Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
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FXUS62 KRAH 080533
Area Forecast Discussion
National Weather Service Raleigh NC
1233 AM EST Thu Dec 8 2016
Weak high pressure over the Carolinas will weaken and shift east
tonight. An arctic cold front will move through the area Thursday,
followed by an expansive arctic high for the weekend.
.NEAR TERM /THROUGH THURSDAY MORNING/...
As of 750 PM Wednesday...
The warm and more moist advection from the southwest has already
become evident over NC, especially just above the surface through 5k
feet. Cirrus and cirrostratus were also increasing in the fast flow
up at jet stream level from the Tennessee Valley. Either cloudy or
becoming cloudy will be forecast for the rest of the night. We will
also raise temperatures a few degrees given the dew points were
already in the 40s outside of the NW Piedmont (30s). Lows generally
should bottom out in the lower to mid 40s as the clouds thicken up.
There may be some light fog; however, with the increasing stratus it
appears that widespread or dense fog is not likely at this time.
Other than a minimal chance of some very light rain or sprinkles,
there appears to be little in the way of mechanisms to produce
anything more that some shallow lift for measurable rain. Expect
only a few hundredths in the western Piedmont by 12z.
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
As of 320 PM Wednesday...
Any light warm advection driven precip Thursday morning will
shift east and may consolidate or become a little more showery as
fgen strengthens and the cold front sweeps across the area.
Northwest flow and increasing cold advection will clear skies by
midday to early afternoon, though the brunt of the cold advection
will likely be delayed until later Thursday night. Highs should
reach the low to mid 50s.
Strong CAA will continue Thursday as expansive Arctic high begins
east into the region. Overnight will fall into the mid 20s to
upper 20s with a steady wind near 10mph and wind chills in the
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
As of 245 PM Wednesday...
Cold air tap will be turned on Thu night as an Arctic ridge builds
south and east out of the central plains. The leading cold front
will be offshore with clear skies and dew points falling into the
teens on Friday. It will be brisk, with northwest winds gusting up
to 20 mph coincident with highs struggling to reach the lower 40s,
with upper 30s more likely across the northwest. Associated wind
chills will top out in the upper 30s in the afternoon. Near ideal
radiational conditions are expected Friday night, and we will see
our coldest temperatures thus far this season, with most areas
falling to the low 20s by sunrise Saturday, and some outlying areas
will see mins bottom out in the upper teens. The high pressure will
be overhead and the cold airmass in place will be hard to warm up
due to the low sun angle, and highs Saturday will again be mostly in
the lower 40s.
The surface high will be edging off the mid Atlantic on Sunday, and
ensuing return flow will begin to moderate temperatures as well as
spread moisture progressively north and west into the area during
the late day. Should see increasing clouds throughout the day and
maybe some patchy light showers in the west by evening, with chance
PoPs across the entire area after midnight. Highs will edge into the
mid to upper 40s.
There are significant timing and feature detail inconsistencies
concerning our next system approaching from the west early in the
work week, with a weaker but faster frontal passage Sunday night per
GFS vs. a stronger, sharper frontal passage later Monday per the
ECMWF. As such, will maintain chance PoPs from Sunday night through
Monday afternoon, with dry weather and near-seasonable temperatures
Tuesday into Wednesday in faster zonal flow. Highs Monday through
Wednesday will be mostly in the 50s with morning lows in the 30s.
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
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Weak/shallow upglide/WAA ahead of an arctic cold front that
will move through the area between 12 to 18z Thursday will result in
the development of IFR to MVFR CIGS areawide between 06 to 12z.
Some patchy/spotty light rain is also possible, but MVFR VSBYS
should be the lowest category forecast.
Strong post-frontal low-level dry cold air advection will clear out
the Sub-VFR ceilings from west to east between 12 to 18z. Expect
sustained west-northwest winds to 8-12kt, with gusts into the 18 to
22kt range, strongest in the west.
Outlook: VFR conditions are expected through the weekend. The next
chance of sub-VFR conditions will be early next week.
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