Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Remove Highlighting --
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FXUS62 KRAH 301852
Area Forecast Discussion
National Weather Service Raleigh NC
250 PM EDT FRI SEP 30 2016
A weak wave of low pressure and associated frontal zone will drift
east across our region through early Saturday, then offshore through
the rest of the weekend, while a persistent upper level low over the
Tennessee Valley lifts across the Lower Great Lakes.
.NEAR TERM /through tonight/...
-- Changed Discussion --As of 250 PM Friday...
Improving conditions are on the horizon. The latest surface analysis
indicates that the leading edge of the drier air has worked through
the two westernmost rows of counties, with surface dewpoints there
having fallen into the upper 50s to lower 60s and a slight shift of
surface winds to a more southerly or SSW direction. The
thermodynamic environment along and east of the front remains
supportive of scattered showers and storms, with MUCAPE up to 1500-
2000 J/kg and steepening low level lapse rates, in conjunction with
50-55 kts of 0-6 km shear, a 50 kt mid level jetlet, and a pocket of
upper divergence pivoting around the east side of the potent low
centered over the KY/IN border. Certainly we could still see a
strong to isolated severe storm or two prior to nightfall based on
the existing environment. Will retain chance pops and partly to
mostly cloudy skies over all but the western CWA for several more
hours. Forecast soundings show slow but steady low level cooling and
drying through the evening and overnight, so a trend toward clearing
from SW to NE looks reasonable, with a corresponding end to shower
chances. Expect lows from the mid 50s west to the mid 60s east. -GIH
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.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
As of 200 AM Friday...
Dry/stable conditions will prevail sat/sat night as a dry low-level
airmass advects into the region beneath an increasingly warm/dry mid-
level airmass as the upper level low retrogrades northward away from
the region (toward the Great Lakes). Expect highs in the upper 70s
to lower 80s and lows mid/upper 50s to lower 60s. -Vincent
.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 350 PM Thursday...
he upper low over the Great Lakes will finally open up and weaken as
it finally ejects eastward off the New England Coast late Monday and
into Tuesday. Warm dry air aloft will cap Central NC off from any
convection Sunday and Monday with daytime highs continuing to run a
good 3 to 5 degrees above normal. Highs in the upper 70s north to
lower 80s south. Lows 60 to 65.
In the wake of the low lingering off the New England Coast, Canadian
high pressure will wedge south down the Atlantic Seaboard, bringing
cooler, more seasonable temperatures Tuesday through Thursday.
The NHC forecasts has Matthew moving northward through the Bahamas
on Tuesday, with large model spread thereafter in both the track
and speed of Matthew for the latter half of next week. Refer to the
National Hurricane Center for the latest information on TC Matthew.
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
As of 210 PM Friday...
MVFR cigs persist at RDU/RWI/FAY with a continued threat for
scattered showers and isolated storms, while conditions have
improved to VFR at INT/GSO as a slow moving cold front has shifted
just east of these locations, with drier air moving in. The dominant
MVFR conditions at RDU/RWI/FAY will improve to VFR from late
afternoon through early to mid evening as dry air gradually works in
from the WSW, with a corresponding end to the shower/storm chances.
There is a small chance of MVFR or IFR vsbys in fog at RWI/RDU early
Sat morning but chances appear too remote at this time to include in
the terminal forecasts. VFR conditions are expected at all sites
late tonight through Sat as high pressure builds in from the WSW.
Surface winds from the SE at 6-12 kts will become light/variable for
much of tonight before becoming southwesterly Sat behind the front.
Looking beyond 18z Sat: VFR conditions are likely to dominate
through Wed, although a period of sub-VFR fog/stratus is possible
areawide early Wed morning. -GIH