Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 281102
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
702 AM EDT Mon Jul 28 2014

...Updated Aviation Discussion...

.SHORT TERM (Now through Tuesday)...
Issued at 335 AM EDT Mon Jul 28 2014

Much quieter this morning and this benign weather is expected to
prevail in the short-term period. Persistence in the models calls
for a chance for light rain showers tomorrow, primarily in the
Bluegrass region and southeastern IN, although a stray shower or
some sprinkles could fall elsewhere, with the focus remaining on
locations east of the I-65 corridor. The Ohio Valley will be on the
backside of the trough tomorrow, leaving the region under NW flow at
the surface and aloft. The upper jet will be digging in and a vort
max is expected to rotate through southern IN and central KY,
providing a lifting source. Additionally, steep low-level lapse
rates and PWATs of around an inch will provide scattered to broken
clouds across much of the forecast area. While the PWATs don`t seem
terribly impressive, what is to note is that the bulk of the
moisture is confined to the lower levels. Once diurnal heating is
lost tonight, expect any showers that had developed to wane, along
with some of the cloud cover. By Tuesday, this forecast area will
have lost some of that support and moisture, so currently
anticipating that precip should remain north of the area,
particularly as surface high pressure attempts to take control from
the west.

Unseasonably cool temperatures and much lower dewpoints are already
advecting in behind the fropa. The airmass change of Canadian
origin, along with the cloud cover, will keep highs today from
reaching the 80 degree mark in southern IN and northern KY. Southern
KY will reach right around 80 degrees. Tonight, lows will be in the
mid 50s with assistance from radiational cooling, if the clouds can
clear out enough. Tuesday will be cooler across the south and about
the same for the north, ranging from the mid to upper 70s.

So how do these forecast temperatures compare to records? Well, FFT
looks to be the only climate site today to have the potential to
come close to their min high temperature of 74 degrees, set last
year. For tonight, SDF and possibly LEX could come close to their
record lows of 58 and 54 degrees, respectively. Tuesday could be a
bit more difficult, with FFT being the only one in range of 74
degrees set in 1994 and previous years.

.LONG TERM (Tuesday Night through Sunday)...
Issued at 305 AM EDT Mon Jul 28 2014

At the beginning of the long term period, a highly amplified pattern
will exist with ridging in the western CONUS and troughing in the
east.  We`ll be under the influence of the trough providing for
unseasonably cool temps.  Will keep a dry, mostly sunny forecast for
mid week since most models are still projecting this but it should
be noted that the latest NAM12 run is a little more aggressive
dropping shortwave energy south in the trough and giving light
precip chances over our southern Indiana/northern Kentucky counties
both Wed and Thurs.  Wed morning will be the coolest morning in the
long term period with lows in the 50s over most locations and low
60s in the Louisville Metro.  Valley locations over east central KY
will see temps bottom out in the low 50s even!

For Friday through the weekend, long range models have come into
agreement that the upper trough will narrow and sharpen on its
southern most extent but will not become a closed low over the
Midwest.  On and off scattered rain chances still look on track
Fri-Sun as multiple vort lobes dive south into the Ohio Valley with
the best activity most likely during the afternoon/evening hours
each day.  This activity will start to decrease on Monday as the
upper trough moves east of our area.

Temperatures throughout the long term period look to be pretty
steady state with highs in the upper 70s to mid 80s and lows in the
upper 50s and lower 60s.  Clouds and precip chances may make temp
forecasting a bit more challenging for the weekend.

&&

.AVIATION (12Z TAF Update)...
Issued at 645 AM EDT Mon Jul 28 2014

A stratus deck as already begun to build into central IN this
morning, looking to overtake the Bluegrass region within the next
couple of hours. As an upper-level disturbance rotates through the
Ohio Valley, a chance exists for light showers to develop across
portions of the Bluegrass region with the potential for sprinkles at
SDF and possibly BWG. Conditionally, much of the day should be VFR
dominated but could teeter into MVFR - either earlier in the day
before the incoming cloud bases have had a chance to rise and/or
with any potential shower activity. BWG will have the best chance of
staying in the VFR category throughout the day.

NW winds will be on the increase after diurnal heating has begun and
with the incoming disturbance. These winds could be gusty at times
with winds upstream already gusting to around 15 to 20 knots this
morning. Once the sun sets this evening, winds aren`t expected to go
calm but will lighten, remaining primarily out of the NW.

&&

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

$$

Short Term........lg
Long Term.........AMS
Aviation..........lg




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