Area Forecast Discussion
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FXUS62 KILM 210847
Area Forecast Discussion
National Weather Service Wilmington NC
447 AM EDT THU JUL 21 2016
Today will be seasonable and rain-free behind a weak cold front.
Temperatures will surge back above normal for the weekend, with the
possibility of showers and thunderstorms increasing early next week.
.NEAR TERM /THROUGH TONIGHT/...
As of 330 AM Thursday...Dry air in the mid and upper levels under
northerly flow will affect the area this period. Subsidence
aloft, along with its inversion, will place a lid on convection
across the ILM CWA this period. A weak mid-level s/w trof will
remain west of the ilm cwa as it drops southward later today into
this evening. Convection associated with it may affect the far
western portions of the ILM CWA and as a result indicated low
chance pops. In addition, enough forcing along the sea breeze may
produce a few isolated thunderstorms along the sea breeze. The GFS
keeps aftn/evening instability on the low side 1800 CAPE or less
whereas the NAM paints 3000-4000 CAPE. Given what occurred Wed,
will stay closer to the GFS soundings. Overall, plenty of sunshine
with diurnally driven cu and a mostly clear night. For temps,
stayed closer to the GFS Mos guidance.
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 345 AM Thursday...NO POPS being fcst in this 2 day period.
Increasing heat combined with the humidity, will result in heat
indices shy of Advisory criteria on Friday but should break
through thresholds and become widespread on Saturday.
High pressure aloft will bake the Central U.S. this period. One
of its ridge axis`s will extend just north of the area during this
weekend. With dry and warming air in the mid levels, along with
primarily subsidence aloft, the ILM CWA will see a decent
convective lid across the region thruout this period. Clouds will
be limited to diurnally driven cu/sc this period...enhanced by the
sea breeze. In all, no POPs. Widespread 90s for both days, with
sfc dewpoints slowly increasing and becoming widespread 70s by
Saturday. Mixing from aloft may bring down some 60 degree
dewpoints inland on Fri but likely not the case for Sat. Will
indicate Heat Advisory conditions for Sat in the HWO.
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 3 AM Thursday...500mb ridge right overhead Sunday and Monday
and this should keep hot temperatures and little to no precipitation
chances in the forecast. Guidance is showing some areas hotter
Sunday vs Monday while other guidance reverses this trend. In the
end unless the sea breeze dictates otherwise along the coast both
days appear quite similar and both likely candidates for Heat
Advisories. The ridge may be more stalwart than previously though
especially according to the 00Z GFS which now shows little to no
retrogression and thus a similar hot and humid forecast. We may now
have to wait until Wednesday for just enough retrogression of the
ridge from some vorticity centers to stream across the area in the
resulting NW flow. This could temper the heat and also lead to
better chances of thunderstorm, maybe strong to severe ones.
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
As of 06Z...Sky has cleared and wind has gone light and variable as
anticipated. This will allow inland sites to radiate to where some
fog and perhaps stratus will develop. At any coastal location fog
should remain MVFR at worst. Inland locales may dip down to IFR or
even brief LIFR (mainly if a low CIG develops). By daybreak all
terminals back to VFR. Winds will be N-NE veering to the E-S as
the day progresses. A few showers possible near KFLO in the
EXTENDED OUTLOOK...Brief periods of MVFR/IFR from isolated
afternoon convection through Saturday. Otherwise expect VFR.
NEAR TERM /THROUGH TONIGHT/...
As of 330 AM Thursday...The stalled front across or just south of
the area waters will provide a n thru e wind directions across
the local waters today into tonight. Winds near shore will become
southeast due to the sea breeze this aftn/evening. The stalled
front will slowly dissipate tonight and Fri with winds tonight
becoming ne thru se. The sfc pg will remain towards the relaxed
side, yielding wind speeds at 10 kt or less. Significant seas will
run 2 to 3 ft. Other than the local wind chop, seas will primarily
be driven by an ese 1 to 2 foot ground swell at 8 to 9 second
periods. Could see an isolated sea breeze induced tstorm this aftn
or early evening.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 400 AM Thursday...High pressure will build across the waters
from the High`s center offshore from the SE States during this
period. Inland, the Piedmont trof will become a mainstay during
this period. The 2 features will combine and affect the area
waters with winds becoming SW thruout on Fri and continuing
thru Saturday. The mesoscale sea breeze will result in S to SSW
winds nearshore each aftn and evening and provide the increased
wind chop. The sfc pg will be somewhat relaxed Fri with wind
speeds generally around 10 kt. The sfc pg tightens Sat thru Sat
night with wind speeds at 10 to 15 kt with gusts up to 20 kt
possible Sat Aftn thru Sat Night. Significant seas will run 2 to
occasionally 3 ft on Fri with the 1 to 2 foot ese-se ground swell
dominating. For Sat, increasing SW winds will build the local wind
chop and when added to the 1 to 2 foot ground swell, significant
seas will run 2 to 4 ft. No convection being forecast this period.
LONG TERM /SUNDAY THROUGH MONDAY/...
As of 3 AM Thursday...A very unsettled set of changing conditions.
This is not only fairly typical during the heart of summer but it
becomes even moreso during a heatwave. Winds will be 10-15kt and
southwesterly with a piedmont trough in place while the Bermuda
high is displaced eastward of its normal position. Seas will
average 2 to 3 and occasionally 4 ft.