Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 281028
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
628 AM EDT Tue Apr 28 2015

...Updated Aviation Discussion...

.SHORT TERM (Now through Wednesday)...
Issued at 246 AM EDT Tue Apr 28 2015

Dry generally northerly flow today at the surface and aloft will
provide us with quite a bit of sunshine and afternoon temperatures
5 to 10 degrees cooler than normal in the middle 60s.

Tonight into Wednesday an upper low to our south will weaken and
open up as it gets absorbed into a large scale trof over the eastern
United States.  Operational model runs have trended drier with this
feature in the LMK CWA, suppressing rainfall to our south.  However,
ensemble means and some individual model members still suggest some
light rain could make it as far north as southern Kentucky tonight
and the Lake Cumberland/Blue Grass regions on Wednesday. Could even
see a stray shower in northern KY and southern IN in association
with the larger upper trof.  So, will keep some PoPs in the forecast
but will reduce them slightly. Low temperatures tonight will be in
the 40s.  With a slightly drier solution for tomorrow, edged high
temperatures up a couple of notches into the middle 60s.

.LONG TERM (Wednesday Night through Monday)...
Issued at 255 AM EDT Tue Apr 28 2015

Main challenge will be the impact of an upper low diving out of
Hudson Bay on Thursday. Models are trending stronger and farther
westward with this impulse, with the latest NAM12 and ECMWF now
taking a closed H5 low center down through west-central Kentucky.
GFS tracks this system down through Ohio and West Virginia, but
still close enough to have an effect.

Will carry chance POPs on Thursday across most of the area, and that
may still be on the conservative side. Highest POPs still in the
east for now, but may need to shift that if the upper low trends
farther west. This will be more of the instability/showery type of
precip, as the boundary layer will be quite mixy. Mid-level temps
are progged to be quite cool with -6 to -8C at 700mb, so lapse rates
will be strong enough to support at least isolated thunder. Max temp
forecast favors the cooler NAM MOS.

Surface high pressure and rising heights will mean picture postcard
weather for Friday and Saturday. Temps will run just a bit on the
cool side of normal Friday, but right on climo values for Saturday.
Will turn a bit more unsettled late in the weekend with a warm front
lifting north across the Ohio Valley on Sunday, and then a cold
front approaching on Monday. Latest model runs are a bit slower and
not as bullish with the moisture return, so will keep Sunday dry and
carry just slight chance POPs for Monday.

&&

.AVIATION (12Z TAF Update)...
Updated at 628 AM EDT Tue Apr 28 2015

Low pressure moving by well to our south combined with high pressure
to our northwest will keep north to northeast breezes blowing during
this TAF period, mostly at speeds below 10 knots.  Clouds should be
inconsequential, consisting of some widely scattered afternoon cu
and cirrus streaming overhead, especially at BWG.

&&

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

$$

Short Term........13
Long Term.........RAS
Aviation..........13





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