Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 150521
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1221 AM EST Sun Jan 15 2017

...Updated Aviation Discussion...

...Forecast Update...
Issued at 830 PM EST Sat Jan 14 2017

Forecast soundings (as well as low-cloud observations!) continue to
show some trapped low-level moisture blanketing the region. Would
not be surprised to see some patches where these clouds intersect
the surface, so patchy fog wording still looks good. Will have to
monitor through the night for any more widespread fog. Did a zone
update mainly to remove the afternoon wording.

.Short Term (Now through Sunday Night)...
Issued at 300 PM EST Sat Jan 14 2017

Widespread rain is pushing into our eastern CWA ahead of an upper
disturbance passing through the zonal flow. The bulk of the
precipitation should be east of the area by 00z, and this is when
most of the measurable precipitation chances should end. That being
said, a look at time heights/soundings show a lot of trapped low
level moisture below 850 mb and expect that lingering drizzle or
light rain is possible until the pre-dawn hours when a brief lapse
in the low level moisture occurs. This may be fortunate across our
northern tier of counties where temps will be down around or just
below freezing toward dawn. Will still mention a slight chance of
freezing drizzle on either side of sunrise up there, but overall the
threat should be pretty minimal for any accumulations. Can`t rule
out a glaze on any elevated surface. Outside of temps around
freezing across our far north, most other spots should bottom out in
the mid to upper 30s. Low 40s are expected along the Tennessee
border. Patchy fog is expected overnight, and will likely leave
mention through at least mid day on Sunday.

Another low to mid level moisture surge works in from the west from
late morning through the day on Sunday so will have increasing
chances of measurable light rain, with most focus across the
northern two thirds of the CWA. Temps won`t go too far on Sunday and
will stay mostly confined to the low 40s where best rain chances
exist. Along the Tennessee border, look for mid to upper 40s.

Brief upper ridging takes hold over our region on Sunday night as
shortwave energy ejects out of the Rio Grande and into the southern
Plains. This will help a warm frontal boundary settle more across
our northern CWA where a slight chance mention of a light rain
shower across our north will continue. Most lows will be in the
upper 30s and low 40s.

.Long Term (Monday through Saturday)...
Issued at 300 PM EST Sat Jan 14 2017

Monday - Wednesday...

A shortwave and it`s associated surface low ejects out of the
southern Plains and into the Great Lakes by Tuesday morning.
Meanwhile, SW flow aloft will dominate over the Ohio River Valley
between this feature and SE CONUS ridging. A secondary shortwave
will dive out of the northern Plains and through our region later
Tuesday into Tuesday night. This will help to drag a stalled
frontal boundary through Tuesday night into Wednesday morning.

Mainly dry weather Monday morning will give way to scattered rain
chances as an isentropic lift component gets going, especially
across our west. Rain chances then increase to the likely range
Monday night into Tuesday as deeper moisture pools and better
forcing arrive ahead of the central CONUS troughing mentioned above.
Will also note a slight chance of thunder on Tuesday. Will keep
lingering chances into Tuesday night and Wednesday, but confidence
lowers during this time as models disagree on how quickly secondary
trough axis swings through.

Highs will be in the mid to upper 50s north, with low to mid 60s
south on Monday. Tuesday brings the low to mid 60s once again,
before temps fall off just a bit by Wednesday. Look for low to mid
50s. Overall, not much of an airmass change behind the front.

Wednesday Night - Saturday...

Very low confidence forecast with respect to rain chances for the
late week into the weekend time frame. Models continue to try and
resolve a very messy upper air pattern. That being said, there is
pretty high confidence in this period continuing the unseasonably
mild theme. After highs around 60 on Thursday, temps should be in
the low to mid 60s each day. After lows in the 30s Wednesday night,
lows will be in the 40s Thursday and Friday nights.

&&

.Aviation (00Z TAF Update)...
Updated at 1220 AM EST Sun Jan 15 2017

Same story, different day.  With little change in the airmass in
place over Kentucky, IFR to LIFR ceilings will again prevail this
forecast period.  Visibilities will again fluctuate greatly, with
some drizzle and light rain at times accompanying fog.

No change in the synoptic situation causing the low stratus will
occur until Monday, when the large surface high covering the
northeast 1/4 of the U.S. moves off shore.

&&

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

$$

Update.........RJS
Short Term.....BJS
Long Term......BJS
Aviation.......JBS



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