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Area forecast discussion 
National Weather Service Jackson Kentucky
703 PM EST sun Dec 28 2014

issued at 647 PM EST sun Dec 28 2014

Two main changes to the forecast. First was to change the probability of precipitation over
the next few hours to center the highest amounts over the more
central portion of the County Warning Area...slowly shifting more eastward into the
highest terrain over the next several hours...then lingering slightly
longer across the SW County Warning Area than was previously forecast. This better
accounted for ongoing well as what both the hi res
and short term models were forecasting. The second change was to add
fog wording to the County Warning Area through the overnight hours. Much of Kentucky is
reporting areas with and without rain. Expect this fog to
continue as we head into the overnight hours with low level moisture
from rain expected to continue. This fog should then burn off during
the morning hours as drier air moves in and rain moves out. Valleys
will be the last to clear out. Updated the near term grids with the
latest observational data for temperatures...dew points...and winds to make
sure the current conditions were reflected in the forecast.


Short term...(this evening through Monday night)
issued at 359 PM EST sun Dec 28 2014

Current conditions across the area features rain continuing to move
into the area from the southwest. The cold front has now pushed east
of eastern Kentucky with northwesterly flow now into the area.
Freezing temperatures look to be north and west of the forecast area
and snow is not expected at this time as the colder air is a bit to
slow to advect into the area before the bulk of the moisture exits to the
east tonight. Meanwhile...surface low pressure has developed and will
move northeast through eastern Tennessee tonight. This will keep precipitation
through far eastern Kentucky through the night as another surge of
moisture will move northeast. With the moist low levels...though
there will be some cloud expect some patchy fog developing
tonight and has already been the case in some of the Bluegrass areas.
Especially places that remain saturated through the night.

Cloud cover and precipitation will slowly move off to the east for Monday
with some rain fall skirting along the far eastern counties as the
low exits of to the east. Heading into Monday night...the colder air
will filter into the area and some lingering rain in the east may
change or mix to snow in the higher elevations towards Tuesday
morning. Partial clearing in the northwestern counties will result in
temperatures dropping into the middle 20s for lows.

Long term...(tuesday through sunday)
issued at 359 PM EST sun Dec 28 2014

The extended portion of the forecast will be broken up into three
segments. Part one...isolated rain and snow showers are forecast to
linger in the northerly meagerly moist flow behind a departing cold
front and upper level low pressure system. The second period will
feature an east to west elongated ridge of high pressure that is
expected to drop southward out of the Great Lakes region Tuesday
through Thursday. Part three will feature a well developed and very
moisture laden weather system that will affect the region from
Thursday night through Sunday. The weather system that will be
leaving the area on Tuesday should bring nothing more than light
rain and snow with little or no snow accumulation. Temperatures to
begin the period look to be below normal...with highs in the 40s
during the day...and lows Tuesday night in the low to middle 20s. An
Arctic air mass is then prognosticated to settle over the region middle week.
Highs on Wednesday and Thursday will likely not make it out of the
30s. Overnight lows Wednesday and Thursday night will be even
chillier...with the Mercury bottoming out around 20 Wednesday
night...and the middle to upper 20s Thursday night.

The big story in the extended will be the weather system that is
forecast to soak the area toward the end of the week. There is no
question that a potent weather system with extensive precipitation
will affect the state of Kentucky Friday and Saturday. The questions
with this system will be how quickly will precipitation move into
the area and how much of the precipitation will be in the form of snow?
Right now the GFS is much slower and warmer than the European model (ecmwf) with the
end of week weather pattern. The GFS has its low moving further
north than the European model (ecmwf). That being said...with so much uncertainty
involved...decided to go with a compromise between the two
models...slightly favoring the colder European model (ecmwf) model. This is based on
the fact that the models have been running a bit too warm lately
with regards to low and middle level temperatures. After a period of
mixed precipitation Thursday area of light snow is being
forecast to develop late Thursday night through early Friday
morning. There could be some light accumulations with this band of
snow as it moves north...but it will likely not stay on the ground
long as temperatures rise into the 40s on Friday. An extended period
of good soaking rain is expected Friday through Saturday...with the
potential for some snow along and north of I-64 Friday night and
Saturday some near freezing air could spill into that
area each night. As is common in winter...the models will need to be
watched very closely to see which direction things trend...more rain
or more snow will be the question as we move forward.


Aviation...(for the 00z tafs through 00z Monday evening)
issued at 701 PM EST sun Dec 28 2014

A cold front has moved southeast of Kentucky...though rain will likely linger
throughout much of the night at the taf sites. Despite surface winds
switching to a more nearly direction behind this front...the middle and
upper levels still possess a strong southwesterly component...allowing this
moisture to continue to filter into the region. Fog is being observed
now across much of Kentucky...and with moisture expected to continue
overnight...the fog will likely linger into the morning hours. While
ceilings will remain near or at Airport minimums...the fog and rain will
likely keep visible fluctuating between LIFR and below Airport mins.
Given the uncertainty and likely variability in this weather
pattern...went with a general and optimistic 1sm at the taf sites
during the overnight hours. Fog will burn off and visible will slowly
improve tomorrow morning. Another weaker boundary is expected to move
through the region during the afternoon from the ceilings will
likely remain MVFR.


Jkl watches/warnings/advisories...


short term...shallenberger
long term...Arkansas

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