Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
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FXUS62 KRAH 250013
Area Forecast Discussion
National Weather Service Raleigh NC
813 PM EDT SAT SEP 24 2016
A cold front will move south through the area late tonight
and early Sunday. The front will move back northward as a warm
front Monday and Tuesday.
.NEAR TERM /THROUGH TONIGHT/...
As of 130 PM Saturday...
With the cold front still located over northern VA, observational data
and the latest models strongly suggest that it will be well into the overnight
before the it makes it into our region. A prefrontal trough was located
over the foothills of VA and NC with dew points mixing out into the
50s and lower 60s into our NW Piedmont Triad region. East of the trough,
lingering low level moisture in the east provided dew points ranging
in the mid 60s to lower 70s.
Highs this afternoon in the upper 80s to lower 90s will be slow to cool
in the pre-frontal environment this evening. CAMS indicate a very low
end chance of a shower with the front between 1100 PM and 300 AM in the
NE zones, but the chance appears to be less than 15 percent.
Otherwise, a clear and warm evening will give way to a low overcast
that will spread/develop into the region from the NE later tonight
and early Sunday. Cool advection will not begin until late, thus lows will
be warm in the mid 60s NE, to near 70 in the south and west.
.SHORT TERM /SUNDAY and SUNDAY NIGHT/...
As of 130 PM Saturday...
A quick turn from summer to fall expected Sunday with some hybrid
CAD expected into the Piedmont region Sunday and Sunday night.
Sunday will bring much more fall-like conditions led by the cooling
NE flow and cloud cover. The cooling conditions will be pushed down
the eastern seaboard by surface high pressure (1025 MB) centered
over SE Canada. The high pressure ridge is forecast to extend
southward into NC/SC into Sunday night before the ridge axis moves east.
Models still bring low stratus deep into our region with even a chance of
light drizzle in the NW Piedmont by early Sunday afternoon. It appears
that little if any QPF can be expected as the moist upglide is expected
to be too shallow for anything more that a trace
to 0.01 or 0.02 in the northwest zones, with nothing more than a sprinkle
expected elsewhere. Highs will be much cooler with overcast skies in
much of the region. Highs Sunday will be coolest in the north-central
Piedmont where readings may hold in the 60s. Elsewhere, highs will range
into the 70s across the south and west. The overcast may break into
variably cloudy skies in the SE, otherwise extensive cloudiness is
expected through the day into Sunday night. Lows Sunday night in the upper 50s
to mid 60s.
.LONG TERM /MONDAY THROUGH SATURDAY/...
As of 310 PM Saturday...
Monday through Tuesday night: Surface high pressure is expected to
shift eastward and off the Northeast U.S. coast on Monday, with any
hybrid CAD eroding from SE to NW with possibly some lingering light
precip (mainly west where the damming should linger the longest).
High temps are expected to generally range from the mid to upper 70s
north/northwest to the lower 80s south.
A mid/upper level low will slowly wobble east and southward across
the Great Lakes region early next week, allowing an associated cold
front to to approach the area on Monday night into early Tuesday,
then slowly cross the area on Tuesday into Tuesday evening as the
cold front begins to become more parallel to the mid level flow
(helping to slow its progress). With regard to any severe threat
instability looks to be weak, however, deep layer shear is expected
to be respectable. Thus, we could see a some storms even some weakly
organization convection, but the severe potential will remain quite
low. Highs Tuesday are generally expected to be in the upper 70s to
lower 80s, with lows Tuesday morning in the mid to upper 60s and
lows Wednesday morning ranging from the mid to upper 50s nw to the
lower to mid 60s se.
Wednesday through Saturday: the mid to upper level flow pattern is
in question mid to late next week, with regard to what happens to
aforementioned deep mid/upper low over the Great Lakes early next
week. The latest GFS continue to show the feature becoming a deep
trough and moving through the area Wednesday/Wednesday night,
helping to push the front (which is expected to linger across
coastal portions of NC on Wednesday) offshore and away from the
area. Meanwhile, this is the second run in a row of the ECMWF
showing the mid/upper low sinking southward towards our area mid
week, and lingering the low as it becomes cut off from the
westerlies. The 00Z ECMWF ensemble members didn`t show much support
for the scenario, so will keep the forecast dry from Wednesday
evening onward (but will need to watch this). Otherwise, surface
high pressure is expected to build/extend into the area through the
period, with highs and lows expected to be near to slightly below
.AVIATION /00Z SUNDAY THROUGH WEDNESDAY/...
-- Changed Discussion --As of 812 PM Saturday...
A cold front nearing the VA border will continue to drop south
through the state overnight. Behind the front, likely IFR stratus
will develop as low level flow behind the front becomes
northeasterly. KRWI and KRDU are likely to be impacted first, around
06z, spreading to other sites between 07-09z. A brief period of fog
is possible at KFAY with moisture pooling ahead of the front before
the stratus moves in.
MVFR conditions will persist into the afternoon on Sunday.
Conditions will begin to trend to VFR Sunday night into early
Monday. Showers and associated sub-VFR cigs are possible Monday
and Tuesday as a cold front approaches and moves through the region.
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