Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 231050

National Weather Service Jackson KY
650 AM EDT Mon Oct 23 2017

Issued at 650 AM EDT MON OCT 23 2017

Updated the grids to input the latest observations. Current precip
is on track as measurable rainfall is now being reported along the
I-75 corridor and quickly inching north and east. Thus, the
forecast is on track.


.SHORT TERM...(Today through Tuesday)

Issued at 359 AM EDT MON OCT 23 2017

Current conditions across eastern Kentucky feature southeast winds
continuing across the area with some gusts to 15 knots still
occurring. This along with some decent dew point depressions due
to down slope is still keeping rainfall out of the area even this
hour. Current satellite this hour indicates the surface low
beginning to develop into the TN Valley from the southwest as the
front out west continues to push east this morning. Based on
observations and satellite, measurable rainfall will begin to
enter the southern I-75 corridor just before dawn. Significant
moistening of the lower levels will then begin in earnest. Once
this begins, a swath of moisture will quickly push through the
Appalachian region through the day today. So went with 100 pops
through the day as the front and associated low pushes through.
Short term models support that once the surface low winds up and
shifts northeast, the bulk of the rainfall will come to an end
just after 00z tonight. Dealing with some 1.25 to 1.50
precipitable water values with this event, nearly 1.50 inch
rainfall totals are possible. The one saving grace for this event
is coming into it dry and with the lack of cold earlier this fall,
mostly all the vegetation is on the trees. But also, this event
seems just enough to quell the drought threat, inhibiting fire
weather issues.

After passage, some of the coldest air of the season will dip down
through the area behind a secondary trough. Will keep a chance of
showers lingering into the morning on Tuesday before this precip
lifts northeast by Tuesday afternoon. Temperatures for Tuesday
afternoon will remain in the 50s as the coldest portion of the
airmass will arrive mid-week behind this secondary trough.

.LONG TERM...(Tuesday night through Sunday)
Issued at 434 AM EDT MON OCT 23 2017

The period will be dominated by various iterations of a
central/eastern CONUS large scale upper trough. As the period
starts, a surface cold front will be pushing east of the
Appalachians, and drier air should be in place locally in the wake
of frontal precip. The axis of the upper trough will be
approaching from the west with another increase in moisture, but
models show light precip associated with it remaining to our north
as the trough passes late Tuesday night into Wednesday. A very
chilly air mass will then be over our area on Wednesday and
Wednesday night, with a potential for frost. Geopotential heights
then rise as the initial axis departs and before the next lobe
descends into the mean trough. A large low pressure system is
expected to move over the Great Lakes late in the week with this
next lobe. This combo results in a period of warm air advection
before its cold front arrives. Although models agree on the large
scale pattern late in the week, they don`t agree on the details of
timing of surface features, including the front. That being the
case, have used a very generalized forecast based on a model
blend, keeping the POP low in the 20-30% range in any given period
Friday through Sunday, with precip in the form of rain.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)

Rainfall is now beginning to overspread the area this morning.
While most cigs are now around 8 to 10 KFT, they will begin to
drop to MVFR and IFR by midday. Expect visibility issues to be
tied to heavier showers moving through, otherwise, MVFR visibility
is expected. Winds will generally be out of the south before
shifting to the southwest later today at around 10 knots at times.
Expect the IFR cigs to last through the rest of the TAF period.




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