Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 011152
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
752 AM EDT SAT OCT 1 2016

...Forecast Update...
Issued at 750 AM EDT Sat Oct 1 2016

Opted to drop portions of the Dense Fog Advisory for south-central
Kentucky per latest webcams and observations that show conditions
have improved significantly. However, across southern Indiana and
north-central Kentucky, conditions remain poor with several sites
still reporting 1/4 mile visibility. Area webcams also show dense
fog continuing. As such, will do a short-term expansion for some
counties.

Near-term forecast weather grids have been adjusted for dense fog
wording, and temps/td blended with the latest observations.

.SHORT TERM (Now through Sunday)...
Issued at 230 AM EDT Sat Oct 1 2016

...Cat 5 Matthew tearing up Far Srn Caribbean Sea...
...Upper Low slowly pulling out...

Well...the main weather story is 941 mb Category 5 Hurricane Matthew
about 400 miles SE of Jamaica. This is the first Cat 5 since Felix
in 2007. Matthew has a very distinct eye (AF Reserve Hurricane
Hunters found 12nm eye surrounded by a ring of very deep convection).
This storm will be impacting Jamaica, Cuba, Haiti, and into the
Bahamas Sun night - Wed. The key of the intensity forecast for this
tempest will be whether it remains over open water of the Windward
Passage (between Cuba and Haiti). Will it be like Category 4 Hazel
in 1954 which annihilated Haiti or will it hit a bunch of land and
weaken like Category 4 Flora in 1963? This will be a HUGE news
story!

Moving back to the Ohio Valley, the 565dam pesky upper low is just
east of LOU at midnight and is drifting and wobbling NNE and will
drift to a position near Richmond IN after daybreak. This shift is
in response to a nudge from upper flow from the Dakotas. High
resolution models and ensembles all show the meandering moving
towards Toledo by sunset but tend to believe it may be a tad further
south of that.

Today will start off with lots of low clouds and fog.  Friday`s days
shift issued an excellent proactive dense fog advisory til 10 am and
crossover temps are about to be achieved across the wrn CWA.  FTK
has been <1/4 all night.  Should be light drizzle west of I-65 and
slgt chance rain across the the Bluegrass this morning.

After the low clouds and fog lift, along with drizzle, there will be
an increase in shra this afternoon with heating mainly across the
nrn 1/2 of the area, and much less near TN border being so far from
the low. Highs will mainly in the mid 60s, but if clouds clear
earlier than expected around 70 is very plausible.

Will keep little or no pops overnight for the Srn 1/2 of the CWA
with the the nettlesome low over the Eastern Wolverine State will
take SWRN vort energy to our north. Lows will be near normal in the
mid 50s. Looks like inversion sets up overnight and sets the stage
for more stratus and low clouds for at least the nrn 1/2 of the CWA.

Sunday will start off cloudy and improve dramatically with mix of
clouds and sun and temps moderating nicely into the low to mid 70s.
As the southern part of the trough pushes thru there is still will
be isol shra in afternoon mainly north of the BG Parkway. However
the big story for Sunday is improving conditions and lots more
sunshine and decent diurnal warmth.

.LONG TERM (Sunday night through Friday)...
Issued at 240 AM EDT Sat Oct 1 2016

...Warmer and Drier for most of the upcoming week...

Alas...the meandering pesky low is long a memory while large dome of
high pressure pushes in. This will be the dominant weather feature
for work week yielding a warmer, drier period with above normal
temps. Expect nice autumn like diurnal swings of 20-25 degrees each
day.

Through Wed Night the upper level pattern will consist of an east
coast ridge and stout Nrn Rockies trough yielding SSW mid level flow
for the Ohio Valley. Forecast soundings show fairly steep lapse llvl
lapse rates allowing temps to mix out to above 850 mb. This will
yield afternoon mercury zeniths of 79-84 F Tue-Wed. This is 5-10
degrees above normal. With dew points in the upper 50s to low 60s,
should be pleasant sunny afternoons.

A cold front will try to run into the ridge on Thu-Fri and for now
isol pops are ok for now across the wrn 1/2 of the CWA, but the 582m
upper ridge will be the crux on how far east the front can move and
if we can get any precip.

The new 00z GFS is much further west for Matthew than last few runs,
and the new ECM came in further east. Very interesting weather
scenario for sure.

&&

.AVIATION (12Z TAF Update)...
Issued at 650 AM EDT Sat Oct 1 2016

Deep cyclonic flow will linger over the Ohio Valley in the wake of
the slowly departing upper low. Expect restricted ceilings and
visibilities for most of the valid TAF period, with light winds
generally out of the S-SW. Vis tanked early but fog has mostly been
lifted into IFR stratus, except in LEX where we have lifted to fuel-
alternate MVFR.

Without much flow or change to the air mass, expect status quo to
hold through the morning, with only slow improvement this afternoon.
Can`t rule out spotty light showers or even drizzle under this
trofiness, but probabilities too low for inclusion in the TAFs.

Will come up to fuel-alternate MVFR around midday, with a few hrs of
higher MVFR, or even VFR late afternoon into the evening. The
improvement will likely be short-lived, and we expect at least some
build-down tonight, albeit not as extensive as what we had this
morning. Will go into fuel-alternate MVFR overnight as the most
likely scenario.

&&

.LMK Watches/Warnings/Advisories...
KY...Dense Fog Advisory until 10 AM EDT /9 AM CDT/ this morning for
     KYZ023>025-028.

IN...Dense Fog Advisory until 10 AM EDT /9 AM CDT/ this morning for
     INZ076-077-083-084-089>091.

&&

$$

Update.........ZT
Short Term.....JDG
Long Term......JDG
Aviation.......RAS



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