Scientific Forecaster Discussion
fxus62 krah 230710
Area forecast discussion
National Weather Service Raleigh NC
310 am EDT Fri Jun 23 2017
low pressure will pass by to our northwest, crossing the central
Appalachians Friday night into Saturday morning, before moving off
the mid Atlantic coast. This will drag a trailing cold front through
our area late Saturday through Saturday night. High pressure will
follow bringing cooler and drier air into our region for next week.
Near term /through tonight/...
as of 310 am EDT Friday...
Central NC is no longer in a marginal risk of severe storms this
afternoon and evening, only general thunderstorms expected.
A large plume of deep tropical moisture with pw's of 2.2+ inches and
a southerly 40kt h85 jet, a large area of showers with locally heavy
rain is expected to move NE across western and northern NC through
12z/today. Since the air mass is increasingly tropical with dew
points well into the 70s and pw's 2+ inches, some locally heavy rain
with rainfall of 1+ will likely occur. It appears that the heaviest
rain should affect the foothills from hky to mwk, but may also
affect parts of the northwest side of The Triad including Winston-Salem. We
will have categorical pop in the NW, ranging to 30 pop in the southeast
through 12z. Very little lightning was noted with this large area of
heavy showers due to the low topped convection in the tropical air
mass. However, there was some in cloud lightning noted near hky to
near Statesville. We will include a chance of thunderstorms in The
Triad, too. Lows 68-73 northwest to southeast.
Later today, the plume of deep moisture and lift will move north of
the region placing central NC in the warm and drier sector. SW winds
are expected to increase to between 15-25 mph during the afternoon.
Mixing and drying from aloft will allow for increasing sunshine.
Highs should reach the mid 80s northwest and 90-95 in the south and
southeast. Only widely scattered thunderstorms are expected this
afternoon and evening due to the lack of a significant trigger.
Tonight, as the remnant circulation of Cindy passes well to our northwest
and north from the Ohio River NE into the Maryland/PA Appalachians - the
trailing surface trough will move east into the NC mountains
overnight. Convection along the trough or outflow boundaries may
sustain the track across the mountains in a much weakened form. We
will carry some low pop in the western Piedmont for this potential.
Otherwise, the south-southwest low level winds at 15-20 mph and dew points in
the 70s suggest a very warm and humid night in the east. Lows in
general will be in the 70s with partly cloudy skies (mostly cloudy
Short term /Saturday and Saturday night/...
as of 310 am EDT Friday...
There remains a marginal risk of a few damaging wind gusts in the
south and East Part of central NC Saturday afternoon and evening.
The trailing surface trough will move into eastern and southeastern
NC Saturday afternoon and evening, then stall near the southeast coastal
plain Saturday night. Scattered showers and thunderstorms are
expected mid-day in the central Piedmont, with upscale development
during the afternoon - mainly south and east of Raleigh. Pw's of 2
inches, very high dew points in the 70s, and heating into the upper
80s to lower 90s will lead to some very heavy showers and possibly a
few strong to locally severe storms across the sandhills and coastal
plain mainly between 200 PM lingering well into the evening. 1 to 2
inches of rain should drench these areas. Pop of 20 in the NW, 30-40
central and 70+ will be forecast in the Fay to gsb to rwi areas.
Showers will linger in the southeast overnight, with partly to mostly
cloudy skies elsewhere in the rear of the surface trough. Lows in
the 60s northwest and lower 70s southeast.
Long term /Sunday through Thursday/...
as of 323 PM EDT Thursday...
The lower/mid tropospheric remnants of Tropical Storm Cindy are
forecast to become increasingly sheared and will accelerate
northeastward through the southern mid-Atlantic states early Saturday as it
gets picked by the westerlies ahead of the northern stream trough
digging into the central US.
With the remnant circulation/pv anomaly associated with Cindy
expected to pass north, so will the heavy rain/flooding threat, with
quantitative precipitation forecast amounts having decreased significantly across the
area. Instead, a concentrated area of warm moist advection, along the
leading edge of a 800 mb 50kt llj, will fuel a band of showers and
thunderstorms into western NC, that will weaken as they progress
eastward into the central and eastern Saturday morning as the
better support aloft lifts off to the northeast. Convective
re-development is then expected during the afternoon
and evening, as the lead cold front moves into the area, before
stalling near the coast Saturday night into Sunday. Scattered
in the west, to possibly numerous showers and storms in the
east are possible Saturday afternoon, with a few strong to severe
storms possible in the east. Additionally, with the front forecast to
stall out, some localized/isolated flooding is possible as storms
train along the stationary boundary.
A stronger disturbance aloft in the cyclonic flow across the eastern
half of the country is expected to approach and move across the area
early next week, along with an associated cold front. This will give
US another chance for some showers and storms on Monday into Monday
night, along with a push of drier and cooler air, with highs by
Tuesday possibly struggling to reach 80 across the Piedmont and some
low temps dropping into the mid to upper 50s by Wednesday morning.
Aviation /06z Friday through Tuesday/...
as of 155 am Friday...
Showers with IFR conditions expected at kgso and kint over to krdu
through 12z/today, with IFR ceilings at kfay and krwi. Showers will end
from the SW between 09z-12z but IFR conditions will linger through
15z or so. MVFR ceilings will become VFR between 18z and 21z with a
gusty SW wind at 15-25kt.
Looking beyond 00z Sat (fri evening), scattered showers and
thunderstorms with a gusty SW wind at 15-25kt are expected Fri
evening, lasting into Sat morning, with prevailing sub-VFR
conditions late Fri night through daybreak Sat.
Generally VFR conditions will return saturday; however, MVFR
conditions with scattered showers and storms are expected from krdu
eastward Saturday afternoon and evening. Then a return to VFR
conditions are forecast Saturday night through early next week with