Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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316
FXUS62 KRAH 230001
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
700 PM EST Thu Feb 22 2018

.SYNOPSIS...
A strong sub-tropical ridge aloft situated off the coast of the
Carolinas will weaken while drifting south toward the Bahamas
through Friday night. Meanwhile, a back door cold front will settle
into north-central NC late tonight and early Friday. That front will
become quasi-stationary over northern NC through Friday night, then
retreat north as a warm front on Saturday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 700 PM Thursday...

Little change required to the near term forecast.

Abnormally strong sub-tropical high just off the Southeast U.S. will
gradually shift south and west with time. Meanwhile a strong cold
front stretching across central VA will edge southward, and lie
close the NC/VA border prior to midnight, and potentially lie close
to the highway 64 corridor by daybreak. The weak convergence along
this feature working with available low level moisture should
trigger a few patches of drizzle/light rain overnight along with a
deck of thick clouds and much cooler temperatures.

To the south of the boundary, mild and dry conditions will persist
overnight. Similar to last night, expect widespread low clouds and
areas of fog to develop. Min temps by early Friday expected to vary
from the low-mid 50s across the far north-northeast, to the lower
60s south.

&&

.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
As of 305 PM Thursday...

Principle forecast challenge remains how far into n-cntl NC the cold
front moves, then to what degree it retreats nwd during the
afternoon and evening hours. Forecast confidence is relatively high
for the srn half of cntl NC, with persistence lifting and scattering
of morning low cloudiness and fog, with with temperatures again in
the upr 70s to around 80 degrees. Forecast confidence is similarly
high that nrn locations from near Roxboro to Henderson to Lake
Gaston and Roanoke Rapids Kerr will remain cool, in the 60s, with
some upr 50s possible, amidst CAD and continued post-frontal low
cloudiness, and a chance of light rain and drizzle in the morning.
The greatest uncertainty and 10-15 degree bust potential will exist
roughly along and just north of Highway 64, including the major
metro areas along I-40. There will be a sharp gradient in
temperatures in this corridor separating the two regimes noted
above. The front will remain quasi-stationary and become
increasingly diffuse Friday afternoon and evening, with an otherwise
persistence forecast of continued mild conditions, with yet another
round of late night low cloudiness and areas of fog owing to the
persist unseasonably humid conditions in place.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 225 PM Thursday...

The subtropical ridge hangs tough through the weekend and looks like
we will remain in the warm sector, with highs well into the 70s
Saturday and Sunday. A cold front will be edging east as the ridge
retrogresses slightly southwest, but the front`s progress will be
glacial and the front will be basically stalled in the vicinity
through Monday. Will have likely PoPs in the West on Sunday,
transitioning slowly across the area to the east on Monday, which
looks to be our best chance for rain as a surface wave lifts
northeast along the boundary. The persistent subtropical ridge will
weaken/dampen as a vigorous mid level short wave lifts out of the
Midwest, hammering the ridge further south and interrupting our warm
spell. Highs Monday will be limited to low and mid 60s by cloud
coverage and potential for some cool air advection as the surface
front reaches the Coastal Plain late in the day.

Drier and seasonable high pressure will build in on Tuesday through
Wednesday, with copious sun and highs mostly from 60 to 65 after
morning lows from 40 to 45. The ridging hasn`t finished with us yet,
as it will be re-amplifying northward up the eastern CONUS on
Wednesday, lifting a warm front north into the area with associated
rain on Wednesday night into Thursday. Highs Thursday will be mostly
low and mid 60s.

&&

.AVIATION /00Z FRIDAY THROUGH WEDNESDAY/...
As of 645 PM Thursday...

24-Hour TAF Period: The persistence forecast continues for this 24
hour period. VFR conditions to start the TAF period will once again
give way to MVFR cigs and visbys after midnight, generally between
06Z and 09Z Friday, then subsequently dropping to IFR/LIFR between
09Z and 15Z, with the best chances at KFAY, then KRWI and less so at
KRDU, KGSO, and KINT. Cigs in the 800-1500 ft range will persist
into the morning, gradually scattering out during the afternoon. A
period of light rain/drizzle is possible Friday morning as a
backdoor cold front drops southward through northern and eastern
portions of Central NC. Generally expect clouds to scatter out with
bases in the 2-4 kft range toward the end of the TAF period. Winds
are expected to be light and variable through the period, the only
exception being a brief period of 5-10 kt winds along the
aforementioned cold front. -KC

Looking ahead: The sub-tropical ridge will weaken and drift south,
but maintain influence over the Carolinas. As a result, a
persistence forecast of late night-morning stratus and fog, lifting
and scattering to high MVFR-low VFR each afternoon, will generally
continue through the weekend. Otherwise, the next chance of rain
will accompany a frontal zone that will settle into, and possibly
stall over the Carolinas, late Sun into early next week. -MWS

&&

.CLIMATE...

RDU Records:

Date     |  High  Year  |  High Min  Year
------------------------------------------
02/22       75    1897        60     1897
02/23       79    1980        57     1962
02/24       81    1982        58     1985

GSO Records:

Date     |  High  Year  |  High Min  Year
------------------------------------------
02/22       74    1925        57     1980
02/23       74    2017        52     1922
02/24       79    1982        55     1985

FAY Records:

Date     |  High  Year  |  High Min  Year
-------------------------------------------
02/22       77    2003        56     1989
02/23       80    1922        55     1922
02/24       83    1930        60     1975
&&

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

&&

$$

SYNOPSIS...MWS
NEAR TERM...WSS
SHORT TERM...MWS
LONG TERM...mlm
AVIATION...KC/MWS
CLIMATE...RAH



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