Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 270530

Area Forecast Discussion
National Weather Service Louisville KY
130 AM EDT FRI MAY 27 2016

...Updated Aviation Discussion...

...Forecast Update...
Issued at 930 PM EDT thu May 26 2016

Convection from earlier has pushed an effective boundary into
portions of TN westward into northern AR.  As an upper-level trough
ejects into the Central Plains, this effective boundary will begin
to lift back north as a warm front.  This process is already
occurring across southern MO/northern AR, where convection has began
to lift back to the north in response.  Main challenge tonight will
be how far northeast this activity makes it.  Current thinking is
that the bulk of the activity will stay to the west where latest
guidance depicts the better isentropic ascent over the boundary.
However, do think we may see a few showers/isolated storms creep
into portions of southern IN/northern KY late tonight as this
boundary lifts back to the north.  Therefore, will continue to leave
low-end pops in the northwest part of the CWA. Updated products
already out.

Issued at 630 PM EDT Thu May 26 2016

Updated the forecast early this evening to account for the latest
radar trends.  Convection had enough of a cold pool to sweep
southeast through the region, thus the threat for any strong storms
has ended.  Still have some ongoing flooding in southern KY, but the
moderate rains there should subside over the next few hours.  Once
again, we could see some additional development toward sunrise as
yet another wave induces weak isentropic ascent over the region,
thus will keep small pops in through the overnight hours.

.SHORT TERM (Now through Friday Night)...
Issued at 250 PM EDT Thu May 26 2016

Main forecast concern is convection currently tracking across the
area this afternoon, and chances again tomorrow as we remain in a
more summer-like pattern.

Latest analysis showed upper level ridging over the southeast US
while a trough remained across the central Plains. Impulses lifting
out of Texas northeast toward the lower Great Lakes have sparked
several complexes of showers/storms on the periphery. One line of
storms originated out of Missouri/Illinois and has tracked all day
toward the I-65 corridor.

Dewpoints in the 60s to near 70 combined with brief clearing earlier
today resulted in 2000 to near 3000 J/kg of SBCAPE, especially south
of the KY parkways to the TN border. Shear environment is weak to
modest at best, but just enough to sustain some organization across
the south.

The threats likely for our area are marginal severe hail and wind
gust but more likely to be torrential rainfall and potential for
flash flooding. With the slow moving convection, anomalously high
PWATs and convection becoming more west/east oriented, training
cells may pose a flash flood risk around and nearby the Bowling
Green metro area through the evening.

Expect a gradual decrease in coverage and intensity of convection
later this evening, giving way to slight chances for the overnight.
Will have to monitor the potential for fog in the favored areas that
see plenty of rain, especially if clouds clear out. Look for
mild/muggy lows in the 60s to near 70.

For Friday, forecast guidance seems to favor a drier day, especially
along/east of I-65. The best storm activity looks to be further to
the west, so will maintain 10 to 20 percent chances. As a result,
bumped up highs a degree or two and some areas may push 90 if indeed
the area remains dry.

.LONG TERM (Saturday through Thursday)...
Issued at 255 PM EDT Thu May 26 2016

On Saturday, a more pronounced upper level shortwave trough will
swing through the Upper Midwest and lower Great Lakes. The 26.12z
guidance shows impulses passing closer to the area and with the
better dynamics aloft and a continuation of the juicy air mass,
precipitation chances were nudged up in the 50 to 60 percent range.
Still not expecting an all-day washout, but just greater coverage of
showers/storms across the area during the afternoon hours.

Sunday into most of next week the upper level pattern flattens out
across the area and generally there`s a lack of shortwaves moving
through the flow. This may lend toward a drier and warmer period of
weather for the region. Tried to incorporate opportunities for dry
days or nights, but again confidence is limited in this summer-like

The other issue is the evolution and eventual track of a potential
tropical system off the Carolina coast this weekend into early next
week. Whether this acts to suppress convection on the northwest
side, or enhance moisture/convection across our eastern areas is the
wild card.

Temperatures through the long term will continue to run above normal
with highs in the 80s and lows in the 60s.


.AVIATION (06Z TAF Update)...
Issued at 120 AM EDT Fri May 27 2016

Convective debris mid and high level clouds continue across central
KY at this time with VFR conditions. With rain yesterday and absence
of low clouds, still expect at least some MVFR vsby fog at times
early this morning at BWG and LEX (possibly SDF).

Current radar shows showers over southwest KY. Models suggest some
showers will move and/or develop northeast overnight, so will
include VCSH at SDF after 09z, although conditions should remain VFR.

On Friday, any showers near and north of OH River will lift north-
east leaving dry VFR weather for the 3 TAF sites for much of the
day. Surface winds will be SSW at 10-15 kts. More mid and high level
debris clouds possible Friday night, but should have little overall
effect, as surface winds become S to SE around 5 kts.


.LMK Watches/Warnings/Advisories...


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