Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 182333

Area Forecast Discussion
National Weather Service Raleigh NC
733 PM EDT Wed Oct 18 2017

Surface high pressure over the Mid-atlantic will extend across
the region into the weekend. A cold front will approach the
area from the west early next week.


As of 245 PM Wednesday...

With high pressure at the surface and aloft firmly in control of our
weather, expect dry and seasonably cool conditions tonight. Latest
model guidance not noting as much of a signal for patchy low stratus
in vicinity of our far southeastern counties as before. So, aside
from a few patches of cirrus, expect clear skies overnight. The air
mass has modified, so expect overnight temperatures to be a few
degrees warmer than last night. Bulk of region will be in the low-
mid 40s, with upper 30s in the normally colder locations.


As of 245 PM Wednesday...

Little change in the weather pattern as high pressure will remain
positioned overhead. Under sunny skies, temperatures should rebound
back to levels close to normal, primarily in the mid 70s. Continued
pleasantly cool and dry Thursday night with min temps in the mid-
upper 40s, lower 40s in the cooler locations.


As of 200 PM Wednesday...

Glorious "fair" weather will continue through the weekend as the
upper ridge axis shifts east and over the area Friday and Saturday,
then offshore Sunday. The dry surface high follows suit, with low
level easterly flow gradually veering more southerly through the
weekend. Expect sunny skies with light winds and highs reaching the
mid to upper 70s each day. Morning lows will be nippy, but warming a
bit, with Saturday morning`s lows mostly in the upper 40s warming to
the lower 50s for Sunday morning, and further to the mid 50s Monday

By Sunday night, the low level winds will be southeast and
increasing as a strong cold front edges east towards the mountains.
Upslope flow will produce increasing cloudiness spreading in from
the west Sunday night, with showers developing as far east as the
western Piedmont (Charlotte and the Triad) by Monday morning. Shower
coverage will increase throughout the day, enhanced by the approach
of stronger upper dynamic support associated with an upper level
short wave which will be moving east across the area Monday night.
While still subject to error, the timing of the deepest moisture,
low level forcing, and upper dynamics which would favor stronger
convection align best Monday night into early Tuesday, missing out
on our strongest diurnal instability. Highs Monday prior to frontal
passage should reach mid and upper 70s, with warm air advection
offsetting the lessened insolation.

There is considerably more uncertainty as to whether we have a
relatively clean cold frontal passage on Tuesday with drying to
quickly follow, or whether we might have a more vigorous upper short
wave move across to produce more widespread convection during the
day, and will maintain ~50% PoPs. The cold air surge behind the
front will be delayed until later in the day, and highs Tuesday
should have a chance to reach upper 60s to lower 70s. The colder,
drier air will be settling into the area Tuesday night and
Wednesday, with mins falling into the 40s Tuesday night, and highs
stalling mostly in the lower 60s on Wednesday.


As of 733 PM Wednesday...

24-Hour TAF period: High confidence VFR conditions will prevail
through the TAF period. The only exception would be a chance for
some patchy fog with some MVFR visbys at KRWI (lesser chances at
KFAY) between 09Z and 12Z Thursday, though confidence is not high.
Otherwise, generally clear skies and light and variable winds will
persist through the period.

Looking ahead: VFR conditions will prevail through the first half of
the weekend, with brief periods of sub-vfr conditions in the pre-
dawn hours possible near KFAY and KRWI. Upslope flow in the west
late Sunday night or Monday ahead of an approaching cold front could
result in some sub-vfr conditions, however the next chance for
widespread sub-vfr conditions will come with pre-frontal convection
between Monday afternoon and Tuesday night as the front moves into
and through the region.




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