Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 212343
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
743 PM EDT Tue Oct 21 2014

...Updated both Forecast and Aviation Discussions...

...Forecast Update...
Issued at 750 PM EDT Tue Oct 21 2014

Cloud cover will be the only challenge in the forecast for tonight
and Wednesday. Louisville is on the southwestern edge of a slowly
eroding strato-cu shield that extends all the way back through
Pennsylvania. Skies will slowly become partly cloudy overnight at
Louisville, with mostly clear skies expected at Bowling Green, and
with Lexington probably remaining mostly cloudy through Wednesday
morning.

.SHORT TERM (Now through Wednesday Night)...
Issued at 330 PM EDT Tue Oct 21 2014

...Frost potential increasing for Wednesday Night...

Latest water vapor imagery overlaid with 500 mb heights shows
cyclonic flow with deep upper level trough across the eastern CONUS.
Altostratus deck exists across much of IN and central into eastern
KY thanks to cooler air aloft steepening lower level lapse rates. As
surface heating wanes later this afternoon, the periphery of this
cloud deck, which is more cellular, is expected to dissipate as main
upper level cyclonic flow shifts to the east.

At the surface, high pressure centered across Wisconsin will begin
to slowly shift southeastward toward the area tonight, which is
expected to keep the western forecast area mostly clear. However,
clouds will be slow to erode across the eastern areas thanks to the
influence from the upper level trough. Plan on seasonably cool
temperatures tonight with lows ranging across the area from the
upper 30s to lower 40s.

For Wednesday, look for pleasant but seasonably cool October
conditions as high pressure centers itself across the Ohio River
valley. Sunny to mostly sunny skies are expected with highs ranging
from the upper 50s in the east to lower 60s across the southwest
forecast area. Winds will be light and out of the north.

Wednesday night into Thursday looks to be the coolest night of the
entire forecast period as the surface high will be positioned over
the forecast area. This will provide ideal radiational cooling
conditions and Thursday morning lows are expected to dip into the
lower to middle 30s. With light winds and the seasonably cool
airmass in place, patchy to areas of frost look likely. The favored
areas appear to be the eastern forecast area where temperatures may
approach the freezing mark. Otherwise, lows look to vary from the
lower to middle 30s. Frost advisories may be needed for Wednesday
night into Thursday morning across portions of the forecast area if
confidence continues to increase.

.LONG TERM (Thursday through Tuesday)...
Issued at 243 PM EDT Tue Oct 21 2014

After a chilly start to the day temperatures will remain on the cool
side Thursday, topping out in the lower 60s despite quite a bit of
sunshine. For Thursday night into Friday a shortwave will drop
southeast through the northwesterly flow aloft. Precipitation with
this system will be weakening as it approaches the area. However,
most of the models now show at least a slight chance for showers
across southern IN and north central KY Thursday night so will
increase pops to around 20% in this area. The strength of the
shortwave varies from model to model and if it does trend towards
the stronger side, a chance for light showers may eventually need to
be added for Friday as well.

Beyond Friday, upper level ridging will be building in across the
lower Ohio Valley with high pressure at the surface. This will bring
mostly clear to partly cloudy skies with warming temperatures
through Monday. Highs Friday will be in the lower to mid 60s while
Monday`s highs look to be in the mid to upper 70s. Lows will
increase from the lower to mid 40s Friday morning to the lower to
mid 50s Tuesday morning. The next chance for rain will come Tuesday
into Tuesday night as a front moves through.

&&

.AVIATION (00Z TAF Update)...
Updated at 700 PM EDT Tue Oct 21 2014

The western edge of an expansive area of strato-cu lies near
Louisville and will only erode to the northeast a little bit
overnight.

Clear skies tonight expected at BWG and mostly sunny skies are on
tap for Wednesday.

Mostly cloudy skies this evening at SDF will give way to partly
cloudy skies after midnight. Partly cloudy skies expected Wednesday.

For LEX, ceilings will be slowest to lift. Mostly cloudy skies for
tonight through early Wednesday are expected with ceilings remaining
above the MVFR threshold. Partly cloudy skies will likely develop at
LEX by late morning.

Northerly winds will continue tonight and Wednesday at around 5 to
8kt.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&

$$

Update.........JSD
Short Term.....AMS
Long Term......EER
Aviation.......JSD





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