Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 311735
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
135 PM EDT TUE MAY 31 2016

.SYNOPSIS...
Moisture associated with the remnants of Bonnie will be very slow
to leave the area even as the actual system finally moves northeast
of the area during Wednesday. The risk for showers and thunderstorms
will persist into the weekend as a cold front drops into the area
and stalls.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1230 PM Tuesday...Quick update to account for latest radar
trends. Band of heavy rainfall has setup across Cape
Fear...orienting itself along an instability gradient where
surface convergence is maximized. This band will likely become the
primary feature to monitor this aftn as shown by most available
high-res guidance as it pivots slowly across the same areas. 850mb
moisture transport vectors are anti-parallel to upwind propagation
vectors...suggesting training and cell regeneration as the sea
breeze rotates mostly in place due to flow around the remnants of
Bonnie. Have added heavy rainfall to the NE corner of the CWA and
some places may receive 3-4 inches of rainfall today.
Otherwise...previous discussion from 10 AM below:

As of 1000 AM Tuesday...Post Tropical Storm Bonnie continues to
swirl about 40 miles east of the Grand Strand this morning...and
will lift very slowly NE through tonight. This will maintain the
very tropical air mass in place...and forecast conditions are very
similar to yesterday. While stepping outside into the near-70
degree dewpoint air may be enough to recognize how tropical the
airmass is...PWAT on the 12z MHX U/A sounding was 1.81 inches
-very near the all-time high of 1.87 inches for the date...a
better indicator of the state of the atmosphere this morning.

As Bonnie lifts slowly NE...tropical showers will rotate
periodically onshore and then drop SW across the CWA. High
instability and breaks in the cloudiness will permit at least
isolated thunder today...but primarily expect scattered showers with
periods of torrential rainfall. Timing and location of the heaviest
rainfall is very uncertain...but the pattern suggests the Cape Fear
region will have the best chance today and have shown the highest
pop in this area. Otherwise...further S/W...less frequent and
lighter rain is forecast. WPC has the area in a "SEE TEXT" for
excessive rainfall today...and while localized flooding cannot be
ruled out beneath any slow moving downpour...this will remain
isolated at worst. Convection will be diurnally enhanced...and then
wane after dark...although showers will likely persist in a much
more isolated fashion through the overnight. Some fog/stratus is
also expected thanks to the continued very moist column.

Highs today will rise to the low 80s most of the area...although
temperatures will be highly variable due to breaks of sunshine in
clouds. Mins tonight will be very warm again...falling only to a
degree or two either side of 70.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 300 AM Tuesday...The remnants of Bonnie may still be hanging
around the the Cape Fear area into Wed as the steering flow remains
weak. Atlantic ridging will build across the eastern Carolinas by
Thu and this should guide the weak circulation further N and away
from the area. A seabreeze is expected to develop on Wed. Low level
convergence associated with this feature should allow for the
development of showers and thunderstorms given the high moisture
content of the air. Will still show chance pops throughout the area
on Wed with likely up through the Cape Fear coast, in closest
proximity to the remnants of Bonnie. A seabreeze circulation on Thu
should prompt the development of more showers and some thunderstorms
given a fair amount of instability and the lack of significant
columnar drying. Will keep pops scattered on Thu. Expect the
convection both days will shrink/wane during the night with the loss
of heating. Low stratus/fog may redevelop Wed night.

Highs both Wed and Thu will be in the upper 80s with lower to mid
80s at the coast due to seabreeze influences. Lows will be around
70.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 300 AM Tuesday... A cold front will drop into the central
Carolinas on Friday and begin to stall. Mid level flow will be
westerly and tend to provide some storm-inhibiting dry air but also
possibly ample directional shear for storm cell organization as
there appears to be moderate to strong instability. The front will
remain overhead on Saturday and the mid level ridge appears to
weaken. Saturday may thus end up a wetter day but with a diminished
capacity for strong storms as widespread cloud cover dampens the
diurnal temperature curve. Strong troughiness digging into the
western Great Lake on Sunday could pull the front a bit to our
north. This could slightly decrease storm coverage while increasing
updraft intensity via stronger insolation. A cleaner passage of the
front and possible legit airmass change may occur late Monday or
Monday night.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
As of 18Z...The remnant low from former tropical storm Bonnie
sits about 70 miles south of wilmington. Counterclockwise winds
swirling around the low are pushing showers onshore. Now through
about 22z the best potential for flight category impacts will
exist across KCRE and KMYR where showers and t-storms are moving
in from the NE. KILM could also see some impacts this afternoon
although these inbound showers currently appear lighter in
intensity. Farther inland...KFLO and KLBT could see a VFR cumulus
ceiling with much lower chances of showers.

Mainly VFR conditions should develop this evening as showers die
away. New showers developing near the offshore low may rotate
onshore but latest models are downplaying this potential.
Beginning around 08z another low stratus cloud ceiling should
develop very similarly to this morning. This should burn off
between 13-14z Wednesday.

Extended Outlook...Mostly VFR with mainly afternoon showers and
thunderstorms.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM Tuesday...The remnant circulation of now Post
Tropical Storm Bonnie will drift slowly NE today...remaining
overhead the coastal waters through the near term. The wind
direction will be determined exclusively by the position of this
weak low...with E/NE winds ahead of it and NW/N behind it.
Fortunately the gradient is light...so wind speeds will be 10 kts
or less regardless of direction...although slightly enhanced
speeds are forecast within the sea breeze circulation this aftn.
Seas will be 2-4 ft today and tonight...with a low amplitude wind
wave and an ESE swell creating the spectrum. Scattered showers and
thunderstorms are also forecast today...with periods of very heavy
rainfall possible.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 300 AM Tuesday...The remnants of Bonnie will be near the
Cape Fear waters into Wed. Atlantic ridging is expected to build
across the waters by Thu and this should help guide the weak
circulation further NE. The seabreeze circulation will dictate
wind direction and speed on Wed and Thu. Wind speeds will
generally be 10 kt or less, around 10 kt Thu night. Swell energy
is expected to wane slightly and this should result in 2 to 3 ft
seas.

LONG TERM /FRIDAY THROUGH SATURDAY/...
As of 300 AM Tuesday...A decelerating cold front will approach
from the northwest on Friday. Southwesterly winds ahead of this
boundary will likely have a tough time much exceeding 10 kt as the
areas of high pressure on either side of the boundary are quite
weak. The front appears to stall just inland from the coastline on
Saturday. This will continue a similar wind field as seen on
Friday. The temporal persistence of the fetch may add a few 3 ft
waves to outer waters.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.

&&

$$
SYNOPSIS...
NEAR TERM...JDW
SHORT TERM...RJD
LONG TERM...MBB
AVIATION...TRA
MARINE...JDW/MBB



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