FXUS64 KOHX 081755

Area Forecast Discussion
National Weather Service Nashville TN
1155 AM CST Fri Dec 8 2023

...New AVIATION...

Issued at 1108 AM CST Fri Dec 8 2023

Strong WAA is underway across Middle Tennessee this morning with
gusty south winds up to 25 mph bringing in higher low level
moisture and warmer temperatures. Current temps are already well
into the 50s to around 60, and nudged up highs for this afternoon
to the low to mid 60s for most of the area and upper 50s to
around 60 on the Plateau. Already seeing a few blips on radar over
our northwest counties, and latest CAMs indicate a few showers
will develop late this afternoon and especially this evening into
tonight areawide - and have adjusted pops based on this latest
guidance. Will take a closer look at tomorrow's severe weather
potential with the afternoon forecast package, but overall
guidance is trending higher with CAPE/shear for our area which
increases the threat somewhat.


(Today through Saturday)
Issued at 1224 AM CST Fri Dec 8 2023

Middle Tennessee finds itself under a strong southerly flow at the
surface, so temperatures are enjoying a quick warm-up following
yesterday morning's bottoming-out. Despite the dryness we
experienced yesterday afternoon, the PWAT+ value from the 00Z
sounding was an even 100 (meaning the observed Precipitable Water
was exactly 100% of the daily mean value), and significant additional
moisture advection is expected ahead of the next active weather
system. Most locations west of the Cumberland Plateau will reach
60F or better this afternoon. It's going to be the last day like
this for awhile, because showers will begin developing later
tonight and certainly on Saturday as a strong cold front begins to
impact the mid state. In addition to widespread showers, some
storms are also possible given modest instability and the strength
of the cold front.


(Saturday Night through next Friday)
Issued at 1224 AM CST Fri Dec 8 2023

It appears that the most opportune period for convection is going
to along or just ahead of the surface boundary, which will sweep
across Middle Tennessee from late Saturday afternoon, through
Saturday evening and into the overnight hours before colder air
begins to infiltrate. Moisture transport ahead of the front looks
to be significant, with 850 mb winds reaching 40-50 kts just ahead
of the surface boundary. That the boundary will still be
undergoing frontogenesis as it enters the mid state Saturday
afternoon hints at the vigorousness of this system. For this
reason, the SPC has placed most of Middle Tennessee west of I-65
under a slight risk of severe storms. Straight-line winds will be
the primary threat. It is unclear whether CAPE values will be large
enough to sustain updrafts needed for large-hail. And, although
there will be plenty of speed shear in the pre-frontal environment,
profiles are likely to remain largely unidirectional.  Showers will
continue into Sunday, with some light snow possibly mixing in during
the afternoon. In fact, light accumulations (~0.2") are possible
along the Cumberland Plateau Sunday evening before the precipitation
entirely departs the mid state. Storm total QPF values from 06Z
Saturday until 06Z Monday range from ~1.5" around Land-between-the-
Lakes to ~2.5" along portions of the Cumberland Plateau. Looking
ahead, temperatures next week will remain quite chilly. Readings
Monday and Tuesday morning are expected to settle into the 20s, with
freezing temperatures again Wednesday morning. Temperatures will
warm somewhat by week's end, but no additional precipitation is
expected through Friday.


(18Z TAFS)
Issued at 1150 AM CST Fri Dec 8 2023

An approaching low pressure system will bring increasingly gusty
south winds throughout the TAF period. Cigs are expected to remain
VFR until after 06z Saturday. They'll likely bounce between MVFR
and VFR as isolated showers and storms develop through 18Z
Saturday. Wind shear is expected to increase as low level jet
winds increase after 10Z at CKV, BNA, and MQY. Additional storm
coverage isn't expected at sites until after 18Z.


Nashville      65  55  67  44 /   0  40  90 100
Clarksville    63  56  66  39 /  10  50  90  90
Crossville     58  47  60  40 /   0  60  50 100
Columbia       64  55  66  40 /   0  40  90 100
Cookeville     61  51  63  41 /   0  60  80 100
Jamestown      59  47  62  41 /   0  50  60 100
Lawrenceburg   64  55  66  41 /  10  50  90 100
Murfreesboro   65  53  68  40 /   0  50  90 100
Waverly        63  55  65  37 /  10  50  90  90