Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 201903
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
303 PM EDT Sat Oct 20 2018

.Short Term...(This evening through Sunday)
Issued at 244 PM EDT Sat Oct 20 2018

...Gusty Winds This Afternoon, Freezing Temperatures Tonight...

A strong cold front located in central IL/IN is moving quick to the
south this afternoon. Observational sites along and behind the cold
front have been gusting in the 35-40kt range, with some gusts
exceeding 45kts. The cold front is expected to arrive in southern
Indiana and northern Kentucky late this afternoon and early evening,
and will result in a small window for +40mph wind gusts. The current
placement of the wind advisory looks good, and no changes have been
made with this forecast issuance.

Overnight temperatures are expected to be around or just below
freezing behind the front, and in coordination with surrounding
offices, have opted to go with a freeze warning vs a frost advisory.
The latest 12z models indicate winds generally staying up through
the night, and only dropping into the 4-8kt range as we head into
sunrise. Winds of this measure would not be favorable for widespread
frost formation, and would expect any frost that does form to be
restricted to very sheltered areas or valleys. The other thing
working against frost tonight is the dry air that will be in place,
as models bring dewpoints down into the low/mid 20s for many
locations resulting in a several degree spread of T/Td. Will keep
patchy frost wording in the forecast for those sheltered locations
that could see it, but the bigger impact will be freezing to sub-
freezing temperatures to vulnerable vegetation.

Strong Canadian surface high will move over the region tomorrow and
set up a cool, but sunny, morning and afternoon. Highs look to only
top out in the low 50s for many spots. Winds will be light through
the day, and eventually switch to the south as the surface high
departs eastward.

&&

.Long Term...(Sunday night through Saturday)
Issued at 250 PM EDT Sat Oct 20 2018

A dry autumn weather pattern will prevail for most of the extended
forecast period as W or NW flow aloft keeps any significant low-
level moisture return from reaching central KY and south-central IN.
Temperatures through the period should continue to average below
normal, with highs averaging in the 50s and lower 60s and lows
generally in the 30s and lower 40s.

On Monday morning, surface high pressure will move off to our east
resulting in a weak low-level S or SW flow developing just off the
boundary layer. However, residual cold air in place at the surface
will still result in frost with temperatures near/around freezing,
particularly in valleys and over the eastern half of the forecast
area. Afternoon temperatures though will rebound into the upper 50s
and lower 60s.

As another shortwave moves across the northeastern U.S. on Tuesday,
a weak surface front should move south across the OH Valley,
although it should come through dry with slightly lower temperatures
on Wednesday. Highs Tuesday afternoon may be the warmest during the
period in the lower to mid 60s.

By the middle of next week, a 500 mb trough axis is progged to
progress east across the central U.S. Models differ a bit on its
handling, but generally agree that the best moisture return and
precip will remain to our south over the southeastern U.S./Gulf
Coast on Thursday and/or Friday, with a separate area of showers to
our north near the core of the shortwave. While isolated showers may
be possible in our area associated with this northern system, the
latest blended forecast came dry, and see no substantial reason to
change it at this time. Additional weather disturbances could bring
isolated to scattered showers, especially to parts of the Bluegrass,
Friday night and/or Saturday night, but this is tenuous and depends
on how weather features unfold by that time.

&&

.Aviation...(18Z TAF Issuance)
Issued at 101 PM EDT Sat Oct 20 2018

A strong cold front currently in the upper Midwest and Great Lakes
region will work toward our area late this afternoon and evening.
Models continue to indicate strong winds along and behind the front,
some of which could gust over 40mph. Winds will subside some after
02z-03z, but still remain gusty (~20mph) through most of the
overnight hours. VFR conditions are expected through the forecast
period.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...Freeze Warning from 4 AM EDT /3 AM CDT/ to 10 AM EDT /9 AM CDT/
     Sunday for INZ076>079-083-084-089>092.

     Wind Advisory until 11 PM EDT /10 PM CDT/ this evening for
     INZ076>079-083-084-089>092.

KY...Freeze Warning from 4 AM EDT /3 AM CDT/ to 10 AM EDT /9 AM CDT/
     Sunday for KYZ023>043-045>049-053>057-061>067-070>078-081-
     082.

     Wind Advisory until 11 PM EDT /10 PM CDT/ this evening for
     KYZ024-025-028>043-045>048.

&&

$$

Short Term...DM
Long Term...TWF
Aviation...DM


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