Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC
FXUS62 KRAH 300704
Area Forecast Discussion
National Weather Service Raleigh NC
304 AM EDT Mon May 30 2016
.SYNOPSIS...Tropical Depression Bonnie, located over the central
South Carolina coast, will drift slowly toward 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 /Today and Tonight/...
As of 925 PM EDT...
Tropical cyclone Bonnie has been nearly stationary over the past
several hours. A slight jog to the northeast is expected late
Convective coverage has certainly been on a wane since loss of
daytime heating. And despite the tropical moisture in place (PWS of
1.75-2.0"...1 to 2 S.D. above normal), much of the Hi-res CAMS
indicate this lull will continue through most of the night.
Will trim back pops for the remainder of the night, with chance pops
over the Piedmont while keeping likely pops in the east where
continued DCVA to the northeast of the circulation center, lifting
atop the inverted trough/coastal front extending along the I-95
corridor will provide the best focus for lift and showers overnight.
Expect a wide range in temperatures overnight with lows in the
lower/mid 60s NW where CADish airmass resides, to lower 70s
over the easter/southeastern counties, east of the sfc trough.
.SHORT TERM /Monday through Monday night/...
As of 215 PM Sunday...
The remnants of TD Bonnie are expected to track very slowly ENE from
northeastern SC into southeastern NC Monday and Monday night.
Additional locally heavy rain is expected over portions of central
NC with the main focus likely along or near the track of the low.
This would place the SE Piedmont, Sandhills, and Coastal Plain in
the heaviest QPF of 1 to 1.5 inches with locally higher totals. POP
and QPF will be lower back in the NW Piedmont where some drier
low level air will advect off the higher terrain into the far
western Piedmont lowering the PW`s and lift there. Skies should
range from Cloudy down east to variably cloudy in the western
Piedmont. Showers and isolated thunderstorms will affect the eastern
third of the region with much more scattered showers to the west.
Highs Monday will again be held down by the clouds and rain,
especially in the east where readings will be in the 70s to near 80.
Highs in the western Piedmont should be around 80. Lows generally in
the 65-70 range.
.LONG TERM /Wednesday through Sunday/...
As of 305 AM Monday...
Wednesday and Thursday: Tropical Depression Bonnie will continue to
churn off the North Carolina coast on Wednesday somewhere between
Wilmington and Cape Lookout. With no steering flow in place the
forecast remains status quo with the best chances for precipitation
in the east but models also hinting at precipitation forming as the
result of orographic uplift as northeasterly flow approaches the
Appalachians. Therefore will carry chance of showers and
thunderstorms everywhere. Hot and humid with highs in the upper to
middle 80s and dewpoints in the mid to upper 60s. Lows Wednesday
night in the mid 60s.
Thursday will see the depression move a bit further northeast and
thus central NC may see a bit of a lull in precipitation before the
next system approaches from the west. Will carry low chance pops in
the forecast but it is possible that precipitation isn`t realized
until later in the day as moisture transport ahead of the front
increases. By evening expect thunderstorms to become more numerous
in the Triad and points west. These will be driven mostly by diurnal
heating as any dynamics associated with the fronts parent low will
reside well to the north. Highs still in the mid 80s with lows in
the mid to upper 60s.
Friday through Sunday: Low pressure moving through the Northern
Great Lakes and into Ontario and Quebec will move a frontal zone
over the east coast and leave it there as it detaches and heads
northeast. Back to the southwest an upper level low developing over
Texas will help to initiate the development of a broad upper trough
that will drape itself over the eastern US for several days. At the
surface a couple of waves, most notably on Saturday afternoon, will
move along the front and supply extra forcing for showers and
thunderstorms over central NC. Expect best chances in the afternoon
each day. Temperatures will cool off some during this time starting
in the mid to upper 80s on Friday afternoon down to the lower 80s by
Sunday afternoon. Lows each night in the mid to upper 60s.
.AVIATION /06Z Monday through Friday/...
As of 1240 AM Monday...
Periods of adverse aviation conditions are expected over the next 24
hours at Central NC terminals, as very moist air remains in place
over the area. At INT/GSO, MVFR cigs are expected to develop and
persist through the morning, before gradually lifting to VFR during
the early afternoon hours. Scattered showers this afternoon may
generate brief MVFR vsbys, but otherwise VFR vsbys are expected
during the daylight hours today. At RDU/RWI/FAY, IFR cigs are
possible early this morning, with the best chances at RDU, where IFR
vsbys are also possible. Vsbys at these three sites should improve
to VFR later this morning, with cigs slower to improve, trending to
MVFR during the afternoon. Isolated showers with MVFR vsbys are
likely to pass near RDU/RWI/FAY through this morning, then coverage
is expected to increase by afternoon, with numerous showers and a
few thunderstorms this afternoon into evening producing brief MVFR
to IFR conditions mainly at RDU/RWI/FAY. Shower/storm coverage is
expected to slowly decrease this evening with a trend to MVFR to IFR
conditions after sunset.
Looking beyond 06Z early Tue morning: MVFR to IFR conditions are
likely to hold through mid morning Tue, with improvement to MVFR
east and to VFR west during Tue afternoon. Nightfall will bring
another trend to sub-VFR conditions at all sites Tue night, as the
air mass remains moist and unsettled with the center of TD Bonnie
tracking slowly toward the NNE along the NC coast. Improvement to
VFR is expected Wed lasting into Thu especially at INT/GSO, as
Bonnie moves out over the sea, although sub-VFR vsbys in fog are
possible late Wed night into early Thu morning with light surface
winds. A cold front approaching from the west Thu night may bring
sub-VFR conditions in showers/storms on Fri. -GIH