Scientific Forecaster Discussion
fxus62 krah 201903
Area forecast discussion
National Weather Service Raleigh NC
303 PM EDT Wed Sep 20 2017
a weak upper level trough will move into central NC later today,
then drift sewd through Thursday. Otherwise, an upper level high
over the Ohio Valley and tropical cyclone Jose meandering off the
southern New England coast will result in warm and dry conditions
across central NC through the rest of the week.
Near term /through tonight/...
as of 929 am Wednesday...
An upper level disturbance that can be seen dropping sewd into the
southern Appalachians, will drift slowly over central NC later today
and tonight. This system interacting with moderately unstable air
mass owing to strong insolation and resultant steep low-level
lapse rates, will trigger a few showers and garden variety T-storms
late today into the evening hours.
Convection will be largely diurnally driven, so expect coverage to
diminish during the evening. However, with the upper disturbance
drifting slowly east-southeast across the forecast area, can't rule out a stray
shower. Min temps in the mid-upper 60s.
Short term /Thursday and Thursday night/...
as of 245 PM Wednesday...
A vorticity disturbance will drift slowly eastward across eastern NC
on Thursday, and will eventually feed into the broad upper trough
extending SW from tc Jose off of the southern New England coast.
This feature will support an isolated to slight chance of weak/shallow
convection, mainly across southern/southeastern portions of the area.
800 mb temps and low-level thickness drop off ever so slightly, so perhaps
a degree or two cooler when compared to today, but still in the same
ballpark with afternoon highs in the 85-90 degree range. Any convection
will die off with loss of heating. Overnight lows in the mid to upper
Long term /Friday through Wednesday/...
as of 257 PM Wednesday...
Friday through Sunday will feature fair weather thanks to ridging to
our north, and the flow assoc with this ridge resulting in a drying
trend during that time. Thus we can expected decreasing clouds on
Friday, then mainly clear skies for the weekend. Models also show
subtle low level thickness decreasing trend during this same time,
so expect temps in the low to mid 80s, rather than the mid to upper
80s that we'll see in the near and short term periods. Lows in the
Still quite a bit of uncertainty regarding the first half of next
week related to the track and possible impacts with Hurricane Maria.
Right now most models suggest that Maria will stay well to our east
with little or no impacts on our weather across central NC Tuesday
into Wednesday, other than perhaps a few passing showers on the far
western periphery of the storm and perhaps a period of breezy
conditions. However, there's still plenty of time for things to
change, so continue to stay tuned!
Aviation /18z Wednesday through Monday/...
as of 134 PM Wednesday...
An upper level disturbance moving into the area during peak
afternoon heating will support scattered showers and a few
thunderstorms, especially near kfay where best destabilization is
expected. Any convection should quickly weaken and diminish with
loss of heating. Much like last night, patchy MVFR fog is possible
area-wide overnight, with some brief periods of IFR restrictions at
On Thursday, there is a small threat for a shower or storm near or
south of kfay. Otherwise, outside of some early morning fog/stratus,
VFR parameters should persist at the taf sites Thursday through
early next week.