Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 230859

National Weather Service Jackson KY
359 AM EST Tue Jan 23 2018

.SHORT TERM...(Today through Wednesday)
Issued at 339 AM EST TUE JAN 23 2018

The morning surface analysis shows a cold front pushing across
the region and the low pressure associated with the front pushing
across the Lower Great Lakes region. Meanwhile, an upper level low
pushes on the heels of the surface low as they continue to become
vertically stacked. The Nighttime Microphysics RGB does shows
broken sky cover across far eastern Kentucky with a narrow back of
clearing moving into portions of the Bluegrass and Lake
Cumberland regions. Then behind this another area of stratus will
push east this morning and bring mostly cloudy skies back into the
area through the morning. There is some shower activity early
this morning that will push north and east. Do bring back a slight
chance of showers this afternoon as a surface trough axis and
upper level trough swing toward the area. Overall did keep wind
gusts going in the 25 to 30 mph range at times today as the
pressure gradient remains a factor. Given the cloud cover and
overall pattern the temperatures will drop or remain steady state
through this afternoon.

This evening into tonight a short wave rides around the broad
nearby upper level low. This will also swing a surface trough
across the area. These will combine leading to a few rain and/or
snow showers this evening into tonight. Overall the model sounding
show the moisture just barely getting into the dendritic growth
zone and therefore think the activity will remain light. Did
however add a few tenths of inch to the grids to better match up
to WPC, but again think this will be limited to elevated or
perhaps grassy surfaces. Temperatures dip below freezing for the
first time in several days with lows in the upper 20s.

Wednesday opted to keep sprinkles and/or flurries going through
the afternoon. This as another upper level shortwave drops
southeast and the axis splits eastern Kentucky by 18Z to 20Z.
While the moisture is quite shallow, the model soundings hint at
enough ice to keep flurries going for much of the area. It will
likely remain cloudy through the day and temperatures will remain
in the 30s for most.

The synoptic models have come into better alignment on the
precipitation chances tonight. The short term guidance agrees that
light precipitation moving across north central Kentucky early
this morning will just miss the region and seem to have a better
indication for the potential showers this afternoon. In terms of
clouds in the near term went toward the RUC which seemed to have
the better handle on the narrow band of clearing. The remainder of
the period leaned toward the blended model guidance with edits as

.LONG TERM...(Wednesday night through Monday)
Issued at 359 AM EST TUE JAN 23 2018

A progressive pattern will be in place during the period. An
upper level trough over the eastern CONUS will be moving eastward
and on the way out at the start of the period, with ridging ready
to move in from the west late in the work week. This too will be
transitory, as another trough ripples eastward across the CONUS,
reaching us over the weekend.

The result for our weather will be dry conditions and moderating
temperatures early on. Both the GFS and ECMWF then show a system
moving in over the weekend, but they do not agree on the timing or
evolution of the system. The GFS shows less amplitude in the upper
wave and is faster. Meanwhile, the slower ECMWF has a deeper upper
level trough and associated surface low development to our south
as the front passes. In light of the differences, will still be
holding POPs no higher than likely category. The overlap of precip
in both models is most prominent on Saturday night, which is when
the highest POP will be placed. There will also be high chance
POPs on either side of this to account for either the slower or
faster scenario. If the ECMWF were to pan out, precip in the
trailing comma head region of the storm system could change to
light snow on Sunday night before it ends. Considering the model
differences which remain, there is not good confidence in the
forecast, and changes can be expected.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)

WSR-88D radar shows a line of showers and thunderstorms continues
to progress in far eastern Kentucky this hour. The more robust
storms have produced 27 to 30 knot gusts and small hail. Most of
the TAF sites are now west of the line except for SJS and
therefore will keep the mention in that site for another hour.
Ceilings have quickly improved tonight to VFR in the wake of this
line of thunderstorms and many locations may actually see clearing
through the early morning hours. An upper level low and lower
stratus deck is still set to progress east and the stratus deck
will work back across eastern Kentucky toward dawn. This will lead
to the potential for MVFR conditions for the remainder of the
period and we could also see some rain and/or snow showers work
across the area in association with this as well. The pressure
gradient winds outside of thunderstorms will be gusty with values
of 20 to 25 knots remaining the norm for much of the night into
early Tuesday.




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