Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 201225 AAA

National Weather Service Jackson KY
825 AM EDT Tue Mar 20 2018

Issued at 825 AM EDT TUE MAR 20 2018

The mid-level short wave continues to cruise eastward, with
a quickly diminishing precipitation shield across southern Ohio.
Meanwhile, some showers have developed along the remnant cold
front still aligned across far southeastern Kentucky. Have
adjusted the POPs through the day, which keep at least some
scattered activity along the boundary. Elsewhere, the lull looks
to be more pronounced through much of the day, as we will be in
short wave ridging, so kept lower in POPs a bit longer. Temperatures
have also cooled quite a bit in the northwest, with some mid 30s
noted. While a little recovery will take place today, adjusted
some of the high temperatures down to account for this cooler
trend. Updates have been sent.


.SHORT TERM...(Today through Wednesday)
Issued at 359 AM EDT TUE MAR 20 2018

The latest surface map features broad surface low pressure
situated from eastern Kentucky down to South Carolina. Aloft, a
short wave trough is moving nearly along the Ohio River, with a
secondary trough moving across the Plains. Widespread showers
have lifted north out of our area, with dry slotting working in
from the southwest, keeping showers limited in areal coverage.

Expect a general lull in the action through early this afternoon,
as the short wave trough continues to move off to our northeast
and east, leaving us in temporary short wave ridging. The next
wave will move in from the west. This wave will cutoff and help
to deepen surface low pressure that will be developing just off to
our east and southeast. Wrap around moisture will fill in across
the area late today and especially tonight into Wednesday. Winds
will become northwesterly, with the column gradually cooling off
enough to allow for snow. Will be leaving much unchanged from the
previous forecast, although, given the generally lighter
precipitation rates, have allowed for a bit more disparity
between the valley accumulations and ridgetop amounts in some
areas. Most of the valleys will range in the 1 to 2 inch range,
while ridges will be in the 2 to 3 inch range. The exception to
this will be our southeast terrain, with the higher elevations
along the Pine and Black Mountain chains seeing 3 to 5 inches by
Wednesday evening.

Temperatures will be averaging well below normal through the short
term, and have favored the cooler NAM MOS numbers, especially for
tonight and Wednesday. Highs today will range from the lower 40s
in the northwest to the mid 50s in the far southeast. Readings
will drop down into the lower 30s tonight, with readings likely
not moving much on Wednesday, given the ongoing precipitation and
cold air advection. Highs will be in the upper 30s for most
locations, some 20 degrees below the normal highs for the latter
half of March.

.LONG TERM...(Wednesday night through Monday)
Issued at 407 AM EDT TUE MAR 20 2018

The extended period begins with the remnants of a system moving to
the east. Lingering snow showers will be possible with the exiting
system early Thursday. The main feature of interest is forecast
to occur this weekend, with another potential system to begin the
next work week.

Before the main system makes its way through Saturday afternoon,
an upper level jet streak coming from the northwest will set up
over the western part of the Commonwealth. The GFS shows a small
band of precipitation Friday morning into the afternoon associated
with this source of lift. However, the ECMWF does not show as much
QPF. This could be because the lift is coming from an area of
ridging to the northwest. Therefore, whether or not there will be
sufficient moisture to go along with the lift generated from the
jet streak before the main system moves in Saturday afternoon is
still uncertain. To account for this, it looks like the Blend gave
slight PoPs in the south Friday morning into the afternoon.

The models are coming into better agreement in terms of timing with
the weekend system, but the GFS is still slightly quicker than
the ECMWF. The GFS also shows higher QPF whereas the ECMWF shows
the precipitation tracking a bit more to the north with lesser
QPF. Most of the precipitation from this will be rain, but there
are chances of a rain/snow mix in the mornings due to the lower
morning temperatures. However, with temperatures gradually on the
increase over the course of the extended period, the better
chance for rain/snow is on Friday as opposed to Monday morning.
Furthermore, where the ECMWF shows showers tapering off early
Monday morning, the GFS shows lingering showers for Monday with a
stout system moving in later Monday into Tuesday. With the model
uncertainty towards the end of the extended period, have opted to
go with the Blend at this time.


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

LIFR/IFR stratus will linger through much of the period, as an
area of low pressure develops just off to our east. Precipitation
will be more isolated through much of today, before filling in
this evening and through dawn Wednesday. As colder air moves in
tonight, rain will change to snow and continue through the end of
the period. Winds will average at 5 to 10 kts, gradually becoming
northwest through the period.


Winter Weather Advisory from 11 PM this evening to 8 PM EDT
Wednesday for KYZ044-050>052-058>060-068-069.

Winter Weather Advisory from 2 AM to 8 PM EDT Wednesday for

Winter Weather Advisory from 10 PM this evening to 8 PM EDT
Wednesday for KYZ087-088-118-120.



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