Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Remove Highlighting --
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FXUS62 KRAH 211448
Area Forecast Discussion
National Weather Service Raleigh NC
1050 AM EDT FRI OCT 21 2016
An amplifying upper level trough and attendant cold front will track
east across the Carolinas today. A cooler and drier airmass will
advect into the region from the northwest in the wake of the
front tonight and Saturday.
.NEAR TERM /TODAY AND TONIGHT/...
-- Changed Discussion --As of 1050 AM Friday...
Despite an impressive water vapor signature associated with the deep
upper wave crossing the Ohio/Tenn Valley, there is very little
precip on radar south of Roanoke VA, owing mainly to a lack of deep
moisture with PW at one inch or less. Still, with 170m height falls
at BNA this morning and intense FGEN showing up from 925mb through
700mb, there should be sufficient forcing to spark a band of showers
this afternoon. Latest HRRR runs have shown a small decrease in the
coverage of showers that develop along the cold front, which
currently extends through western VA to just west of the Triad, as
it approaches US 1 around 18Z and I-95 by 21Z. Given the amount of
dry air, the environment will be supportive of some 25-35kt wind
gusts through dry air entrainment and DCAPE increasing to around
800J/KG across the south, but this conditioned on whether or not any
deeper convection can develop without any appreciable instability,
which RAP forecast soundings don`t show much support for.
Changes to the forecast this morning as minor, mainly to reduce POPs
in the west this morning based on radar trends and adjust temps to
the lack of early precip. Have also nudged up sky cover in the
west with the slowly burning off of fog. Highs should still end up in
the upper 60s to upper 70s, with temps starting to fall by mid
afternoon the west.
Expect rapid clearing from west-east 3-6 hrs after the cold frontal
passage at any given location, with clear skies and a NW breeze
prevailing tonight. Lows Saturday morning will be driven by both
cold advection and radiational cooling, ranging from the low/mid 40s
N/NW to mid/upper 40s S/SE. -Vincent
-- End Changed Discussion --
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
As of 300 AM Friday...
Cool, clear and breezy today due to cold advection in the wake of an
amplifying upper level wave tracking offshore the Carolina/Mid-
Atlantic coast tonight and Saturday. Expect clear skies and a breezy
NW wind with highs in the upper 50s to lower 60s, coolest NW
Piedmont. Chilly lows sat night in the lower 40s. -Vincent
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 315 AM Friday...
Dry and seasonably cool weather is expected from Sunday through mid
week. Gradually rising heights as high pressure builds in from the
south will provide us with a short-lived warming trend Sunday and
Monday, with highs warming to the mid and upper 60s Sunday, and
further into the low and mid 70s on Monday.
A reinforcing shot of dry and cooler air is expected as a cold front
moves south and through the area on Monday. This airmass will be
locked into place through the midweek as high pressure builds south
down the Atlantic coast. Highs Tuesday through Thursday will be
mostly 65 to 70 after morning lows mostly in the mid 40s.
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
As of 600 AM Friday...
24-hr TAF Period: IFR/LIFR visbys in fog or low stratus will affect
eastern terminals (FAY/RWI/RDU) through 12-14Z before dissipating.
Shower activity and borderline MVFR/VFR ceilings are expected at all
terminals today as a cold front tracks east across central NC.
Expect the best chance for showers between 12-17Z at the INT/GSO
terminals, 16-21Z at the RDU/FAY terminals, and 17-22Z at the RWI
terminal. Southwesterly winds at ~10 kt will prevail in advance of
the cold front, shifting rapidly to the NW at 10-15 kt sustained
gusting 20-25 knots for 1-3 hours in the wake of the front. Somewhat
stronger winds will be possible at eastern terminals where fropa
timing will better coincide with peak heating.
VFR conditions will rapidly return in the wake of the front,
earliest at INT/GSO (this afternoon) and latest at RWI (this
Looking Ahead: Breezy NW winds will persist into Sat, sustained at
10-15 kt with gusts up to 20-25 kt, becoming westerly and weakening
on Sunday. VFR conditions are expected to rule for the remainder of
the weekend and through the majority of next week. -Vincent