957
FXUS64 KOHX 211041
AFDOHX

Area Forecast Discussion
National Weather Service Nashville TN
541 AM CDT Mon Aug 21 2017

.UPDATE...
FOR 12Z AVIATION DISCUSSION.

&&

.SHORT TERM...
(Today-Wed)

A lot of model solution comparisons and detailed coordination
with surrounding offices, especially LMK and PAH, come into play
this morning as the partial/total solar eclipse day is finally
upon the mid state region. Will be making some minor changes as
press time approaches. Have analyzed a plethora of short range
models including the latest HRRR trends, along with the
traditional "Big Three", i.e., 21/00Z EURO/GFS/NAM solutions,
including model sounding profiles and atm rh model layers. With
all of this said, will generally continue with the trend of moclr
skies this morning with ptcldy skies this afternoon hrs across the
mid state region. Some iso light to mdt shwrs/tstms possible far
SW portions by late afternoon after the eclipse passage. Rest of
mid state is expected to remain dry today. Below is presently what
is expected at Nashville during the eclipse time frame. Other
locations across the mid state will have slightly different temps
and sky conditions. This is preliminary, as of 08Z (3am CDT).
Continued detailed analysis of the latest in current sky
condition and temp trends, along with the latest in short term
model trends will be needed as the morning hrs progress. Thus,
expect updates to forecasted cloud coverage and temps if needed as
the morning hrs progress. Again, here is what is expected in
Nashville.

12 PM CDT...90 degrees, 22% cloud coverage(Mostly Sunny Skies)
1 PM CDT...90 degrees, 27% cloud coverage (Partly Cloudy Skies)
2 PM CDT...85 degrees, 31% cloud coverage (Partly Cloudy Skies)
3 PM CDT...90 degrees, 35% cloud coverage (Partly Cloudy Skies)

Do expect hrly temps around 2 pm CDT on average to cool down
5 degrees or so for locations experiencing totality or close
to it. Because of solar totality also, highs this afternoon
might be a few degrees cooler than yesterday, but will continue
to be seasonally warm. Highs today will mainly be in the lower
90s, upper 80s to around 90 Cumberland Plateau Region, and maybe
reached a little later in the afternoon than what is normal for
a typical August summer day.

Will keep the mid state dry with seasonal warm lows continuing
tonight. Lows will generally be in the lower 70s, upper 60s to
around 70 Cumberland Plateau Region.

Increasing chances of light to mdt shwrs/tstms are expected as
Tue progresses. Afternoon highs will continue to remain seasonably
warm, but additional cloud coverage will result in afternoon high
temp values not as warm as those expected today. High temps will
generally be around 90, mid to upper 80s Cumberland Plateau
Region.

A frontal passage is expected across the mid state on Tue night
bringing numerous light to mdt shwrs/tstms to the mid state
region. Still looks like this frontal passage will bring with it
some potential of strong thunderstorms mainly Tue evening across
the mid state region. With cloud coverage in place, continue to
expect seasonally mild lows in the lower 70s, upper 60s to around
70 Cumberland Plateau Region.

Sct to numerous shwrs/tstms should continue thru the morning hrs
on Wed. Decreasing chances of shwrs/tstms NW to SE across the mid
state is expected as the afternoon hrs on Wed progress per sfc
ridging influences build into the Great Lakes region and above
mention frontal system pushing SWD of mid state. Passage of
this frontal system on Wed will result in afternoon high temps
near seasonal normal values by Wed afternoon. Afternoon high
temps will be actually a few degrees lower than seasonal normal
values, low to mid 80s, upper 70s Cumberland Plateau Region.

Again, expect further updates as the morning hrs progress if
needed on sky conditions, temps, and even possible rainfall
for SW mid state as the window for partial/total solar eclipse
approaches.

31

.LONG TERM...
(Wed Night-Sun)

Wednesday night`s weather map will feature a cold front to our
south. An examination of the lower level wind pattern does depict an
850 mb front across the mid state along with some weak post frontal
lift, mainly across the Plateau. Will go ahead and include a slight
chance of convection along our Plateau for Wednesday evening.

On Thursday, sfc high over WI will pump drier air our way. Mrh
gradient is quite impressive with the drier air winning out by
afternoon. Thermal troughing is rather flat across the deep south.
850 mb temps have trended up just a skosh compared to prior model
runs and will range in the 15c to 17c range. Thus, look for the
drier air to remain in play through Friday. However, high
temperatures look like mid to upper 80s but with the lower humidity.
Overnight lows will be mostly in the lower 60s, with perhaps a few
upper 50s readings along the Plateau.

On Saturday and Sunday, models still trend toward some weak easterly
wave development across the deep and mid south. Upper pattern not
really offering much support and is generally flat, with just
minimal areas of curvature and shear upstream. Lower level axis
looks most pronounced along the MS river Sat nt. Some moisture
return is evident, but primarily to our west and south. Thus, pops
for our area will be included but will be kept down into the min slt
chance category. As for temps, high temps remain in the mid 80s but
we will see our nighttime lows come up into the mid to upper 60s by
Sunday night.

21

.AVIATION...
06Z TAF DISCUSSION.

VFR with MVFR fog possible. KCKV and KCSV may see some MVFR fog by
sunrise, with fog possible at KBNA and KMQY as well. Left out
mention at those terminals for now as chances are slightly higher
at KCKV and KCSV. Otherwise calm winds overnight will become more
southerly around 5 knots during the day with VFR conditions.

&&

.AVIATION...
12Z TAF DISCUSSION.

Some early morning patchy fog can be expected prior to 14z. Otw,
upper ridging should remain in control. Scattered high clouds
will be the extent of the weather for this taf period.

&&

.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

DISCUSSION......31
AVIATION........21