Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 170859
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
359 AM EST Wed Jan 17 2018

.SHORT TERM...(Today through Thursday)
Issued at 358 AM EST WED JAN 17 2018

Early this morning a trough extended from Eastern Canada south
into the Eastern Conus. A ridge extended from the southern Rockies
to the Great Plains while a trough was slowly approaching the west
coast of the Conus. The axis of the 500 mb trough axis is
approaching the area with a shortwave trough working into the TN
Valley. Regional radar and surface observations generally indicate
flurries or light snow showers falling in locations with low
clouds persisting.

The trough axis will approach the region today with an upper low
closing off at 500 mb over the Appalachians and departing to the
east this evening and tonight. the coldest air at 850 mb moving
across the area this morning. The combination of these will lead
to rather steep lapse rates especially with some solar insolation
today and should keep stratocu or cu rather persistent. Model
forecast soundings indicate the most saturation in the low levels
through early afternoon and isolated snow showers and flurries
should persist. These clouds will reside in the dendritic growth
zone for a continuation of fluffy flurries or light snow showers
that could measure a dusting to a third of an inch in most
locations with the highest terrain above 2500 feet possibly
picking up as much as an inch today. Snow cover and the cold 850
mb temperatures should keep temperatures on the lower end of
guidance and undercut Superblend Max T by a couple of degrees
today.

Behind the departing 500 mb trough/closed low heights will rise
tonight into Thursday morning while high pressure over the MS
Valley builds into the area. Overall a decrease in stratocu is
expected this evening and tonight and with slackening winds and
snow pack on the ground of the fluffy variety lows below blended
guidance appear likely tonight for valley locations. Opted to go
closer to if not below Coop MOS guidance numbers for tonight.

High pressure will remain in place on Thursday with the airmass
moderating at 850 mb temperatures. Most locations outside of the
high terrain should moderate to above freezing.

.LONG TERM...(Thursday night through Tuesday)
Issued at 304 AM EST WED JAN 17 2018

The extended will start off cold, as the last dregs of arctic air
remain in place across the area. Friday morning low temperatures
will likely range from the mid teens to the lower 20s across the
area. Saturdays lows will still be cold, with min readings in the
upper 20s expected, but should feel much warmer than the single
digits and teens we`ve been experiencing lately. However, as winds
swing around to southwest on Friday, warmer air will finally begin
filter into the area. These winds, combined with mostly clear skies,
should allow the mercury to climb into the low to mid 40s across the
entire by Friday afternoon. This warming trend is expected to
continue through out the upcoming weekend, as a ridge of high
pressure builds across the entire southeastern CONUS. The southerly
flow and continued clear conditions should allow temperatures to
warm into the upper 40s and lower 50s by Saturday afternoon, and into
the mid to upper 50s on Sunday. The warm weather will be the primary
feature of note in the extended. After dry weather on Friday,
precipitation will finally begin moving back into the area early
Saturday evening, as an area of low pressure approaches from the
west. This system will initially have a difficult time moving very
far east however, as the strong ridge that will already be in place
will be slow to erode. By Sunday morning we should see isolated to
scattered rain showers affecting portions of the forecast area
generally north of the Mountain Parkway through Sunday afternoon.
After this initial round of rain exits the area Sunday evening, a
second round of more widespread rain is expected to move across the
area from late Sunday night through Monday evening. This
precipitation will be in response to the passage of a passage of a
weak cold front. The rain should be exiting the area by late Monday
night. Temperatures to begin the new work week should remain quite
mild, with highs topping out in the lower 50s on Monday, and the
upper 40s to lower 50s on Tuesday. Nightly lows should be mainly in
the 30s from Saturday night onward. The exception looks to be Sunday
night, when the mercury may only bottom out in the lower 40s across
the area. Lower 30s can be expected for Monday and Tuesday night
respectively.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 135 AM EST WED JAN 17 2018

A narrow band of clearing is moving southeast across the area with
more low clouds upstream of the area in the MVFR range in general.
At this time, MVFR is reported across the north and south with a
few of the TAF sites in the clear slot for up to 2 or 3 more
hours. However, low clouds and MVFR should return with some light
snow showers and flurries. These areas of MVFR should persist
through the 15Z to 21Z period before drier air moves in and lapse
rates become not as steep. Winds will remain 10kt or less out of
the west and northwest through the period.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...JP
LONG TERM...AR
AVIATION...JP



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