Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS62 KRAH 191852
Area Forecast Discussion
National Weather Service Raleigh NC
150 PM EST Sun Feb 19 2017
-- Changed Discussion --An upper level trough will shift off the Carolina coast this
afternoon. High pressure will build into the region behind the
exiting low pressure system tonight through Monday night, then move
off the East Coast on Tuesday.
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.NEAR TERM /THROUGH TONIGHT/...
As of 130 PM Sunday...
Quiet and mild weather tonight. The mid level trough is now shifting
off the NC coast, and heights aloft will continue to rise over NC
while high pressure builds in at the surface. A shallow layer of
moisture that has managed to sneak past the mountains is generating
a few high-based flat cumulus over the NW CWA this afternoon, but
these will clear out later this afternoon with increased mixing of
drier air within the boundary layer. Clear skies are expected
tonight, with light winds slowly veering to northerly overnight.
Expect lows fairly comparable to this morning`s readings, from
around 40 to the mid 40s. -GIH
.SHORT TERM /Monday through Monday night/...
-- Changed Discussion --As of 150 PM Sunday...
The center of a high pressure ridge will drift across southern
Quebec during this time frame while nosing southward through central
NC. Dry and deeply stable air will persist through Monday, yielding
mostly sunny skies, with just a few high clouds within fast
northwesterly upper flow. Thicknesses will start out a bit lower
than in the last couple of mornings, particularly over the NE
sections of the forecast area, beneath the heart of the ridge axis.
But values will still be well above normal, supporting highs from
the upper 60s NE to the mid 70s in the far southern CWA. As the
ridge axis shifts to our east Mon night, resulting in a
southeasterly and southerly low level flow into central NC, low
level moisture will steadily advect into the area, with increasing
moist upglide focused around 290K across the western CWA overnight.
Will have increasing clouds Mon night, especially in the west, with
the relatively cooler ridge lingering in the NE CWA. Expect lows
from the upper 30s NE ranging to the mid to perhaps upper 40s in the
western CWA. -GIH
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.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 255 AM Sunday...
The upper level ridge over the eastern U.S. will shift east over the
Atlantic as the next weather system approaches from the west. As the
aforementioned system moves east, a closed low will break away from
the northern stream trough late Tuesday and move east-southeast over
the Gulf of Mexico on Wednesday (well south of the North Carolina).
Meanwhile, the remnant northern stream trough will move over Central
NC. The strength of the trough and whether it will generate light
rain is still in question, however a slight chance for light rain
cannot be ruled out Tuesday Night into Wednesday. Regardless,
accumulations should be minimal as the best moisture will be well
south of the area. At the surface, the high that had been ridging
into the region will push eastward off the Mid-Atlantic coast on
Tuesday, resulting in a more southeasterly then southerly return
flow setting up over Central NC. The lingering dry air over the
region may help keep rain from reaching the ground Tuesday night.
Warm advection will increase as the southerly flow increases,
resulting in a moderating temperature trend for Tuesday through
Friday night. With the continued surge of warm air and the frontal
passage not expected until the weekend, temperatures will remain
well above normal through Friday night (highs in the mid to upper
60s Tuesday, increasing into the mid 70s Wednesday through Friday.
Lows will follow a similar trend, upper 40s Tuesday night into the
low to mid 50s by Friday night).
There are still significant model differences for Friday onward with
respect to the timing of the frontal system and associated weather.
Generally, expect increasing chances for rain, with the highest
chances Friday Night/Saturday ahead of the front. Temperatures,
particularly the overnight lows, will decrease behind the front.
However, temperatures still appear to remain slightly above normal.
.AVIATION /18Z Sunday through Friday/...
As of 1140 AM Sunday...
High confidence in VFR cigs/vsbys at all central NC terminals
through Monday afternoon. A few clouds based around 3500 ft AGL will
pass near INT/GSO through early-mid afternoon today, but otherwise
skies will be cloud-free as high pressure builds in from the NW.
Surface winds from the NW may gust infrequently to 15-20 kts
through this afternoon, subsiding by 22z.
Looking beyond 18z Mon, VFR conditions will hold through Mon
evening. As the high pressure ridge shifts off the East Coast, a
return flow of low level moisture will bring a chance for sub-VFR
cigs/vsbys late Mon night/Tue morning especially at Piedmont TAF
sites (INT/GSO/FAY). We will see this chance for late-night and
early-morning sub-VFR fog/stratus repeat areawide through the
remainder of the work week. A few showers are possible late Tue
night through Wed morning as a weak upper trough crosses the area,
but VFR conditions should remain dominant. -GIH