Scientific Forecaster Discussion
fxus64 kmrx 142308
Area forecast discussion
National Weather Service Morristown Tennessee
608 PM EST Thu Nov 14 2019
for 00z aviation.
Short term...(tonight and friday)...
A digging mid/upper level trough will dive down into the lower
Mississippi Valley tonight and absorb a, weak, southern stream cut
off low just offshore of the Louisiana coast. As these two
features phase, cyclogenesis then begins and the low starts to
deepen. This system still looks like it will stay well to our
south and east as the surface low will move across the Florida
Panhandle and then offshore of the Carolinas as it heads
northeast. What does this mean for us? Increasing cloud cover
tonight and into tomorrow. The greatest cloud cover will be east
of I-75. Clearing will first occur tomorrow afternoon across the
northern Cumberland Plateau and will slowly move from northwest to
southeast through the day. However, southwest North Carolina, and
our eastern mountains and foothills will hold on to clouds
through most of the day. I do have a slight chance pop in for the
southeast corner of our cwa, which includes portions of Polk,
Cherokee and Clay County. Very low confidence in this forecast due
to the dry surface shown in soundings. The GFS is more moist than
the NAM though. Again, low confidence that they see any precip.
If southwest NC does see precip, there could be a few hours where
they might see some freezing drizzle during the early morning
hours of Friday. It won't last long though with temps only dipping
close to freezing for an hour or two.
Overnight lows will range from the upper 20s north of I-40 and lower
30s south of I-40. We will be in the upper 40s to low 50s by
tomorrow afternoon with light winds out of the north once we get on
the backside of the low.
Long term...(friday night through thursday)...
Surface low will be moving off the Atlantic coast as we head into
the weekend leaving our area in the drier and cooler air from the
north/northwest. Dry weather is expected through the weekend as weak
ridging builds in before the next system makes it's way to the
eastern Tennessee Valley. High's over the weekend are expected to
top out in the mid 50's across much of the area under sunny skies,
but westerly/northwesterly winds will keep temperatures
slightly cooler than average.
A fast move shortwave will move across the mid-Atlantic states at
the end of the weekend and into early next week. Models continue to
keep the better forcing and associated moisture to our north, so
will continue with a dry forecast to begin the upcoming work week.
Long range models are coming into a bit better agreement that a
secondary wave on Tuesday/Wednesday will bring the better chances
for precipitation. Models are trending slightly wetter with this
system, but there remains discrepancies in quantitative precipitation forecast amounts. Either way
it looks to be a relatively weak and short lived system with
locations in northeast Tennessee and southwest Virginia having the
best chances for precipitation. Can't rule out some light snowfall
during the overnight hours, but at this time models continue to show
that this system will be a predominately cold rain event.
Ridging begins to build back in after the exiting shortwave leading
to temperatures back around 60 degrees by Thursday.
00z taf discussion.
VFR conditions are expected to prevail at all taf sites through
the period. Will have some high clouds across the area due to low
pressure to our south and will have increasing northerly winds on
Friday afternoon with a tightening pressure gradient across the
Preliminary point temps/pops...
Chattanooga Airport, Tennessee 34 54 33 57 33 / 10 10 0 0 0
Knoxville McGhee Tyson Airport, Tennessee 30 53 30 55 31 / 10 10 0 0 0
Oak Ridge, Tennessee 30 52 29 54 30 / 10 10 0 0 0
Tri Cities Airport, Tennessee 27 51 27 54 27 / 10 10 10 0 0