Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
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FXUS62 KRAH 121736
Area Forecast Discussion
National Weather Service Raleigh NC
1235 PM EST Thu Jan 12 2017
High pressure over the western Atlantic will extend westward across
the Southeast U.S. through Friday. A cold front will enter the state
from the north late Friday, and push through central NC Friday night.
.NEAR TERM /THROUGH TONIGHT/...
AS OF 950 AM Thursday...
A spring-like afternoon in store for much of central NC as a deep sw
flow advects a warm air mass into the region. With mid-late morning
temperatures already approaching or even exceeding 60 degrees,
several locations will see high temperatures around 70 degrees.
While these temperatures are well above normal, they are still a few
degrees shy of the record highs for January 12th. Heating of the
relatively moist lower levels of the atmosphere should result in the
development of scattered-broken stratocu layer this afternoon.
Southwest sfc winds will be breezy with gusts 18-23 mph probable.
Tonight, expect partly cloudy skies with patchy fog once again
developing late, mainly north of highway 64. Overnight temps will be
mild for this time of year, primarily in the upper 40s-lower 50s.
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
AS OF 340 AM Thursday...
The passage of a shortwave over the Great Lakes will weaken the
northern periphery of the upper ridge on Friday, with the cold
front to our north aided south into the area late Friday afternoon
and evening by an arctic high shifting east over New England.
Timing of the front will influence high temps, with guidance
currently indicating it reaching the northern Piedmont at or after
peaking heating. An increasing in clouds (mainly high at first)
may hold back heating in the north as well, but it seems
reasonable for temps to reach the mid 60s north to lower 70s
southwest, a general consensus of statistical guidance. This type
of pattern typically features a side range from north to south.
The cold front will surge through the area Friday night,
accompanied by 10-15kt winds and the obvious drop in temps.
1000-850mb thicknesses remain above 1310m and forecast soundings
suggest wetbulb temps will remain just above freezing, such that
the light qpf that models generate from weak 285-290K
isentropic/upslope ascent should not result in any freezing rain.
expect lows in the mid 30s north to mid 40s south.
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 355 AM Thursday...
The mid latitudes, including the Srn Middle Atlantic states, will be
a battleground between 1) a subtropical ridge over the SErn U.S., 2)
a srn stream trough over the SWrn U.S., and 3) a broad nrn stream
trough over Ern Canada. Confluent flow between the three, over the
NErn quarter of the U.S., will support the Ewd migration and
maintenance of arctic surface high pressure --a series of them--
from the Nrn Plains to the NErn U.S.
Episodes of resultant damming E of the Appalachians and into the Srn
Middle Atlantic (VA/NC) will result through early next week.
CAD --and associated cool and cloudy conditions in the 40s to lower
50s-- will be maximized both Sat and Mon. The subtropical ridge will
become increasingly amplified/dominant Tue-Wed, supportive of a
warming and more humid southwesterly flow.
After a chance of drizzle or light rain during the episodes of CAD
through early week, the best chance of any appreciable precipitation
--in the form of rain showers-- will be with the approach and
eventual passage of a slow-moving cold front mid to late week.
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --AS OF 1235 PM Thursday...
VFR conditions expected through this afternoon and into the first
half of this evening. After 03Z Friday, patches of MVFR/IFR
visibility due to fog will begin to develop. After 06Z Fri, should
see areas of MVFR/IFR in fog and/or low clouds across central NC.
These areas of fog/low clouds should dissipate shortly after
VFR conditions anticipated for most of Friday, though could see MVFR
ceilings begin to encroach upon KRWI and possibly KRDU by the end of
the day as a strong cold front drops southward across the area.
The frontal passage will be noted by the sfc winds veering from a
westerly direction to a north-northeast direction. At this time,
expect frontal passage in vicinity of KRWI and KRDU between 18Z-
21Z,the Triad terminals between 21Z Friday-00Z Saturday, and in the
KFAY vicinity between 22Z Friday and 01Z Saturday.
There is a high probability of sub VFR ceilings across central NC
Saturday into Sunday. There is a chance that extended hours of
sub VFR ceilings may occur Monday and Tuesday.
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