Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 231913

Area Forecast Discussion
National Weather Service Wilmington NC
313 PM EDT Sat Sep 23 2017

High pressure will continue the warm and dry weather through the
remainder of the weekend. Hurricane Maria is expected to move
northward a couple of hundred miles east of the Carolina coast
Monday through Wednesday. Hazardous boating conditions, strong
rip currents, and large surf are all expected to develop. A cold
front is expected to reach the area Friday, bringing cooler
weather for late next week.


As of 3 PM Saturday...Surface ridge will persist from the north
tonight and Sunday as Hurricane Maria moves northward. At H5 an
upper low will become positioned across the northern Gulf Coast
as a ridge lingers across the Great Lakes, New England and part
of the Mid-Atlantic regions. RH in the H85-H5 layer will remain
meager with UVVs lacking through Sunday thus no POPs required
in the near term period. Even with northeasterly flow
temperatures will be a category or two above normal with lows
tonight and highs during Sunday. Favored a blend of MET/MAV
numbers each period. Some fog possible again tonight, more-so
for the coastal counties and a touch farther inland where
dewpoints will be highest.

Otherwise, ocean and surf conditions will be deteriorating
through Sunday with potential for ocean over-wash, erosion, high
surf and strong rip currents. Please see the section below for
further details.


As of 300 PM Saturday...Mid-level high centered over PA-NY area
is expected to hook up with the Atlantic ridge once the
remnants of Jose dissipate by Monday morning. At the same time,
a rather weak upper level low will reside over the Gulf Coast
between LA and FL. And finally, Hurricane Maria is expected to
slow down by Monday once the blocking ridging to it`s north
becomes established. Flow around the upper ridging and the upper
low will have a tendency to actually pull Maria slightly
westward beginning by Tuesday morning at which point it would
be at the 33 degree N latitude and 72.5 longitude. A couple of
degrees in Longitude to the west at this point will be the
difference for whether Hurricane Watches/Warnings will be

As for sensible weather conditions during this period. The FA is
looking at basically mostly clear nights and mostly sunny days  with
the exception for the immediate coast where partly sunny may be the
right wording due to the increase of exhaust Cirrus emitted by
Maria. By Tuesday morning, could even see a few showers from
Maria reach the immediate coast and possibly progress inland
across the ILM NC CWA before quickly dissipating. With mid-level
dry air and subsidence, ie. sinking air, occurring ahead of
Maria will for the most part keep the ILM CWA pcpn- free.

For Max/Min temps, looking at the continuation of summer like
conditions with highs each day in the 80s and lows in the 60s to
around 70. This is basically 1 to 2 categories above climo

Maria`s swell will continue to increase in size Sunday into Monday
then plateau Monday night into Tuesday. As a result, surf
conditions will surpass thresholds that require a High Surf
Advisory. In addition, strong rip currents are expected and may
occur at any time, not just low tide, given the size of the
expected surf and all of that water that runs up onto the
beaches. In addition, minor beach erosion is possible during
this 2 day period, mainly at high tide where water may reach the
dune lines of area beaches.


As of 300 PM SATURDAY...the big question will be how far
offshore will Maria stay. The latest global models continue to
show the center of Maria slowing down and staying just offshore
Cape Hatteras middle of next week. A trough of low pressure will
pick up Maria and carries it out to sea by late next week.

At the surface a cold front will move into the eastern
Carolinas and offshore by Friday. Cooler temperatures and drier
air will move into the region for Saturday. At this time only a
chance of showers is expected on the western fringe of Maria
during mid-week. With the best chances along the coast mainly
north of Little River, SC. There will be a slight chance of
precipitation late Thursday and Friday.

High temperatures Tuesday through Thursday will be in the
middle to upper 80s but as the front approaches maximum
temperatures fall into the lower 80s Friday and the upper 70s on
Saturday. Low temperatures are expected to be in the upper 60s
to around 70 Tuesday night and Wednesday night. Lows Friday are
expected to fall into the lower to middle 60s.


As of 18Z...High confidence in VFR conditions prevailing
through the evening with the area influenced by high pressure
ridging in from the north. Some confidence with TEMPO MVFR
conditions developing during the early morning hours, especially
at the coastal terminals where the dewpoints will be a touch

Extended Outlook...Mainly VFR conditions through the period with
the exception of possible MVFR/IFR conditions due to low clouds
and fog each morning, mainly between 08z-12z.


As of 3 PM Saturday...East to northeast winds expected with
high pressure ridging in from the north, and Maria`s circulation
far to the south-southeast. Winds around 10 knots should be the
rule through the rest of the day before increasing a notch
tonight. A stronger northeasterly fetch will become established
during Wed, especially across the outer coastal waters. Higher
frequency waves will develop during Sunday and super-impose
withe impressive swell emanating toward the northwest from
Maria. A Small Craft Advisory is already in place to account for
the developing hazardous maritime conditions.

As of 3 PM Saturday...SCA remains in effect for the local waters
due to increasing significant seas.

The story for this time-line will be the increasing 15+ second
period swell from Maria. Significant seas will peak in the 7 to 10
foot range late Sun thru early Tue. The sfc pressure gradient
will be slowly tightening as Maria pushes or inches closer
during this period. This will result with increasing NE winds
Sun that will back to the North, Mon thru Mon night. Wind
speeds will also be increasing with SCA threshold for windspeeds
being reached.

With the increasing swells, verbiage will be added to the MWW for
hazardous navigating conditions likely across local area inlets to
and from the Atlantic as well as the mouths of the Lower Cape Fear
River and Winyah Bay.

As of 300 PM SATURDAY...this portion of the forecast will be
controlled by Hurricane Maria as it moves northward and slows
just off Hatteras. The winds are expected to be from the north
20 to 33 knots north of Little River and 15 to 25 knots to the
south. Winds will shift to the northwest on Wednesday with the
same speeds. Seas are expected to range from 7 to 12 feet north
Cape Fear and drop down to 5 to 8 feet south of Cape Fear.


As of 2 PM Saturday...Minor coastal flood thresholds may be
reached at the beaches generally north of Cape Fear during high
tide early Sunday afternoon and again early Monday afternoon. In
the least we expect ocean overwash from the wave run-up from
Maria`s swells, especially in those areas which have suffered
erosion from previous storms. Wave power will increase as
Maria`s swells build through Monday. A High Surf Advisory has
been issued as a result for all beaches from 10Z Sun through 00Z
Tue as a starting point. The potential for dangerous rip
currents will continue through the weekend into next week.


SC...High Rip Current Risk until 8 PM EDT this evening for SCZ054-
     High Surf Advisory from 6 AM Sunday to 8 PM EDT Monday for
NC...High Rip Current Risk until 8 PM EDT this evening for NCZ106-
     High Surf Advisory from 6 AM Sunday to 8 PM EDT Monday for
MARINE...Small Craft Advisory until 6 PM EDT Wednesday for AMZ250-252-



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