Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 231032
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
533 AM EST Mon Jan 23 2017

.SYNOPSIS...
Stacked low pressure system will move overhead today...and lift
northeast to off the DELMARVA Coast by Tue daybreak, and to off
Cape Cod by Tue evening. The area could see scattered showers
later today along with an isolated rumble of thunder from midday
thru this afternoon. High pressure from the south will ridge
across the area Tue and Wed with temperatures running above
normal. A cold front pushes across early Thursday followed by
cooler high pressure for the end of the week becoming even
colder during this upcoming weekend with daily temperatures
dropping back to and below normal.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 330 AM Monday...Vertically stacked low pressure is
currently centered over the western Carolinas early this
morning. The vertically stacked low will slowly track to the
eastern Carolinas by sunset today. The low will begin a jog to
the NE tonight, reaching the DELMARVA Coast by daybreak Tue. The
cold core low being overhead during the max heating of the day,
will result in some decent lapse rates across the FA. The pcpn
that develops today will convective in nature and would not be
surprised if very small hail is produced given freezing levels
dropping to 5k to 6k feet at their lowest this aftn and plenty
of moisture avbl thru the atm column up to 5h also where the
-20 degree C level is found this aftn. Overall instability
remains in question for TSTORM action but cannot ignore the
passage of a stacked upper low overhead during this time of the
year. Stayed closer with the moisture profile of the GFS and
kept POPS below 50 percent. Projected QPF will generally run
less than one quarter of an inch. A cold front will push across
later this aftn inland...early evening at the coast. This will
end the pcpn threat with sfc winds veering from SW to W to NW.
The sfc pg will tighten-some later tonight on the backside of
the upper closed low lifting to the NE. This will keep winds
active tonight and thus fog no longer being a problem. For
temps, basically stayed slightly lower by a couple degrees after
applying a consensus of MOs guidance.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 400 AM Monday...The ILM CWA will remain under
cyclonic flow during Tue associated with the Stacked Low
moving from off the DELMARVA Coast Tue morning to Cape Cod by
Tue evening. Models are in decent agreement late Tue thru Wed
with a low amplitude mid level and sfc ridging extending north
across the FA from Florida and the Bahamas. The atm column dries
out nicely by the start of this period and continues into Wed
evening. Thus, sky conditions will be conducive to Mostly Sunny
and clear nights. The exception will be for late Wed night when
a cold front approaches from the west. Have included an increase
in clouds with low chance POPs for light showers during the
pre-dawn hrs, mainly west of the I-95 corridor. For temps,
stayed with a Mos Guidance Consensus.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Previous forecast used...
As of 3 PM Sunday...Upper level ridge axis moves offshore
on Wednesday yielding deep layer SW to WSW flow. Expecting a
mostly sunny and unseasonably warm afternoon. Cold front comes
through late Wednesday night driven by very low amplitude and
confluent upper system keeping rain chances minimal. Cold air
advection Thursday is weak initially allowing for highs in the
low to mid 60s early before temperatures possibly start a non-
diurnal decline. The remainder of the period will bring cool and
dry advection. The southern branch of the upper jet splits off
and gets hung up as a positively tilted trough over the SWrn
U.S. The northern branch will end up a broad and positively
tilted trough over the Eastern U.S. Daytime highs will be stuck
below climatology in the cold advection regime whereas breezy
well-mixed nights will be seasonably cool.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
As of 12Z...Deep moisture has exited, however the strong upper low
still needs to come through this afternoon. There will be decent
solar insolation, however given the sun angle, do not expect too
much CAPE this afternoon, but enough to kick off some fairly
vigorous showers around max heating. Given the cold air aloft,
expect gusty winds with the showers. Most of the activity will end
by late afternoon with VFR conditions expected tonight.

Extended outlook...Expect mainly VFR. A dry CFP slated for
early Thu.

&&

.MARINE...
NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As of 400 AM Monday...SCA for all waters thru Tue afternoon.
Elevated winds and seas expected this period. Exception is when
the center of the stacked low moves across the area during
today. The sfc pg will relax enough for SW winds to temporarily
drop below SCA thresholds. By late this aftn and early this
evening, the stacked low will finally lift NE of the area
allowing the passage of a sfc cold front. The sfc pg will re-
tighten and result in WNW to NW winds increasing back to SCA
thresholds, and continuing during the early Tue morning hrs.
Significant seas will continue elevated and be dominated by
wind driven waves at 5 to 7 second periods. Seas initially at
5 to 9 ft may temporary drop a few ft later today but then
re-stabilize in the 4 to 8 ft range tonight as gusty WNW to NW
winds take over. Low chance exists for showers to occur later
today.

SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
As of 415 AM Monday...Cyclonic flow to continue thru Tue as the
stacked low lifts further NE reaching Cape Cod by sunset Tue,
much further away from the ILM Waters. Looking at a sfc pressure
pattern and relaxing sfc pg with diminishing NW to W winds
likely below SCA levels by or during the aftn. Weak ridging to
extend northward from Florida and the Bahamas Tue night thru
Wed, resulting in winds backing to the W to SW around 15 kt.
Wed night, an approaching cold front from the west will result
in the sfc pg tightening and SW winds back up to 15 to 20 kt.
Significant seas will peak at the start of this period. An
offshore wind trajectory Tue into Tue night will help subside
the seas except for the waters from Cape Fear to Little River
Inlet where a Westerly wind direction will have a longer fetch
to produce slightly hier seas than surrounding zones. Seas will
subside to 2 to 4 ft Tue night and hold in that general range
thru Wed. Seas will begin to build Wed night ahead of an
approaching cold front with increasing SW wind driven waves.

LONG TERM /WEDNESDAY THROUGH FRIDAY/...
Previous forecast used...
As of 3 PM Sunday...Coast-parallel southwesterly flow on
Wednesday ahead of a cold front. Though the winds will increase
to the 15 to 20kt range any headline or advisory-worthy seas
will remain outside of the 20nm forecast zone. With the approach
of the boundary Wed night into Thursday we may add some
gustiness and possibly introduce some 5 ft waves. A sharp late
morning veer to NW Thursday will give way to abating wind
speeds. Wave faces will steepen and a cautionary headline may be
appropriate for a narrow span of time. A broad and weakening
band of NW flow will be found across the eastern U.S on Friday.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory until 6 PM EST Tuesday for AMZ250-252-254-
     256.

&&

$$
SYNOPSIS...DCH
NEAR TERM...DCH
SHORT TERM...DCH
LONG TERM...MBB
AVIATION...43


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