Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
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FXUS62 KRAH 180225
Area Forecast Discussion
National Weather Service Raleigh NC
1025 PM EDT MON OCT 17 2016
Ridging at the surface and aloft will prevail through the majority
of the work week. An upper level disturbance and attendant cold
front will approach the region from the west Thursday night into
Friday, at the same time a cut-off low and associated surface low
pressure system are expected to retrograde westward from the Bahamas
toward the Southeast coast.
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --As of 1025 PM Monday...
Surface high pressure will continue to ridge westward into Central
North Carolina through tonight. Clear skies and calm to light
southerly winds will persist, allowing for good radiational cooling
and lows in the mid to upper 50s. Low dewpoint depressions could
result in some fog/low stratus in the pre-dawn hours, however
coverage will be patchy and confidence is not terribly high.
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.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
As of 1200 PM Monday...
Little change in comparison to today aside from additional height
rises as the aforementioned upper level ridge builds eastward from
TX to the Deep South, maintaining Bermuda high pressure and the dry
surface ridge extending west onshore the Southeast/Carolina coast.
Expect dry/benign weather to persist with temperatures rising a few
more degrees in comparison to today, in the lower 80s (a good 10F
above normal), lows Tue night near 60F. -Vincent
.LONG TERM /WEDNESDAY THROUGH MONdAY/...
As of 255 pM Monday...
Wednesday and Wednesday night...a ridge aloft centered over
southern AL/GA will ridge northeast into the Carolinas while
surface high pressure over the western Atlantic will ridge west into
NC/VA. A dry and rather warm air mass across the region will be
characterized by low precipitable water values of around 1.0 inches
and morning low-level thickness values of 1395-1400m. The result
will be mainly clear skies with a period of early morning
fog/stratus possible across the Coastal Plain. High temperatures
will warm into the mid 80s in most locations, which will be around
15 degrees above normal. Record highs for Wednesday (10/19) include
86 at GSO, 86 at RDU, and 90 at FAY. Lows Wednesday night will fall
back into the lower 60s.
The weather pattern will become more active for Thursday through
Friday night as northern stream energy drops into the central
Plains on Thursday and heights begin to fall across the Carolinas.
NWP guidance in fairly good agreement that a higher amplitude
trough sets up near the central Mississippi river on Thursday
evening. Guidance then diverges in the handling of this system with
the 12Z ECMWF aggressively pushing the trough and the associated cold
front across central NC Friday morning with little/no
precipitation while the GFS is slower, more amplified with the
upper trough, eventually pushing it across the Carolinas in a
negatively tilted fashion with a few tenths of an inch of
precipitation. Further complicating things is an upper level low
pressure system near the Bahamas that the National Hurricane Center
now notes has a 60% chance of developing into a tropical or
subtropical cyclone late in the work week as it moves slowly
north or northwest. A slower arrival of the upper trough (per the
operational GFS) would allow this system to get closer to the
Southeast coast and possibly bridge some moisture into the area. WPC
prefers the more progressive (ECMWF) solution which would result in
a more benign system for central NC. Given this we have lowered PoPs
a bit with a low chance or slight chance of showers in the forecast
for Friday and Friday night. Highs on Thursday will range in the
lower 80s and highs Friday will range in the lower and mid 70s with
lows Friday night falling into the upper 40s to lower 50s.
Quiet but cooler weather arrives for the weekend and Monday as
northwest flow aloft develops on Saturday and persists into Monday.
Surface high pressure will slowly build into the region on Sunday
and Monday. It will be chilly on Saturday with highs in the lower to
mid 60s along with cool northwest wind at 10 to 15 MPH with gusts
up to 25 MPH. It will turn quite chilly on Saturday night with lows
in the lower to mid 40s expected. Temperatures could be even
chillier if the winds relax and optimal radiational cooling
conditions develop. Fair weather and a slow moderation of
temperatures is expected on Sunday into Monday with Monday`s highs
ranging near normal from 69 to 74. -Blaes
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
As of 730 PM Monday...
24 Hour TAF period: VFR conditions are generally expected to continue
through the 24 hour TAF period as high pressure at the surface and
aloft continues to provide the area with dry weather and mostly
clear/mostly sunny skies. However, with light and variable to calm
winds again tonight along with clear/mostly clear skies, we could
again see some patchy sub-VFR visbys. KRWI stands the best chance of
seeing any sub-VFR conditions, similar to last night. Any sub-VFR
conditions that develop are expected to be quickly dissipate with
Outlook: Aside from the possibility of a short period of early
morning fog each morning expect mostly clear skies and light/
variable winds through the majority of the work week as ridging
prevails at the surface and aloft. The next chance for sub-VFR
conditions will be Friday/Friday night when an upper level trough
and attendant cold front are expected to progress east across the
Carolinas/Mid-Atlantic and a low pressure system attendant a cut-off
low offshore the Southeast coast is expected to retrograde westward
from the Bahamas toward the Carolinas, however, forecast confidence
remains below average in this period.