Area Forecast Discussion
Issued by NWS Louisville, KY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS63 KLMK 250523

Area Forecast Discussion
National Weather Service Louisville KY
123 AM EDT Tue Apr 25 2017

...Updated Aviation Discussion...

.Forecast Update...
Issued at 930 PM EDT Mon Apr 24 2017

Cloud cover has been slow to give up across central Kentucky and
southern Indiana this evening, but we have seen slight erosion from
the west, as well as some holes opening up. While we don`t expect
wholesale clearing given the moisture trapped under the inversion
near 800mb, light and variable winds combined with the weekend rains
will allow the formation of at least patchy fog well after midnight,
mainly across south central Kentucky. Current forecast has a good
handle on this, but some tweaks have been made to the grids to
better capture the areal extent and timing.


.Short Term (Now through Tuesday Night)...
Issued at 330 PM EDT Mon Apr 24 2017

Some ridging continues to build into the region this afternoon.
Model soundings still show an inversion around 5-7Kft AGL with some
moisture trapped below it.  This has resulted in a flat Cu field
developing.  Where clouds have been less today, temperatures has
warmed into the lower-middle 70s.  Down south, cloudiness delayed
insolation a bit and temperatures were running in the mid-upper 60s.
Expect high temps for the day to occur within the next hour or two
and then temps should drop off into the 60s this evening.

Quiet weather is expected overnight with clear to partly cloudy
skies expected.  Some patchy fog will be possible, mainly south of
the WK/BG Parkways.  Lows tonight will drop into the lower 50s,
though some of colder spots could drop into the upper 40s.

Quiet, dry, and warmer weather is expected for Tuesday with highs
warming into the 75 to 80 degree range.  Lows Tuesday night will
cool into the mid 50s in the east with upper 50s in the west.

.Long Term (Wednesday through Monday)...
Issued at 333 PM EDT Tue Apr 24 2017

As we move into the extended period, the weather looks to remain
quiet for Wednesday and into Wednesday evening as the area will
remain under upper level ridging.  Wednesday should be quite warm
with highs in the lower 80s.  Lows Wednesday night look to cool into
the 60s.

An upper trough axis will move through the Plains late Wednesday and
into the Ohio Valley during the day on Thursday.  A cold front will
approach the region early Thursday morning.  The GFS/GEM/Euro have
converged a bit on their timing of bringing the front through the
area.  A band of showers and storms will likely accompany the front
as it pushes through.  While it will be passing through during the
diurnal minimum, some upscale development will be possible Thursday
afternoon/evening in our east.  Some of those storms may be strong
to severe depending on instability.  With anticipated clouds and
precip, temperatures will likely be a bit cooler on Thursday with
highs in the upper 60s to the lower 70s.  Overnight lows look to
drop into the lower 50s.

Several perturbations are forecast to pass through the region
Thursday night through Friday night.  Overall precip coverage
confidence remains low, but the models are generous on dropping
precipitation across the region.  For this reason, have kept chance
PoPs going through this time period.  Highs Friday look to warm into
the upper 70s with lows in the 60s.

By Saturday, a deepening of the 500hPa height pattern will likely
occur out over the western US.  We`ll probably see another strong
low pressure system develop across the Plains and then head toward
the Great Lakes.  As this occurs, we`ll likely see a warm front
surge through the region bringing a round of showers and storms to
the area early Saturday.  Depending on how fast the warm sector
clears out, highs Saturday could be quite warm with readings warming
well into the 80s.  Saturday night would be a mild one as well with
lows in the mid-upper 60s.

Sharp upper trough is then forecast to push eastward and will drag a
cold front across the region on sometime on Sunday.  Depending on
the timing of the front, we could see a round of strong to severe
thunderstorms as this boundary pushes through.  Strong signaling in
the model data shows decent instability and shear in the region to
support strong/severe convection.  Cooler and drier weather look to
drop into the region for Monday with highs only warming up into the
upper 60s to around 70.


.Aviation...(06Z TAF Issuance)
Issued at 115 AM EDT Tue Apr 25 2017

Low clouds have cleared at all TAF sites early this morning.  Clear
skies, moist low levels, and light winds will result in a decent fog
setup this morning.  Think that BWG will see fog formation first and
go down to IFR/possibly lower during the pre-dawn hours.  SDF/LEX
should see some MVFR fog develop early this morning.  Fog at all TAF
sites will improve by 13-15Z.  Light SSE winds will continue through
the TAF period as well.




Short Term.....MJ
Long Term......MJ
Aviation...AMS is the U.S. government's official web portal to all federal, state and local government web resources and services.