Area Forecast Discussion
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FXUS62 KRAH 311828
Area Forecast Discussion
National Weather Service Raleigh NC
225 PM EDT Tue May 31 2016
.SYNOPSIS...Post Tropical Cyclone Bonnie over northeast South
Carolina will drift slowly to the northeast along the North Carolina
coast through mid week, before moving offshore. A cold front will
approach from the west late in the week.
.NEAR TERM /through Wednesday night/...
As of 1230 PM Tuesday...
Quick update for recent trends. Stratus this morning was slower to
develop than previous mornings and it was accordingly easier to burn
off. Much of central NC is experiencing a mix of sun and clouds
with a few areas including the Triad and parts of the Coastal Plain
experiencing a good deal of sunshine. This has allowed temperatures
to warm to the upper 70s to lower 80s in most locations including 83
in Greensboro last hour. The radar is rather quiet in central NC at
this point although some cumulus build ups are now appearing in the
southern Coastal Plain and across the Triad where sunshine has
allowed the boundary layer to warm and MLCAPE values have
accordingly increased to greater than 1000 J/Kg. Convection allowing
models suggest convection will be slower to light up today than
previous (which appears on target) with the greatest chances across
the Coastal Plain with the convection pushing westward into the
Piedmont with time. No real severe weather threat with lackluster
lapse rates and weak shear although PW values in the 1.4 to 1.8
range combined with slow motion will result in locally heavy rain in
at least a few storms. Showers will gradually decrease in coverage
this evening with the loss of heating. While some fog and stratus is
expected tonight, it will likely develop later and wont be as
widespread as previous nights. Greatest fog impact likely to be
across the Sandhills and Coastal Plain from KFAY north to KRWI and
KRZZ. Lows in the mid to upper 60s. -blaes &
.SHORT TERM /Thursday through Friday night/...
As of 305 AM Tuesday...
Post-tropical storm Bonnie will continue to spin along the North
Carolina coast on Thursday with most of the precipitation occurring
east of I-95. Back to the west, a frontal system will move towards
the Appalachians and into western NC. For central NC this could mean
a lull in the soggy weather and perhaps a mostly dry day for much of
the area. Still expect partly to mostly cloudy skies however and
still a tropical air mass in place with highs in the mid 80s and
dewpoints in the upper 60s. Any showers and thunderstorms that do
occur could produce some locally heavy rain but otherwise not much
QPF expected. Lows Thursday night only dropping down into the upper
On Friday, the remnants of Bonnie will finally move offshore to our
northeast and attention will turn to the frontal system moving in
from the west. Any dynamics with this system will be well to the
north of our area. A few waves moving along the front from the south
to north will provide some vorticity in the mid to upper levels. The
main forecast problem surrounds how far south the front will be able
to push. At this time...the GFS solution has a big stronger of a
surface high over the Ohio Valley that helps to push the front
further south by Friday afternoon. This scenario suggest plenty of
showers and thunderstorms for the entire forecast area on Friday,
whereas the ECMWF solution has rain only in the north and western
portions of the CWA. With the lack of forcing the ECMWF solution
seems more likely at this time. This will also keep temperatures and
dewpoints up in the mid 80s and upper 60s respectively as there will
not be any air mass change on Friday. Lows Friday night in the upper
60s to near 70 degrees.
.LONG TERM /Saturday through Monday/...
As of 305 AM Tuesday...
The evolution of the front in both models is fairly similar for
Saturday as a tropical upper ridge helps to stall the front out over
the area making another wet weekend the most likely scenario for
central NC. Looking back to the west, a new and more organized low
pressure system moves into the western Great Lakes on Saturday with
a frontal system extending down the Mississippi Valley with an upper
trough to support it. This system will eventually take the stalled
front back to the north as a warm front as the cold front approaches
from the west later on Saturday and into Sunday. Pre-frontal
precipitation, supported by several strong waves from the southwest
will affect the area on Sunday. The current GFS scenario is very wet
on Sunday night into Monday and the ECMWF is much more subdued. This
leads to a very low confidence forecast for day 7 but will carry
pops through Monday. Continued low to mid 80s for highs with lows in
the mid to upper 60s.
.AVIATION /18Z Tuesday through Saturday/...
-- Changed Discussion --As of 225 PM Tuesday...
VFR conditions are noted across central NC this afternoon with a
deck of SCT-BKN cumulus clouds at several layers between 3-6kft.
A band of showers and thunderstorms across the far southeastern NC
this afternoon will shiftslowly northwest into the Sandhills and
southern Coastal Plain this afternoon, likely impacting KFAY and
KRWI with a period of MVFR CIGS an VSBYS from 20-24Z. These showers
will likely diminish in coverage and intensity as they move into the
eastern Piedmont toward KRDU late this afternoon or early evening.
Elsewhere, isolated to scattered showers and thunderstorms are
possible although the overage will preclude a mention in the TAF.
Just about all of the convection will wane during the course
of the evening with little activity after midnight.
Stratus and fog will likely develop again late tonight although
later than previous nights and with reduced coverage and duration
than previous nights. Look for a period of MVFR-IFR CIGS and VSBYS
tonight with the worst conditions likely to occur across the Coastal
Plain and Sandhills impacting the FAY and RWI terminals with a much
reduced chance of reductions in the Triad at the INT/GSO terminals.
The stratus and fog should quickly dissipate Wednesday morning with
VFR conditions expected to dominate by 14Z Wednesday.
Looking beyond 18Z Wednesday: Another round of scattered afternoon
and evening showers and isolated storms is expected on Wednesday
and Wednesday evening with brief MVFR conditions. A repeat of
MVFR/IFR stratus/fog is expected to develop Wednesday night. Chances
of afternoon/evening storms on Thursday decrease a bit compared to
previous days before increasing again on Friday into Saturday as a
cold front approaches from the west. -blaes
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