Area NWS Forecast Discussion

FXUS62 KILM 180237

Area Forecast Discussion
National Weather Service Wilmington NC
1037 PM EDT Fri Aug 17 2018

Bermuda high pressure remaining offshore will pump warm and
humid air across the Carolinas through the weekend. Showers and
thunderstorms should become more widespread Saturday and Sunday
as a front stalls to our north. Another cold front could
approach from the west Wednesday and Thursday, accompanied by
more wet weather.


As of 1000 PM Friday...For the most part the offshore ridging
sfc and up thru the mid-levels has kept convection in check. But
farther inland and SW of the ILM CWA, convection has been able
to develop and push downstream and has reached and partially
pushed across the ILM CWA. The activity will weaken intensity-
wise and also coverage-wise during late this evening thru
daybreak Sat. A few SPS worthy statements may still be in the
offering before the activity finally falls apart or just
continues to weaken as it pushes across the FA. Overall, have
lowered POPs across the majority of the FA with the exception of
the current tsra activity and POPs associated with it as it
tracks NE across the FA during the pre-dawn hrs. Very little if
any tweaking to temps applied.

As of 300 PM Friday...Downsloping mid level flow has won out so
far today with deep convection failing to develop-merely
isolated showers. This will change somewhat gradually through
the period. The mid level ridging will weaken and move east
allowing for more of a moistening southwesterly flow to develop.
Along with the SW flow will be a few small scale embedded
shortwaves. POPs will be rising overnight though with no
instability coverage should remain low. Saturday on the other
hand could be rather unsettled. Will cap POPS in the chance
range for now as the trend towards busier weather has been
seemingly rushed by guidance lately.


As of 300 PM Friday...A more active period is in store for our
local forecast area through this period, over the latter
portion of the weekend. The upper ridge that was maintaining
drier aloft and increased subsidence in the upper levels, will
shift farther south and east as an upper trough pushes east
toward the Southeast Coast. Pcp water values will reach up near
2.25 inches in deep SW flow Sat night through Sun. The main
forcing mechanisms will remain the same with the sea breeze and
trough inland as initial points of convergence each aftn. The
gradient will tighten between a cold front dropping south and
east into VA/NC vicinity and Bermuda High off shore. The
stronger SW flow on Sat will act to increase shear and the mid
to upper level dynamics will help enhance the localized
convective activity. This should fuel the storms along with
boundary interactions to produce a general increase of activity
through Saturday. Also expect coastal showers to be more
widespread in a brief period of increased S-SW flow Sat night
into Sun morning. Overall, a hot and humid air mass will
continue to be in place with temps in the mid 70s for lows and
near 90 overnight.


As of 300 PM Friday...An active period of weather looks likely
much of the extended as a series of fronts/troughs impacts the
Southeast. The net result will be an extended period during
which at least scattered convection is possible each day. Max
temperatures will be seasonable, reaching the upper 80s to lower
90s through Wednesday before a front in the area results in max
temperatures in the low to middle 80s for Thursday and Friday.
Mins should generally be in the low to mid 70s but a few upper
60s are possible well inland Thursday night.


As of 00Z...Little to no convection is expected overnight, with
little to no fog as well. Winds will diminish after sunset.
Saturday, the ridge breaks down a bit, allowing for mid and upper
level moisture to take hold. There should be more cloud cover than
in previous days. This may hold CAPE down a bit, but we still should
see scattered convection breaking out after midday. Southwesterly
winds will become gusty by late morning.

Extended Outlook...Precipitation chanced will be fairly high through
Monday. Mainly diurnal thunderstorms will continue into mid week.


As of 1015 PM Friday...Latest winds of SW 15 to occasionally 20
kt will continue across trhe local waters overnight. Have taken
out the 25 kt gusts for the overnight into daytime Sat. Latest
Obs indicate gusts are confined to around 20 kt except for 41013
which indicates closer to 25 kt gusts. Significant seas will run
3 to 4 ft with 5 footers developing just outside of 20 nm off
Cape Fear. Wind driven 4 to 5 second period waves will dominate.
A fading 1 to 2 foot SE ground swell remains present at 8 to 9
second periods.

As of 300 PM Friday...Southwesterly flow is gradually
strengthening and will continue to do so through the period.
This is mostly in response to a developing piedmont trough but
also a deepening of the southwest flow as mid level flow backs
from being westerly. The increase in seas will largely occur
outside of the 20nm forecast zones but 4 ft seas will still make
their way into the forecast.

As of 300 PM Friday...SW flow will continue through the period.
The gradient will tighten as a cold front drops south into NC/VA and
the Piedmont trough strengthens. This will increase S-SW flow
through late Sat aftn into the evening possibly enough to lead
to a short period SCEC. Overall expect SW flow 5 to 15 kts, but
up closer to 15 with higher gusts through Sat aftn into Sat
night in more of a pinched gradient. This should drive seas up
to 4 to 5 ft in the outer waters. The SW component to flow
should keep highest seas in the outer waters. Otherwise expect
seas 2 to 4 ft through the remainder of the period.

As of 300 PM Friday...Overall, SW winds in the 10 to 15 KT range can
be expected through the long term period. Seas will run 2 to 4 FT
through much of the period, though 3 to 5 footers are possible
northern waters Tuesday into early Wednesday.





NWS ILM Office Area Forecast Discussion