Area Forecast Discussion
Issued by NWS Nashville, TN

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FXUS64 KOHX 200827
AFDOHX

Area Forecast Discussion
National Weather Service Nashville TN
327 AM CDT Sun Aug 20 2017

.SHORT TERM...
(Today-Tue)

Will be monitoring sfc obs and satellite imagery for the
potential of patchy fog development across the mid state
during these early morning hrs. Will make final decision
close to press time, but am inclined to mention patchy fog
thru at least 20/13Z. Otherwise sfc high pressure influences
along with building upper level ridging dynamics will support
moclr skies thru tonight. A few diurnally driven cu are expected
by this afternoon. For tonight,the beginning of strands of sct
ci especially after midnight is expected to move into the mid
state region. Will go with a Superblend/ 00Z NAM/00Z GFS/00Z
EURO blend for afternoon highs today. Afternoon highs today
will be seasonable warm and mainly in the lower 90s, mid 80s
to around 90 Cumberland Plateau Region. Overnight lows will be
mild also, with lows around 70, upper 60s Cumberland Plateau
Region. Leaned toward a consensus model solution blend here
also.

As for the highlight of the short term forecast period,
now just a day away, Monday, August 21st, partial/total
solar eclipse day across the mid state. First, dry
conditions are expected to prevail as broad upper level
ridging will prevail across the SE contiguous U.S. and
sfc ridging influences persist across our area centered
across the central Appalachians. Secondly, made a slight
adjustment up in cloud coverage for the early afternoon hours
during eclipse time. Strands of sct ci will be possible moving
into the mid state as blow-off from convection across cntrl
MS River Valley Region. But most of this should be rather
translucent and not result in viewing hindrance. Believe that
the morning hrs should thus be moclr. 00Z NAM/00Z GFS hinting
at the potential of higher level diurnally driven sct cu 5kft-
7kft forming and then slightly increasing in coverage as the
afternoon hours progress. So will up the sky coverage amounts
slightly. However, for a typical summer August day, this is
certainly not bad at all. Here is a closer look at hourly sky
coverage and temp values from 21/17Z (Noon CDT) to 21/21Z
(3 pm CDT) for the Nashville area. Of course this is preliminary
information and is subject to change.

17Z...88 degrees, 26% cloud coverage (Partly Cloudy Skies)
18Z...89 degrees, 27% cloud coverage (Partly Cloudy Skies)
19Z...84 degrees, 27% cloud coverage (Partly Cloudy Skies)
20Z...90 degrees, 28% cloud coverage (Partly Cloudy Skies)

Hourly sky conditions should be similar across other parts
of the mid state too during this time frame. Of course the
below is preliminary information also and is subject to
change too. Temps at 17Z will span across the mid state
from 83 degrees Crossville to above mentioned 88 degrees
at Nashville. Temps at 18Z will span across the mid state
from 83 degrees at Crossville to 88 degrees at Nashville.
Temps at 19Z will span across the mid state from 80 degrees
at Crossville to 84 degrees for much of cntrl and wrn portions
of the mid state. As the eclipse is ending around 20Z, temps
will span across the mid state from 84 degrees at Crossville
to 90 degrees at Nashville.

Will go with consistency of Superblend values in association
with 00Z GFS/00Z NAM/00Z EURO values with the potential of
high temps being reached just a little later time wise in
the afternoon than would be normal on a August day. Highs
will generally be in the lower 90s, around 90 Cumberland
Plateau Region. There maybe some isolated locations that
reach heat index values approaching 100 degrees during the
late afternoon hrs also.

Mid state should experience moclr skies on Mon night with
generally seasonable mild lows. As for Tue, will go with
increasing cloudiness along with increasing chances of
shwrs/tstms, greatest potential afternoon northwest and
north central, as the day progresses as a frontal system
approaches the mid state region. Highs will range from the
upper 80s to lower 90s, mid 80s Cumberland Plateau Region.

31

.LONG TERM...
(Tue Night-Sat)

Tuesday night is looking wet as both the gfs and euro solutions
bring a cold front through the area late Tuesday night. Somewhat
elevated mrh values and forcing matches up quite well so 50-60
pops will be included. The convection will continue into
Wednesday as the 850 mb front trails the sfc front. The activity
will shut down from nw to se by late afternoon. Looks as though
rainfall amounts of 1/4 to 1/2 inch can be expected.

Drier and slightly cooler air will move in Wednesday nt and
Thursday. Thermal troughing looking rather strong, especially to
our north. 850 mb temps will cool down to the 13c-16c range. As a
result, high temperatures will be in the lower to mid 80s, and
another 3 to 5 degrees cooler along the Plateau. The sfc high
will move slowly eastward across the Great Lakes so the less
humid weather will persist toward the weekend.

Models attempt to bring some moisture back on Saturday. However,
sfc trough development looking iffy as a retrograde motion
encounters prevailing westerlies. Will go ahead and include a
slight chance of showers and tstms southeast half.

21

&&

.AVIATION...
06Z TAF DISCUSSION.

VFR with MVFR/IFR fog possible overnight. Some high clouds look to
move into the mid state overnight, which may impact fog
development, however model consensus still places MVFR fog for
KCKV, KMQY, and KCSV. KCKV looks to possibly see IFR fog as well
just before sunrise. Otherwise expecting VFR conditions with
light southeast/southerly winds during the day Sunday.


&&

.PRELIMINARY POINT TEMPS/POPS...
Nashville      93  70  93  72  92 /  10  10  10  10  40
Clarksville    92  69  92  72  88 /  10  10  10  10  50
Crossville     86  67  88  69  85 /  10  10  10  10  40
Columbia       91  69  92  72  90 /  10  10  10  10  30
Lawrenceburg   90  69  92  71  90 /  10  10  10  10  30
Waverly        92  69  92  72  89 /  10  10  10  10  50

&&

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

&&

$$

DISCUSSION......31
AVIATION........Barnwell


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