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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 290709
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
309 AM EDT Sat Jul 29 2017

.SYNOPSIS...
A cold front will bring another chance of showers and
thunderstorms to the area before moving offshore this afternoon.
High pressure will build into the area Sunday through much of
next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 3 AM Saturday...Water vapor imagery this morning shows a potent
shortwave diving into the southern Appalachians with deep moisture
residing to its south. The attendant cold front is now in western
North Carolina then draped east to west across the Mississippi
Valley. Guidance, both Cam`s and global, continue to insist on
development of showers with embedded thunder this morning across the
area via a good area of upper level divergence. This "seems" to be
occurring at the moment with some development and cooling cloud tops
just to our west. However the guidance has been too robust with the
convection at least for our area throughout this event, or non event
I should say. Long story short, I have walked back pops somewhat
from previous values with the highest numbers still centered in and
around 12 UTC. The severe risk looks minimal citing the current
stable conditions and anticipated cloud cover later this morning.
The front and its associated dry air mass will make steady progress
through the area this afternoon and evening with all areas being dry
by later this evening. Regarding temperatures, leaned heavily toward
the cooler MAV numbers for daytime highs and overnight lows
Sunday.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 3 PM Friday...Cold front will be pushing offshore as the
period begins with any lingering convection likely quickly winding
down. Forecast soundings show a large amount of mid level dry air
spreading over the area in the wake of the cold front. Precipitable
water values will have dropped almost an inch across inland areas by
Sat evening with coastal sites dropping a few hours later. Cold
front pushes off the coast overnight as weak shortwave moves through
the 5h trough. A much stronger shortwave drops in from the northwest
on Sun and the 5h trough axis moves into the eastern Carolinas. Wave
rotates through around 18Z and will be accompanied by an increase in
mid level moisture. Anticipate at least some diurnally driven
showers and thunderstorms with this feature. Best chances will be
across North Carolina counties where mid level moisture is highest
and forcing is strongest. Loss of heating and exit of shortwave will
help bring a quick end to any convection Sun evening. The biggest
factor however will be the return of mid level dry air with pwats
dropping under 1 inch. Cooler and drier air mass building in for the
start of the week will drop temps below climo with lows in the low
to mid 60s and highs in the low to mid 80s.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 3 PM Friday...Unseasonably cool Canadian high pressure
will start next week with temperatures and absolute humidity
below normal for the season, debuting an early but brief
offering of an early fall feel across the Carolinas. Cool air
advection will linger into Monday as interaction of the high
and deepening low pressure offshore tighten the gradient of
pressure, sending a gusty N-NE wind flow over the area Monday
morning. As the high settles over the region into mid-week
and upper troughing lifts north, maximum temperatures will
begin to approach normal values, with minimums remaining
relatively cool due to low dewpoints and mainly clear nights.
A low chance of rain this period, at least until late next week
as upstream troughing deepens and draws moisture into the area.

&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
As of 06Z...Expect mostly VFR conditions through the period.
Models have been overestimating the rainfall coverage
throughout this event. There is one more period of possible
MVFR conditions early this morning as an upper level area of
divergence moves across acting on a front and ample moisture in
the column. The guidance has been more or less consistent with
this feature as well. VFR conditions should develop late this
morning and through the afternoon hours (if the MVFR
materializes) as dry air moves in.

Extended Outlook...VFR expected Sunday thru Tuesday with Sunday
possibly seeing brief MVFR from showers and/or ceilings during
the aftn.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 3 AM Saturday...Winds and seas now increasing across the coastal
waters with 41013 near 20 knots sustained with seas nearing five
feet. This trend will continue for the next few hours as good low
level jetting moves slowly across the region. Expect winds from the
southwest at just over twenty knots. Seas should reach a maximum of
5-7 feet. Its probably not the strongest Small Craft Advisory we
have seen with some areas barley (if at all) reaching criteria but
will maintain the headline as is. The cold front associated with the
stronger low level winds will move across the waters late this
afternoon and evening with winds acquiring a northerly component
across all waters.

SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
As of 3 PM Friday...Southwest flow at the start of the period
will be short lived as the front moves off the coast and then
east of the waters Sat evening. High pressure over the Upper
Midwest Sat will expand southeast Sat night, commencing a period
of north to northeast flow across the waters that will continue
through Sun night. Speeds Sat night may briefly touch 20 kt
before dropping closer to 15 kt on Sun. A secondary surge of
colder air Sun night will pick speeds back up to near 20 kt Sun
night. Seas will be at their peak at the start of the period,
possibly requiring a SCA for the first few hours of Sat evening.
Seas will drop to 3 to 5 ft Sat night and remain 3 to 5 ft for
much of the period.

LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 3 PM Friday...A rough start on the waters early Monday as
N-NE winds rip at 15-20 KT and gusty, and a Small Craft
Advisory or Caution headline may be in effect Monday morning.
After this however a trend in improvement is in the marine
cards, as the interaction of low pressure offshore and Canadian
high pressure inland weakens late Monday through Wednesday. The
position of the high center nearby but north of the waters will
allow an E flow TUE/WED, becoming SE during the afternoons. No
significant coverage of storms this period. Seas 4-5 feet early
Monday will settle to around 3 feet by early Tuesday and hold.
NE swell of 2-3 feet every 8 seconds is expected TUE into WED.

&&

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

&&

$$
SYNOPSIS...SHK
NEAR TERM...SHK
SHORT TERM...III
LONG TERM...MJC
AVIATION...SHK