Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 190533

Area Forecast Discussion
National Weather Service Louisville KY
133 AM EDT Mon Mar 19 2018

...Updated Aviation Discussion...

.Forecast Update...
Issued at 950 PM EDT Sun Mar 18 2018

Just issued a quick update to dry out most of the overnight period,
except for a very small chance of showers getting into south-central
Kentucky around daybreak. Dry mid-level air between 850-700mb looks
to hang on well into Monday, so most of the area will have to wait
for the stronger dynamical forcing to develop precip in the
afternoon. Still looking at thunder potential close to the KY/TN
border where instability develops, so really no changes beyond early
Monday afternoon.


.Short Term...(This evening through Monday night)
Issued at 300 PM EDT Sun Mar 18 2018

...Strong Storms Possible Across Southern KY Monday Afternoon...

As of mid afternoon, high pressure was centered across the lower
Great Lakes region. Satellite imagery showed clear skies from
Huntingburg, IN to Danville, KY and points north/east while lower
stratus continued across portions of south-central Kentucky.
Readings were in the 50s, on the way to reach the low 60s across
southern IN and north central KY. Winds were light and out of the

A potent shortwave trough currently over the 4 corners region will
cross the central Plains and reach the mid-Mississippi River Valley
by Monday afternoon. A warm front, currently across middle AL/GA,
will begin lifting toward the area tonight and Monday morning, and
is expected to reach the KY/TN border vicinity by Monday afternoon.
A compact surface low will cross through middle TN in the afternoon.

SPC HREF shows an axis of surface-based CAPE reaching around 1000
J/kg along the KY/TN border by Monday afternoon/evening while 0-6 km
shear values approach 60 to 70 kts. The best severe thunderstorm
chances will be from middle TN southward into Alabama, but a few
strong to perhaps marginally severe thunderstorms will be possible
right along and south of the warm front across extreme southern
Kentucky. There was a slight northward jog with the SPC Day 2
outlook, which puts the southern 2 tiers of counties in a marginal
to slight risk. The main threat for any strong storm that does
develop would be hail and damaging winds. Elevated instability is
expected to develop across much of central Kentucky, so a few
thunderstorms will also be possible as far north as the Ohio River.

Rain chances will begin to increase after midnight across southern
Kentucky, then a lull is likely from mid morning through early
afternoon before the main line of showers/storms arrives in the mid
afternoon to evening hours. Rainfall totals of 1/2 to 1 inch are
expected, highest across southern Kentucky.

.Long Term...(Tuesday through Sunday)
Issued at 302 PM EDT Sun Mar 18 2018

While the near/short term is focused on convective, spring-like
weather, the long term period will feature more winter-like weather
across central Kentucky and southern Indiana.

A strong upper level shortwave trough will pivot through Tuesday and
Tuesday night. This enhances lift across the Ohio Valley and in
response, the 18.12z models spread QPF across the entire area. With
some dynamic cooling and nighttime temperatures in the 30s,
soundings show precipitation could changeover to wet snow if
precipitation rates are high enough. There`s potential for
accumulating snow along/east of I-65 though amounts and potential
impacts remain uncertain. The Wednesday morning commute could be

Temperatures Tuesday/Wednesday will be unseasonably cold with highs
likely in the 40s and perhaps in the 30s Wednesday across the

Beyond that, another concern is the potential for a hard freeze with
lows forecast in the mid 20s Thursday morning. For areas that have
already started greening up, especially southern Kentucky, this
could create some early-season agricultural impacts.

Another weather system looks to come through late in the week or
next weekend. Leaned on the model consensus which spreads in
precipitation chances throughout Saturday in the 50 to 70 percent


.Aviation...(06Z TAF Issuance)
Issued at 131 AM EDT Mon Mar 19 2018

VFR conditions are expected to prevail at all sites through the
remainder of the night. Winds will continue to be light overnight
and generally out of the northeast, but could be variable at times.
High and mid level clouds are expected through dawn. A stray shower
will be possible near BWG towards 12Z, but given chances are low and
little impact is expected, will keep the mention of it out of the
TAFs for now.

Through the rest of the day and evening, a low pressure system will
work its way across TN and into south and east central KY. Winds
will strengthen ahead of this system out of the east and become
gusty this afternoon. Rain will overspread the region this afternoon
and early evening. The best chance for thunderstorms will be at BWG,
so will carry VCTS there. Ceiling will lower to MVFR and possibly
IFR as the lower levels of the atmosphere saturate.




Short Term...ZT
Long Term...ZT
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