Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 241457
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
955 AM EST Fri Nov 24 2017

.SYNOPSIS...
High pressure will remain over the Carolinas until a cold front
crosses the region Sat night.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 955 AM Friday...

Little if any adjustments required to the near term forecast.

An area if high pressure at the surface and subsidence behind a weak
upper level disturbance exiting offshore will maintain sunny skies
across central NC today. After a chilly start to the morning which
saw low temperatures as cold as the mid-upper 20s across the
Piedmont, the air mass will quickly modify by afternoon. High
temperatures this afternoon will be solidly in the 50s with the
Sandhills and southern Piedmont warming to around 60. There will be
a slight uptick in high level cloudiness late this afternoon into
the evening as another weak/weakening upper level disturbance passes
overhead. Still, expect chilly overnight conditions with areas of
frost highly probable. Min temps by early Saturday will be a few
degrees warmer due to the moderating air mass. Overnight
temperatures in the low-mid 30s expected.

&&

.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
As of 355 AM Friday...

The models indicate a positively-tilted trough extending this
morning from n-cntl Canada wswwd through the Pacific NW will amplify
from the Great Lakes sswwd into the GOM on Sat, with the associated
trough likely to reach the sern US coast by 12Z Sun. An associated
988 mb surface low now over cntl Canada will migrate ewd through ern
Canada, while the trailing cold front will sweep into the cntl
Appalachians by 00Z Sun, before spilling across cntl NC Sat night.

A mid-high level moist axis preceding the surface front and
accompanying the aforementioned mid-upper trough --mostly above 8-10
thousand ft-- will sweep ewd across cntl NC late Sat aft through
early Sat night. Already limited low level moisture and associated
transport, and wly/downslope low level flow, suggests any light
precipitation aloft/virga accompanying the moist axis will not reach
the surface, so dry conditions remain favored at this time. It will
warm well into the 60s ahead of the front, with any afternoon mostly
cloudiness over the wrn half of the forecast area not likely to have
an effect on high temperatures due to their late arrival in the
diurnal cycle, and offset by downslope/compressional warming. CAA-
driven lows, with some radiational cooling potential over the wrn
Piedmont late as the MSL pressure gradient relaxes there, favor lows
in the mid 30s to lwr 40s.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 340 PM EDT Friday...

...Dry and mild temperatures expected next week...

In the wake of the cold front passage Saturday night, mild surface
high pressure centered over the Lower MS Valley will build west into
the area through Monday, before shifting offshore on Tuesday.
Meanwhile aloft, the eastern US trough will lift out as the strong
ridge over the Western US de-amplifies as it shifts eastward across
the Southern and SE CONUS. As a result, the slightly below normal
temperatures(55-60 F)Sunday and Monday will be rather short-lived,
with temperatures moderating to above normal levels by Tuesday,
likely peaking on Wednesday with afternoon temperatures warming well
into the 60s and possibly even near 70 across the southern coastal
plain and Sandhills.

The latest 00z/24 solutions of the GFS and EC have come into much
better model agreement with the upper trough ejecting out of the
Rockies Wednesday and Thursday, with the general consensus tracking
the sheared system well north/northwest of the area. This will favor
a continuation of dry and mild conditions through Thursday.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
As of 620 AM Friday...

Aside from patchy radiation fog that may linger at climatologically-
favored RWI for the next hour or so, VFR, generally clear conditions
are expected to result from surface high pressure over our
region.

Outlook: The passage of an upper level trough and accompanying
moisture-starved, surface cold front will result in areas of virga
from ceilings at or above 8-10 thousand ft Sat aft-eve, but no
precipitation is expected at this time to reach the surface. There
will be a small chance of sct to bkn MVFR stratocumulus at FAY and
RWI, in sly return flow around offshore high pressure, Tue aft.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SYNOPSIS...MWS
NEAR TERM...WSS
SHORT TERM...MWS
LONG TERM...CBL
AVIATION...MWS



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