Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 151747

Area Forecast Discussion
National Weather Service Louisville KY
1247 PM EST Sun Jan 15 2017

...Updated Aviation Discussion...

.Short Term (Now through Monday)...
Issued at 255 AM EST Sun Jan 15 2017

Another largely precip-free night across the Ohio Valley as we sit
between two areas of isentropic lift, but low clouds and fog are not
giving up. Visibilities are mostly better than last night, but a few
pockets of thicker fog persist mainly on ridgetops.

Next disturbance in zonal flow aloft will push through this
afternoon, generating just enough lift to support areas of light
rain, with the main focus paralleling the I-64 corridor. By tonight,
ridging over the Deep South amplifies just enough ahead of shortwave
energy lifting into Texas, that a surface warm front will develop
and lift north of the Ohio River by early Monday. Precip chances
will shift northward accordingly, with most of the area free of POPs
on Monday morning. Will see rain chances return from the west Monday
afternoon as the low closes off and lifts into eastern Kansas, and
SW flow deepens ahead of it.

After 24 hrs of little or no diurnal temp change, unseasonably warm
air will come in Monday with the warm front. Max temps on Monday
afternoon will push 60 near the Ohio River, and punch well into the
60s across south-central Kentucky.

.Long Term (Monday Night through Saturday)...
Issued at 255 AM EST Sun Jan 15 2017

Main player in the longwave pattern for most of the upcoming week
will be upper ridging over the southeast CONUS, and that will keep
the Ohio Valley unseasonably warm through the period, with temps
running at least 10 degrees above normal, with departures near 25
degrees at times. Fairly persistent trofiness over the Mexican
desert will eject disturbances NE to bring us intermittent precip
chances, and the main challenge will be the timing of these systems.

Will begin the period with a stacked low opening up as it lifts NE
from near Kansas City on Monday evening, into the Great Lakes by
Tuesday afternoon. Just enough phasing expected with the northern
stream the we expect this low to drive a front through the Ohio
Valley Tuesday/Tuesday night. Will go with categorical POPs and
possible thunder given just enough elevated instability and a 45 kt
low-level jet feeding into the area. Precip will be slow to exit on
Tue night as a secondary trof axis could develop another ripple that
would ride along the slow-moving front.

Wednesday is our best shot at a dry day, with continued unseasonable
warmth as there is still no Arctic air mass to tap behind the front.
Models diverge Thursday through the weekend as the upper pattern
turns fairly messy. Not only is model agreement lacking, there isn`t
much continuity between successive runs of the same model. Will
carry 20-30 POPs for much of the period given the uncertainty, but
the one high-confidence part of the forecast is that temps will
remain unseasonably mild.


.Aviation...(18Z TAF Issuance)
Updated at 1235 PM EST Sun Jan 15 2017

IFR conditions still look to prevail through much of the TAF period
with LIFR likely tonight and VLIFR possible.  VLIFR chances are not
high enough to include in the TAFs at the moment though.  Conditions
will improve to IFR by mid to late morning tomorrow and possibly
MVFR by mid to late afternoon.

Rain showers are a good bet at the TAF sites this afternoon but
should diminish this evening.  Drizzle is possible overnight along
with light br. Easterly winds today and tonight will become SE for




Short Term........RAS
Long Term.........RAS
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