Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 181916
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
316 PM EDT Tue Jun 18 2019

.Short Term...(This evening through Wednesday)
Issued at 313 PM EDT Tue Jun 18 2019

The morning rains moved off to the east and clouds have cleared out
enough to allow destabilization of the atmosphere in the heat of the
afternoon. With SBCAPE around 2k J/kg and precipitable water values
just under two inches some of the showers and storms this afternoon
and evening will be capable of locally heavy downpours. DCAPEs,
lapse rates, and shear are weak, so organized severe weather is not
expected.

Tonight the diurnal storms will dissipate, leaving us with a
relative lull in the rain overnight into Wednesday morning (a few
showers can`t be entirely ruled out). It will be another muggy night
with little wind and lows in the 65-70 degree range.

Tomorrow we still will be in the warm sector south of the stationary
front as low pressure crosses Missouri along the boundary.
Increasing mid and upper winds will overspread the region in the
afternoon as we destabilize. The same wet atmosphere will be in
place, with moisture content possibly even increasing slightly over
what we`ve been mired in lately. Thunderstorms will once again
develop in the afternoon. Deep layer shear and mid-level lapse rates
will be slow to increase, but some strong storms will be possible.
The main worry, though, will be locally torrential downpours on
ground that will have difficulty accepting heavy rain. So, after
discussion with neighbors, have extended the Flash Flood Watch
through Thursday. Chances for severe storms will increase into the
evening hours...see below for Wednesday night-Thursday discussion.

&&

.Long Term...(Wednesday night through Tuesday)
Issued at 305 PM EDT Tue Jun 18 2019

...Severe Storms Possible Into Late Wednesday Evening...

A convectively-enhanced shortwave trough will swing in from the west
Wednesday evening. A combination of global and hi-res guidance
suggests this could be in the form of an MCV. Sfc low pressure is
forecast to deepen over southern IL and central IN to around 1000 mb
by early Thursday. Wind fields aloft all strengthen out of the SW,
with the strongest mid and low level jets punching in after 03z.
Backed southerly sfc flow related to any meso low would enhance the
low level shear and SRH.

While instability will wane, especially after 03-06z, a brief
overlap period appears possible with sufficient surface-based
instability and strengthening shear. Thus, some storms could be
severe with a threat for damaging winds, possibly a tornado,
torrential rainfall, and lightning.

While there is a meaningful risk for damaging winds, significant
flash flooding has the potential to impact more people. 1-hr FFG
values are currently sitting at around 1-1.25 inches or less across
a significant portion of southern Indiana, north-central KY, as well
as the Lake Cumberland region. Precipitable water values will
increase to 1.75-2 inches Wednesday night. Storms will put down
copious amounts of rainfall in a relatively short period of time.
The Flash Flood Watch has been extended through Thursday.

The cold front sweeps through Thursday, with rain chances
diminishing from west to east in the afternoon and evening. An
influx of slightly less humid air will allow temps to drop into the
lower 60s in many places Friday morning. Friday still looks quiet
with an elongated sfc ridge building east across the region.

While upper ridging is forecast to build over the eastern US this
weekend, a warm front lifting north will likely result in additional
showers and storms Friday night into Saturday. Scattered diurnally-
enhanced storms then look likely through the rest of the weekend in
a warm, humid airmass. A stronger system may try to force another
cold front through the region early next week, which could result in
more widespread storms. All convection into early next week will
bring at least some risk for flooding.

&&

.Aviation...(18Z TAF Issuance)
Updated at 116 PM EDT Tue Jun 18 2019

Scattered showers will continue today, with thunderstorms developing
as well as the atmosphere continues to destabilize with the heat of
the day. Those scattered showers and storms will continue into the
evening hours before dissipating and allowing us a lull overnight.

With copious low level moisture still in place, sub-2k` clouds are
expected to develop once again during the pre-dawn hours. Some light
restrictions to visibility will also be possible, especially at
HNB/BWG that are more susceptible to BR.

Storm development will return Wednesday afternoon as an upper level
disturbance from the west interacts with the moist and unstable
atmosphere.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...Flash Flood Watch through Thursday evening for INZ076>079-083-
     084-089>092.

KY...Flash Flood Watch through Thursday evening for KYZ025-029>043-
     047>049-055>057.

&&

$$

Short Term...13
Long Term...EBW
Aviation...13



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