Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 211830 AAA

National Weather Service Jackson KY
230 PM EDT Wed Mar 21 2018

Issued at 200 PM EDT WED MAR 21 2018

Updated the grids to mainly fine tune the PoPs and snow showers
chances in the Wx one and also to lower temps through the rest of
the afternoon as that latest band from the northeast will keep
insolation to a minimum. These updated grids have been sent to
the NDFD and web servers.

UPDATE Issued at 1050 AM EDT WED MAR 21 2018

14z sfc analysis shows a deep low pressure center now to the
southeast of Kentucky with west to northwesterly cyclonic flow
feeding into its core. This is resulting in gradually more upslope
wind flow over eastern Kentucky late this morning and into the
afternoon prolonging the ongoing snow showers even as the sfc low
pulls away and jumps to the coast. Temperatures (and dewpoints)
throughout eastern Kentucky are generally in the upper 20s to
lower 30s with some mid 20s on the higher ridges above 2000 feet -
with Black Mountain reporting 20 degrees. The heaviest snows this
morning have been banded and mainly through the southern portions
of the area for the most part and this is expected to continue
into the afternoon before the upslope kicks in further favoring
the higher terrain in the east. Have updated the forecast,
including snow fall and PoPs with these thoughts in mind. Given
temperatures around or slightly above freezing for most, some
insolation, and the late march solar inclination, do expect most
places to see around a half an inch or less additional
accumulation through the day outside of the better snow bands and
ridge top/colder locations. The WSWs continue across the area with
snow amounts from 1 to 3 inches common - though many locations in
the far northeast have seen little more than a trace at this
point - expect that to change this afternoon - but still looking
at less than an inch additional snow possible there. The forecast
grids have been updated and sent to the NDFD and web servers, with
a freshened set of zones and HWO to be issued by noon to remove
morning wording.

UPDATE Issued at 643 AM EDT WED MAR 21 2018

Forecast is on track so far this morning. No major updates were
needed besides ingesting current observations and blending into
current forecast. Did update PoPs with CONSShort to reflect
current trends as well. An updated zfp was not needed at this
time. Updates have been sent to NDFD and to the web.


.SHORT TERM...(Today through Thursday)
Issued at 506 AM EDT WED MAR 21 2018

The main low pressure system is progressing eastward, but looks
to redevelop past the Appalachians. With this transition, the HRRR
as well as the RAP model show rising heights over eastern
Kentucky. This means subsidence is taking over, leading to
diminishing precip through the morning and early afternoon. Will
continue with current advisories, but with lighter accumulation
than expected in most areas, have lowered overall QPF and snowfall
amounts. The highest snowfall amounts are still forecasted to
occur in higher elevations above 2000 feet, but mainly in the
southeastern terrain. Lingering snow showers will persist late
tonight into early Thursday morning in the southeastern portion of
the CWA, but drier weather will take hold Thursday mid- morning
through the rest of the short term period.

In terms of temperatures, with the cloud cover to remain through
the day, temps most likely will not rise above the mid 30s in
most places. Tonight`s lows will be cooler than last with the
passage of this latest system. However, with clouds clearing
later on tonight as a surface high pressure builds in, high
temperatures will be on the increase for Thursday, ranging from
mid to upper 40s.

.LONG TERM...(Thursday night through Tuesday)
Issued at 556 AM EDT WED MAR 21 2018

The long wave pattern will be fairly amplified through the period,
with an upper level ridge poised to move from the Plains to the
Eastern Seaboard. Meanwhile, deeper troughing will evolve across
the West, with more of a split-flow pattern developing by early
next week as a cutoff low drops across southern California.

Dry weather with below normal temperatures will start out across
eastern Kentucky through Friday. A compact short wave trough and
reflective surface low pressure system will then track from the
central Plains to the Ohio/Tennessee valleys for the weekend,
temporarily buckling the ridge. This will bring another round of
precipitation to our area from Friday night through Sunday. Some
snow may occur at the leading edge of this system as it moves in,
and also as it exits off to our southeast. The predicted thermal
profile this far out is low confidence at best, so have not
mentioned any specific impacts at this point.

Once this system exits on Sunday, another baroclinic zone will
take shape from northeast to southwest across the center of the
CONUS. The models are varying in timing on the approach of this
boundary closer to the Ohio and Tennessee valleys. As such, have
only carried some low chance POPs at times from Sunday night
through Tuesday.

Below normal temperatures through the weekend will modify to near
or slightly above normal by Tuesday.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)

IFR/MVFR ceilings with light snow will continue across the area
through 21z, before gradually diminishing from west to east late
this afternoon and early evening. VFR conditions will then
eventually return into the early overnight hours into the day
Thursday, as high pressure builds in from the west. West to
northwest winds at 10 to 15 kts, with gusts of around 20 kts this
afternoon will diminish to less than 10 kts after dusk remaining
light through the night and before picking up again to near 10 kts
later Thursday morning.


Winter Weather Advisory until 8 PM EDT this evening for KYZ044-



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