Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS62 KRAH 232319
Area Forecast Discussion
National Weather Service Raleigh NC
619 PM EST Mon Jan 23 2017
A stacked low pressure system overhead will track east-
northeast away from the Carolinas today, then track off the
Mid- Atlantic coast on Tuesday. Highs pressure will then influence
the region through midweek.
.NEAR TERM /THROUGH TONIGHT/...
As of 250 PM Monday...
Stacked low pressure system is essentially overhead this
afternoon and will depart to the northeast tonight. there are
two main areas of precip that may impact central NC tonight; 1)
low-topped convection currently southeast of FAY associated with
a vort max within the upper low and a -22C cold pool at H5,
which has resulting in a couple hundred J/KG of MLCAPE nudging
into the southern Coastal Plain, and 2) deformation band
moisture over the Foothills and Blue Ridge. the area of
convection should rotate north and may reach Clinton/Goldsboro
areas before being shunted toward the coast this evening. Still
can`t rule out some small hail or graupel given a freezing
level down to around 7k ft, but the convection does not look
very robust so far. The deformation band to the west will slide
east across the CWA between 00Z and 09Z, and hi-res guidance
suggests some light rain will be possible over the western
Piedmont before a northwest wind (that may gusts to 15-20kt as
cold advection kicks in) scours the remaining moisture. The
coldest air behind the low may stay west of the mountains
tonight and lows should end up on the warmer side of guidance,
such as the MAV. 42-46.
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
As of 250 PM Monday...
Ridging aloft will develop behind the departing low on Tuesday,
with cold advection easing up through the day. Skies will have
generally cleared, but forecast soundings suggest some
scattered cu during the afternoon and wind gusts to near 20kt.
prefer a blend of MOS for highs, 59-62 and coolest northeast
where cold advection lasts longest.
Relatively mild high pressure will nose in from the south
Tuesday night before quickly retreating ahead of the next cold
front. Lows 38-42
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
As of 210 PM Monday...
A transition from mild conditions to more seasonable, but generally
dry ones, will occur during the medium range.
Ridging aloft will crest over the Ern U.S. on Wed, then move
offshore in advance of a broad, positive tilt longwave trough that
will migrate Ewd and encompass the Ern two thirds of Ern North
America by the weekend.
A surface cold front --one related to the lead shortwave trough that
will initiate the Ewd progression of the longwave trough, and which
will trail a parent surface cyclone that will migrate NEwd across
the Great Lakes-- will settle across NC late Wed night-Thu. Both
moisture and lift are forecast to be limited, as the parent forcing
lifts to our NW, so rainfall chances and amounts are likewise
expected to be limited.
Behind this lead front, temperatures will cool to more seasonable/
average levels for the end of the week and weekend. The positive
tilt configuration of the trough aloft will cause surface high
pressure to sprawl into the SErn U.S. and suppress any additional
precipitation chances until Sun-Mon, at which time a Nrn stream
shortwave trough in NW flow aloft will amplify into the Middle
Atlantic region and possibly support some degree of cyclogenesis
over the Wrn Atlantic. At this time, it appears that a generally dry
reinforcing cold frontal passage will result for our region, though
the prospects of nearby coastal cyclogenesis will be worth
watching in the coming days.
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
As of 618 PM Monday...
24-Hour TAF period: The surface low will move northeast away from
Central NC, however lingering low level moisture will result in
continued or redevelopment of MVFR/IFR conditions across northern
portions (KINT/KGSO/KRDU/KRWI) of the area through the night.
Confidence is not high on how log the sub-vfr cigs and visbys will
last, but expect gradual improvement to begin between 04Z and 09Z.
Northwesterly winds will continue to be strong and/or gusty through
the TAF period and should help scour out cloud cover early Tuesday.
Periods of light rain are possible over the next several hours,
however additional impacts should be minimal. -KC
Looking ahead: VFR conditions are expected through Wednesday. A cold
front will cross the region late Wednesday night/early Thursday,
bringing with a chance of showers and sub-VFR ceilings to the area.
VFR conditions should return late Thursday afternoon/evening. -Smith