Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 191217 AAA

National Weather Service Jackson KY
817 AM EDT Mon Mar 19 2018

Issued at 817 AM EDT MON MAR 19 2018

Freshened up the POP and sky trends through this afternoon. Some
thinness in the clouds is noted on satellite this morning across
our area. Have therefore lowered the sky cover a bit through this
morning, and then ramped it up into this afternoon, as the surface
low draws closer from the west. Have also delayed the thunder a
bit longer in the day, as the latest model data has trended a bit
slower with the meager instability. Updates have been sent.


.SHORT TERM...(Today through Tuesday)
Issued at 403 AM EDT MON MAR 19 2018

The latest surface map features low pressure moving across the
southern Plains. A weaker inverted trough is currently aligned
from the Tennessee Valley to the central Appalachians, with a more
defined warm front aligned from west to east across the Gulf
Coast States. Aloft, an upper level low is moving east across the
southern Plains. Some showers have broken out across the Tennessee
Valley overnight, thanks to some ongoing isentropic lift between
850 and 700 mb. Drier air in the low levels have kept this
activity out of eastern Kentucky.

The dry air will continue to keep most of our area precipitation-
free through the morning, with the exception of perhaps a few
sprinkles. Moisture will be on the increase this afternoon, as
the short wave and surface low continue to trek east across the
Mississippi Valley. Showers, and perhaps a few storms will
threaten from southwest to northeast, with the best rain chances
holding off until this evening as the surface low moves across
the eastern portion of the Commonwealth. Temperatures will top out
in the upper 50s to lower 60s.

Some dry slotting will work in after midnight and through the
morning on Tuesday, with less rain chances. Light precipitation
will then fill back in again across the area during the afternoon,
as a deeper trough takes shape across the eastern CONUS. The
surface low will be just off to the east, allowing for a good
gradient of temperatures. Highs on Tuesday will range from the mid
40s across our northwest to the mid 50s bordering Virginia.

.LONG TERM...(Tuesday night through Sunday)
Issued at 451 AM EDT MON MAR 19 2018

The extended forecast begins with an amplified trough centered
right over the Ohio Valley, progressing east. This will bring
precip chances to eastern Kentucky through early Thursday. Brief
ridging will then take hold, with the weather drying out and temps
warming up until the second system of interest develops over the

The models seem to agree decently well with the first system. But,
the GFS looks to be slightly faster with less wrap around precip
mainly affecting the Commonwealth late Tuesday into Wednesday,
with residual precip lingering into Thursday. The ECMWF is showing
higher QPF with this wrap around, resulting in higher chances of
snow showers. Therefore, there is still a bit of uncertainty in
snowfall amounts but any accumulation should be light.

There is higher uncertainty, resulting in less confidence, in the
second system that looks to move into eastern Kentucky late
Friday into Saturday. The GFS is faster with this system by at
least 6 hours according to the latest model run. Not only that,
but the GFS QPF is much more stout with three quarters to near an
inch over the CWA. The ECMWF, however, shows the system tracking a
bit further north and not producing as much QPF. With the
uncertainty in timing and precip amounts, have opted with the
Blend for the most part, but also trended a bit slower with the
entrance of the precip as more guidance has leaned towards a
slower advance.

As for temperatures, there will be a gradual warm up for eastern
Kentucky. Temps start in the 40s Wednesday, but by the end of the
period warm to the mid to upper 50s in the north and low 60s in
the south. Lastly, with calm winds and clear skies, there is
potential for a ridge/valley temperature split Thursday night.
However, with northerly flow, the split is not anticipated to be


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

Clouds will increase and lower through the period, with rain
showers and an isolated thunderstorm threatening from southwest
to northeast after 21z. In general, VFR conditions will hold on
through the afternoon, before lowering to MVFR/IFR by the evening
and overnight, as widespread showers move in. The showers will
diminish in areal coverage from southwest to northeast between 06
and 12z. Winds will be variable at 5 to 8 kts through the period,
as a surface low approaches and eventually passes through the
region overnight.




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