Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS62 KRAH 150557
Area Forecast Discussion
National Weather Service Raleigh NC
1250 AM EST Sun Jan 15 2017
-- Changed Discussion --A cold front will drop southward across central NC today. High
pressure will build in behind the front and reinforce a cold air
damming airmass over the area through Monday night.
-- End Changed Discussion --
.NEAR TERM /THROUGH TONIGHT/...
As of 845 PM Saturday...
The low-level west-northwesterly downslope flow east of the
mountains has helped to disperse and erode the low-level moisture
associated with Saturday`s cold air damming regime across the NC
Piedmont. Weak shortwave impulses embedded in the westerly flow
aloft will interact with the ribbon of mid-level moisture laying
atop the region, producing partly to mostly cloudy skies overnight
with the slightest chance of some sprinkles across the far northern
Wedge boundary over upstate SC is forecast to lift back north into
southern portions of the forecast overnight/towards daybreak, which
could yield slight warming across the southern counties, while
central and northern counties will either hold steady or just cool
slightly. Min temps ranging from lower 40s north to mid/upper
40s south. Additionally, with the boundary lifting north into the
area, could see some areas of fog develop, possibly dense in some
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
AS OF 300 PM Saturday...
Sunday, a strong s/w will cross southern New England/northern Mid-
Atlantic region. The sfc cold front attendant with this feature will
enter our northeast counties by early afternoon and drive southwest,
exiting our southern Piedmont shortly after sunset. Similar to the
last frontal passage, very little if any rain will occur ahead or
along the front. In fact, skies Sunday will be variably cloudy with
peaks of sunshine probable, especially across the Sandhills and
southern coastal plain. This may lead to a wide range in high
temperatures Sunday afternoon, varying from near 50/lower 50s far
northeast to the lower 60s southwest. if sunshine is more prevalent
than current thinking, afternoon temps may end up 3-5 degrees warmer
Sunday night, a dry air sfc ridge will build south along the
Carolina coast. Meanwhile the the flow in the 925-850mb layer will
be veering to a south-southwesterly direction as a waa regime
commences. This will lead to the development of another stratus
layer along with patches of light rain, primarily over the western
Piedmont. This set-up will initiate a hybrid cold air damming event.
Min temps Sunday night will vary from the upper 30s northeast to the
low-mid 40s southwest.
.LONG TERM /MONDAY THROUGH SATURDAY/...
As of 300 PM Saturday...
A 1030-1032 mb surface high will settle over the New England coast
Monday resulting in a CAD wedge over northern and western NC. The
high will shift off the Mid-Atlantic coat Monday night, but the
wedge will remain over northwest portions of the area through
Tuesday, as the return flow from the high offshore and increasing
southerly flow ahead of the approaching front won`t erode it before
then. Meanwhile aloft, the closed low over the Baja will swing
northeast into the Midwest by Monday and toward the Great Lakes
through Monday Night. The aforementioned low will get absorbed in
the northern stream Tuesday while a lingering trough/low remains of
the southwest U.S. The strength of the low/shortwave as it moves
through the Great Lakes and the high ridging over the southeast U.S.
will play an important part in how the weather plays out over
Central NC Tuesday through Thursday. It is even uncertain at this
time when the actual frontal passage will occur. Given all the
uncertainty, the forecast confidence is very low at this time, with
respect to both temperatures and precipitation.
The secondary southern stream low will progress eastward Thursday
through Saturday as a strong upper low approaches the Northwest U.S.
coast, digging a very deep trough over the western U.S. Although
confidence is low, it does appear that another round of
precipitation will occur as the low moves eastward in the Mid-
Atlantic late in the week/early weekend, but exactly when and how
much is far to uncertain to specify at this time.
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --AS OF 1250 AM Sunday...
Pretty high confidence in VFR early this morning, with clouds at 6-
8k ft drifting east across the area and a chance of MVFR/IFR vsbys
between 09z and 12z, especially at FAY. A cold front will surge
south across the area between 15z and 21z today, causing the
currently light and variable winds to become northeasterly at 6-
10kt. Models have struggled with this weather pattern the last
couple of days, and seem to still be in disagreement on how quickly
MVFR ceilings will redevelop, but recent trends suggest some
scattered MVFR ceilings this afternoon and then a better chance of
cigs lowering at FAY/INT/GSO/RDU after 00Z. RWI may stay VFR
through the period.
Outlook: Conditions are expected to at least MVFR by 12Z Monday, and
more likely IFR at INT/GSO, as southerly flow reinforces a cold air
damming airmass over the area. Low cigs should persist into
Tuesday, when there will be a chance for low clouds to scatter ahead
of a cold front approaching from the west. The cold front and
associated rain and low cigs/vsby will should impact the area
Wednesday. VFR Conditions will return to all terminals in the wake
of the cold front Wed night and Thursday.]
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