Area Forecast Discussion
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FXUS62 KRAH 082011
Area Forecast Discussion
National Weather Service Raleigh NC
311 PM EST Thu Dec 8 2016
An arctic cold front will move through the area today.
An expansive arctic high will dominate Friday through
.NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM Thursday...
A few returns on radar this morning are associated with mainly mid
clouds and at best just a few drops of rain are possible across the
eastern Piedmont and Coastal Plain. The previously stalled front
over western NC is now moving east through central NC as an
expansive arctic high build east in its wake, with northwest winds
now observed to I-95. 850mb and 925mb analysis show cold advection
underway, though it`s not terribly strong yet. The best 700mb
moisture will push east of the area this morning, but south-
southwest flow aloft will keep some high clouds over the area, so
the combination of clouds and cold advection will hinder warming
some, especially across the northwest half of the area. A blend of
NAM and GFS temp guidance looks reasonable, with only 3-6 rises in
most locations, resulting in highs of 49-57.
Strong CAA will continue overnight as expansive Arctic high begins
east into the region. Overnight lows in the mid 20s to upper 20s
with a steady wind 7kt breeze resulting in chill values in the teens.
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
As of 250 AM Thursday...
The expansive arctic high pressure will dominate the eastern two-
thirds of the country Friday and right on through the weekend. H8
temps crash to -10 Celsius Friday-Friday night, which is easily
2 to 3 standard deviations below normal, while low-level thicknesses
bottoming out around 1275 meters. This will support temps a good 10
to 15 degrees below normal. Highs in the upper 30s to lower 40s.
Lows in upper teens to lower 20s.
.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. &&