Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
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FXUS62 KRAH 200928
Area Forecast Discussion
National Weather Service Raleigh NC
528 AM EDT THU OCT 20 2016
An amplifying upper level trough will dig southeast into the
Tennessee valley tonight, progress east of the mountains on Friday,
then track offshore Friday night. An associated cold front will
track east across the Carolinas on Friday. Seasonably cool high
pressure will build into the region in the wake of the front this
.NEAR TERM /TODAY AND TONIGHT/...
As of 230 AM Thursday...
Expect similar conditions to the past several days (unseasonably
warm and sunny) except a few degrees cooler (highs in the lower/mid
80s or 82-85F) as height falls commence downstream of an amplifying
upper level trough over the central MS river valley. Little cloud
cover and weak southerly flow will precede a cold front approaching
the mountains from the west tonight. As such, lows will not be as
warm as might otherwise be the case, in the lower 60s. -Vincent
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
As of 300 AM Thursday...
Very little moisture/theta-e advection will occur in advance of the
approaching cold front in central NC late tonight/Friday morning
given a weak/baggy MSLP gradient in place, poor diurnal timing/
insufficient time prior to fropa. Strong height falls /DCVA/
associated with the amplifying upper level trough progressing east
across the Carolinas will generally lag the attendant cold front on
Friday, though it will do so with favorable diurnal timing. As a
result, model guidance continues to indicate light anafrontal
precipitation (showers along/behind the cold front) on Friday,
during the mid/late morning in the Western Piedmont, early/mid
afternoon along the Highway 1 corridor (Triangle/Fay) and mid/late
afternoon in the Coastal Plain (along/east of I-95). Highs on Friday
will occur relatively early in the day west of Hwy 1, and by
early/mid afternoon east of Hwy 1. In fact, rapid temperature falls
(~15F, falling from the 70s to upper 50s) and gusty NW winds
sustained at 15 knots with gusts as high as 30 knots may accompany
the cold frontal passage along/easy of Hwy 1 during the early/mid
afternoon where cold advection will be augmented/enhanced by
evaporative cooling assoc/w anafrontal precipitation. Expect highs
ranging from the mid/upper 60s in the Triad to mid/upper 70s in the
far SE Coastal Plain. 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 Friday night. 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
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 230 AM Thursday...
A much cooler airmass will settle into the area over the weekend,
with highs on Saturday struggling into the lower 60s in northwest
flow despite sunny skies. Saturday night will provide ideal
radiation conditions as the pressure gradient relaxes and Sunday
morning mins will be mostly in the lower 40s with possibly some
upper 30s in outlying areas. Milder high pressure edges in from the
southwest Sunday, and highs will be a bit warmer, though still a
little below normal...mid to upper 60s.
The first half of next week looks mostly clear and dry, but a
reinforcing shot of cool air will move through on Monday, which will
maintain daily highs in the upper 60s to lower 70s after morning
mins in the mid and upper 40s.
.AVIATION /12Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --As of 530 AM Thursday...
24-hr TAF Period: Expect sub-vfr conditions assoc/w fog to rapidly
improve within an hour or two after sunrise. Otherwise, expect VFR
conditions to prevail through the TAF period with light/variable or
calm winds this morning becoming south at 5-10 kt this afternoon.
Looking Ahead: Shower activity/MVFR ceilings are likely at all
terminals on Friday as a cold front tracks east across central NC.
Expect the best chance for showers between 12-18Z at the INT/GSO
terminals, 15-21Z at the RDU/FAY terminals, and 17-23Z at the RWI
terminal. Southwesterly winds at ~10 kt will prevail in advance of
the cold front, shifting rapidly to the NW at 15G25 knots for 1-3
hours in the wake of the front. Somewhat stronger winds will be
possible during the cold frontal passage at the RDU/RWI/FAY
terminals where fropa timing will better coincide with peak heating,
perhaps NW at 20G30 knots for 1-3 hrs in the wake of the front. VFR
conditions will also rapidly return in the wake of the front,
earliest at INT/GSO (Fri afternoon) and latest at RWI (Fri evening).
Breezy NW winds will persist into Sat, sustained at 10-15 kt with
gusts up to 20-25 kt, becoming westerly and weakening by Sunday. VFR
conditions will rule over the weekend and through the majority of
next week. -Vincent
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