Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 230900
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
400 AM EST Thu Nov 23 2017

.SHORT TERM...(Today through Friday)
Issued at 307 AM EST THU NOV 23 2017

High pressure will dominate the weather through Friday. At the
same time airmass will start to moderate over the region, allowing
for slightly warmer afternoon highs today and even warmer readings
on Friday. Overnight lows tonight will remain on the cold side
with light winds and clear skies allowing for good radiational
cooling. This will put lows in the valleys fairly close to the
readings we are seeing this morning. Ridges and more unsheltered
areas may see a slight increase in low temperatures tonight, but
still likely below freezing.

.LONG TERM...(Friday night through Wednesday)
Issued at 400 AM EST THU NOV 23 2017

While the models all begin the extended portion of the forecast in
good agreement aloft, they diverge early in the new work week
lowing confidence in any specific solution with time. The models
depict a gradual amplification of a trough centered over the Great
Lakes heading into the weekend. With this, a trough axis and
energy band will push across Kentucky by Saturday evening with
similar timing and strength. Heights will rebound mildly in the
wake of this trough heading into the new week, though additional
batches of weak energy will pass overhead Sunday and Monday. At
this point, the models` spread increases with the GFS and ECMWF
differing on a large trough moving on shore of the West Coast -
the GFS being quicker and shallower. Downstream, this keeps the
pattern out of sync over Kentucky through mid week with respect to
the amount of any ridging that forms over the state. With time,
the West Coast trough moves into the middle portion of the nation
though the GFS is much faster than the ECMWF as this key feature
approaches Tuesday night. The GFS`s version of this trough passes
through Kentucky early Wednesday while the ECMWF keeps its back
to the west through Thursday. With the differences later in the
period anticipated the need to make some adjustments for the
Wednesday time frame to account for a blend of these nearly
diametrically opposed solutions.

Sensible weather will feature a continuation of our period of
quiet and seasonable conditions as one slow moving area of high
pressure is replaced by another with little moisture available for
the fronts in between. The first of these boundaries looks to move
through early Saturday with just a very small potential for a
shower - but left out of the forecast for now. Following this,
high pressure keeps a lid on all activity well into the new work
week. The question arises from Tuesday night into Wednesday when
the GFS pushes a cold front into the state with a potential for
showers while the ECMWF keeps high pressure in control. Not
prepared to bite on any particular solution at this point have
allowed for increased PoPs to close out the extended forecast and
not clear the area too quickly, though still faster than the
blends. Temperatures will be seasonable through the period with a
slow moderating trend noted - at least through Tuesday.

Made just minor adjustments to the temperature grids each night
anticipating a small to moderate ridge to valley split. Also,
narrowed the range of slight chance to chance PoPs with the cold
front for later in the new week - per collaboration with neighbors
and with consideration of the WPC guidance.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
ISSUED AT 1225 AM EST THU NOV 23 2017

VFR conditions and light winds will prevail through the period.

&&

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

$$

SHORT TERM...KAS
LONG TERM...GREIF
AVIATION...KAS


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