Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 231603
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
1103 AM EST Fri Feb 23 2018

.SYNOPSIS...
A strong sub-tropical ridge aloft situated off the Southeast U.S.
coast will weaken while drifting south toward the Bahamas through
Saturday. Meanwhile, a quasi-stationary front over s-cntl NC this
morning will retreat slowly nwd through this evening, then more
appreciably so as it dissipates on Sat.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1100 AM Friday...

AT 16Z, the surface cold front was analyzed from just northeast of
ILM, nwwd to near SOP, where it had become stationary from there wwd
to near IPJ. Associated surface temperatures ranged from mid-upr 40s
across the far nrn Piedmont and Coastal Plain (46-48 at TDF/HNZ/IXA)
to around 70 degrees in the srn Piedmont (70-72 at AFP/RCZ/MEB).

12Z upr air data and pilot reports indicate the overcast layer over
the Piedmont is relatively thick, between 1-2 k ft deep; and visible
satellite imagery this morning indeed reveals a thick blanket of low
cloudiness there. To the south, and even behind the front, over the
Sandhills and srn and cntl Coastal Plain, the moist layer is more
shallow and thinner and will be more readily eroded/mixed out with
diurnal heating/mixing during the next few hours. This erosion will
subsequently cause the srn fringe of the thicker ovc to the north to
likewise erode and allow the surface front to retreat slowly nwd
through the Highway 64 corridor mid-late afternoon, with associated
late day sun and warming into the upr 60s/around 70 degrees there,
though not the persistence upr 70s to around 80 degrees that are
expected in the current warm sector over srn NC. Meanwhile, the low
clouds and much cooler conditions are expected to persist across the
nrn Piedmont and nrn Coastal Plain, with many locations nw of I-85
likely to hold in the 50s, to perhaps around 60 degrees, throughout
the day.

While the low clouds may briefly scatter even in these far nrn areas
this evening, the associated remnant wedge air mass there will make
those same areas most susceptible to the earliest development of
very low overcast and fog tonight, with that occurrence likely to be
delayed until very late tonight-early Sat morning elsewhere -
similar to previous mornings. Low temperatures are expected to range
from low-mid 50s in the remnant wedge regime to around 60 degrees in
the srn Coastal Plain.

&&

.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
As of 325 AM Friday...

While slightly dampened, the subtropical ridge over the SE US will
continue to be the dominate weather feature over the region,
deflecting the better rain chances west of the area, with a
continuation of record warmth in both daytime highs and warm
nighttime lows.

Shortwave disturbances, ejecting NE in the SW flow aloft, ahead of
the shortwave trough lifting from the Rockies into the Northern
Plains and Upper Midwest, could support a stray shower or two,
especially across the NW Piedmont. Otherwise it remain mostly dry
with a mixture of clouds in the morning, and some sun by the
afternoon. Breezy SWLY winds will develop by the afternoon and will
continue into the evening and overnight as a 40 to 50 kt low-level
jet spreads in from the west. Highs in the 75 to 80. Lows in the
60s.


&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 345 AM Friday...

The Long Term period continues to look active, with two pertinent
weather systems likely to impact the forecast area. Warmer than
normal conditions Sunday afternoon will be replaced with more
seasonable values by Monday afternoon and likely persisting through
at least Thursday.

A strengthening mid latitude cyclone will progress north and east
across the Great Lakes on Sunday inching an associated cold front
east of the mountains. A relatively strong area of high pressure
over the western Atlantic will slowly slide east, allowing the front
to cross through portions of central North Carolina before stalling
across our area. Some significant model differences when it comes to
how far the front will make it east, with the GFS consistently
showing a more vigorous initial surge with the boundary, stalling
the front closer to the coast. The ECMWF on the other hand stalls
the front further inland, allowing a disturbance to develop Sunday
night into Monday, spreading higher QPF amounts across the forecast
area. Have tried to blend the two solutions, allowing POPs to linger
through Monday evening, and notching the average QPF amount closer
to a half inch between Sunday and Monday.

High pressure will build into the mid Atlantic briefly Tuesday and
Wednesday, allowing the sun to re-emerge and drier conditions along
with more seasonable temperatures to win out albeit briefly. Cloud
cover will be on the rise by Wednesday morning as a warm front lifts
north through the Carolinas, once again introducing showers that
will likely persist through Thursday night.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
As of 643 AM Friday...

24-Hour TAF Period: The back-door cold front will briefly stall over
the area this morning, before retreating north into VA this
afternoon and evening. LIFR to MVFR ceiling across the northern
terminals will persist through the morning, gradually lifting and
scattering out during the afternoon. Expect a brief period of ENELY
winds behind the front through 15z, becoming southerly by the late
afternoon and evening. Will follow a persistence forecast overnight,
with areas of stratus and fog(south) developing overnight.


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. Isolated to scattered showers are
possible Saturday afternoon, especially at KINT and KGSO. However,
the better chance of rain will accompany a frontal zone that will
settle into, and possibly stall over the Carolinas, late Sun into
early next week.

&&

.CLIMATE...

RDU Records:

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

GSO Records:

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

FAY Records:

Date     |  High  Year  |  High Min  Year
-------------------------------------------
02/23       80    1922        55     1922
02/24       83    1930        60     1975

&&

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

&&

$$

SYNOPSIS...MWS
NEAR TERM...MWS
SHORT TERM...CBL
LONG TERM...JJM
AVIATION...CBL/MWS
CLIMATE...RAH



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