Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS62 KRAH 091939
Area Forecast Discussion
National Weather Service Raleigh NC
240 PM EST Fri Dec 9 2016
Arctic high pressure will build across the area through Saturday. A
cold front will approach from the west late Sunday and move through
the area on Monday.
.NEAR TERM /THROUGH TONIGHT/...
As of 240 PM Friday...
A chilly day (temps around 12-15 deg below normal) will become a
chilly night, as arctic high pressure continues to build into the
area from the NW. Passage of a weak sheared wave just to our north
will bring a few high clouds mainly to the northern forecast area
overnight (some of this cloudiness could be orographically enhanced
late). But otherwise skies will be generally clear tonight, and this
in combination with light surface winds will foster good radiational
cooling, with thicknesses likely to be a bit lower than they were
this morning. Expect temps to bottom out in the 18-24 degree range,
with the cooler readings in outlying areas of the northern/western
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
As of 200 AM Friday...
Flow aloft transitions to zonal on Saturday. Otherwise, very little
little change as the modified arctic high pressure migrates east
atop the region. Temperatures Saturday and Saturday night will be
very similar to today and tonight. Highs 40 to 45.
Lows 20 to 25.
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 400 AM Friday...
Overview: Long range model guidance has come into better agreement
on Sunday/Monday, however, considerable uncertainty plagues the
remainder of the extended forecast.
Sun/Mon: A shortwave trough and attendant low pressure system
expected to move onshore the Pacific NW on Saturday is progged to
track rapidly east across the Upper Midwest (Sun), Great Lakes (Sun
night), and New England (Mon) via a 125-150 knot upper level jet
extending from coast-to-coast at ~40 degrees latitude. An associated
cold front will rapidly approach the mountains from the west Sunday
night, however, the front will slow down as it tracks SE through the
Carolinas on Monday and will likely stall in a west-east orientation
over the Deep South/Southeast Tuesday morning. With the above in
mind, expect increasing cloud cover and highs in the 40s on Sunday
(coolest NW/warmest SE), with light rain assoc/w southerly return
flow /warm advection/ possible Sunday evening/night, primarily in
the SE coastal plain. Chances for precipitation will increase on
Monday as the front progresses into the Carolinas. Temperatures on
Monday will be a function of strong warm advection, cloud cover, and
precipitation, resulting in low confidence. At this time will
indicate highs ranging from the mid 50s NW to mid/upper 60s SE.
Mon Night-Thu: Considerable uncertainty persists from Monday night
onward as the aforementioned front stalls in a west-east orientation
across the Deep South/Southeast, beneath an energetic upper level
pattern characterized by numerous small amplitude waves embedded
within a ~150 knot jet that extends from the Pacific to the
Atlantic. With confidence so low, will make little change to this
period of the forecast. -Vincent
.AVIATION /18Z Friday through Wednesday/...
As of 120 PM FRIDAY...
High confidence in chilly but tranquil aviation conditions for the
next 24 hours. Skies will be virtually cloud-free with unrestricted
vsbys for the rest of today through tonight and into Saturday as
high pressure builds in from the NW. Only a few high clouds tonight
are expected as a weak mid level wave passes by within a fast flow
Looking beyond 18z Saturday, VFR conditions should hold through the
first half of Sunday as high pressure builds overhead. As a warm
front approaches from the south, moisture will increase, and cigs
will trend to MVFR then IFR Sunday afternoon from south to north.
There is a good chance of low level wind shear conditions Sun night
into Mon morning with 35-40 kt winds from the SW at 1500-1800 ft
AGL. Adverse aviation conditions, including sub-VFR cigs and vsbys,
are expected to dominate from late Sunday through at least Monday
night -- and perhaps into Wednesday -- as waves of low pressure
track along the frontal zone as it holds over or just south of the