Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 172000

Area Forecast Discussion
National Weather Service Raleigh NC
300 PM EST Sat Feb 17 2018

A weak cold front will approach from the west and cross our region
tonight. High pressure will build into the area Sunday, then quickly
drift offshore Sunday night.


As of 300 PM Saturday...

Areas of light rain and/or drizzle developing across central NC this
afternoon in response to strengthening upglide in the 925-850mb
layer. Expect this trend to continue with areas of light rain likely
along and north of highway 64. The areas of light precip will
persist through the evening hours as a mid level s/w approaches from
the west. This feature projected to traverse our region after 06Z.
Once it does, expect the precip to diminish and skies begin to clear
from the northwest. The partial clearing across the Piedmont prior
to daybreak will likely promote the development of patchy fog. Not
highly certain if dense fog will occur so will limit the visibility
reduction to no worse than 1-2 miles.  Expect early morning min
temps in the mid 30s to near 40 north, and low-mid 40s south. if
clouds are slow to depart, min temps may end up being 2-3 degrees
warmer than forecast.


As of 300 PM Saturday...

Sunday, high pressure will build in the wake of the departing s/w.
Subsidence and drier air associated with the high will lead to rapid
dissipation of any fog/low clouds that develop, with mostly sunny
skies expected from late morning into the afternoon. Mild conditions
expected for this time of year with afternoon temperatures well into
the 50s to around 60 north, and the low-mid 60s south.

The sfc high will depart early Sunday evening, setting up a low
level return flow. Another isentropic upglide/lift event projected
to occur overnight as a minor s/w lifts newd from the TN
Valley/southern Appalachians into central NC.  Based on the expected
trajectory of the s/w, expect the highest threat for rain across the
nw half of central NC. Based on timing, expect the rain to hold off
until well after midnight, potentially not starting until close to
daybreak. Temperatures will remain mild enough so that precip
expected to be all liquid. min temps will vary from the upper
30s/near 40 northeast, to the mid-upper 40s south and west.


As of 130 PM Saturday...

...Unusually warm temperatures will shatter some records
during this week...

The daily record highs and record high minimum temperatures are
included in the Climate section below for February 20 and
21 (Tuesday and Wednesday). These are the most likely days
that will see new records. We will add to this the chance of record
warmth continuing Thursday (February 22), and this may be extended
in later forecasts due to the slowing of the decay of the strong
upper ridging.

To start off the warming, a warm front will push northward into
the area. Some areas of light rain and showers are expected, with
the highest POP in the NW zones into early Monday. Guidance
continues to favor the warm front and WAA drying advection to
bring clearing into the region Monday afternoon, especially
south and west. Highs should moderate back into the 60s, except
some upper 50s north. This may be tempered if the cloudiness
persists into the afternoon more than currently expected.

The main storm track is forecast to remain to the west and north of
central NC this week. This occurs as a very strong and unusual
subtropical ridge is forecast to set up just off the south Atlantic
coast, most likely waxing Tuesday and Wednesday.

A battle between arctic air over the northern Rockies into the upper
Midwest and the record warmth in the southeastern states will lead
to an active storm track, but much of the significant rain is
expected to remain just to our NW, or from the Appalachians west and
north. One front will likely make a run at us on Thursday, but due
to the extensive upper ridge, will likely stall and return north on
Friday. Most models now depict the strong ridge to remain in place
into next weekend, with the potential for more record warmth
depending on the position of the "backdoor" fronts.

Sensible weather will be for only a slight chance of lingering
light rain or drizzle Monday morning, otherwise increasing warmth
and humidity Tue-Wed. leading to highs potentially in the upper 70s
NW ranging into the lower 80s elsewhere. Some 83-84 degree
readings will be possible from Laurinburg to Fayetteville) Tue-Thu.
Lows in the 60s mid to late week will also likely set records.

We will back off on highs some Thursday, especially NW given the
increasing clouds and chance of showers associated with the slowing
front. Otherwise, a return to SSW flow again Thursday night and
Friday may extend well into next weekend. Highs again may surge
toward records. More on this in later forecasts.


As of 1240 PM Saturday...

Aviation parameters will gradually deteriorate across central NC
through the afternoon as ceilings will lower into the IFR/low end
MVFR range while areas of light rain and/or drizzle develop,
reducing the visibility into the IFR category. These adverse
aviation conditions will persist through the evening. A weak sfc
cold front will traverse the region overnight. Nwly winds will usher
in a drier air mass, leading to lifting/dissipating ceilings and an
end to the spotty light precip. There may be a brief period of
IFR/LIFR visibility due to fog between 09-13Z Sunday in proximity of
the Triad terminals and possibly KRDU, but forecast confidence is
not high enough at this time to mention in the terminal forecast.

VFR parameters expected Sunday but this will not last much into
Sunday night as another low pressure system will begin to effect our
area, leading to MVFR/IFR ceilings and areas of light rain late
Sunday night through Monday.

While an improvement in aviation conditions expected Tuesday through
Thursday with periods of VFR parameters, a moderately moist
atmosphere will lead to the probability of sub VFR parameters,
primarily during the late night-early morning hours due to low
clouds and patchy fog.



RDU Records:

Date     |  High  Year  |  High Min  Year
02/20       75    1939        62     1939
02/21       76    2011        55     1939
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
02/20       74    1922        56     1939
02/21       74    2011        50     1954
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
02/20       82    2014        60     1939
02/21       80    1991        61     1953
02/22       77    2003        56     1989
02/23       80    1922        55     1922
02/24       83    1930        60     1975




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