Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 210018
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
718 PM EST Tue Feb 20 2018

.UPDATE...
Issued at 718 PM EST TUE FEB 20 2018

We have seen a decrease in the winds early this evening and
therefore the Lake Wind Advisory was cancelled early. The latest
satellite trends have indicated some mid to high level clouds
will continue to stream across eastern Kentucky under general
south to southwest flow. Updated the forecast to account for the
clouds and winds, but otherwise the forecast was in good shape
this evening.

&&

.SHORT TERM...(This evening through Wednesday night)
Issued at 303 PM EST TUE FEB 20 2018

Impressive height anomalies over eastern Kentucky has led to
record breaking high temperatures today. We have in fact set the
all time record high for Jackson for February, with London likely
to fall just a few degrees short. Gusty southwest winds continue
to crank across the area with wind gusts up to 35 mph still likely
occurring in our northern and western zones. Plan to let the lake
wind advisory continue through the evening hours. With clear
skies in place, we should see temperatures in the eastern valleys
drop quickly as they decouple. Skies could stay mostly clear
through a good chunk of the night, allowing lows in the eastern
valleys to dip well into the 50s. Our western areas could stay
fairly mixed tonight given the stronger gradient to the west. A
cold front will work east across the Ohio river valley tonight
into Wednesday and Wednesday night. Showers will be ongoing along
the front throughout the period. As the front pushes east and
southeast, the forcing along the front will be weak through
Wednesday. However, enough convergence should be present to allow
for good rain chances for most of the area. A shortwave riding
northeast across the region may provide an uptick along the front
late Wednesday night. While there will be instability developing
Wednesday afternoon, model guidance is suggesting the better
thunder chances may be Wednesday night with the shortwave
providing some added lift. Models are likely overplaying dewpoints
on Wednesday, accounting for the surface instability. Rain
amounts through Wednesday night should remain under an inch and
fairly spread out. Thus, no plans for any flood watches for our
area.

.LONG TERM...(Thursday through Tuesday)
Issued at 501 PM EST TUE FEB 20 2018

The first several days of the period still look like a very wet
time due to frontal boundary oscillating over the region. It will
be in the process of slowly passing through as a cold front on
Thursday, with rain expected. The front is expected to stall to
our south with a brief break in precip likely on Thursday night.
However, it will turn around as a warm front and should be heading
back north through the area by Friday morning with at least a
potential for more rain. A relative lull in precip is expected
from late Friday into Friday night while we reside in the warm
sector in between frontal waves. Friday night into Saturday
another wave is expected to move along the front with an
enhancement of precip. Current indications are that the heaviest
will be just to our north. A more substantial low pressure system
will develop on the front and track northeast through the Midwest
Saturday night. This will bring still more rain, but will finally
give the front a definitive push through the area as a cold front
and allow high pressure to build in with drier air to start the
new week.

A couple of other issues to be considered during the period
include the potential for thunder and excessive rain. In terms of
thunder, some very weak deep instability was present in models at
times, but looked very marginal for thunderstorm support. Even
though the most unstable levels supported negative lifted
indices for parcels rising to 500 mb, the 500 mb temperatures
were warmer than -20C, with weak lapse rates above, making it
questionable if convective parcels would reach the magic -20C.

In terms of precip amounts, we may eventually have some problems.
The heaviest precip for the JKL forecast area is likely to be
Friday night into the weekend. It is still unclear where the axis
of heaviest rain will be, and model changes can still be expected
before the event arrives. Depending on the model depictions in the
next couple of days, the situation may need to be addressed with
products beyond the daily routine.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 642 PM EST TUE FEB 20 2018

The gusty winds we have seen this afternoon have continue to
subside this hour. We are seeing some CU this hour, but these
will dissipate through the evening, with loss of sunlight. The
TAFs will remain VFR through the night, before lower CIGs advect
southeast Wednesday morning into Wednesday afternoon. Right now
will keep this MVFR for most sites, but SYM will probably see IFR
toward the end of the period. Also a cold front dropping
southeast will bring rain showers from northwest to southeast
across eastern Kentucky Wednesday morning into wednesday
afternoon. This could also lead to brief lowering of CIGs and VIS
in heavier rain showers or thunderstorms. The winds will also gust
15 to 20 knots ahead of the cold front Wednesday morning and
early afternoon.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...DJ
SHORT TERM...KAS
LONG TERM...HAL
AVIATION...DJ



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