Scientific Forecaster Discussion
fxus62 kmhx 201947
Area forecast discussion
National Weather Service Newport/Morehead City NC
347 PM EDT Tue Aug 20 2019
high pressure offshore will extend west into eastern North Carolina
through mid week as a troughing lingers well inland. A cold
front will slowly approach the area late this week and into the
Near term /tonight/...
as of 3 PM Tue...scattered thunderstorms, mainly triggered by
outflow boundary collisions, are possible through the rest of
the day, with activity likely peaking through the late
afternoon and early evening before quickly diminishing after
sunset. A few storms could be strong to severe given cape values
over 3000 j/kg, but organized convection is not expected.
Tonight will be mainly dry as Bermuda high pressure ridging just
south of the area remains in control. Most inland areas will
decouple, but radiational cooling will be inhibited by
persistent cirrus coverage through the night. The warm and humid
airmass in place will keep lows several degrees above normal.
Short term /Wednesday/...
as of 3 PM Tue...a weak upper low over the SC upstate this
afternoon will slide across the NC Piedmont Wednesday as it is
absorbed into a shortwave trough passing across the Great Lakes
and northeast. The attendant surface low will remain very weak
as it passes inland through the day before deepening as it moves
into the mid-Atlantic late in the afternoon. Thunderstorm
coverage is expected to be greatest for inland areas in closer
proximity to the enhanced lift inland, though increased cloud
cover with the low will limit thermodynamic instability to some
extent. Closer to the coast, isolated to scattered convection is
to tap with the sea breeze and outflow boundary collisions.
Highs will be a couple of degrees above normal, with low level
thickness values favoring highs near 90 away from the beaches
under partly to mostly cloudy skies.
Long term /Wednesday through Monday/...
as of 240 am tues...high pressure will extend over the area
through Thursday with only scattered thunderstorms expected.
A cold front will approach the area Friday, and then slowly
cross through the forecast area over the weekend, leading to
another period of unsettled weather.
Wednesday night and Thursday...scattered afternoon
thunderstorms are expected again Thursday with a weak Lee
trough forming over central NC, and continued possible
convective initiation along the sea breeze each day. Also
expecting some nocturnal offshore convection to Blossom and move
over coastal areas in the overnight hours both Wednesday and
Thursday nights. High temps will be slightly above average
through this period, with readings in the low 90s inland and the
mid to upper 80s along the coast. Warm and humid nights will
Friday through Monday...major model differences remain from
Friday through early next week as a cold front moves south into
the area. The latest GFS still shows a quick moving front
dropping into NC on Friday and then sinking south of the area
by Friday night...and into the deep south by the end of the
weekend. In this solution Friday and the first half of Saturday
would be very wet, with drier and much cooler air moving into
the region. Meanwhile the latest European model (ecmwf) shows a slower moving
front still in southern Virginia Friday night, which finally crosses
into the area by Sunday...and then stalls just south of the
forecast area, which would lead to an extended period of
unsettled weather Saturday through at least Monday.
Will continue to hedge towards a middle solution, but with much
of the upper level trough remaining north of the area and with
the current time of year in mind, would tend to favor a solution
closer to the European model (ecmwf) with a slow moving front eventually stalling
around or just south of the area. So, will keep high chance pops
in the forecast from Friday into early next week. Temperatures
will likely be slightly below normal through this period with
highs mostly in the low to mid 80s, and low temps seasonably
cool in the 60s and low 70s.
Aviation /19z Tuesday through Sunday/...
short term /through Wednesday/...
as of 120 PM Tue...VFR conditions are expected for the rest of
the taf period. A few isolated showers or storms may pop up this
afternoon, but coverage is expected to be low and any impacts
to taf sites would be short-lived. The latest guidance continues
to suggest a low probability for fog overnight.
Long term /Wednesday night through Sunday/...
as of 300 am Tue...mostly VFR conditions expected through
Friday morning, with scattered convection expected during the
afternoons and evenings. Then Friday afternoon through much of
the weekend, low visibilities and ceilings are possible as a
cold front moves into the area and rain chances increase. Patchy
fog also possible in the early mornings with high dewpoints and
rather light winds.
short term /today and tonight/...
as of 3 PM Tue...Bermuda high pressure will continue to dominate
through Wednesday, keeping southwest winds in place. Overnight,
expect moderate winds, with the chance for some isolated
thunderstorms producing locally gusty winds. Wednesday, low
pressure developing over the mid-Atlantic later in the day will
tighten the gradient locally in the afternoon, with moderate
winds becoming breezy through the day. The gradient will be
tight enough that occasional to frequent gusts to 25 kt are
possible mainly for the sounds and coastal waters north of Cape
Lookout by late afternoon, and a Small Craft Advisory may be
needed. Seas will be mainly be around 3 ft through tonight,
increasing to 3 to 5 ft as increasing winds develop more locally
generated wind swell by late Wednesday afternoon.
Long term /Wednesday through Saturday/...
as of 300 am Tue...winds will be SW 15-20 kts Wednesday night
through Friday morning, with gusts up to around 25 kts along the
coastal waters and Pamlico Sound. Winds will weaken and turn to
the west, and eventually north, as a cold front crosses the
region on Saturday.
Seas will be 2-4 ft through Wednesday night, and then increase
to 3-5 ft early Thursday morning through Friday afternoon, with
some 6 foot seas possible along the outer coastal waters. Seas
then continue to subside to 2-4 on Saturday.