Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 231616
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
1115 AM EST Tue Jan 23 2018

.SYNOPSIS...
A cold front will bring showers and a few thunderstorms today,
along with gusty winds. Dry and seasonable weather will follow
Wednesday through Friday. Weekend temperatures will warm again
ahead of a cold front, along with showers late Saturday and
especially on Sunday. The passage of another cold front will
bring a return to seasonable temperatures Monday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 815 AM Tuesday...Whirlwind start to the morning with a
line of moderate convection moving offshore. A few wind gusts of
30 to 40 mph were observed, with an elevated station near Bald
Head Island measuring 47 mph. This line is not the front, the
boundary still lies well west of the area. The front will push
eastward quickly today, and latest HRRR/NSSL WRF suggest a
secondary line of convection will develop along the immediate
boundary. This should be much weaker as drier air begins to fill
the column from the top, but do expect a secondary line of
showers to move across the area from late this morning through
early aftn, and have tried to show best timing in the forecast.

Winds behind this front have shifted to the SW and this is
allowing sea fog to develop and spread across the Grand Strand.
Have added sea fog to the immediate coast where SREF probs for
VSBY less than 1mile are highest, but this should be a pretty
transient event as winds gradually shift more the W/SW through
the aftn pushing sea fog away from the coast.

Other concern today is gusty winds, especially as the column
dries and sun breaks out this aftn. There is likely to be a
period this aftn/eve when wind gusts of over 30 mph will occur,
potentially highest thanks to wind speeds at the top of the PBL
of 40 kts possibly mixing towards the surface. Previous
discussion below:

As of 240 AM Tuesday...The actual cold front or wind shift as
it is is defined well to the west by a fine line of showers and
this may take most of the morning to clear the area and if it
holds together, pops may have to be extended to the east by a
couple of hours. Overall the small severe threat hasn`t changed
with the best coupling of stronger low level winds (around 50kts
at 850mb) coupled with the showers from about 9-12 UTC. Warm
and very blustery later today with highs into the 70s and west
to southwest winds gusting well over 30 MPH. Lows Wednesday
morning in the middle to upper 30s.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 240 AM Tuesday...Prime caption this period, `Dry and
Seasonable`, as W and NW flow aloft overspreads the region in
wake of a cold frontal passage. Drying will mix to the surface
Wednesday and Thursday, as surface dewpoints fall into the 20s.
Thursday and Friday minimum temperatures will dip to a few
degrees either side of freezing. Sunshine minutes will be
plentiful this period, although maximums will hold in the 50s.
Resurgence of high pressure from the west Wednesday night and
early Thursday, will bring an increase in north wind, which will
produce wind-chills in the 20s at daybreak on Thursday, as day
time temperatures struggle to eclipse 50.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 3 PM Monday...Friday will bring transition to seasonable
weather as high pressure goes from our west to our northeast.
Onshore flow Saturday will import Atlantic moisture into the
area and clouds should increase. A warmer afternoon is also
expected though ocean moderation may extend pretty far inland.
Winds go south on Sunday ahead of a strong upper wave and
surface cold front. Showers and thunderstorms appear likely
including some areas of moderate to heavy rainfall. Back to
sunny and seasonable on Monday.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
As of 17Z...Front has entered the western CWA and will reach the
coast in a few hours. An isolated shower is possible with rope cloud
crossing into Marlboro county, but aviation should not be affected
much. MVFR conditions will improve to VFR later this afternoon with
scattering skies. Gusty southwest winds will diminish this evening
and become northwesterly. VFR Wednesday with sunny skies.

Extended Outlook...VFR through the end of the forecast period.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 815 AM Tuesday...Line of convection is clearing the last
legs of the coastal waters and will push east and out of the
area in the next hour or two. A few strong wind gusts are still
possible through this morning in the strongest cells. A second
line of showers is expected to move across the waters this aftn
as the actual FROPA occurs, but this will be much weaker.

Marine fog has developed as SW winds overspread the waters. Have
issues an MF.Y for Cape Fear South, and may need to expand this
to AMZ250 later this morning. Confidence is lower there as
trajectories will be shorter and SREF vsby probs are lower.
Marine fog will persist until the winds shift more to the W/SW
with the actual front this aftn. Previous discussion below:

As of 240 AM Tuesday...Winds from the south/southwest of 15-20
knots will continue for several hours this morning before
diminishing later this afternoon with the direction veering more
to the west/southwest. By tonight the direction will be from
the northwest with speeds decreasing further to 10-15 knots.
Significant seas will be 5-7 feet a good part of the day. Seas
will decrease to 2-4 feet tonight.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 240 AM Tuesday...No advisories expected this period, in a
moderate offshore west wind, and as a result, highest seas will
reside offshore. Inshore seas will remain manageable, but do
expect NW wind gusts to 20 KT Wednesday night and early Thursday
as a resurge in high pressure works in. In addition to offshore
chop and wind-seas, a SSE swell of 1-2 ft every 7 seconds may
be expected. The dry atmosphere this period will prevent TSTMs
and fog from forming. Sea surface temperatures inshore were in
the upper 40s and lower 50s.

LONG TERM /FRIDAY THROUGH SATURDAY/...
As of 3 PM Monday...High pressure shifts offshore and becomes
centered further to the north on Friday. Northerly winds will
start diminishing and veering. Expect easterly winds by Friday
and SE on Saturday. Swell energy will increase as a long onshore
fetch develops but any increase in wind wave should be minimal.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Dense Fog Advisory until 4 PM EST this afternoon for AMZ252-
     254-256.
     Small Craft Advisory until 6 PM EST this evening for AMZ250-
     252-254-256.

&&

$$
SYNOPSIS...MJC
NEAR TERM...JDW/SHK
SHORT TERM...MJC
LONG TERM...MBB
AVIATION...43
MARINE...



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