Area Forecast Discussion
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FXUS62 KRAH 031624
Area Forecast Discussion
National Weather Service Raleigh NC
1110 AM EST Sat Dec 3 2016
High pressure will continue to build SE into the region this
afternoon and tonight. The high pressure will extend from NY state
south through the Carolinas Sunday as a coastal front develops. A
storm system will move from the Gulf Coast states into the Southeast
states early in the week increasing the chance of rain.
.NEAR TERM /THROUGH TONIGHT/...
As of 1110 AM Saturday...
Mostly sunny skies in the east and partly sunny skies in the west
will be dominate into the afternoon. The cirrus/cirrostratus may
occasionally thicken up in the western areas to produce mostly
cloudy to cloudy skies by mid to late afternoon. CAA continues as
the 1030mb surface high centered over the Midwest to the Ohio Valley
builds toward NC. This high will slide slowly east and will
eventually extend down the eastern seaboard Sunday delivering chilly
air into the region from the north. Highs this afternoon are
forecast to top out between 50 and 55 N to S with the north breeze
around 10 mph adding a briskness to the air. Readings in the upper
40s may hold on across the far northern Piedmont if the high clouds
Tonight... high cloudiness will overspread the region as the system
developing over northern Mexico and Texas spreads deep mid/upper
moisture NE. Lows should hold in the 35-42 range due to the
thickening cloudiness. There is a low chance of measurable (0.01)
light rain very late tonight over the western Piedmont. Temperatures
will be well above 32; therefore, high confidence of liquid if
.SHORT TERM /SUNDAY THROUGH MONDAY/...
As of 405 AM Saturday...
Low chance pops move into Central NC Sunday, ~30% chance west
ranging to slight or no pops in the east where the relatively dry
subcloud layer will be deeper. Thick clouds will further hold temps
down, and expect highs from the mid 40s NW (beneath the most
pronounced combination of thick clouds and cool/stable low levels)
to the lower 50s SE. The arrival of a 40+ kt low level jetlet across
GA/SC/NC Sun evening along with strengthening IVT will result in a
ramping up of moist upglide and overall forcing for ascent, in
tandem with the departure of the surface ridge, making the low
levels vulnerable to saturation. Expect rain coverage to increase to
likely in the NW CWA and categorical south/southeast Sun evening,
followed by a slow exit later Sun night as the low level jetlet
shifts to our east and deep moist upglide shuts down. Rainfall from
late Sun through Sun night could approach 0.25-0.50", higher in the
south. Expect lows from around 40 NW to mid 40s SE. -GIH
.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 325 AM Saturday...
Monday will be a transitional day with high pressure moving off the
coast, a weak wave along the coast and new high pressure moving into
the mid-Atlantic region from the Ohio Valley. The upshot of this is
that we will move from more of an in-situ damming situation to more
of a hybrid scenario but northeasterly winds across the area and
chances for precipitation early in the day with a lull later on. The
cold air damming should keep temperatures down around 50 degrees in
the Triad with middle 50s across the southeast.
Tuesday the Miller B scenario takes full effect a pair of lows on
either side of the wedge parked over the Piedmont. Precipitation
should begin early Tuesday morning and continue all the way through
Tuesday night before the system starts to move off to the northeast.
Accumulations for this event should be over an inch and possibly up
to two inches. Temperatures will be tricky and dependent highly upon
the track of the coastal low. With fairly high confidence, the Triad
should stay cold throughout the day under the wedge with highs
possibly only in the upper 40s. The bigger uncertainties in the
temperature forecast lay in the south and east where highs could be
as much as 60 degrees.
Wednesday and Thursday will be dry and a little warmer on the front
side of a longwave trough bisecting the continent. Highs in the 60s.
By Thursday night, models begin to diverge on timing and available
moisture leading to two very different possible scenarios for
Thursday night into Friday. The GFS solution has a very progressive
trough and a drier solution which brings very cold temperatures into
the area on Thursday night. The ECMWF solution is slower and wetter
which means warmer temperatures hanging around longer Thursday
night. For now we are taking the dry, colder forecast so expect
temperatures below freezing both Thursday and Friday nights with
Friday being the coldest as very anomalous thickness values move
into the area and bring low temperatures down into the 20-25 degree
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
As of 1118 AM Saturday...
High confidence in VFR conditions through 06Z/Sunday, then CIGS will
lower between 06Z-18Z Sunday into the MVFR range. VSBYS remain VFR
with a chance of light rain arriving around 12z in the west/ and
later in the day in the east Sunday.
OUTLOOK FOR LATE SUNDAY THROUGH WEDNESDAY... Confidence is high that
conditions will become IFR Sunday evening/night and remain IFR or
LIFR into Monday with periods of rain and drizzle.
LIFR TO IFR conditions are expected Monday night and Tuesday with
the storm system arriving from the SW and the cold air damming over
the region. Rain should taper off Tuesday night but IFR/LIFR
conditions may hold through daybreak Wednesday, followed by
improvement to VFR by midday Wednesday.