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315
FXUS63 KLMK 260506
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
106 AM EDT Wed Jul 26 2017

...Updated Aviation Discussion...

.Short Term (Now through Wednesday Night)...
Issued at 300 PM EDT Tue Jul 25 2017

Combination of satellite imagery and observations reveal a stalled
out east-west frontal boundary centered just south of the KY/TN
border.  Some convection has developed along and south of the
boundary from the MO bootheel eastward toward the land between the
lakes region.  KY mesonet observations showed temperatures were in
the lower to middle 80s across the Bluegrass region and down into
the I-65 corridor of central Kentucky.  Temperatures were generally
in the mid-upper 80s along and west of I-65.  Drier air (noted by
lower 60 dewpoints) was most concentrated across northeastern KY,
with a gradient of dewpoint noted across the central portion of the
state.  Dewpoints were generally above 70 degrees south and west of
a line from near Albany to Leitchfield.   In the near term, mostly
sunny skies are expected to continue across the region with highs
occurring within the next hour or so.  Some isolated-scattered
convection will be possible mainly across our SW sections (mainly SW
of the Natcher Parkway) through early this evening.  Temperatures
will fall into the 70s this evening.

For tonight, skies are expected to clear back out.  A strong
gradient of low temperatures are expected.  Lows will drop into the
upper 50s to around 60 in the northern Bluegrass region.  However,
by the time one reaches the I-65 corridor and points west, readings
will only fall into the 68-71 degree range.

As we move into Wednesday and Wednesday night, the quasi-stationary
boundary to the south will lift back northward.  So dewpoints will
start to rise again across the region.  Although, it will not be
that big of a change across southern KY, but areas toward the
southwestern Bluegrass region will see a return of the humidity.
Precipitable water values will increase as well, but remain below
seasonal normals.  Lapse rates will steepen in the afternoon, but
the overall profiles will remain rather meager.  Winds aloft will
remain weak, but some isolated convection may develop during the
heat of the afternoon and into the evening hours.  We believe the
best chances for convection will be west of I-65 and south of the WK
Parkway region.  Highs on Wednesday will warm into the 83-88 degree
range across our northeastern sections with highs in the 85-90
degree range along and west of I-65.

By Wednesday night, a cold front will approach the region from the
northwest.  Convection along this front may work into the northwest
portions of the forecast area late in the period.  Thus, will
maintain chance PoPs across the northwest regions.  Lows will be
mild with overnight lows mainly in the lower 70s.

.Long Term (Thursday through Tuesday)...
Issued at 316 PM EDT Tue Jul 25 2017

As we head into the extended forecast period, the upper level
pattern is forecast to revert back to a western CONUS ridge, and
eastern CONUS trough pattern.  This will lead to an unsettled
weather pattern initially at the beginning of the extended period
(Thursday into Friday), followed by drier/cooler and less humid
conditions as we head into the upcoming weekend.

On Thursday, we`ll see a significant short wave trough move through
the region on Thursday and into Thursday night.  Associated surface
cold front will accompany the wave as it moves through.  As this
occurs, a widespread band of convection will precede the front.
Precipitable water values will increase ahead of the front as deep
moisture pools out ahead.  Stronger core of mid-level winds will
approach as the shortwave pushes through the Great Lakes region. The
strongest jet core will remain to our north and northeast, but the
combination of moisture, wind shear, and instability will result in
a period of strong to possibly severe storms Thursday afternoon and
evening with the main weather hazards being torrential rainfall,
gusty winds, and localized flooding issues (especially if storms
train repeatedly over the same areas).  Highs Thursday will warm
into the mid-upper 80s with lows dropping back into the upper 60s to
the lower 70s.   Showers and storms will likely linger across
southern KY during the day on Friday with drier conditions holding
off until the evening hours.  Highs Friday will be a bit cooler with
upper 70s in the north to the low 80s in the south.  Cooler and much
less humid air will arrive by Friday night with lows dropping into
the upper 50s in the north with lower 60s in the south.

Canadian high pressure will continue to build into the region on
Saturday resulting in a rather stunning weather weekend.  Plenty of
sunshine is expected on Saturday and Sunday with highs in the upper
70s to the very low 80s across southern Indiana and the northern
Bluegrass region.  Highs in the lower 80s are expected across
southern KY (south of the BG/WK Parkways). With dewpoints in the
middle to upper 50s, humidity levels will be much more comfortable.

As we move into next week, the upper level pattern looks to remain
in a ridge west, trough east type pattern.  The ridge will attempt
to build back to the east somewhat.  So temperatures and humidity
are likely to rebound a bit as we head into next Monday and Tuesday.
With the increase in humidity, a threat of mainly diurnally driven
convection will return.  Overall, coverage looks to remain rather
limited, thus will continue a mainly dry forecast at this point for
early next week.  High temperatures look to rebound back into the
mid-upper 80s with overnight lows in the upper 60s to the lower 70s
which is near normal for late July.

&&

.Aviation...(06Z TAF Issuance)
Issued at 104 AM EDT Wed Jul 26 2017

Plan on VFR conditions through the period. High pressure over the
eastern Great Lakes will slowly work east during the day.
East/northeast winds will become light and variable for much of the
period, and expect mostly sunny skies with just a few diurnal
afternoon cumulus and perhaps some cirrus overhead.

&&

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

$$

Short Term.....MJ
Long Term......MJ
Aviation...ZT