Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Jackson Kentucky
310 am EST sun Dec 21 2014

Short term...(today through monday)
issued at 310 am EST sun Dec 21 2014

A fairly calm period is on tap for the first 36 hours of the
forecast. Lingering cloud cover will continue to move out of eastern
Kentucky early this morning north of the mountain Parkway. After a
few hours of mostly clear skies...a few low and high level clouds
will begin to slowly move back into the area from the southwest ahead
of an area of low pressure that will move past well to our south.
This low pressure area is prognosticated to move across the eastern
Tennessee Valley tonight and tomorrow. As it does so...a bit of
moisture that the system brings from the Gulf of Mexico could spill
over our eastern mountains. This meager moisture may even spawn some
isolated rain showers in our far eastern counties along the Virginia
border. Southeasterly flow associated with the passing low will make
even isolated showers a bit of a stretch...but there could be just
enough moisture available for a few to form...so a slight chance of
rain will be carried in our southeastern counties from late Sunday
into through middle morning morning. Broken to overcast low level cloud
cover will likely be the primary weather feature associated with the
area of low pressure as it moves across the Tennessee Valley and
southeastern Continental U.S..

Temperatures will start out right around normal...with highs today
expected to climb into the middle to upper 40s across the area.
Locations north of the mountain Parkway may only reach the lower 40s.
With cloud cover on the increase...and winds shifting to the south
and southeast...overnight lows should not be quite as cold as this
mornings forecast lows. We should see min temperatures on Saturday morning
generally in the low to middle 30s across the area. Once persistent
southeasterly winds become established on Sunday...downslope warming
will occur...allowing temperatures to warm significantly around
eastern Kentucky. Highs on Monday should have no problem maxing out
in the low to middle 50s.

Long term...(monday night through saturday)
issued at 310 am EST sun Dec 21 2014

Unsettled weather is expected heading into Christmas morning...but
we should dry out for the majority of the Holiday weekend. The
exception will be a shearing out cold front that could bring a small
chance of rain to the area late Friday or Saturday.

To begin the period...a northern stream trough will reside across
the Central Plains with southeast flow locked in across eastern
Kentucky. This downsloping flow will keep dry weather across eastern
Kentucky through Monday night and likely much of Tuesday. Further
away from the effects of this downsloping...we may see some rain
push into the Bluegrass or south central Kentucky by midday Tuesday
or sometime in the afternoon. While models continue to differ on how
this whole system evolves...one thing seems pretty sure is that we
will have tremendous lift and forcing go across the area Tuesday
night through Wednesday as a cold front works across the area. For
this reason...will go with categorical probability of precipitation. The GFS remains more
pronounced with the middle level trough heading into Wednesday and
Wednesday night...while the European model (ecmwf) holding to a less wrapped up
system. These two widely different scenarios brings into question
exactly when we might see any transition over to snow across the
area. In fact...the GFS never really gets cold enough air into the
area to support much snow at all. What cold air it does portray does
not coincide with an area of lift or very deep moisture. While the
European model (ecmwf) looks a little better for snow...even it has been backing off
on the snow potential. This combined with an unfavorable upslope
westerly wind...will really make it hard to see much in the way of
snow shower activity. While we may still see a few flakes...thinking
this may not be much of an impact for our area Wednesday night.

The one concern that still exist is the high wind potential on
Wednesday as a cold front surges east across the area. Winds along
and just behind the front could gust as high as 45 miles per hour. While we
should see winds subside some into Wednesday night...some wind gusts
to 35 miles per hour will remain possible.

By Christmas day ridging will already be pushing into the area with
highs making a nice recovery to around 50. Our next weather maker a
moisture starved cold front will head towards the area late in the
week. Models differ quite a bit on timing...so have backed off on
the higher probability of precipitation and gone with a longer period of low chance probability of precipitation
from Friday into Saturday. Most likely any rain chances will be
limited to a 3 to 5 hour window...but pinning it down this far out
is just about impossible. Mild weather will persist into Saturday
before colder air returns for the rest of the weekend in the wake of
the cold front.

&&

Aviation...(for the 06z tafs through 06z Sunday night)
issued at 1235 am EST sun Dec 21 2014

The taf sites at jkl and sjs will experience VFR conditions through
the end of the period. Sym will continue to have MVFR ceilings and visibilities
with fog and an overcast deck of stratus clouds through 7z or so. Based on
trends observed in the latest satellite imagery...the clouds at sym
should begin to scatter out nicely by 8z...giving way to clear skies
by 9z. A few low and highs clouds may make their way back into
eastern Kentucky around 12z today with VFR conditions continuing
throughout the day.



&&

Jkl watches/warnings/advisories...
none.
&&

$$

Short term...Arkansas
long term...kas
aviation...Arkansas

National Weather Service Glossary of Abbreviations