Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 082015
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
311 PM EST Thu Dec 8 2016

.SYNOPSIS...
In the wake of a cold front moving offshore, an expansive arctic
high will dominate through the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 310 PM Thursday...

Cold advection has ensued in the wake of a cold front that finally
pushed east across the area earlier this morning, with a northwest
wind gusting to 15-20kt at times.  Temps have only risen a few
degrees, if any, owing to the cold advection and a veil of mid and
high clouds.  A few radar echoes continue to race northeast across
the Piedmont and Coastal Plain, but with dewpoints crashing into
the 20s and 30s, this is likely all virga.  Cold advection will
continue tonight as the pressure gradient briefly tightens in
response to an expansive 1040mb high building out of the northern
Plains. Meanwhile, skies will clear as upper jet to our northwest
shifts east, resulting in lows in the mid to upper 20s, per model
consensus.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
As of 310 PM Thursday...

Arctic high pressure will build east toward the Tenn Valley Friday
and Friday night, keeping central NC int he cold advection regime
for another day.  The pressure gradient will relax a bit, with
forecast soundings only showing 15-20kt of wind in the boundary
layer, though some slightly stronger gusts are possible at the onset
of mixing mid-morning.  Otherwise, skies will be clear and MOS
guidance products are in good agreement on mostly lower 40s for
highs. The surface high will nudge eastward Friday night, though it
won`t quite settle overhead.  The pressure gradient should be weak
enough, however, for decoupling (especially west) and a 1270m
thickness supports highs in the lower 20s, with teens in outlying
areas.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 310 PM Thursday...

The medium range models are in good agreement with the migration of
~1035 mb modified arctic high pressure across the Central
Appalachians and Middle Atlantic states Sat and Sat night. Cold
temperatures --10-15 degrees below average-- will result, with highs
40-45 and lows in the lower to middle 20s. Aside from cirrus, some
of which may become briefly orographically-enhanced over the wrn
Piedmont early Sat, the column will otherwise remain dry/clear.

A Pacific shortwave trough, embedded within fast and broadly
cyclonic flow across much of the Lower 48, will support a migratory
wave of low pressure from the TX panhandle Sun to the Nrn
Appalachians Mon. A preceding warm/coastal front will retreat Nwwd
across central NC with an associated chance of showers during that
time (Sun-Mon). Temperatures will moderate with the retreat of the
warm front, and clouds. The trailing cold front, and continued
chance of showers, will follow and cross NC late Mon-early Tue.

Uncertainty in the mid to late week forecast remains above average.
There are indications that a flat frontal wave will zip off the SE
U.S. during the middle of the week; and this feature may spread a
shield of light rain across NC late Tue-Wed.
Thereafter, the models continue to indicate another cold frontal
passage and associated arrival of colder temperatures will occur by
Wed night-Thu, but recent model runs have backed off somewhat on how
far S the next dome of arctic air will plunge.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
As of 1245 PM THURSDAY...

Winds are turning to northwest in the wake of a cold front crossing
central NC today, with gusts to around 20kt likely to spread west to
east as cold advection strengthens.  Skies will clear through the
evening hours as high clouds slowly shift east, and VFR conditions
will continue.  Some of the gusts could continue overnight, but for
the most part guidance suggests winds will weaken to 6-10kt out of
the northwest and then increase to 10-15kt gusting 15-20kt on Friday.

Outlook: VFR conditions are expected through the weekend. There
is a small chance of sub-VFR ceilings on Sunday, with better
chances Monday and Thursday. &&

.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SYNOPSIS...Smith
NEAR TERM...Smith
SHORT TERM...Smith
LONG TERM...MWS
AVIATION...Smith


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