Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 151854
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
153 PM EST Fri Dec 15 2017

.SYNOPSIS...
High pressure will move across the southeastern US through the
weekend.

&&

.NEAR TERM /TONIGHT/...
As of 153 PM Friday...

As of 18Z, the sfc low was off the NE NC coast, and is on its way to
the northeast.  A trailing cold front extends from the Albemarle
Sound southwest toward upstate SC.  Low clouds north of the boundary
(mainly along and north of the I-85 corridor) are beginning to break
up as the front is starting to push south and drier air is moving in
from the north.  The boundary will continue shifting south as high
pressure (that`s currently centered over the southern Plains) begins
to build in from the west.  As such, look for partly cloudy skies
the rest of this afternoon and this evening with mostly high clouds
persisting. The high clouds should also finally exit to our east
later this evening and overnight as the upper short wave trough axis
(currently located over the Ohio and Mississippi Valleys) crosses
our area and moves east.  The combination of mainly clear skies
after midnight, diminishing winds (given the high that`s building
in), and a cooler airmass behind the aforementioned front...
overnight temps should run about 5 deg colder than last night...mid-
upr 20s for lows.

&&

.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
As of 153 PM Friday...

Tranquil weather expected during this time with NW flow and mid/upr
short wave ridging, and high pressure over the area.  This will
result in ample sunshine on Saturday.  Skies will become partly
cloudy Saturday night as high clouds move up into our area from the
south.  Forecast soundings and thickness profiles suggest subtle and
gradual warming tomorrow.  Highs Saturday from around 50 north of I-
85 to lower-mid 50s south.  Lows Saturday night around freezing.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 235 AM Friday...

The surface high will shift offshore on Sunday as a warm front lifts
northward through the area Sunday eve/night, resulting in south-
southeasterly return flow and warm advection into Central NC.
Meanwhile aloft, the Southeast US will be under an upper level
ridge, while a deep trough dominates over the Rockies and Southwest.
A shortwave will break off from the low, migrating east-northeast
through the Midwest toward the Mid-Atlantic. As of the latest model
runs, the shortwave should ride the northern periphery of the ridge
and stay north of the area Sunday/Sunday night. Temperatures will be
on the rise, with highs in the mid to upper 50s and lows in the low
to mid 40s.

Although the models are in much better agreement with the overall
upper level pattern, there are still some significant differences in
the temperature and precipitation forecasts. The closed low over the
Southwest US will become more of an open trough on Monday, gradually
deamplifying as it lifts ENEward into the Midwest Tuesday/Tuesday
night. The southwest flow into Central NC will increase during this
time, increasing the moisture advection and thus chances of
precipitation. Meanwhile, a cold front will drop southward toward
and into Central NC Tuesday/Tuesday night. The highest chances for
and amount of rain will be across the south, ahead of the front. The
weakening trough turned shortwave may enhance the precipitation
along the front Tuesday night as it passes near/over the area.

Temperatures will be unseasonably warm Monday and Tuesday, with
highs in the upper 50s to mid 60s and lows in the mid to upper 40s.
Expect a slight decrease in temperatures for mid week, albeit still
a bit above normal (highs in the mid to upper 50s and lows in the
30s Wed night and 40s Thu night).

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
As of 1255 PM Friday...

Through 18Z Saturday: Stratus and StratoCu with cigs aoa 2kft AGL
are persisting north of the I-85 corridor, with VFR conditions
farther south with mainly just cirrus.  As the low off the coast of
the Outer Banks exits northeastward later today, drier air will move
in from the west, leaving mostly high clouds, even where sub-VFR
conditions are occurring now.  That`s expected to occur around 20 or
21Z. Thereafter VFR conditions are expected this evening, tonight,
and Saturday morning through the end of the TAF period.

After 18Z Saturday:  VFR conditions expected through the rest of the
weekend, then sub-VFR conditions possible early next week as
moisture lifts north toward our area and interacts with an
approaching cold front.

&&

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

&&

$$

SYNOPSIS...np
NEAR TERM...np
SHORT TERM...np
LONG TERM...KC
AVIATION...np


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