Area Forecast Discussion
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FXUS62 KRAH 291814
Area Forecast Discussion
National Weather Service Raleigh NC
215 PM EDT Sun May 29 2016
.SYNOPSIS...Tropical cyclone Bonnie will track inland along the South
Carolina coast today, then turn northeast and track along the North
Carolina coast through early next week.
.NEAR TERM /Today and Tonight/...
As of 1215 PM Sunday...
Quick update to the forecast discussion for this morning. As of 1130
am EDT...tropical cyclone Bonnie has tracked inland over southern
SC. Shower activity has increased over central NC this morning, with
the heaviest activity focused invof an inverted trough/coastal front
south and southeast of the Triangle where PWAT values are AOA 2.00"
and weak diurnal destabilization has occurred. The primary forecast
concern this afternoon will be a potential for isolated flash
flooding in areas repeatedly affected by heavy showers, and a low-
end potential for an isolated/brief tornado in the far southeast
coastal plain (Cumberland/Sampson/Wayne counties) where the latest
SPC mesoanalysis indicated a supercell composite parameter of 1-2
and mlcape of ~500 J/kg. With a mean storm motion from the SE (from
~160 degrees), rotating updrafts exhibiting deviant motion will tend
to propagate to the N/NNE (from ~190 degrees). A rotating updraft
exhibiting deviant motion toward the N/NNE and echo tops approaching
40 KFT has already been observed in Lenoir county late this morning,
lending strong support to the notion that a low-end risk for a
brief/isolated tornado is present in southeast NC this aft. -Vincent
.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 /Tuesday through Sunday/...
As of 205 PM Sunday...
The remnants of TD Bonnie are still expected to be a factor into
Tuesday and possibly Wednesday for eastern sections of NC. We will
follow the latest NHC forecasts which indicates a very slow moving
depression finally beginning to get steered a bit quicker NE along
the coast Tuesday afternoon through Wednesday.
Models are in good agreement in depicting the highest
POP near the coast along a low level boundary and very
near the track of the low. This appears very reasonable although
there will be a chance of showers and isolated thunderstorms inland
with the QPF much lower than along the track of the low. QPF of
0.25 to 0.50 with locally higher totals can be expected over the far
eastern Coastal Plain with QPF of 0.25 or less inland over much of
central NC. Day time temperatures will be held in check but the
humidity levels will remain high. Expect highs to reach back into
the 80-85 range Tuesday and Wednesday. Lows in the mid to upper
Later in the week, expect the influence of the TD to give way as the
remnant low is bumped east as mid level troughing moves out of the
Rockies and heads eastward. This system should approach the
Appalachians and mid-Atlantic region next weekend and is expected to
bring significant convective rains at times by the end of the week
into the weekend. A slow moving cold front is expected to stall over
the SE states by the weekend focusing heavy QPF. Lows will be well
above normal 65-70 and highs in the 80s cooling into the 75-82 range
.AVIATION /12Z Sunday through Thursday/...
As of 615 AM Sunday...
FAY has already dropped to IFR in rain, and elsewhere, the current
VFR conditions will slowly deteriorate to MVFR or IFR later this
morning, although some brief improvement back to VFR may occur this
afternoon. The center of Tropical Storm Bonnie, currently located
off the SE coast east of SAV (see www.nhc.noaa.gov for the latest),
is expected to push slowly to the NW before stalling out near the
central SC coast through much of today. A surge of Atlantic moisture
to the NE of Bonnie will bring a band of showers toward the NNW
through central NC this morning into early afternoon, followed by
patchier and more widely scattered showers and perhaps a storm or
two during the mid to late afternoon, with the best chance of storms
at RDU/FAY/RWI. Within this first band of steady showers, cigs and
vsbys should drop to MVFR with cigs potentially IFR at times. Once
this main band shifts northward by early afternoon, conditions
should vary between MVFR and VFR through early evening. MVFR to IFR
fog and stratus are apt to redevelop after sunset, especially at
INT/GSO/RDU, with scattered showers persisting areawide.
Looking beyond 12z Mon: Unsettled weather will linger with periods
of sub-VFR conditions expected through Mon, including a good chance
of showers and storms Mon afternoon, especially at RDU/RWI/FAY. IFR
fog/stratus is likely to redevelop for Mon night / Tue morning.
Numerous sub-VFR showers and storms expected Tue afternoon at
RDU/RWI/FAY, with less coverage and mostly VFR conditions at
INT/GSO. Chances for sub-VFR showers diminish by Wed/Thu as the TS
Bonnie circulation and associated upper level disturbance finally
shifts NE away from the forecast area. -GIH