Area Forecast Discussion
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FXUS62 KRAH 271716
Area Forecast Discussion
National Weather Service Raleigh NC
116 PM EDT THU OCT 27 2016
A cold front will approach from the west today, crossing central NC
late tonight. High pressure will build into the region Friday, and
persist over the area through the weekend.
.NEAR TERM /through Tonight/...
As of 1000 AM Thursday...
Weak DCVA between shortwaves over the Great lakes and Southern
Plains will impact this area late this afternoon, with the associated
cold front lagging until after midnight. Ahead of the trough axis,
some patchy stratus in the Piedmont is scattering and we should see
a fair amount of sun as periods of high clouds drifting overhead
from the southwest. Statistical guidance is in good agreement on
highs in the low to mid 70s, which with dewpoints in the mid 50s
this afternoon doesn`t suggest much instability. However, mid-level
lapse rates are actually in the 6-7 C/km range, so with moistening
there could be weak instability develop from southwest to northeast.
This could help some of the showers that trigger ahead of the
aforementioned trough to move east into the Piedmont late this
afternoon, and an isolated thunderstorm is possible. Deep layer
shear will likely increase to 30-40kt given ~35kt flow at 500mb in
upstream raobs this morning, but the lack of instability will limit
updraft strength and should preclude any real strong storms. Hi-res
guidance offers quite a variety of solutions when it comes to
coverage, but most at least hint at a stronger convective cell or
two in the western Piedmont by 20z. -BS
Tonight, sfc cold front will advance east across central NC between
06Z-12Z. Northwest flow behind the front will advect a drier air
mass into the region. This arrival of the drier coupled with the
downslope component of the low level wind will aid to decrease
cloudiness nw-se toward daybreak. Expect the clearing to initiate
in the Triad around 06Z, reaching our eastern periphery shortly
after daybreak. Min temps on the mild side due to the low level
mixing and extensive cloudiness. Min temps lower 50s nw to the mid-
upper 50s se.
.SHORT TERM /Friday and Friday night/...
As of 338 AM Thursday...
High pressure will build into central NC Friday and Friday night in
the wake of the exiting cold front. Low level cold air advection
brief as core of the cold air will slide to our north, just brushing
our far north-northeast counties. Where clouds are still prevalent
early Friday will depart by mid day with sunny skies expected
areawide Friday afternoon. Clear skies and near calm winds Friday
night will lead to excellent nocturnal cooling conditions. High
temperatures near 70 far north to the mid-upper 70s south. Min temps
Friday night upper 40s northeast to near 50-lower 50s south.
.LONG TERM /Saturday through Wednesday/...
As of 304 AM Thursday...
Dry and warm conditions on Saturday as high pressure sinks south
across the region. Shortwave will cross the Mid Atlantic on Sunday
bringing a weak dry cold front through NC late Sunday/early Monday.
Expect a dry passage with upper level westerly winds and limited
moisture return. Ahead of the front, southwesterly flow and
increasing low level thicknesses will support temperatures near 80
degrees. Surface high pressure will move in to the region Monday
through Wednesday, as upper level ridging will builds over the
Southeast. This will support continuing dry conditions and above
average temperatures through midweek.
.AVIATION /18Z Thursday through Tuesday/...
As of 116 PM Thursday...
Warm advection in advance of a weak, low-amplitude shortwave trough
moving through the area this afternoon/early evening will support
a broken band of pre-frontal showers from NW to SE across the area
between 20z in the west to 03z in the east. A brief period of
MVFR restrictions may accompany the heavier showers.
The lagging surface front is expected to be mostly dry as it crosses
central NC late tonight, primarily between 06Z-12Z Friday. It`s
possible that before the arrival of the front into the area, central
and eastern terminals(from RDU eastward)could see some MVFR and
possibly IFR fog develop between 09 to 12z, before low-level dry
cool advection spreads in from the west.
High pressure will build into our region in the wake of the
departing front Friday. This weather system will maintain control of
our weather through the weekend.