FXUS64 KOHX 250927

Area Forecast Discussion
National Weather Service Nashville TN
427 AM CDT Sat Mar 25 2017


The first wave of today's system crossed the Mississippi River
around 08z this morning. The line has weakened as it's moved east
and should continue to weaken over the next few hours. There are
already a few light elevated echoes showing up on radar over our
southwestern counties and we could see a few more substantial
showers cross over the Tennessee River before 7am. While scattered
showers and a few thunderstorms may develop before 18z in our
western most counties, the bulk of today's activity is expected in
the afternoon and evening. As we begin to destabilize this
afternoon with moist air surging up from the south, we could see
some strong to isolated severe storms develop mainly west of I-65.
Instability doesn't look much, if at all better than it did
yesterday, but still seeing around 600 to 700 j/kg of CAPE
according to the NAM, with the GFS only mustering up about 300
j/kg. We do still have decent 0-6km shear values of around 30 to
40 knots. So as the low pressure swings northeast from Arkansas
through Missouri, it should provide enough forcing for us to see
storms develop/strengthen from 1pm to 6pm over the west. The NAM
is also showing 0 to 1 km helicity values around 200 to 300,
allowing just enough turning in the atmosphere to mention a small
tornado threat this afternoon. However, the main threats with any
storms that do develop will be damaging winds and hail. It
doesn't look like there will be a whole lot of eastward movement
to this afternoon's wave of storms as the low pressure heads
north. Storms may pass over the same general area as we head into
tonight. Expect any strong or severe activity to decrease by 10pm
tonight as we stabilize, but showers will likely hang around
throughout the overnight hours. Soundings indicate Pwats of 1 to
1.25 inches lasting through the late evening tonight and into
morning Sunday. Some places mainly east of I-65 could see rainfall
totals of one half to three quarters of an inch early Sunday

We should see a break in precip on Sunday night after showers and
a few thunderstorms exit the Plateau. The next system isn't too
far off though. A shortwave over the central plains will head east
and into the mid Mississippi Valley on Monday bringing with it a
chance of showers and thunderstorms. The NAM and GFS both indicate
at least slightly more instability with Monday/Monday night's
system than with todays, so we could be in store for another round
of strong to severe storms. Right now, the western counties in
Middle Tennessee are under a slight risk for severe storms. Steep
mid level lapse rates and strong winds aloft will make hail and
damaging winds the main threats. The main time frame for storms on
Monday will be in the afternoon and early evening.

Precip will move off to the east Tuesday and leave us with a
quiet night, but the active pattern will continue for the
remainder of the work week. An upper level trough will swing
across the eastern portion of the U.S. Wednesday through Thursday
bringing along another chance of thunderstorms.

Temperatures will remain mild throughout the forecast with highs
in the upper 60s and mid 70s and lows in the 50s.



BNA/CKV/CSV...A storm system is approaching Middle Tennessee from
the west late this evening, although the active weather is still
west of the Mississippi River, and won't begin to affect the mid
state until after 12Z. The moisture band producing the bulk of the
existing convection is well ahead of the cold front, and this will
remain so as convection rolls through Middle Tennessee mainly
during the afternoon and evening on Saturday. So look for VFR wx
overnight, with gusty winds and some LLWS, with surface winds
increasing after 12Z.


Nashville 75 58 74 56 76 / 70 80 40 10 60
Clarksville 72 55 72 53 75 / 80 80 30 10 60
Crossville 70 54 68 55 71 / 30 90 70 20 50
Columbia 73 57 74 56 75 / 80 80 30 10 50
Lawrenceburg 74 58 74 57 76 / 80 80 40 10 40
Waverly 71 57 73 55 75 / 80 80 20 10 60





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