Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 142035
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
335 PM EST Sat Jan 14 2017

.SHORT TERM...(This evening through Sunday night)
Issued at 335 PM EST SAT JAN 14 2017

A front which has been wavering across the forecast area today,
will push off to the south tonight as a wave of low pressure
moves off to the east. Rain will be widespread across the area
into early evening, but with the front pushing into the TN valley
tonight, rain chances will diminish. The front will stall and
begin making its way back north on Sunday as surface high pressure
moves from the eastern Great Lakes into New England. As the front
shifts back north the threat for showers will return Sunday into
Sunday night.

Colder air will push into the area in the wake of the front
tonight, with low temperatures in the 30s across the northern
part of the area, and lower to middle 40s in the south. The
temperature range will not be as great across the area on Sunday
as it was today. Highs on Sunday will range from the lower 40s
north, similar to today, but in the lower 50s south, or about 10
degrees cooler than today. With the front pushing back north
Sunday night and cloudy skies temperatures will not fall much,
with lows upper 30s north to middle 40s south.

.LONG TERM...(Monday through Saturday)
Issued at 335 PM EST SAT JAN 14 2017

The period is expected to begin with an upper ridge of high pressure
centered over or near the Caribbean and extending into the
Southeastern Conus, with another ridge extending into the west coast
of the Conus with an upper level trough extending from Central
Canada through the Northern Plains south to the Central Plains and
Four Corners region and then southwest to Baja region. Within this
trough, the model consensus is for a closed low over western OK or
southern KS. At the surface, an area of low pressure is expected to
be centered over the OK/KS area with a warm front extending east
into the TN Valley region and the Southeastern states.

With the axis of the upper level ridge extending into the OH Valley
at the start of the period, a relative lull in shower chances should
be featured at the start of the period. However, by Monday night the
axis of the ridge moves east and the closed low/shortwave and sfc
low initially over KS/OK should reach the mid MS Valley region.
Meanwhile, the warm front and associated isentropic lift should
increase as the ridge moves east, leading to increasing moisture and
lift across the Commonwealth by Monday evening and into Monday night
and good chances for showers. The surface low should track into the
Western Great Lakes region while the weakening upper low/shortwave
begins to interact with a northern stream shortwave. Models handle
this differently as well as some of the individual shortwaves
ejecting northeast from the Four Corners region by the Monday night
period and timing uncertainties increase.

The surface low should continue tracking across the Great Lakes on
Tuesday as the upper level ridge axis and the cold front moves
across the Commonwealth. The low level jet should increase by
Tuesday ahead of this front and some limited generally elevated
instability should also exist at some point. Since the boundary
should also be moving through during the day, temperatures should
generally reach the 60s with dewpoints in the 50s, slight chance of
thunder has been included on Tuesday. With the uncertainty with the
interaction of the northern stream and timing of individual waves in
the southwest flow it is possible that chances for thunder might
need to extend into Tuesday night for some of the southern or
southeastern portions of the area. However, chances for thunder have
been held at slight chance due to the timing uncertainties.

Chances for showers will linger into Tuesday night and as late as
early on Wednesday especially in the east as the boundary and upper
level trough axis move through. Confidence decreases even more from
mid to late week as a portion of the trough may hang up over the
Four Corners and Baja region and the models generally have a lead
shortwave ejecting northeast as well. Differences with a trough
nearing the Pacific northwest likely are lading to different timing
of the shortwaves being ejected northeast. The ECMWF is quicker with
the lead wave and would offer a wetter solution Wed night into Thu
compared to the current dry forecast. The models then bring the last
bit of this trough across the area on Thu night into Friday evening.
Due to the timing uncertainties, pops were carried most of the time
from mid to late week other than on Wed night and Thu. At this time,
systems are rather progressive and individual rounds of rain appear
to be on the moderate to possibly heavy side. This pattern will
still need to be monitored as even the current forecast rainfall
would probably lead to at least elevated water levels on downstream
river points sometime during the period.

What is more certain is that temperatures through the period will
remain above normal and at times well above normal as 850 mb temps
are forecast to remain well above 0C for the period. Highs during
the period are expected to average in the 15 to 20 degree range
above normal, if not more on a couple of days, with overnight lows
averaging about 10 to 20 degrees above normal.  Some of these days
could also flirt with record high temperatures, mainly Tue and
perhaps at the end of the period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 101 PM EST SAT JAN 14 2017

Early this afternoon IFR to LIFR conditions continued to prevail
across eastern Kentucky, mainly due to low ceilings. Visibility
improved to 7 miles or greater in many locations early this
afternoon, but rain will spread east across the area this
afternoon and evening with visibilities once again lowering.
Behind the rain, drizzle and fog will prevail later tonight into
Sunday, with IFR or worse conditions expected to continue into the
day on Sunday.

A slow moving cold front was across eastern KY early this
afternoon, and this front will drift south of the state this
evening, but then stall and begin moving back to the north on
Sunday. As a result poor weather conditions will continue to
prevail into early next week.

&&

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

$$

SHORT TERM...SBH
LONG TERM...JP
AVIATION...SBH



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