Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC
FXUS62 KRAH 011431
Area Forecast Discussion
National Weather Service Raleigh NC
1030 AM EDT SAT OCT 1 2016
A weak surface front will slowly move east to coastal North Carolina
today through tonight, as an upper level low drifts from the Ohio
Valley northeast into the Great Lakes. Weak high pressure will build
into the region early next week.
.NEAR TERM /through tonight/...
As of 1030 AM Saturday...
Dense fog advisory was allowed to expire with the slow dispersion
and improvement in visibilities. The latest surface analysis shows
the frontal zone bisecting the forecast area with dewpoints having
fallen into the lower 60s and upper 50s to its WSW while values
across the northern and eastern CWA remain in the mid-upper 60s to
lower 70s. This distinction will largely drive the development and
extent of flat convective clouds this afternoon, with better
coverage far north and east with few to no clouds west where deep
dry air is evident on water vapor imagery and in surface/upper air
data. An isolated shower risk will persist over the far eastern CWA
as a weak wave tracks northward through eastern NC, bringing a quick
shot of moist upglide noted on 300k model progs. But forecast
soundings depict the moisture as being somewhat shallow, so will
keep pops and QPF low. Latest high res model runs support highs from
the upper 70s to lower 80s, oriented NW to SE, although if the
cloudiness in the east trends more expansive than currently
anticipated, we may need to trim a couple degrees off forecast highs
in the SE CWA. -GIH
Earlier discussion as of 635 AM Saturday: Water vapor imagery early
this morning still depicts a decent plume of moisture lifting
northward across eastern North Carolina. Presence of this moisture
coupled with afternoon heating and weak perturbations within the
flow aloft should be sufficient to spark a few showers and isolated
thunderstorms, mainly east of I-95. Some question as to the threat
for a shower in vicinity of highway 1. Models insist that the
atmosphere will dry out to the point that shower development will be
prohibited due to lack of moisture.However, considering that the
models are too dry over our western counties early this morning,
would not be surprised if an isolated shower develops as far west as
the highway 1 corridor this afternoon.
The upper level low over the lower Ohio Valley, driving the moisture
plume across eastern North Carolina, expected to drift northward
today. Drier air aloft rotating around this maturing system will
eventually rotate into most of central NC later today and tonight.
Highs this afternoon will range from near 80 nw to the lower 80s
elsewhere. If clouds are less extensive than forecast (ie more sun),
then could see mid 80s over the far east-se sections of the forecast
Tonight, close proximity of the moisture plume to our eastern border
suggest a continued threat for an isolated shower this evening into
the overnight, mainly east of I-95. Potential for patchy or areas of
fog, mostly along the highway 1 corridor including the triangle
area. Overnight temps mid 50s west where skies will be mostly clear,
to the mid 60s in the far east where clouds may prevail. -wss
.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
As of 310 AM Saturday...
Expect a continued gradual improvement in weather conditions across
central NC as the upper level low begins to lift off to the
northeast across the eastern Great Lakes. This should shunt the
moisture plume farther east, leading to drier conditions with a
mixture of sun and clouds expected across the east, and mostly sunny
skies west. Will likely see an uptick in mid-high level clouds late
in the day along our western periphery as a disturbance rotating
through the upper level approaches.
Afternoon temps should remain a few degrees above normal, though
fairly uniform, ranging between 80-84 degrees. Expect warmer
overnight temps in the west Sunday night due to a blanket of mid-
high level clouds. Overnight temps in the low-mid 60s areawide.
.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 328 AM Saturday...
The upper level low will move off the Northeast coast by late
Monday. Upper level ridging will build across the East Coast
midweek, while surface high pressure centered over New England
extends into the area. Expect a mainly dry forecast through
Wednesday with near normal highs in the upper 70s.
Uncertainty increases after Wednesday. An upper trough and attendant
cold front will move into the MS Valley Thursday and progress
eastward Friday. Front will likely weaken as much of the main upper
level support remains well north into Canada. Meanwhile, current
guidance differs significantly with respect to the proximity of
Hurricane Matthew to the East Coast due to differences in resolving
the aforementioned trough. Influence of any tropical moisture and
consequent cloud cover and rain chances will be highly track
dependent. Please refer to the National Hurricane Center for the
latest information on Matthew.
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
As of 730 AM Saturday...
Widespread sub-VFR conditions are highly likely across central NC
through mid morning due to widespread fog and low clouds. Conditions
are expected to improve first in the Triad region shortly as drier
low level air is in close proximity to this area. Aviation
conditions should improve between 14Z and 16Z elsewhere, though
ceilings may remain MVFR in vicinity of KFAY and KRWI through the
Scattered showers and isolated thunderstorms are expected to develop
this afternoon in proximity of KFAY and KRWI with the greatest
threat between 19Z and 23Z. Another round of IFR/LIFR conditions due
to ceilings and possibly visibility (due to fog) appear likely in
vicinity of KRWI, KFAY, and possibly KRDU.
Aviation conditions are expected to improve Sunday through Wednesday
with mainly VFR conditions. The exception will be a chance for MVFR
ceilings and visibility each early morning, with the threat greatest
in proximity of KRWI and KFAY.