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fxus62 krah 190731 

Area forecast discussion
National Weather Service Raleigh NC
330 am EDT Sat Oct 19 2019

high pressure extending into the area from the north will move
northeast and away from North Carolina this morning. The remnants of
tropical storm Nestor will approach from the southwest this
afternoon, then track over the eastern Carolinas tonight through
Sunday morning, before pushing offshore Sunday afternoon. Weak high
pressure will pass over the area Sunday night through Monday. A
storm system will move in from the west Monday night and Tuesday.


Near term /today through tonight/...
as of 310 am Saturday...

..remnants of Nestor will bring gusty winds and soaking rains late
this afternoon through tonight...

The center of what is now ts Nestor is currently located roughly 90
miles south-southwest of Panama City FL, moving NE. Most of the convection is
still to the north and east of the center, and this should remain the case
as the storm center makes landfall over the central Panhandle of Florida
this morning, with the solid rain shield maintained by confluent
high-precipitable water feeds from the Gulf and Atlantic. Model output and
extrapolation of the existing rain shield shows spotty light rain
working into the SC border counties of central NC just before noon,
and this will be followed by the gradual overspreading of the more
steady and moderate rain from SW to NE during the afternoon as the
storm center pushes NE through S Georgia. Have used a GFS/European model (ecmwf) blend for
precip timing, although these along with the NAM/Canadian/icon and
cams are all pretty close. Expect pops to trend up to 50-100% from
Raleigh to the SW during the 18z-00z window with pops under 50% over
the NE. The low center will continue a NE motion through eastern SC
into southeast NC from mid evening through tonight. While it will continue
losing tropical characteristics after landfall, the incoming precipitable water will
be well over 200% of normal with high rainfall efficiency (lcl-0c
depth near 4 km) and the added forcing for ascent from the
approaching shortwave trough and intense upper divergence will favor
widespread rain with elevated rates. Categorical pops (100%) for
moderate to heavy rain will rule this evening/tonight areawide,
although the heavier rain should start to taper down in intensity
and coverage over the SW County Warning Area toward daybreak sun. Have bumped up
rainfall a bit through tonight, based on the above factors, to 1.5-
2.5", matching with wpc's superensemble and the latest sref mean
quantitative precipitation forecast. Still leaning toward no Flood Watch at this time, given the dry
soils and relatively fast movement of the passing remnant low,
however we'll need to closely monitor upstream rates today. Would
not be at all surprised to see pockets of storm totals of 3+", but
still have reservations about such totals covering a sufficiently
large area.

Any threat of tornadic activity should be confined to coastal
sections late tonight, in the climo-favored NE quadrant. But models
do indicate marginal MLCAPE nosing into our southeast sections overnight,
which could support a weak circulation translating to the northwest into
our far southeast and E, so have kept a mention of isolated thunder in
these areas overnight.

Little change needed to earlier wind forecasts, except to nudge
forecast gusts upward slightly, given that the latest Max winds of
60 mph will take a little time to dampen. And with the expansion of
the wind field as it moves into the eastern Carolinas, sustained
speeds around 15 mph with gusts to 20-30 mph look reasonable.

Temps today will depart a bit from the typical diurnal trend,
peaking early in the S before leveling off or slipping a bit as we
wet bulb. Expect highs today in the mid-upper 60s. Lows in the 50s,
except near 60 se, and these readings may be a bit too cool given
the steady rain in most places tonight. -Gih


Short term /Sunday through Sunday night/...
as of 330 am Saturday...

The remnant low center is expected to be over interior southeast NC early
Sun morning, tracking NE and off the coast of the northern Outer
Banks during the afternoon. Trying to time the exit of the rain is
challenging, but it's most likely that the most widespread rain, to
the north and east of the center, will be moving out of the NE forecast
area during the early morning. And this could occur even sooner,
prior to sunrise, if we get the significant mid-upper drying that
models suggest, and based on the latest WV imagery showing the very
dry air aloft to the west of Nestor and wrapping into its center from
the SW, it is quite possible that we'll see an earlier end to
precip. This will leave patchier, lighter, and more broken light
rain bands (and lower pops) to the northwest and west side of the low through
early afternoon, before precip chances end entirely by mid
afternoon. We're likely to see a period of partial clearing or even
mostly clear skies from mid afternoon through the evening hours,
especially across the west. But with weak low level flow in the wake of
the low as weak/narrow high pressure builds in, the leftover low
level moisture will have nowhere to go after nightfall and nocturnal
stabilization, and the limited dispersion should support development
of patchy fog east and areas of stratus west late Sun night. Expect highs
sun from the low-mid 60s NE to lower 70s SW (within decent
insolation from late morning through the afternoon). Lows Sun night
from the upper 40s to lower 50s. -Gih


Long term /Monday through Friday/...
as of 210 am Saturday...

Through Tuesday night: surface high pressure will briefly build
south into the region in the wake of the remnants of Nestor moving
out over the Atlantic on Monday. Weak ridging will also be present
aloft between Nestor and the next approaching trough/low pressure
system. As a result of the above, Monday should be dry, with
increasing cloudiness late in the day. Highs will be near normal,
ranging from around 70 degrees north to mid 70s south. The ridge
will break down Monday night, with increasing southerly flow
advecting some warmer, more moist air into the area ahead of the
approaching cold front. Temperatures Monday night will be a bit
higher than previous nights, upper 50s to low 60s, with cloudy skies
and rainfall chances increasing from west to east Monday night
through Tuesday. Best chances will be during the day Tuesday before
tapering off in the wake of the fropa Tuesday eve/night. The parent
upper low associated with this front will move eastward from the
northern High Plains into the western Great Lakes, then northward
into Canada through Tuesday night. The best dynamics with this
system will likely stay to the north of central NC, thus while
chances for rain are fairly high, amounts may be somewhat limited.
Highs Tuesday will be determined by the rain, clouds and fropa
timing, but for now expect upper 60s northwest to upper 70s southeast. As the
front should push through the area during the early overnight hours,
lows in the mid 40s to low 50s are expected, though that is
dependent on the current timing of the front.

Wednesday through friday: the upper level trough will linger over
the area through Wednesday as cool high pressure builds into and
over the area from the west-southwest. Forecast uncertainty
increases quite a bit during this time period. Generally expect
cool, dry weather to persist through Thursday night. Expect highs in
the mid 60s to low 70s Wednesday and Thursday and lows in the mid
40s Wednesday night. Some moderation in temperatures and an increase
in precipitation chances is expected Thursday night and Friday as a
trough digs over the Midwest and a warm front tries to lift
northward into the region. Current model analyses indicate another
round of wet weather Friday night and Saturday.


Aviation /06z Saturday through Wednesday/...
as of 1245 am Saturday...

VFR conditions will hold through at least 18z today, although high
clouds will continue to spread in from the SW and become more opaque
with steadily lowering bases as the remains of tropical storm Nestor
approach the area from the SW. Rain will spread in from the south-southwest
starting close to noon today, eventually covering all of central NC
after 22z. Far southern portions of central NC are expected to trend
down to MVFR after 20z, with Fay dropping to MVFR in light rain
after 21z and to IFR/LIFR with heavier rain moving in after 00z.
Int/gso/rdu should drop to MVFR after 23z this evening then to
IFR/LIFR after 01z, while rwi sees later MVFR conditions, after 01z,
with IFR/LIFR arriving after 03z. While low level wind shear appears
unlikely, surface winds will strengthen later today and become gusty
from the east and se, yielding strong and shifting winds with height.

Looking beyond 06z sun, steady moderate to heavy rain will continue
to bring IFR/LIFR conditions to all of central NC through early Sun
morning, with blustery winds. Rain will taper down 09z-15z sun,
first in the S including Fay, but low clouds will hold on a bit
longer through the morning. Slow improvement to VFR is expected from
SW to NE during the 15z-21z time frame. VFR conditions will then
hold 22z sun through Mon, although a Little Shallow fog is possible
early Mon morning. Our next chance for sub-VFR conditions will be
Mon night through much of Tue as a frontal system approaches and
crosses the region west to east, bringing a chance for showers and
strong S and south-southwest winds above 6 thousand ft above ground level. High pressure and
calm VFR conditions will then return for Tue night/Wed. -Gih


Rah watches/warnings/advisories...




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