Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Nashville Tennessee
329 am CST Sat Nov 28 2015
(today through monday)
inverted surface trough axis is located over Louisiana and extends
northward across far western Tennessee and into southern in. A large swath of
rainfall is associated with this feature and extends back across
much of OK and Texas. This surface trough is expected to work slowly
eastward today and as this happens...the rainfall is expected to
spread this way. As the trough weakens some...our eastern counties
will carry lesser pop values than the west.
Tonight and Sunday...the surface boundary is expected to drop slowly
southward. As the 850 mb front gets hung up north of the surface
boundary...some overrunning and low level forcing will continue
and will trend our probability of precipitation upward. Deep mrh coverage is rather
bullish and with additional impulses aloft moving within the
jet...categorical probability of precipitation will be included tonight and into Sunday.
Sunday night and Monday...the better dynamics will shift to our
south but will still keep a general likely pop category going. The
rainfall by this time however...will be light as opposed to the
moderate intensity that is expected tonight and Sunday. A stronger
cold front will be on approach from the west as we move into
Overall average quantitative precipitation forecast totals through Monday looks to be on the order of 1
to 2 inches area wide. However...a few locally heavier amounts may
occur across mainly our western quarter of the area.
For the near term temperatures...a trend toward cooler maximum temperatures is
indicated with this round of models. Apparently...the aforementioned
surface boundary may make a bit more progress southward.
Furthermore...overrunning precipitation looks a little more favorable than
before. Will lean toward the mav numbers but will go above by a few
degrees for each period. After reaching the 60s today...look for
highs to hold in the 50s for Sunday and Monday. Lows look like 45 to
55...for the most part.
(Tue through fri)
with surface front at least through the western half of middle state as of the
middle morning hours on Tuesday begin...and expected to move rather
quickly eastward per building surface rockies high pressure influences...
enough Post frontal moisture should still be in place to support
likely moderate rain across at least the eastern half of middle state...
with chance remainder as the day on Tuesday progresses. A weak upper
level disturbance in a continuance of a southwesterly upper level flow
pattern is expected to move across the region bringing with it a
slight chance to chance of showers across all but northwest portions of the
middle state Tuesday night. Some lingering moisture across plateau is
expected to interact with yet another weak upper level disturbance
in southwesterly flow aloft to possibly result in a slight chance to chance
of light showers across locations just west of and across the plateau
region on Wednesday. Dry conditions Wednesday night into Thursday should prevail as
a subtle upper level ridging pattern develops across the area. 28/00z
Sat GFS/latest dgex solutions showing moisture advection pattern into
the middle state from the SW becoming established in association with a
more pronounced short wave trough within a subtle upper level
troughing pattern...including possible closed low development...as Thursday
night into Friday progresses...resulting in a slight chance of light
showers across the middle state on Thursday night...and with Friday morning lows
expected in the low to middle 30s...there also may be a slight chance of
a rain/snow mixture after midnight Thursday night into at least the middle
morning hours on Friday. A slight chance of light showers is expected to
continue across the plateau region from the middle morning through the
afternoon hours on Friday.
As for temperatures...even behind frontal passage on Tuesday...mild temperatures are
expected with highs mainly in the upper 50s. As a continuance of
rockies originating surface high pressure influences build across the
region as next work week progresses...temperatures will begin to cool to
around seasonal normal values.
06z taf discussion.
VFR conditions persist as ceilings are holding up and should for
another couple of hours at kckv. Very slow ceiling drop for
kbna/kcsv...in fact...kcsv may be at the end of the taf cycle
before they even go MVFR. Kckv gets IFR ceilings by 18z Saturday.
Winds will be light while shifting from the south early in the
cycle to westerly by the end.
Preliminary point temps/pops...
Nashville 67 53 58 52 61 / 60 80 90 80 60
Clarksville 62 48 52 46 59 / 90 80 90 70 50
Crossville 65 54 57 52 59 / 20 60 90 90 70
Columbia 69 55 59 52 61 / 40 80 90 80 70
Lawrenceburg 70 55 60 53 62 / 30 70 90 80 70
Waverly 64 50 54 48 60 / 80 80 90 70 60