Area Forecast Discussion
Issued by NWS Wilmington, NC
FXUS62 KILM 200520
Area Forecast Discussion
National Weather Service Wilmington NC
120 AM EDT Mon Mar 20 2017
High pressure will move in from the north through Monday and
wind up south of the area by Tuesday. A cold front will then
move south across the area Wednesday morning. A large high will
follow this boundary moving east and winding up off the coast
over the weekend.
.NEAR TERM /THROUGH TODAY/...
As of 900 PM...Winds have decoupled quicker than anticipated,
basically once the sfc based inversion developed. All clear
skies and the calm winds spell for an excellent night of
radiational cooling. Sfc dewpoint depression has lowered quickly
after winds decoupled and now are generally at or just under 10
degrees. Latest guidance still shows min temps in the mid 30s
with some outlying low 30s possible between Back Island across
central Bladen and Robeson counties to Bennettsville. The Frost
Advisory areal coverage remains unchanged. However, will issue a
SPS for localities not covered within the Frost Advisory area
but has the potential to produce patchy frost.
As of 300 PM Sunday...High pressure will continue to build in
this afternoon and overnight. Mid level low with an associated
surface trough continues to advect and develop broken to
overcast skies across mostly North Carolina this afternoon. As
this feature moves away and we lose surface heating, skies
should clear. Guidance remains consistent with overnight lows in
the middle 30s area wide with the lower ranges inland of
course. With anticipated light winds very late and these
temperatures will hoist a frost advisory for mainly northern
counties. Confidence is not that high citing temperatures,
moisture and winds but the embattled agriculture community can
do without any surprises.
.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
As of 300 PM Sunday...Warm and moist advection will be underway
Monday night in a WNW mid level flow and SW surface flow. The
advection will be confined to the low levels so clouds will
increase but the lack of deep layer moisture precluding any rain
chances. Despite the continued increase in cloudiness Tuesday
the warm advection will bolster temperatures into the mid and
upper 70s. Some rain chances will be cropping up later in the
day as a cold front approaches but with a continued dry
downsloping zonal mid level flow they may be overplayed in
guidance. The better rain chances will come Tuesday night with
the arrival of a healthy cold front though due to the high
vertical tilt of the front most of the rain may fall after the
end of the period.
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 300 AM Sunday...A surface cold front should be traversing
the area Wednesday morning, pushing all the way down to
Charleston by lunchtime. Shallow cold air surging south behind
the front coupled with a moist westerly flow over the top of the
frontal surface means Wednesday could remain cloudy with
patches of light rain or sprinkles. By Wednesday evening the mid
level flow should veer more northerly, dragging in enough dry
air to dissipate the post-frontal clouds. Unfortunately this
means radiational cooling within the chilly airmass could create
headaches with frost or even a mild freeze by Thursday morning.
Model ensembles still show enough spread in forecast low-level
temperature/moisture for Wednesday night/Thursday morning that I
don`t have high confidence, but it definitely bears watching.
Surface high pressure moving across the Great Lakes Wednesday
night and Thursday will move off the East Coast late Thursday
night. Veering low-level winds will modify our airmass Friday
and Saturday with rising temperatures and dewpoints. Precip
chances may increase Saturday as the next synoptic frontal
systems approaches from the west.
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
As of 06Z...High confidence in VFR through the valid period.
Expansive high pressure ridging down from the Great Lakes will push
southeastward through today, orienting offshore tonight. This
creates a weak gradient with winds less than 10 kts, slowly backing
from north early, to southwest late. W/NW flow through much of the
column combined with this dry high pressure will keep SKC the rule
as well, although some mid-level cloudiness begins to advect into
the NC terminals late with no cig or restrictions forecast. Despite
the clear sky and light winds, the surface appears too dry for any
fog and have removed inherited TEMPO groups for vsby
Extended outlook...VFR expected through the period except for
possible MVFR/IFR conditions from low ceilings and pcpn ahead of
the next cold front Tuesday night into Wednesday.
NEAR TERM /THROUGH MONDAY/...
As of 900 PM Sunday...Both winds and sea conditions will
continue to improve thru the night and into Monday. This a
result of the center of sfc high pressure dropping to the
central Carolinas by daybreak Mon, and further dropping
southward across the local waters on Monday. The pinched
gradient is now well east of the area waters with local winds
exhibiting a diminishing trend. Significant seas will also be in
a subsiding trend with 3 to 5 ft currently dropping to 2 to 4 ft
overnight. With the end 4 footers mainly off Cape Fear and
Romain respectively by daybreak Mon.
As of 300 PM Sunday...Winds and seas remain elevated this
afternoon with north to northwest winds of 20-25 knots and seas
of 5-7 feet across the outer waters. Winds and seas should
diminish rapidly later this evening but the small craft advisory
may need to be extended a few hours. Still have until 6 PM so
will let the evening shift make the final call. Perhaps a
strongly worded SCEC would suffice.
SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 300 PM Sunday... Monday night will place the area between
high pressure over FL/Bahamas and a cold front approaching from
the north. Southwesterly flow will become a bit gusty as the
approach of the boundary tightens the gradient slightly. The
front will continue to approach on Tuesday veering the flow in
direction some but not so much increasing the gradient strength,
the stronger gradient being relegated to the prefrontal flow
regime to our south. The front itself will have a weak pressure
troughiness that will actually ease the gradient some.
LONG TERM /WEDNESDAY THROUGH THURSDAY/...
As of 300 AM Sunday...A wave of low pressure moving off the
North Carolina coast early Wednesday morning will kick a cold
front southward. Latest model projections show the boundary
passing by Cape Fear around sunrise and blowing clear through
Charleston by noon. Breezy northeast winds behind the front will
probably lead to Small Craft Advisory conditions Wednesday
SC...Frost Advisory until 8 AM EDT this morning for SCZ017-023-024.
NC...Frost Advisory until 8 AM EDT this morning for NCZ087-096-099-