Scientific Forecaster Discussion
fxus64 kohx 182305
Area forecast discussion
National Weather Service Nashville Tennessee
605 PM CDT sun Aug 18 2019
for 00z aviation discussion.
Leaned toward a consensus blend model approach thru next weekend
unless otherwise noted. Overall, it continues to look like a
fairly benign wx pattern will continue into first part of work
week with iso shwrs/tstms here and there before more of a
sct/numerous shwr/tstms develop by mid/late work week, with
potential of iso to sct shwrs and iso tstms continuing over next
Quasi zonal flow aloft this afternoon will evolve into a weak
troughing just to the east of the mid state area as tonight
progresses, as closed upper low moves into eastern Canada.
In response to this, latest GFS solution brings a weak shortwave
across mid state region from MO bootheel region as the evening
hrs progress and Ushers it sewd across our area. Some iso
shwrs/tstms could occur this evening across cntrl and northwest portions
of mid state region. Overnight lows tonight will remain a few
degrees above seasonal normal values. The recent trend of mild
overnight lows should continue thru mid week.
Weak moisture return will begin to return to the mid state region
as Mon commences, but it will probably be Mon afternoon until
entire mid state region experiences enough to support diurnal
iso shwrs/tstm development. Weak upper trough still looks like
it will move well east of mid state region as Mon into Tue
progresses as upper ridging influences build in and strengthen
from the west. However, with persistent sfc high pressure
influences across the cntrl/srn Appalachians, the influx of
low level moisture should becoming increasing abundant
resulting in mainly sct shwrs and iso tstms on Tue.
As Wed thru Thu progresses, upper pattern transitions to more
of a nwly orientation as upper trough/shortwave approaches
mid state region towards 12z Thu. A weak sfc boundary is also
expected to approach the mid state region towards 12z Thu also.
Ahead of these features as Wed progresses, moisture becomes even
more abundant, and Wed into Wed night will be characterized
by sct shwrs/tstms. Expect shwrs/tstms to become numerous by
Thu afternoon as sfc boundary moves into mid state region and
bulk of upper level troughing influences anticipated.
As of Fri thru next weekend, models have their individual
differences here and there, with the latest GFS solution showing
more of a zonal flow pattern aloft vs latest European model (ecmwf) with a little
bit more of a nwly flow pattern aloft. However both these models
show mid state experiencing influences from weak sfc boundary
that will remain just south of mid state region after its passage
across mid state on Thu. This weak sfc boundary may even move be
pushed ewd as second half of next weekend progresses. Thus, in so
many words, both are generally pointing to a unsettled summertime
wx pattern being in store for mid state region. This pattern
should support at least diurnal based iso/sct shwrs and iso tstms
under variable skies.
Afternoon temps will remain in the mid 90s, upper 80s to lower
90s west of Cumberland Plateau region thru Wed afternoon, with
afternoon high temps in the lower 90s, mid 80s to around 90
Cumberland Plateau region on Thu afternoon. Thus, maximum
afternoon heat index values will range between 100 to 105
degrees in some locations west of the Cumberland region
Mon afternoon thru Thu afternoon. Updated our hazardous
weather outlook product to mention these values. As for
Fri thru Sun, afternoon high temps and overnight low values
generally will be near seasonal normal values.
00z taf discussion.
VFR with MVFR fog possible. Have in MVFR fog for kckv/kcsv/kmqy
overnight, with IFR fog also possible at those terminals.
Otherwise, expecting VFR cigs and calm winds through mid morning,
then southerly/southwesterly winds around 5 knots during the day
Monday. A few isolated showers and storms will be possible Monday
afternoon, but confidence is low on coverage so no mention in the
taf at this time.