Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 240018

Area Forecast Discussion
National Weather Service Raleigh NC
718 PM EST Thu Nov 23 2017

Initially cool high pressure will weaken and modify as it expands
east across the middle Atlantic and southeast states through Friday
night. Meanwhile, at least a couple of areas of low pressure will
track from the eastern Gulf of Mexico northeastward across FL and
offshore the southeastern US coast.


As of 218 PM Thursday...

A short wave trough with embedded sheared vort max is lifting NE
along the SE states coastal region.  A shield of mainly light rain
along and ahead of this disturbance is ongoing across coastal
sections of GA and SC.  It is slowly lifting NE, but according to
the latest running into much drier air located
north of the SC/NC boundary and thus is making very slow progress
NEWD as the northern edge is drying up in the process. Nevertheless,
the latest HRRR shows that eventually this light rain shield will
lift into coastal sections of NC as the atmos there eventually
moistens enough to allow very light rain to reach the ground there.
While earlier runs of the HRRR showed that the NW edge of the rain
could get into southern Sampson Co, the latest runs and most recent
mesoanalysis moisture fields suggests otherwise. So for now, will
keep rain out of our SE zones and will monitor closely. Farther
west, it`s just a matter of cirrus and how much of it, and it`s
effects on temps tonight.  The thickest cirrus, now along and east
of the I-95 corridor, is expected to remain east of I-95 and
gradually shift east of there overnight as the aforementioned short
wave trough axis shifts east.

Otherwise, at the sfc, high pressure now centered to our north over
VA will continue building southward, becoming centered over NC by
12Z Friday.  Consequently, winds should go calm across our entire
CWA after midnight, and when combined with clearing skies, will set
up good radiational cooling conditions overnight. Latest sfc dwpts
and low level thickness, when combined with radiational cooling,
suggest lows in the upper 20s to lower 30s.  Chilly temps for
those venturing out tonight or early Friday morning!


As of 218 PM Thursday...

High pressure and a dry airmass with westerly flow aloft and a
seasonable airmass is the weather story for Friday. Look for plenty
of sunshine during the day Friday with highs in the upper 50s to
around 60.  Friday night, the next short wave embedded in the
longwave trough over the East will be crossing the Ohio Valley.
While it`s assoc cold frontal passage won`t occur until late
Saturday, we will see an increase in high clouds Friday night in
advance of it.  Thus with these high clouds, low temps Friday night
should be a little warmer than tonight`s lows.  Low temps Friday
night in the mid 30s, under increasing high clouds.


As of 150 PM EDT Thursday...

Little change in longer range forecast.

A mild day is in store for Saturday with a westerly flow ahead of an
advancing, rather dry, cold front. Next area of high pressure will
settle over the region Sunday through the middle of next week.

The cooler temperatures behind the cold front Sunday and Monday will
be rather short-lived as the upper ridge over the Western US
transitions eastward atop the Eastern US by Tuesday/Wednesday. Highs
Sunday and Monday in the low to mid 50s north to upper 50s south,
then warming back up into the 60s and possibly even near 70 across
the southern coastal plain and Sandhills by Wednesday.

Model spread increases Wednesday and Thursday with the timing of
upper trough ejecting out of the Rockies into the southeastern US.
It still does not appear that this system will produce significant
rainfall across the Carolina region.


As of 715 PM Thursday...

24 Hour TAF Period: Surface high pressure will build into and settle
over the area tonight into Friday. Meanwhile, high level moisture
moisture over the eastern half of the area will shift to the east
this evening as a slow moving mid level trough axis shifts eastward
and over the area. Otherwise, skies will remain clear/mostly clear
with generally light and variable winds.

Outlook:  A cold front will move across the region late Saturday and
may bring a brief period of sub-VFR conditions during that time.
Otherwise, VFR conditions expected through Tuesday.





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