Area Forecast Discussion
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FXUS62 KILM 181817 CCA
Area Forecast Discussion
National Weather Service Wilmington NC
217 PM EDT Tue Apr 18 2017
A cold front will drop south stalling in South Carolina later
today before lifting back north as a warm front on Wednesday. The
Bermuda High will expand west over the region Thursday through
Saturday. Another cold front may reach down into the Carolinas
.NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM Tuesday...A cold front was progressing southward
this morning reaching through our forecast area. By mid morning
it was draped just north of the tip of Cape Fear southwest into
SC. A moisture rich air mass with fairly deep column of
moisture and more stable air mass behind was producing low
clouds with northerly winds behind the front. Ahead of the front
the winds were still S to SW with some mid clouds mixing with
the sunshine. Temps to the north were in the mid 60s while to
the south the temps were into the 70s. The heating to the south
will produce more unstable conditions this afternoon and
therefore included some thunderstorms into northeast SC this
aftn. Temps to the north of the front will struggle to reach
into the 70s.
The main focus for shower activity will be along the front but
will also be aided by some differential heating and convergence
along the sea breeze. HRRR shows the main focus of showers over
coastal NC this morning but over SC this aftn where the greater
heating and instability will be. Also focuses some shower
activity along the sea breeze boundary in SC. May see a few
showers producing a quick shot of heavier rain but overall QPF
will be on the low side and will be focused mainly south and
west of the local forecast area overnight. Lows tonight will be
influenced by the moisture and will fall modestly to within a
couple of degree of 60 area wide.
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 315 AM Tuesday...Chief feature this period is a weak and
meandering frontal boundary over the area, perhaps enough to
focus a few showers or a TSTM Wednesday, while interacting with
a flimsy inland migrating sea breeze boundary aligned with the
synoptic trajectories. This should provide an opportunity for a
shower or storm for any local but not all will see fruition of
measurable rainfall, as dynamical energy remains mediocre at best.
Thursday will be warmer than Wednesday as low-level winds cut off
the maritime influence ashore, becoming W-SW. Have opted to remove
thunder Thursday since mid-level drying will set in capping the
column above 10 thousand feet. Consequently, also expect more clouds
Wednesday compared to Thursday. Small POPS were inserted Wednesday
night despite diurnal cooling as weak boundary remnants begin to
lift north over the area.
.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 300 PM Monday...A low amplitude upper ridge and Bermuda
high pressure will bring unseasonable warmth. The ridge will not
be strong enough to suppress isolated sea breeze convection by
the looks of it. A very slow moving front will enter the area on
Friday and so isolated storms will be possible just about
anywhere while temperatures remain elevated above their
seasonable norms. Thereafter the details become a bit convoluted
but the late weekend trend does seem to be rather unsettled.
Strong troughiness will be developing to our west leading to
cyclogenesis. The speed at which this brings the front back as a
warm front as well as the timing of the system`s trailing cold
front are not well agreed upon between various guidance. Right
now it appears the former occurs Saturday and the latter on
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
As of 18Z...A cold front has almost cleared the TAF forecast area
as it is making its way south through NE SC early this
afternoon. Just to the north of the front was decent coverage of
low IFR stratus and spotty pcp and fog bringing vsbys into
MVFR. Overall expect IFR to MVFR cigs along and just north of front
into early eve as front slows to a halt over SC. To the south of the
front expect mainly VFR but scattered showers will erupt producing
possible MVFR ceilings in SHRA and iso TSRA with possible IFR in
brief heavier rain until this eve, but this activity should remain
inland from CRE/MYR. Expect conditions to improve up to MVFR over NC
TAFS into this evening but IFR will return in light rain and fog
overnight into Wed.
Extended outlook...MVFR/IFR conditions possible in showers and
TSTMS Wed and Wed night.
NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM Tuesday...A rather weak cold front is dropping
slowly south across the waters, but will stall out near or just
south over SC waters later today. Winds will be N to NE north of
the boundary and S to SW to the south of the south. Most of the
coastal waters will see a northerly component to the winds
develop through today with the exception of AMZ256 where the
front may stall producing more variable winds. Winds will be
generally light but will increase and become gusty behind the
front later today. The increase in winds with a greater on shore
component will push seas up from less than 3 ft up to 3 to 5 ft
overnight into Wed morning.
SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
As of 315 AM Tuesday...Manageable marine conditions to prevail
Wed/Thu. Seas in recovery mode Wed with onshore winds so the
subsiding trend will be a slow one Wed, but no advisories or
caution statements appear to be needed, but it will be a bit
bumpy in 3-4 foot seas in 7 second intervals from the E. An
improving trend Thu as surface winds turn to WSW-SW and ease
up, as weak and broad high pressure over the area unravels the
pressure gradient. Thu 2-3 foot seas in a mix of E-SE wave trains.
This period do expect a few marine showers and isolated TSTMS.
Getting a radar check is recommended before venturing out both
LONG TERM /FRIDAY THROUGH SATURDAY/...
As of 300 PM Monday...The period may start with light W wind
but a SW flow should become established at Thursday wears on
with a large area of high pressure off the coast. This SW flow
will continue through the period and may become a bit more gusty
as a cold front approaches from the NW. The appearance of 4 ft
seas will be gradual but should increase through the Friday-