Scientific Forecaster Discussion
fxus62 krah 200126
Area forecast discussion
National Weather Service Raleigh NC
926 PM EDT Tue Sep 19 2017
a weak upper level trough will move into the area on Wednesday and
will linger while gradually dissipating through the end of the week.
Near term /tonight/...
as of 925 PM Tuesday...
Quiet weather as central NC sits between Hurricane Jose which is
spinning off of the Delmarva Peninsula this evening and a short wave
moving through eastern Tennessee and northern Georgia. Calm winds and clear
skies will prevail overnight with some MVFR fog possible across the
north and possibly at krwi. Overnight lows will be in the middle 60s
with a few lower 60s possible due to the great radiational cooling
Short term /Wednesday and Wednesday night/...
as of 307 PM Tuesday...
A weak shortwave upper trough, comprised of several individual
shortwaves that currently extend from the Ohio Valley SW into the
middle/lower MS valley will progress slowly ESE, moving into central
NC Wednesday afternoon and evening, before stalling out near the
NC/SC late Wednesday night and Thursday. Limited by the lack of
support/lift in the low-levels and the deep northwesterly flow preceding the
trough, convective coverage should be no greater than isolated to
widely scattered Wednesday afternoon and evening, and largely driven
by daytime heating. Weak deep layer shear of 10 kts or less coupled
with MLCAPE values of 700 to 1500 MLCAPE will keep any convection
The real story on Wednesday will be the return of near to 90 degree
heat across central and southern portions of the state as low-level
thicknesses and 800 mb temps increase to 1420-1425 meters and 17-18 c
respectively. This should support highs a full category warmer than
today, with highs ranging 85 to 90. Lows in the mid to upper 60s.
Long term /Thursday through Tuesday/...
as of 235 PM Tuesday...
Lingering troffing in the wake of Jose across the Carolinas will be
pushed slowly south Thursday and Friday. This will potentially
produce scattered showers across the southern tier of central NC
during peak heating, during which highs will reach mid and upper 80s
with perhaps some very low 90s.
A surge of drier and modestly cooler air will advect south (hard to
call it a front) late in the day Friday, cooling temperatures back
to the low and mid 80s and lowering the chance of precipitation to
the single digits through the weekend. This pleasant airmass will
remain in place, reinforced by low level flow veering gradually
northeast as Maria lifts up the Atlantic coast. Maria's official
track does not bring the storm near enough to produce any sensible
weather impacts to central NC other than perhaps some gustiness and
bands of showers into the coastal plain Tuesday.
Aviation /00z Wednesday through Sunday/...
as of 820 PM Tuesday...
The low level flow will continue to become increasingly wly on the
back side of tropical cyclone Jose, which will result in a much
lower probability of sub-VFR conditions relative to previous days.
Only patchy MVFR visibility restrictions in fog are expected late
tonight-early Wed, mainly at rwi, and perhaps int/gso. Otherwise,
the approach of a mid to upper level trough, and associated pocket
of colder temperatures aloft, may result in the development of a few
showers late Wed and Wed evening, mainly in the vicinity of triad
Outlook: generally VFR conditions are expected. The exception will
be a chance of mainly MVFR fog Thu and especially Fri mornings,
mainly at Fay and rwi.