Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
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FXUS62 KRAH 191342
Area Forecast Discussion
National Weather Service Raleigh NC
940 AM EDT WED OCT 19 2016
A deep ridge of high pressure will extend across the region through
Thursday. A surface cold front and upper level low pressure trough
will approach from the west Thursday night, then cross the area
Friday through Friday night. Cool high pressure will build in from
the west over the weekend.
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --As of 940 AM Wednesday...
Basically a temperature forecast today, and the current forecast
appears to right on track. A 590dm ridge at H5 spans the Southeast,
resulting in strong subsidence and a 1403m low level thickness at
KGSO this morning. This will yield near record highs in the mid
80 this afternoon. GSO AND RDU may break these record highs:
GSO - 86 in 1938
RDU - 87 in 1941
FAY - 90 in 1926
Tonight, Skies should be mostly clear with light southwesterly
winds. Low temperatures Wednesday night into Thursday morning
staying up in the low 60s.
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.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
As of 320 AM Wednesday...
Not quite as hot on Thursday as the ridge begins to break down and
we start to see cloud cover increase ahead of a frontal system that
will be moving through the Ohio Valley. Still will see low to mid
80s though across the area with light southwesterly winds ahead of
the front. Dewpoints will come up into the mid 60s ahead of the
front as well as some moisture advection begins. Despite this,
Thursday will be dry precipitation wise. This will be the last 80
degree day for a while as the front moves through on Friday and
brings a new airmass for the weekend and into next week. Lows
Thursday night in the lower 60s.
.LONG TERM /Friday through Tuesday/...
As of 240 AM Wednesday...
Fri-Fri night: Models agree on the incoming cold front being aligned
along the mountains early Fri, although they differ a bit in speed,
with the NAM/ECMWF about 3-6 hours slower than the GFS. Will lean
toward the slower solution based on the strength of the deep
longwave trough driving frontal movement. Moisture along and ahead
of this front remains rather shallow and fleeting, given the
weakening but lingering deep ridging and weak flow ahead of the
front (between it and the offshore-tracking potential tropical or
subtropical low) providing no good opportunity for moisture
transport into the region. Will maintain good chance pops focused on
the NW forecast area including the Triad, where large scale ascent
in the form of DPVA and upper divergence will be greatest, trending
to small chances across the southern and SE CWA. QPF is expected to
be quite low, less than a tenth of an inch in most places. Any
showers are likely to be exiting the forecast area prior to sundown,
with rapid clearing taking place thereafter. The front should swing
through the western forecast area during the morning and midday
hours, with thicknesses plunging there and limited insolation only
allowing highs to reach the mid 60s, while in the east with at least
a little sunshine and delayed front, temps should get up into the
lower to mid 70s. Winds pick up considerably from the NW just behind
the front, and momentum transport noted on forecast soundings
suggests that gusts over 20 mph are likely in the afternoon. Lows
Fri night in the 45-50 range with diminishing winds.
Sat-Tue: Still looks fair, dry, and cool, but with moderating temps
back to near normal by Mon, as the mid level trough axis kicks to
our NE with rising heights aloft, and modifying high pressure
building into the Mid-South/Gulf states and Southeast. We return to
above normal thicknesses Sun night through Mon night as we get into
a relative warm sector with the surface high sitting over the
central Gulf Coast. Then, energy diving into a mean polar low over
southern Quebec will help draw a dry backdoor front into the region,
and both the ECMWF and GFS indicate cooler high pressure nosing in
from the north on Tue. After cool highs Sat in the lower to mid 60s,
warming to the upper 60s Sun and lower 70s Mon, expect highs to slip
back into the upper 60s for Tue. -GIH
.AVIATION /12Z WEDNESDAY THROUGH MONDAY/...
As of 700 AM Wednesday...
24 Hour TAF period: A few stations showing some MVFR fog this
morning but the main TAF sites have remained VFR. Otherwise another
repeat of previous days with weak southwesterly flow and little to
no cloud cover.
Long term: VFR conditions expected until Friday when a front
approaches from the west and could provide some precipitation and
adverse aviation conditions.