Area Forecast Discussion
Issued by NWS Wilmington, NC

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414
FXUS62 KILM 281920
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
320 PM EDT Wed Jun 28 2017

.SYNOPSIS...
Dry high pressure will move off the Mid-Atlantic coast tonight
and Thursday. A warm front will lift northward across the
Carolinas Friday, accompanied by increasing chances of showers
and thunderstorms. Bermuda High Pressure offshore this weekend
and much of next week will bring warm and humid conditions along
with scattered thunderstorms each day.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 300 PM Wednesday...Almost perfect weather this afternoon
with a a few cumulus developing northwest of a line from
Darlington to Lumberton. The high pressure center that is
controlling our area is over the DelMarVa this afternoon and
will continue to slide to the east. This will allow for a return
of moisture and the warm up will begin for the area.

The statistical guidance continues to show a dry Thursday but the
GFS20 model indicates possible convective activity along the sea
breeze on Thursday afternoon.  At this time will keep just below
20% for the afternoon thunderstorms.

Lows overnight will range from 62 degrees inland to the upper 60s at
the beaches. Thursday`s highs will reach the upper 80s inland to the
middle 80s at the coast.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 300 PM Wednesday...High pressure off the Mid-Atlantic coast will
spin in place through the end of the week as mid-level ridging
amplifies offshore. The increasing 1000-500mb thicknesses will back
into the Carolinas this period, so temperatures will slowly begin to
warm, most notably by increasing overnight mins vs higher aftn maxes
thanks to onshore flow. Highs Friday will rise into the mid and upr
80s, with mins Thursday night hovering around 70, and only cooling
into the low 70s Friday night.

As the ridge amplifies offshore, mid-level moisture gets funneled
into the Carolinas from the Gulf Coast and PWATs approach 2 inches
during Friday. This occurs in tandem with a slow moving shortwave
lifting SW to NE across the Southeast, and Friday should feature
quite a bit of thunderstorm coverage. The peak of this activity will
be diurnally forced as MLCape rises over 1500 J/kg, but will be
mainly of the pulse variety thanks to 0-6km shear less than 20 kts.
However, as thicknesses climb and moisture increases, the warm cloud
depth will climb to near 14 kft, so torrential rain will be possible
in any stronger storms. Most activity will wane diurnally, but the
presence of the upper vort necessitates at least SCHC POP through at
least the first part Friday night, although the best axis will
likely shift offshore.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 300 PM Wednesday...After the cool weather of the last couple
of days, summer heat and humidity should come roaring back next
week. Persistent upper level ridging across Florida and the Gulf
Coast and the Bermuda High offshore will allow heat and humidity to
build through the period. A time-series plot of forecast 850 mb
temps shows +17C Saturday, +17.5C Sunday, and +18C Monday through
Wednesday. The ECMWF actually has some forecast 850 mb temps near
+20C by next Wednesday, however we`ve noticed over the past several
years there is a summer warm bias in the ECMWF at the extended range.

The airmass should be moderately to strongly unstable through the
period with CAPE values rising to 2000-3000 J/kg each afternoon.
West to northwest flow aloft, a pinned seabreeze near the coast, and
a well-defined Piedmont trough (perhaps evolving into an inland
thermal low for a few days next week) should set the stage for
scattered diurnally-driven storms each day. Precipitable water
values are highest Saturday (2.0 to 2.2 inches) falling to around
1.8 inches Monday and Tuesday.

With afternoon in the 90s inland with dewpoints in the lower 70s,
heat indices should reach 100 to 103 degrees in most locations away
from the beaches each day next week.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
As of 18Z...VFR conditions are expected through this forecast
period as high pressure and drier air will remain. At the end of
the period few to sct clouds below 4000 ft are possible as
onshore flow begins. Northeast winds are expected to veer to the
east this afternoon with speeds reaching 8 to 10 knots in the
afternoons. Overnight winds will be less than 4 knots except
along the southeast coastal TAFS which see winds of 5 to 8
knots.

Extended Outlook...MVFR and IFR conditions are possible in and
near diurnal convection each day from Friday through Monday.

&&

.MARINE...
NEAR TERM /THROUGH THURSDAY/...
As of 300 PM Wednesday...Northeast to east winds of 10 knots
over the waters will continue to veer slightly overnight and
will be from the east over all the waters by daybreak. Seas are
running 2.5 feet at Frying Pan Shoals and 2.0 feet at 41110 and
the seas of 2 to 3 feet are expected to continue throughout the
overnight.

SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 300 PM Wednesday...Surface high pressure off the Mid-Atlantic
coast will gradually retreat to the east through Friday night
allowing winds to shift from E/SE to S/SW through the period. The
gradient remains relaxed in the vicinity of this high pressure, so
wind speeds will be 10 kts or less regardless of direction. This
will keep seas at relatively low amplitude, 2-3 ft, with a 2 ft SE
swell and 2 ft S wind wave comprising the spectrum.

LONG TERM /SATURDAY THROUGH MONDAY/...
As of 300 PM Wednesday...Bermuda high pressure well offshore will
extend its ridge axis westward across Florida and into the northern
Gulf of Mexico this weekend into early next week. With the ridge
remaining south of the ridge, mainly southwesterly winds are
expected through the period with the typical afternoon seabreeze
backing wind directions more southerly with an increase in wind
speeds.

With inland highs in the 90s and westerly winds aloft, there should
be scattered thunderstorms making their way down to the beaches and
offshore virtually every afternoon. The best potential appears to be
Saturday, however no day will be immune to this potential.
Average sea heights of 2-3 feet are expected.

&&

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

&&

$$

SYNOPSIS...TRA
NEAR TERM...DRH
SHORT TERM...JDW
LONG TERM...TRA
AVIATION...DRH



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