Scientific Forecaster Discussion
fxus64 kohx 171802
Area forecast discussion
National Weather Service Nashville Tennessee
1202 PM CST sun Nov 17 2019
for 18z aviation discussion.
Clear skies and a little nippy out there at forecast time. The
Mercury might drop another degree or two before sunrise, but dew
points are such that temperatures have flatlined this morning.
Satellite imagery would also suggest that the clear skies will be
disappearing later this morning as high clouds move in from the
west. This should keep US from getting too warm today, but
afternoon highs in the mid 50s can be expected again today.
The first half of this week should be mostly dry. We're still seeing
two clippers in the near-term; one tonight and another Monday night.
Forecast soundings are such that sprinkles will be possible, but I
highly doubt anyone will measure any rain. With the extra cloud
cover each night, I have also bumped overnight lows a touch, so any
precip that falls will be the liquid kind. Sprinkles versus flurries.
The big story with this forecast is the end-of-the-week system that
should finally bring a soaking rainfall to the mid-state. While
there are still a few glaring discrepancies between the GFS and the
Euro as far as evolution, both are showing some light rain showers
Thursday, during the day, but that the bulk of the rainfall will
come Thursday night and Friday as a cold front sinks into middle Tennessee.
Have focused pops through these two time frames, however, both are
now showing that this cold front won't make it all the way through
the mid-state before it slowly returns northward as a warm front.
This is where the biggest discrepancy occurs: both have an upper
level low developing over the Southern Plains that will push
eastward into the region. However, the timing of this low is such
that the Euro is dry on Friday, with rain returning Saturday, and
the GFS has rain across the area right through Friday and Saturday.
Will highlight only chance pops until this is straightened out, but
in any event, qpfs could be a little better than an inch for
everyone Thursday through Saturday.
One change I did make was to bump some of the overnight lows in the
same time frame as this system as the nbm was much too cold in this
type of pattern. Extended temperature guidance still suggests no
Arctic blast behind this system, so we should remain only a few
degree below normal.
18z taf discussion.
VFR conditions expected over the next 24 hours. Skies will
continue to be broken to overcast as high clouds move over middle
Tennessee. Cigs are expected to drop to around 5kft by early
Monday morning as an upper low swings just to our north. There is
a small chance of rain, but didn't include it in the forecast for
now as it could be spotty and may not impact terminals. Winds will
be light, but will gradually shift to be out of the south and
west by late tonight.