Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 151133
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
633 AM EST Wed Nov 15 2017

.UPDATE...
Issued at 633 AM EST WED NOV 15 2017

The GOES-16 Nighttime Microphysics product continues to show the
river valley fog and high clouds streaming across eastern
Kentucky. No major changes needed this update given the grids are
in good shape so far this morning. Did a quick update to add some
of the latest obs.

&&

.SHORT TERM...(Today through Thursday)
Issued at 318 AM EST WED NOV 15 2017

The morning surface analysis shows an area of high pressure across
the northeast states, and a surface low of interest for the
period now across southern Minnesota, with attendant cold front
stretching back into the Central Plains. This morning will be a
cool start particularly in the valleys under mostly clear skies
and weak upper level ridging. This is also leading to some mainly
deeper valley and river valley patchy fog this morning. This fog
will lift out by around 13Z this morning. The latest GOES-16
Nighttime Microphysics product shows the fog well and some thin
high clouds building east into eastern Kentucky. Underneath these
high clouds across western Kentucky we can see a mid deck of
clouds working eastward. This will slowly work east into eastern
Kentucky through the late morning into the early afternoon hours.

We then turn to the upper level shortwave trough axis across the
Northern Plains this morning and the aforementioned surface low
pressure and cold front. This will shift east into the Great Lakes
and Northern Ohio Valley regions this afternoon and evening. Ahead
of the front we expect rain showers to breakout and progress
eastward across the Bluegrass state and into eastern Kentucky this
afternoon and evening. Given the guidance remains in reasonable
agreement did lean toward a short term blend of POPs. POPs will
generally peak this afternoon and evening from northwest to
southeast. Overall kept the better POPs across the Bluegrass due
to the better height falls and overall stronger jet support aloft.
The front will be slower to move across the region and therefore
did keep some relatively higher wind gusts particularly in the
Lake Cumberland and Bluegrass tonight. Otherwise tapper the
showers off through the late evening and overnight hours. Do
think given the west to northwest flow on the back side of the
front we could see some lingering showers in the southeast.

Then by Thursday, an area of surface high pressure will work
southeast from the Upper Midwest. The orientation of this does not
support the prolonged stratus period we saw recently. Therefore,
think we will see clearing on Thursday. However, given the
northwest flow think afternoon high temperatures will struggle,
with upper 40s to lower 50s being the story. This will be around
10 or so degrees below normal for this time of year.

.LONG TERM...(Thursday night through Tuesday)
Issued at 406 AM EST WED NOV 15 2017

Surface high pressure passing through the Ohio Valley at the start
of the period will bring mainly clear skies. Once the high passes
to our east, winds will turn back toward the south and
temperatures will moderate on Friday.

The only precip to contend with during the long term period will
come from a cold front passing through during the weekend. Warm
air advection will be joined by moisture advection as the front
approaches. Models are still not in sync for timing, but are at
least showing less variability (both between models and run to
run) than in recent days. A compromise solution places cold fropa
late Saturday. While some rain can`t be ruled out in the warm air
advection pattern ahead of the front in our northern counties on
Friday night, most of the rain should come with the front, with
the highest POP shifting southeast across the region Saturday
afternoon and evening.

The parent low sending the front through our area will become
very deep as it crosses the Midwest and Great Lakes, and its wind
flow will be effective at sending a very chilly and dry air mass
southward for Sunday. It will result in dry weather to start the
week, with temperatures well below normal. Daily sunshine will
help readings to moderate with time, also aided by a return of
south to southwest winds by Tuesday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
ISSUED AT 627 AM EST WED NOV 15 2017

We continue to see VFR conditions for the TAF sites this morning
and this will hold through the the afternoon and evening time
frame. There is some mainly river valley fog this morning, but
this should remain out of the TAF sites. We are going to see a
surface low and cold front progress east today and rain showers
will spread east ahead of this boundary. This will also usher in
some lower CIGs by late afternoon and evening in the MVFR range.
These MVFR CIGs will stick around for the rest of the period. The
winds will remain light to start the TAF period out of the
southeast, but we could see some gusts of around 15 knots as winds
veer to the southwest by the afternoon ahead of the cold front.

&&

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

$$

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



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