-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 200523
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
123 AM EDT Wed Sep 20 2017

.SYNOPSIS...
A disturbance aloft will bring isolated showers Wednesday and
Thursday. High pressure will build in from the north for the
remainder of the week while Jose spins nearly stationary off
the Mid-Atlantic coast. Dangerous hurricane Maria approaching
Puerto Rico tonight, will bring increasing southeast swell and
strengthening rip currents to the Carolinas beginning late week.
Maria is expected to move north and offshore of the Carolinas
early next week.

&&

.NEAR TERM /THROUGH TODAY/...
As of 950 PM Tuesday...Changes not needed at this time to the
ongoing forecast aside from minor T and Td tweaks, as evening
temperatures have dropped off rapidly. A few sites inland were
already reporting upper 60s. The final game day decision was not
to include fog overnight, as most guidance and our local fogger
tool do not convincingly support its formation.

As of 635 PM Tuesday...A delightful evening on tap despite the
overwhelming, visual arrest, of Jose in satellite presentations.
Meanwhile in the tropics, Maria is bearing down on the Virgin
Islands and Puerto Rico, but no sensible weather effects or even
SE swell has arrived yet locally from Maria. Visibility can be
measured in light years tonight under a clear celestial dome. As
Jose`s very outer wind field completely releases its grip on NE
SC and SE NC overnight, look for winds to trend from NW to W to
WSW by daybreak Wed but speeds light. The downslope wind flow
may act as an inhibitor to fog/mist formation but isolated
pockets may still form in the protected, cool, or more damp
locals. Will use trends in the hours ahead to determine if fog
inclusion in the forecasts is warranted. The mostly clear skies
overnight will aid cooling and allow minimum temps to dip to
65-68 degrees at daybreak.

As of 300 PM Tuesday...Subsidence associated with Jose is still in
effect over eastern zones but cu fields show it lessening as one
heads south and west. However being mainly fueled by diurnal heating
these clouds will thin towards sunset and most of the night should
bring generally clear skies. The exception will be some minor
coverage of mid cloud that should start to impinge upon NW zones
late tonight ahead of diving upper trough/cold pool. This feature
will remain over the area into Wednesday and even deepen somewhat.
Whereas the mid levels should be cool enough to support some degree
of cloud cover the low levels look too dry to support meaningful
rain chances.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
As of 3 PM Tuesday...Weak mid-level trough in the wake of Jose will
allow for some isolated diurnal convection ongoing at the start of
the period. Some of this convection could be extended into the
overnight period by an approaching shortwave. It could end up that
convection developing west of the area prior to the start of the
period moves in from the west during the evening and overnight
hours.

Similar theme for Thu with weak mid level troughing and heating
coupled with some shortwave energy leading to diurnal convection.
Think chances a slightly better on Thu with convection once again
lingering into the evening and overnight hours. However, the lack of
large scale forcing and mid level dry air will limit convection
during the period. Temperatures will run above climo through the
period.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 245 PM Monday...At onset Friday Jose will be meandering off
the New England/Mid-Atlantic coasts while Maria approaches the
eastern Bahamas with weak high pressure in place across the
Carolinas. Weak high pressure will remain across the Carolinas early
next week as Maria moves northward off the Southeast U.S. coast. We
will obviously need to keep a very close eye on Maria`s progression,
however in the least we expect very hazardous surf conditions as
large swells impact the coast. Held onto a small POP for primarily
SC areas during Friday, then no POPs thereafter (ultimately
dependent on Maria`s track early next week). Favored a blend of
MEX/ECE highs/lows through the long term period.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
As of 06Z...Expect VFR conditions through the period. Some
regional sites are showing modest fog formation and I did add a
tempo group to LBT for MVFR this morning to address. There may
also be a few isolated thunderstorms late this afternoon and
evening but coverage and confidence is not sufficient to include
in the current forecast.

Extended Outlook...Mainly VFR conditions through the period are
expected with the exception of a few hours of early morning low
clouds or fog most mornings through the period. The highest
risk of IFR conditions will be in the 0900-1200Z timeframe each
morning.
-- End Changed Discussion --

&&

.MARINE...
NEAR TERM /THROUGH WEDNESDAY/...
As of 635 PM Tuesday...Plots of wave spectra across the 0-20 NM
waters, shows E swell in 12-13 second intervals dominates wave
energy with seas 2-3 feet. Flat pressure pattern will result in
light winds, which will trend from NW early this evening to WSW
into daybreak Wed. No TSTMS expected over the 0-20 NM waters
through Wednesday.

As of 300 PM Tuesday...Winds slacken and Jose swell energy
abates through the period. Flow will tend to veer some to NW as
the outer curved isobars of Jose lift out to the NE. Seas will
settle into the 2 to 3 ft range.

SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...

As of 3 PM Tuesday...Elongated weak high pressure south and east of
the area into Thu will yield to slightly stronger high building down
the coast. Light southerly winds Wed night into Thu will become
northeast late in the period but speeds should remain under 10 kt
through Thu night. Seas will run 2 to 3 ft.

LONG TERM /FRIDAY THROUGH SUNDAY/...
As of 245 PM Monday...Very hazardous maritime conditions expected
during the long term period as large waves emanate outward from
Maria. At this time Maria is likely expected to remain offshore as
it moves northward from the Bahamas, but all marine interests should
closely monitor the progression of this storm given forecast track
uncertainty at this time. Winds on Friday will be around 10 knots
from the northeast to east with similar conditions Saturday. Speeds
will increase during Sunday out of the northeast as the peripheral
circulation of Maria begins to come into the picture. Wavewatch III
guidance indicates significant swells impacting the coastal waters,
especially Sat into Sun. Very steep waves are possible, especially
near inlet entrances during the falling tide.

&&

.TIDES/COASTAL FLOODING...
As of 300 PM Tuesday...The Cape Fear River will once again
reach minor tidal flooding thresholds with this evening`s high
tide at 10 PM as the new moon approaches. Coastal Flood Advisory
being hoisted for 2 hours either side of low tide for standing
water in Battleship Park and downtown Water Street. ET surge
data continues to keep ocean/ICW tides below thresholds.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
SC...None.
NC...None.
MARINE...None.
-- End Changed Discussion --

&&

$$

AVIATION...SHK
MARINE...REK/RGZ
TIDES/COASTAL FLOODING...