Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 230434
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1234 AM EDT Fri Jun 23 2017

.Forecast Update...
Issued at 1150 PM EDT Thu Jun 22 2017

Issued an update for current radar trends.  Looks like we can cut
down on pops some for the rest of the night period, and latest hi-
res guidance does not call for the banded precip over southern IN
until a little later this morning. Also, the development may end up
over our northern row of counties, if not just north of them in
IND`s area. Latest NAM has backed off quite a bit on the low-level
jet ramping up overnight, so consequently, it does not have nearly
as strong of a rains as in its previous runs. Latest RAP is more
in line with current winds on the LVX VWP, and it still brings in
a stronger jet the rest of the night, with the best convergence
again along that northern row of counties in southern IN.

We still look to have a solid slug of rains moving across the entire
region Friday...so no need to change any of the current Flash Flood
Watch.

Issued at 637 PM EDT Thu Jun 22 2017

The widespread area of light to moderate rainfall has lifted to the
north of the Cumberland Parkway early this evening. To the south of
this area, scattered showers continue to move north out of TN. There
looks to be a relative lull in precipitation later this evening as
the larger rain shield lifts out. Thereafter, rain chances will be
on the increase again, particularly across southern IN during the
early morning hours as discussed in the short term discussion below.
Some changes were made to the pops for this evening to better
reflect the expected lull, though at least slight chances were left
in everywhere through the night.

&&

.Short Term...(This evening through Friday night)
Issued at 223 PM EDT Thu Jun 22 2017

...Torrential Downpours Expected...
...Minor Flooding of Small Rivers and Streams Possible...
...Isolated Tornado Not Out of the Question...

~~Main Threats and Timing~~

The best chance for heavy rain in southern Indiana will be from
after midnight tonight through Friday. The best chance for heavy
rain in central Kentucky will be Friday afternoon and evening.

The best chance for isolated tornadoes or damaging wind gusts will
be Friday afternoon in central Kentucky, especially the Lake
Cumberland region. There is also a small chance of an isolated brief
spin-up or wind gust over southern Kentucky this evening.

~~Summary~~

A cold front coming in from the northwest will meet up with the
remnants of Tropical Storm Cindy coming up from the southwest,
leading to widespread rain. Plentiful atmospheric moisture will
result in locally torrential downpours.

~~Rainfall Amounts~~

General amounts of 1 to 3 inches are expected, with embedded bands
of heavier rain. Today`s model runs, with some exceptions, have come
into decent agreement showing the band of heaviest rain between I-64
and the Cumberland Parkway.

~~Confidence~~

At this time, confidence is high that a band of heavy rain will set
up, likely over central Kentucky. Confidence of heavy rain is less
in southern Indiana and southeastern sections of central Kentucky
(Lake Cumberland area).

Small changes in the track and timing of Cindy will lead to
significant changes in where the heavy rain sets up.

~~Details~~

Tropical Depression Cindy, centered near Shreveport, Louisiana at
the start of the short term, will head north into Arkansas tonight
and then northeast into southern Kentucky Friday afternoon.
Meanwhile, a cold front will approach from the northwest, reaching
the Ohio River by Friday evening. It will then pick up Cindy`s
remnants and whisk them off to northern Virginia by dawn Saturday.
The models, including the HWRF, have come into pretty good agreement
with this.

The rain this afternoon has been efficient, with moderate to
briefly heavy rain despite radar dbz`s only in the 40s. As of 1pm
CDT the Kentucky Mesonet site in Simpson County already received
nearly an inch and a half of rain. The rain will continue to move to
the northeast late this afternoon and evening. The HRRR has been
very consistent with the idea of sprouting isolated convection
behind the departing steady rain early this evening. The chance of
isolated showers/storms will be enhanced during a brief window
before sunset if the breaks in the overcast currently over the lower
Mississippi Valley can work their way in. Isolated wind gusts or
even a brief, weak spin-up wouldn`t be out of the question given
strong low level shear and stronger winds aloft as seen on OHX VWP.

After midnight rain chances will increase significantly over
southern Indiana as moisture pools ahead of a cold front approaching
from the northwest and low level jetting increases. Precipitable
water values will increase to 2 to 2.5 inches, leading to locally
heavy downpours.

On Friday the front and Cindy`s circulation will feed on deep
moisture to produce widespread showers and scattered thunderstorms
with torrential downpours. Low and mid level winds will increase
Friday afternoon and low level shear will be strong ahead of and to
the right of the circulation. Though insolation will be at a premium
and instability will be weak, rotation will be possible in the low-
topped convection and could result in isolated wind gusts or brief,
weak tornadoes in central Kentucky. If we get some breaks in the
cloudcover to increase instability, severe chances will increase.
The best chances will be in the Lake Cumberland region.

.Long Term...(Saturday through Thursday)
Issued at 229 PM EDT Thu Jun 22 2017

The long term will be quiet as Canadian high pressure slowly makes
its way across the central and eastern United States. Could see some
valley fog in the Lake Cumberland region Saturday morning.

Temperatures will be very mild for early summer, with highs in the
70s to around 80 through Wednesday, then warming up a bit late in
the week.

&&

.Aviation...(06Z TAF Issuance)
Issued at 1230 AM EDT Fri Jun 23 2017

Regional radars reveal dry conditions across central Kentucky and
southern Indiana at this hour. A band of precipitation in western
Kentucky may clip parts of southern Indiana and north-central
Kentucky later this morning, and could come close to clipping the
SDF terminal. The LEX/BWG terminals should remain dry.

It`s not until late morning and early afternoon that we`ll
see widespread precipitation develop and move into the region.
Expect MVFR cigs/vis with areas of IFR in the heavier showers and
thunderstorms. Drier air will work in from the northwest this
evening and gradually improve cigs/vis.

&&

.Hydrology...
Issued at 259 PM EDT Thu Jun 22 2017

Areas of heavy rain will extend northward tonight. The rain will end
after midnight early Saturday morning. This is due to a combination
of the remnants of Tropical Storm Cindy coming up from the south and
a cold front sweeping in from the northwest. Between 1 and 3 inches
of rain are expected with the entire system. It is important to
note, though, that within this general area of rain there may be
narrow bands of higher amounts where thunderstorms train over the
same locations.

This will lead to rises streams in the area with minor flooding
possible. The largest threat will be in the Green, Barren, and Rough
basins. However, only minor flood levels are expected.

In addition, thunderstorms will produce locally torrential downpours
which could lead to flash flooding.

If you live in a flood prone area, watch water levels closely over
the next few days.

&&

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

KY...Flash Flood Watch from 11 AM EDT /10 AM CDT/ this morning
     through Saturday morning for KYZ023>043-045>049-053>057-
     061>067-070>078-081-082.

&&

$$

Update...RJS/EER
Short Term...13
Long Term...13
Aviation...DM
Hydrology...CMC


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