Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
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FXUS62 KRAH 201947
Area Forecast Discussion
National Weather Service Raleigh NC
247 PM EST Mon Feb 20 2017
High pressure will extend along the East Coast through early
Tuesday. A weakening upper-level disturbance will cross the
Southeast states Tuesday night into Wednesday.
.NEAR TERM /THROUGH TONIGHT/...
As of 950 AM Monday...
Forecast is on track. Plentiful sunshine is a near certainty beneath
dry high pressure at the surface and deep ridging and stable/warm
air aloft. Observed thicknesses are higher than yesterday morning by
around 10 m, although they shouldn`t rise quite as high through the
afternoon as they did yesterday, given that the surface ridge will
be building down the Eastern Seaboard. Temps are already in the mid
50s to lower 60s, comparable to yesterday`s pace, so still expect
highs from around 70 NE to the low-mid 70s elsewhere, with light
winds veering from NE to E then SE through the day. -GIH
Earlier discussion from 315 AM: A narrow upper level ridge extending
from the eastern Gulf into southern Ontario coupled with a dry air
surface ridge building southward along the East Coast will maintain
mostly clear skies, and very mild conditions for this time of year.
While the low level flow is northerly, it`s a neutral flow, meaning
little if any cold air advection. Thus, afternoon temperatures
should be fairly comparable to Sunday`s, in the 70-75 degree range.
Tonight, the low level flow becomes ely as the parent high to our
north moves a little farther to the east. This ely flow will advect
moisture off the Atlantic and into central NC. Due to the upslope
component of the flow, the rising/lifting of the moisture should
cause a layer of stratus clouds to develop late tonight/early
Tuesday morning in vicinity of the Yadkin River Valley, possibly
spreading into our western counties including the Triad region. This
moisture band is fairly narrow so no precipitation should be
generated from these clouds. Elsewhere, expect mostly clear-partly
cloudy skies, with patchy fog possible. Overnight temperatures will
vary from the upper 30s-around 40 northeast to the mid 40s over the
far south and west. -WSS
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
As of 315 AM Monday...
Tuesday, the low level ely flow will advect a cooler air mass into
central NC, resulting in afternoon temperatures 4-6 degrees cooler
than today`s high temperatures. In addition, expect to see more
clouds, though still partly sunny.
Tuesday night, the low level flow will continue to slowly veer to a
south-southeast direction in response to the departure of the high
pressure system and the approach of an area of low pressure from the
southwest. The tightening pressure gradient will enhance the low
level sly flow and attendant warm air advection, leading to increase
isentropic lift/upglide and the possibility of a few showers
breaking out overnight night across the western Piedmont. Additional
lift may be supplied by increasing divergence aloft. Thus, have
tweaked PoPs up 10-15 percent from the previous forecast with chance
PoPs covering portions of the western/southern Piedmont after 06Z
Wednesday. If model trends continue or remain consistent, solid
chance/low end likely PoPs may be warranted. At this time, not
anticipating rainfall amounts of any significance, with amounts of
just a few hundredths expected. Overnight temperatures near 50-lower
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --As of 247 PM Monday...
The pattern begins to change for midweek and although we stay warm,
a wetter pattern will bring more clouds and some chances for rain
late in the week. That being said no day looks like a washout at
this point and rainfall totals for the week look only to be about a
half an inch at the most with some locations receiving very little
rain. Temperatures will remain in the 60s and 70s throughout the
To break it down further, Wednesday will bring our fist chance for
rain as a low pressure system in the Gulf of Mexico dives
southeastward towards the Florida Peninsula. As a surface high
sinks southward, central NC will be on the northern fringes of this
system and any rain that does occur will be a result of some
isentropic lift and moisture advection from the south. Best chances
will be in the western part of the forecast area. On Thursday a
developing low pressure system to the west will establish a warm
front along our northern border and begin to advect northward. As a
result, best chances for any appreciable rain Thursday will be along
the VA border counties.
For the most part Friday looks dry as the low to the west tracks
northeastward into the Great Lakes. As it does so frontogenesis will
occur just west of the Appalachians as a cold front moves into North
Carolina Saturday morning and across our area by Saturday late
afternoon/evening. This may be our best chance for rain during the
long term with a non-zero chance of some Thunder, especially in the
southeast where some better instability may be allowed to develop.
Behind the front, high pressure moves in for Sunday signaling a
return to clear skies and dry weather.
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.AVIATION /18Z Monday through Saturday/...
As of 112 PM Monday...
High confidence in VFR conditions areawide through at least this
evening, as high pressure builds in from the north, topped by warm
and stable air aloft. Mostly just high clouds based above 18000 ft
AGL are expected through tonight and Tuesday across the area,
however at INT/GSO, increasing low level moisture within stable low
levels late tonight may result in a few low clouds based below 900
ft AGL and perhaps shallow MVFR fog 08z-12z tonight. Elsewhere, no
low clouds/fog are expected tonight. Winds will stay light from the
NE, trending to ESE areawide over the next 24 hours, but speeds will
be a bit stronger at RWI/FAY this afternoon.
Looking beyond 18z Tue, VFR conditions will hold through Tue
evening. We will see a chance for late-night and early-morning sub-
VFR fog/stratus repeat areawide each day through the remainder of
the week. MVFR to IFR conditions with a few showers are possible
late Tue night through Wed as an upper trough crosses the region. A
cold front will cross the area Sat, bringing a chance for showers
and MVFR cigs. -GIH