-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS62 KILM 060932
Area Forecast Discussion
National Weather Service Wilmington NC
432 AM EST Tue Dec 6 2016
A strong storm system will bring periods of heavy rainfall
through today. Dry and seasonable weather will follow for mid-
week ahead of an arctic front which will cross offshore late
Thursday. Very cold temperatures will follow for Friday and
Saturday. A warming trend will begin Sunday.
.NEAR TERM /THROUGH TONIGHT/...
As of 330 AM Tuesday...Miller type B storm system to affect the
area today. At the sfc, currently a rather strong wedge has
developed across the Carolinas with the offshore frontal system
now slowly backing to the north. What once was a closed mid-
level low over TX last night, has opened up into a s/w mid-
level trof now over LA and MS early this morning. Modest Sfc low
is basically underneath this upper s/w trof. The dynamics aloft
will track to the NE today, staying west and north of the ILM
CWA this morning and afternoon. The sfc low underneath is
progged to weaken and fill in while off the southeast NC coast a
new low will develop early this afternoon on a frontal system
that has been back and forth across the coastal and adjacent
offshore waters the past couple days. Models bring this frontal
system to the coast and just like the previous scenario, the
front may temporarily push just inland from the coast by midday
thru this afternoon. This will play havoc with temperatures,
with 40s and 50s west and north of this front and 60s to around
70 south and east of the coastal front. In addition, the frontal
position will become the focus of isolated thunderstorms due to
enough instability either sfc based or elevated for convection
to key off of. West and north of this front, expect overrunning
ie. isentropic lift, light to moderate rains with embedded
heavier showers. The low will slowly intensify as it moves
northeast along the coastal front this afternoon, reaching off
the Outer Banks early this evening. The pcpn will come to an end
from southwest to northeast during the mid to late afternoon
hours. QPF from this storm system will observe a nice uniform 1
to 1.5 inches of rainfall. Tonight, will see a drying trend with
residual low cloudiness possible given various models rh time
height displays. Lows will drop back into the 40s. Northwest
winds during this evening with diminish enough for possible
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
A deep layer ridge hangs on over the region through Wednesday night,
then shifts south and east as the next upper trough moves into the
Ohio River Valley. This upper trough will move into the eastern U.S.
Thursday, then the axis will shift offshore later Friday.
At the surface, high pressure will start off centered northeast of
the area on Wednesday, then shift south over the area on Thursday
and then south Thursday night. By Friday, a strong cold front is
expected to push through the region. Models have not been very
aggressive with producing any significant precipitation with this
front. In fact, the latest ECMWF barely has any precipitation at
all. Have continued slight chance to very low end chance pops,
mainly over SC where best moisture, upper forcing and low level
convergence will combine. Any precip should be short lived and
confined to near the surface front. Clearing, cooler and breezy
later Friday morning and afternoon behind the front.
There is some potential for at least patchy fog Wednesday night
given the surface ridge will be centered east-west over the area.
Thus, have put patchy fog in the grids for Wednesday night.
Temperatures will remain above normal through Thursday night, with
highs in the lower 80s, and lows in the upper 50s to lower 60s. By
Friday, much cooler, with highs likely struggling to reach 70 most
areas. These cooler temperatures, combined with breezy northerly
winds, will make it feel a little brisk.
.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 300 AM Tuesday...Very cold temperatures greet the extended as
an arctic front will be well offshore Friday morning. Highs and lows
Fri/Sat will be 10-15 degrees below climo, peaking in the upper 40s
both aftns, and dropping into the low 20s by Saturday morning. This
will be the coldest air since last winter, and gusty winds Friday
will create an even more significant "bite" to the air despite full
sunshine. The cold Canadian high pressure responsible for this chill
will push offshore quickly by Sunday thanks to broad cyclonic flow
aloft, setting up a warming trend back to seasonable values Sunday
and into early next week. As this high moves offshore, return flow
develops, and a weak coastal trough may develop offshore, advecting
warm and moist air into the region for Monday ahead of a rapidly
approaching cold front for Monday night. This will allow Monday to
warm to above seasonable temps, but at the same time rain chances
will increase ahead of the front late on Monday.
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
As of 06Z...High confidence in IFR overnight, and persisting through
much of this valid period. Low pressure consolidating near Florida
will ride up a stalled front just offshore through this period,
creating widespread rain, heavy at times. IFR cigs are slowly
advancing NE tonight, and will envelop all terminals in the next few
hours. Once this occurs, cigs will slowly lower, and LIFR is
forecast much of Tuesday. VSBYS will fluctuate considerably during
periods of heavier rainfall, but MVFR is forecast to be predominant.
Winds will increase from the NE overnight to 10-15 kts, but will
then back to the NW as the low pulls away during Tuesday, driving
the front offshore. This wind shift will create subtle dry
advection, and cigs will gradually improve late Tuesday, with VFR
possibly developing inland by the end of this valid period.
Extended Outlook...Fog possible Tuesday and Wednesday nights.
VFR conditions expected to prevail late week through this
NEAR TERM /THROUGH TONIGHT/...
As of 330 AM Tuesday...Small Craft Advisory raised for all
waters due to effects from this Miller Type B storm system.
Modest to strong wedge in place across the Carolinas with the
frontal system offshore now returning north and west toward the
coasts later this morning. The positioning of this frontal
boundary will make wind direction forecasts across the local
waters rather difficult. Models indicate this front will
temporarily progress onshore but just if and how far inland and
how long it meanders across the local waters. For now will go
with the scenario of temporarily pushing 5 to possibly 10 miles
inland around midday. Low pressure will develop off Cape Fear,
on the front by midday and intensify as it tracks northeast
away from the local waters this afternoon. This will pull the
front as a cold front back off the coast and offshore this
afternoon and evening. The sfc pg tightens enough to produce 15
to 25 kt wind speeds, with gusts on the warm side of the front
30+ kt. Significant seas will peak in the 5 to 8 foot range this
aftn and mainly dominated by wind driven waves at 4 to 6 second
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
No highlights expected through Thursday night. High pressure
will shift from northeast of the area Wednesday to south of the
area by later Thursday. Winds east-northeast Wednesday, becoming
variable Thursday, then southwest Thursday night. Winds
generally 15 knots or less and seas 4 feet or less.
LONG TERM /FRIDAY THROUGH SATURDAY/...
As of 300 AM Tuesday...SCA conditions possible to greet Friday
morning as an arctic front will be positioned well offshore. In
the wake of this front early Friday, NW winds of 20-25 kts will
push seas up to 4-6 ft, and an SCA may be required. These winds
and elevated seas will fall through Friday however as high
pressure builds eastward. As this surface high moves eastward
and offshore the Mid-Atlantic region during the wknd, winds will
weaken to around 10 kts by late Saturday, with a slow veering
to the NW. Seas fall quickly late Friday and on Saturday as
well, from 3-5 ft Friday aftn to just 1-2 ft at the end of the
MARINE...Small Craft Advisory until noon EST Wednesday for AMZ250-252-