Area Forecast Discussion
Issued by NWS Wilmington, NC-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS62 KILM 010215
Area Forecast Discussion
National Weather Service Wilmington NC
915 PM EST Wed Nov 30 2016
-- Changed Discussion --Mild and moist south to southwest winds will continue through
tonight as a strong cold front approaches the Carolinas from
the west. The front will move off the Carolina Coasts and
offshore during Thursday morning, basically around daybreak.
Cooler and drier Canadian high pressure will infiltrate the area
during Thursday through Sunday. Areas of low pressure will
affect the area late Sunday thru the first half of next week
with clouds and increasing rain chances.
-- End Changed Discussion --
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
-- Changed Discussion --As of 830 PM Wednesday...After the line of convection pushed
across the Appalachians, a decrease with intensity was noted as
well as some pcpn areal coverage. The activity is now pushing
across the I-95 corridor and has now stabilized with respect to
intensity. Meaning, it`s basically light shra with embedded
moderate shra. Occasionally, will see a reflectivity more in the
form of a convective cell, but they have become less and less of
an occurrence as this pcpn as a whole moves eastward. The
activity will become somewhat more diffuse in coverage when it
reaches the ILM CWA Coast. This due to question instability and
the main dynamics aloft, ie. 300 mb wind jet streak further
staying further west and north of the ILM CWA as it moves off to
the NE. Thus, the area does not directly experience the RR
quadrant of this upper jet along with the associated UVVS.
Have made adjustments to the POPs and QPF thru daytime Thu
morning in response to this area of pcpn tracking to the east
with individual elements accelerating to the northeast. Have
indicated 3 hr QPF blocks to better gage the occurrence of pcpn
Very little tweaking of temps and dewpoints needed at this time
with expected CFP followed by CAA and drier air basically
occurring late this period, but mainly during the short term
As of 300 PM Wednesday...Strong southwesterly winds aloft
continue ahead of a large upper level-low that is still centered
over the northern Mississippi River valley of Minnesota and
Wisconsin. Water vapor imagery is showing the strong jet
rotating up the southeast side of the low with speed nearing 110
knots at 500 mb over the lower Mississippi River valley.
Most of the showers that formed on the convergence boundary this
morning have shifted off the coast with a scattered showers
developing back to the west over Columbus and Bladen counties. The
showers are expected to be isolated to scattered through the early
evening. The 17 UTC HRRR shows the convective line that is moving
across Georgia at this time will approach the western counties
around 7 PM, and will weaken as it moves across the county warning
area through the night. Also, the 12 UTC NAM, GFS and ECMWF all
show this strong line weakening as it moves across the region. The
chances for significant precipitation in our area are not looking as
good with this model cycle. The models are indicating the chances
of precipitation will extend to just after 12 UTC for southeast
South Carolina but earlier for the areas to the west.
The lows overnight will drop into the middle 50s west of Interstate
95 and lower 60s at the coast.
-- End Changed Discussion --
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
As of 300 PM Wednesday...This period will see the remainder of any
showers exiting the southeast North Carolina coast with high
pressure building in behind the cold front. This high pressure is
expected to continue through Friday night.
High temperatures are expect to only be in the upper 60s on Thursday
and with cold air advection behind the cold front highs on Friday
will only be around 60. Low temperatures on Thursday night will fall
into the upper 30s well inland to the lower to middle 40s at the
immediate coast line. On Friday night temperatures will drop into
the middle 30s well inland and 40 to 42 at the beaches.
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 300 PM Wednesday...A deep cutoff upper low across the
Baja peninsula will eject out into the southern stream flow
early next week, bringing rain chances to the Carolinas. However
the timing of this remains uncertain owing to extremely large
model differences between the slower GFS and faster ECMWF.
Forecasters at WPC have access to a great deal of data we don`t
at the local NWS level, and noted in their extended discussion
that the ECMWF ensembles resemble the GFS operational run and
its ensembles much more than they do the ECMWF operational run.
For this reason, we favor a GFS-centric forecast for the
Surface high pressure and a low-amplitude upper level ridge
should keep Saturday dry. However by Sunday moisture should
begin increasing in advance of the big upper system ejecting out
of Mexico. While even the fast GFS doesn`t bring the trough to
our longitude until Tuesday, increasing flow of Gulf moisture in
the mid-levels should bring clouds and perhaps a little light
rain to the area Sunday afternoon or Sunday night. Rain chances
then develop again on Tuesday when I`ve increased rain chances
to 40-50 percent.
A northern stream trough which is shown in both the GFS and
ECMWF should roll east out of the Rockies during the middle of
next week and could begin to spread another risk of rain into
the area by late Wednesday.
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
As of 00Z...Persistent fog along the coastal terminals has broken up
leaving IFR ceilings with low stratus. A cold front will track
across the TAF sites from west to east tonight. This should produce
a line of showers with gusty SW to W winds. Have not included
thunderstorms in TAFs due to timing of frontal passage, but expect
rapidly moving showers with some heavier rain and stronger winds
possible just ahead of and along the front from 02-06z inland and
05-09z along the coast. Post fropa expect VFR with westerly winds
through end of TAF period.
Extended outlook...Expect VFR. Expect clouds and pcp back in
forecast by end of period with some MVFR/IFR conditions possible by
-- Changed Discussion --NEAR TERM /THROUGH TONIGHT/...
As of 830 PM Wednesday...Winds over the waters have veered
slightly from due S to SSW-SW at the moment. Enough cooler SSTS
remain nearshore to keep winds aloft from mixing down to the
ocean sfc. This is evidenced with Johnny Mercer Pier at 10 to 15
kt wind speeds with latest SSTS at low to mid 60s...and Frying
Pan Shoals buoy at 20 to 30 kt wind speeds with latest SSTS in
the mid to upper 70s. Thus, will forecast the ILM coastal waters
basically in the middle of these 2 extremes.
Significant seas will run 4 to 7 ft for the ILM SC Waters and 4
to 8 ft for the ILM NC Waters. The higher seas will occur across
locations with the higher SSts and thus hier wind speeds. This
includes the local waters off Cape Fear and Cape Romain.
As of 300 PM Wednesday...South winds of around 20 knots are
occurring over the waters this afternoon well ahead of cold
front that is located just west of Georgia to southern
Mississippi. As the front moves closer to the coastal waters the
winds will become southwest and increase to 20 to 25 knots with
higher gust. Seas are running between 4 and 6 feet from 20
miles offshore to the coast. Seas are expected to increase to 5
to 7 feet overnight. A small craft advisory will continue for
all the water through the night.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 300 PM Wednesday...At sunrise the cold front will be
approaching the coastal waters and will move across the waters
during the morning. As the winds direction shifts behind the cold
front they will weaken, and the seas will diminish below small craft
conditions south of Little River around 7 AM and 10 AM north of
By Thursday evening, the winds will shift from the west to the
northwest by Thursday evening, and remain north to northwest through
Friday night. Winds will relax to 10 knots by Friday and seas will
settle out around 2 to 3 feet during this time frame.
LONG TERM /SATURDAY THROUGH SUNDAY/...
As of 300 PM Wednesday...Canadian high pressure over the Mid-
Mississippi Valley will build east into the Carolinas early
Sunday, weakening slightly as the centers sits across the
interior of both states Sunday night. Moderate offshore breezes
Saturday should gradually die down Saturday night, but may get re-
energized Sunday night as a wave of low pressure begins to take
shape along the Georgia coast late.
-- End Changed Discussion --
MARINE...Small Craft Advisory until 7 AM EST Thursday for AMZ254-256.
Small Craft Advisory until 10 AM EST Thursday for AMZ250-252.