Area Forecast Discussion
Issued by NWS Louisville, KY

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521
FXUS63 KLMK 220509
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
109 AM EDT Sun Oct 22 2017

.Forecast Update...
Issued at 830 PM EDT Sat Oct 21 2017

Quiet weather so far this evening, at least at the surface. Aloft,
have some light returns near KHNB, but these should dry out before
making it anywhere near the surface. Winds will pick up just above
the surface overnight. These winds should mix down to the surface in
the mid morning hours, in the form of gusts. Have bumped up winds
a little in the forecast for Sunday. Otherwise, the forecast rest
of the forecast is on track.

&&

.Short Term...(This evening through Sunday night)
Issued at 315 PM EDT Sat Oct 21 2017

Currently, cirrus continues to flow north from the Gulf of Mexico
providing a broken layer of sky cover over the area. The low and mid
levels are dry. Winds are from the south at 6 to 8 mph. Temperatures
are steadily warming through the 70s with a push from the southerly
winds. Expect the afternoon highs in the upper 70s.

Tonight, the cirrus will stick around with light southerly flow
around 5 mph to keep temperatures in the mid 50s to 60 which is
warmer than last night. Louisville could be the warm spot at 61. The
area will remain dry.

Sunday, a deep sharp trough and cold front will approach the region
from the west. As this front approaches the pressure gradient will
strengthen causing winds to increase to 10-15 mph with gusts 20 to
25 mph with good mixing.  Strong southerly flow will allow temps to
reach the upper 70s/lower 80s for highs.  Rain chances remain low
during the daylight hours. Clouds will continue to build in during
the day from the advancing front.

Sunday night, rain will enter the area around sunset spreading west
to east through the overnight hours.  Precipitable water values will
be above normal...around 1.5 to 1.7 inches.  That`s about double the
normal value for this time of year.  Given this environment, expect
efficient rain producers Sunday night.  Even though rainfall may be
moderate to at times briefly heavy, dry antecedent conditions
should prevent flooding issues.  Lows Sun night should drop into the
upper 50s/lower 60s.

.Long Term...(Monday through Saturday)
Issued at 305 PM EDT Sat Oct 21 2017

Monday - Wednesday...

A low pressure system will continue to push east through the Ohio
Valley on Monday bringing widespread rains with perhaps moderate to
briefly heavy rain Mon morning.  By Monday afternoon rain intensity
should lighten with only light rain showers expected by Mon evening.
Overall rainfall totals for Sun/Mon should range from 1-2 inches
over most locations with areas of south central KY likely to see 2+
inches.  Still with very dry antecedent conditions, flooding is not
expected to be an issue.  High temps on Monday should fall back into
the low to mid 60s.

A much deeper upper level trough will drop into the Midwest behind
the aforementioned low pressure system causing continued isld-sct
light rain shower chances Tue-Wed.  The trough will also bring much
cooler temps to the region.  Tuesday will be a rather raw day with
WNW winds gusting to 25-30 mph under partly to mostly cloudy skies
with highs limited to the 50s.  Wednesday won`t be as windy but
after a chilly start in the upper 30s/lower 40s, highs will only top
out in the lower 50s.

Thursday - Saturday...

Thursday morning looks to be the coldest morning in the 7 day
forecast as skies clear with good rad cooling.  Lows should drop
into the 30s and could result in widespread frost.  The rest of
Thursday will feature dry and warmer weather as the upper trough
moves out. Expect highs to rebound into the 60s for Thu and Fri.

Another strong cold front and upper level trough will arrive for the
Fri/Sat time period bringing more rain chances to the area as well
as another punch of cold air for the weekend.

&&

.Aviation...(06Z TAF Issuance)
Issued at 1245 AM EDT Sun Oct 22 2017

Prevailing VFR conditions expected through the valid TAF period.
Main overnight challenge is wind shear, as low-level jetting will
start to pick up. Will initialize BWG and HNB with 35 kt at 2000
feet, and spread that into SDF for the pre-dawn hours. Those winds
start to mix down shortly after daybreak, with 20-25 kt sfc wind
gusts likely Sunday afternoon.

Next question is the timing of precip as a cold front makes slow
progress into the Ohio Valley. Will bring at least PROB30 or VCSH
into HNB in the afternoon, with prevailing SHRA and MVFR conditions
in the evening. SDF and BWG won`t see precip until after 00Z, and
not expecting significant cig/vis restrictions as drier air will
take some time to overcome. Will keep LEX dry and VFR through 06Z.

&&

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

$$

Update...RJS
Short Term...KDW
Long Term...AMS
Aviation...RAS



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