Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Remove Highlighting --
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FXUS62 KRAH 191955
Area Forecast Discussion
National Weather Service Raleigh NC
255 PM EST Sun Feb 19 2017
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.
.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/...
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
.LONG TERM /TUESDAY THROUGH SUNDAY/...
-- Changed Discussion --As of 254 PM Sunday...
Tuesday will begin with the upper level ridge axis right overhead
and a surface low pressure system over New England. Clouds will
increase throughout the day ahead of a frontal system over the
Mississippi Valley. Highs in the mid to upper 60s. As the surface
high moves offshore and the front gets closer, warm air advection
will begin and temperatures on Wednesday will soar into the mid 70s.
As the front moves through there will be some chance for rain
showers but not a soaker of a day by any means.
Despite the front moving through it eventually washes out and the
high pressure that was over new England dips southward off of the
Carolina Coast and thus no real change in airmass occurs as return
flow keeps warm air moving into central NC. This will keep
temperatures in the mid to upper 70s for Thursday as frontogenesis
begins to occur across the Appalachians as a low pressure system
develops over the plains and pushes eastward. This will give slight
chances for rain across the north on Thursday but again with meager
moisture content as a warm front organizes and pulls away to the
north as the parent low moves front the Plains northeastward towards
the Great Lakes. The timing of the evolution of this system is in a
big of question with the GFS showing a quicker progression of the
advancing cold front and the ECMWF still a little slower but faster
than yesterday. As a result the best chance for some significant
rainfall and perhaps a thunderstorm or two will begin on Friday and
progress through Saturday but clearing out for Sunday. Highs in the
70s through Saturday before easing back into the mid 60s for Sunday.
-- End Changed Discussion --
.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