FXUS64 KOHX 242318

Area Forecast Discussion
National Weather Service Nashville TN
618 PM CDT Thu May 24 2018




Another warm albeit slightly less humid day across Middle
Tennessee today with surface obs showing temperatures in the mid
to upper 80s. Dewpoints have mixed down into the upper 50s to
lower 60s due to substantial dry air aloft above 850mb per the 12Z
OHX sounding. This has also kept convection from developing in
our area with latest radar imagery showing scattered showers and
thunderstorms in an arc around our forecast area from the Great
Smokies down into north Alabama then curving back northward into
west Tennessee. None of this activity is anticipated to affect our
area tonight with another warm humid night on tap. Some patchy
fog is possible once again but does not look like it will be
significant or widespread.

Deeper gulf moisture will begin spreading back northward into the
area tomorrow with PWATs rising above 1.5 inches areawide. With
daytime heating, this will lead to scattered pulse shower and
thunderstorm development by late morning/afternoon especially in
southern and eastern counties. With MLCAPE rising above 1000 J/Kg
by afternoon and some dry air remaining aloft, cannot rule out a
strong storm with a microburst or two and/or small hail tomorrow.
PWATs looks to increase further to around 1.75 inches over the
weekend as a tropical system organizes in the Gulf of Mexico and
ushers more moisture northward, with likely pops warranted on
both Saturday and Sunday. With it being the Memorial Day holiday
weekend and a large number of people outside and on area lakes,
lightning will be a major hazard and those outdoors are urged to
have a plan in place ahead of time to seek shelter in case of
thunderstorms. Locally heavy rain and some localized flooding are
also possible due to the highly moist airmass, weak deep layer
shear, and slow storm motions.

Forecast for much of next week is highly dependent on what
happens with the tropical system in the Gulf. Latest 12Z models
strengthen the system as it moves northward into the northern Gulf
Coast, with subsidence around the system leading to a reduction
in precip chances for Monday and Tuesday. Although coverage of
showers and storms currently looks to rise back into the high
chance/likely category by Wednesday and Thursday, this again
depends on what track the tropical system ends up taking - and if
the system remains to our south or dissipates prior to getting
this far north, precip chances may not be as high. By the end of
next week, guidance suggests a northwest flow pattern will become
established across the Tennessee Valley as an upper ridge shifts
westward over Texas and strengthens. This may allow for some MCSs
to impact the area by next weekend, which is fairly typical for
June, but we shall see.



BNA/MQY/CKV/CSV...The atmosphere across Middle Tennessee has
continued to dry out, with mostly sunny skies late this afternoon
and a low potential for radiation fog overnight. Winds will remain
generally light the next 24 hours owing a weak surface pressure
gradient. However, look for moisture to begin advecting back into
Middle Tennessee tomorrow as we start picking up return flow, with
scattered POP's mainly during the afternoon.





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