Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 281721
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
121 PM 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
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 (18Z TAF Update)...
Issued at 120 PM EDT Mon Jul 28 2014
Mainly VFR conditions are expected through the valid TAF period.
MVFR strato-cu from this morning has recently lifted to borderline
VFR thresholds and should remain there for the rest of the
afternoon. Winds will be out of the NNW around 10 knots, with some
gusts into the teens possible.
For tonight, expect skies to go mainly clear to partly cloudy at
KSDF/KBWG, with KLEX having the best chance of retaining a ceiling.
This ceiling may dip to around FL025, but will only leave SCT for
now. Otherwise, VFR conditions will continue through the period,
with NNW winds at 5-10 knots.