FXUS62 KRAH 140849
AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
350 AM EST Thu Nov 14 2019
High pressure extending into the region from the northeast this
morning will weaken and pull away from the area this afternoon. A
strengthening storm system approaching from the west and south later
today will track slowly over the Carolinas tonight through the
weekend, bringing cool and unsettled weather.
.NEAR TERM /TODAY THROUGH TONIGHT/...
As of 315 AM Thursday...
The cool surface ridge continues to extend into central NC from the
NE, although its influence will wane today as the high center shifts
further NE off the Canadian Maritimes, leaving us vulernable to the
effects of falling surface pressures near the Southeast coast. This
developing frontal zone will extend through N FL into the NE and N-
central Gulf today, and the tightening MSLP gradient and uptick in
the isallobaric wind over the E Carolinas will enhance northerly
flow over central NC. As the 925/850 mb anticyclone shifts off the
Mid Atlantic and Northeast coast this morning, the ensuing Atlantic
inflow from the E and SE will draw increasing moisture just aloft
into the area, resulting in a trend to overcast stratus today with
development of patchy light rain from S to N, particularly this
afternoon as moist isentropic upglide at 280-295K cranks up.
Meanwhile, further aloft, the upper low over NE Mexico will cross S
TX and dampen as it tracks along the Gulf Coast before becoming
absorbed by a strengthening northern stream wave diving through the
Plains and lower Miss Valley to TN/MS/AL through tonight. A
perturbation that is tracking NE out ahead of this trough (now
helping to support rain over LA/MS) will cross the Carolinas today
in lockstep with an area of jet-induced upper divergence, and this
saturation aloft may help seed pockets of more substantial rain this
afternoon across our S. Will start the day with minimal pops, slight
chances only in the far S toward noon, before spreading chance pops
NE through the area as both moisture and forcing for ascent deepens.
With such a chilly start this morning and low insolation beneath
overcast skies for much of the day, expect highs only in the mid 40s
to around 50. By tonight, the moist upglide will deepen further in
conjunction with a surge of stronger SE flow at 925 mb ahead of
developing low pressure along the front over the NE Gulf and N FL.
Rain is fairly certain over SE sections (roughly E of Hwy 1) where
the 925-700 mb lift will be strongest within high PW, but the
vertical extent of the saturation even back over the NW Piedmont
necessitates a chance pop there as well this afternoon through
tonight, despite the fact that we may be in a relative lull in terms
of the mid/upper dynamics (as the aforementioned forcing features
shift offshore) with a slight downturn in deep upglide overnight.
Rainfall amounts in the Coastal Plain may exceed a half inch
tonight. Expect lows in the mid 30s to mid 40s. -GIH
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
As of 350 AM Thursday...
The potent mid level low will cross MS/AL to the FL/GA line Fri
before emerging off the FL/GA coast, while at the surface, what
should become the primary low (there will likely be more than one
low along this front) tracks up along the SC/NC coast. While the
greatest QPF will likely be near the coast and offshore, we could
see enough moisture surging inland ahead of the low to throw decent
rainfall further west Fri, particularly considering the period of
strengthening upper divergence crossing the area from late morning
through Fri afternoon. Will maintain high pops over the E (likely to
categorical) with much lower pops over the NW Piedmont. Temps are
likely to peak only in the mid 40s to near 50 (with these "warmer"
readings SE of Clinton and NW of INT), and even this may be
optimistic. Rain chances will persist into Fri evening, albeit with
a downturn in intensity and westward extend, followed by a further
decrease and eastward nudge to pops Fri night as the strengthening
northerly lower level winds draw cooler but drier air through the
lowest 2-3 km into central NC, with a gradual departure of the
surface low. Expect lows from the mid 30s to lower 40s. -GIH
.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 347 AM Thursday...
Saturday: Upper low INVOF the Florida-Georgia line will become
vertically stacked as it moves offshore and secondary sfc
cyclogenesis ensues of the SE Coast. The low pressure system will
not be in any hurry to move out to sea and will jog slowly eastward
through early Sunday before finally accelerating NEWD late
Sunday/Sunday night, owing to the approach of the kicker upstream
trough into the Ms Valley.
Models have come into better agreement with the inland/westward
extent of this "second round" of precip, confining the back-edge of
the rain shield along and east of the I-95 corridor on Saturday,
with rain gradually tapering off west-east Saturday evening/night.
An additional 0.10" to 0.25" of rainfall is expected across eastern
areas on Saturday.
Strong pressure gradient between the coastal low and a chilly high
pressure extending down the Eastern Seaboard will result in windy
conditions of 25 to 35 mph on Saturday. The continuation of rain in
the east and cloud cover will keep temperatures down in the mid 40s,
with wind aided wind chills in the mid to upper 30s north to lower
40s south. Skies across the western Piedmont could start to scatter
out late Saturday and Saturday night. Lows ranging from near 30 NW
to mid 30s east with no p-type concerns.
Sunday through Wednesday: In the wake of the coastal low moving up
the Mid-Atlantic waters, expect mostly dry conditions and moderating
temperatures to near normal through early next week. High model
variability/spread with individual shortwave troughs rotating
through the base of of a deepening long wave trough in place across
the eastern CONUS is resulting in lower than average confidence for
the Tuesday through Wednesday period. While the synoptic pattern
favors yet another coastal low development, exactly where/how far
offshore is uncertain. Will continue to monitor and once there is
better agreement, may need to introduce rain chances Tuesday and
Wednesday. Temperatures are expected to remain at or just below
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
As of 120 AM Thursday...
VFR conditions will continue over central NC terminals for the rest
of the nighttime hours, but starting near sunrise this morning, high-
end MVFR to low-end VFR stratus (based 2500-3500 AGL) is expected to
spread into central NC from the south today. FAY should be impacted
first, by mid morning, with the remainder of sites becoming MVFR
between 17z (INT/GSO/RDU) and 21z (RWI). Confidence is high in the
presence of these clouds, but whether or not they will rise up just
into VFR territory as the day progresses is much less certain.
Patchy light rain is also expected to spread in from the south later
today, starting in the mid afternoon. Vsbys are likely to stay VFR
with precip staying very light through sunset, although FAY may
briefly have MVFR vsbys in the late afternoon. Then, aviation
conditions are likely to remain MVFR (INT/GSO) or drop to IFR
(FAY/RDU/RWI) by early evening, lasting through tonight, with more
steady rain most likely to impact eastern terminals (FAY/RDU/RWI)
tonight as low surface pressures form along the Southeast coast.
Looking beyond 06z Fri: Poor aviation conditions are likely to
persist over much of central NC into Sat, especially over the E, as
coastal low pressure and a slow-moving upper low impacts the
Southeast and Carolinas. The worst conditions (IFR to LIFR with
rain) are mostly likely to be at RDU/FAY/RWI, while at INT/GSO,
cigs/vsbys may improve to VFR for a time on Fri into Sat. Conditions
are expected to improve to VFR at all sites except FAY/RWI late Sat
as the upper low shifts slowly offshore, while FAY/RWI should see at
least MVFR cigs lasting into early Sun. All should trend to VFR
starting Sun. -GIH
Record minimum and low-maximum temperatures...
DATE RDU GSO FAY
Min Low Max Min Low Max Min Low Max
11/14 20 1977 39 1976 19 1986 38 1904 23 2013 45 1997
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