Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Nashville Tennessee
521 am CST Tuesday Jan 27 2015
Update...added aviation section for 12z taf's.
Aviation...bna/ckv/csv...clouds deck is going to be slow to
erode, with VFR ceilings lasting into the evening at bna and csv. Ceilings
will alternate between IFR & MVFR at csv as bands of light snow
move across eastern middle Tennessee during the morning. Clouds
will improve to VFR later in the day as the deepest moisture pulls
Previous discussion... /issued 315 am CST Tuesday Jan 27 2015/
currently...some light snow indicated over central areas of Kentucky.
Latest model runs support the southward moving impulse.
However...best region of positive vorticity advection through the morning hours will be
mainly east of the middle state...northern areas of the plateau may
be on the western fringe. Thus...with hrrr in agreement with
trending toward less in the way of snowfall...will opt to trend
downward the snow threat. Half inch accumulations will be possible
for the northern plateau only for this morning...generally a trace to a
quarter inch elsewhere across the Plat. Areas just west of the
plateau could see a few flurries. Otherwise...clouds will hang on
through today...but clearing line not too far off to the
Partial clearing will begin tonight as high pressure settles in just
to our north. Cold temperatures for tonight with lows ranging from near 20
plateau...and mostly lower to middle 20s elsewhere.
Sunshine will be the rule for Wednesday. A weak ridge axis will
stretch across the middle state so we should see temperatures warm up close to
50 degrees for most areas.
A clipper system will then be on approach and the associated
frontal boundary will move through on Thursday. This will
translate to a chance of showers late Wednesday nt into Thursday. The
surface low will pass a good distance to the north of Tennessee. Temperatures will
therefore reach into the lower to middle 50s during the day.
In the ext forecast...colder and more seasonal air will work in behind
the clipper system. Then...the Gulf storm...that we have been
looking at for several days now...will begin to get its act
together. For several runs now...the Euro model was colder and was
supporting a potential snow event while the GFS was a warmer rain
scenario. Well...the Euro has backed off and is now showing more of
a north-S trough inversion as opposed to the colder west-east axis. This now
matches up with the warmer GFS solution. Thus...will trend toward
more of a rain event for Sat nt into Sunday. At any rate...looks
like about 1/2 to perhaps 3/4 inch rainfall amounts.
Cold air to work into the area by Sunday as the moisture is pulling
out. Will include a slight chance of snow.
Monday and Tuesday of next week look cold...but nothing too bad as upper
flow is more westerly. Split flow is indicated but the southern jet
will be well south of the area. Just dry with temperatures 5 degrees or so