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Area forecast discussion 
National Weather Service Jackson Kentucky
1108 am EDT Sat Oct 10 2015

issued at 1108 am EDT Sat Oct 10 2015

Trailing upper level low continues to sink south into the Tennessee
Valley this morning. This is aiding in keeping a thick deck of
stratus across a good portion of eastern Kentucky. These clouds will
slowly lift through the day as upper level feature tracks
southeast into the GA/SC. No major changes needed to the grids
mainly just maintenance on the temperatures...dews...winds..and sky with
latest observation and trends.

Update issued at 740 am EDT Sat Oct 10 2015

The rain has departed the area and with the fog quite limited have
updated to clean up the weather grids. Also tweaked the T and dew point grids
per the latest observation and trends. These have been sent to the ndfd
and web servers along with the issuance of zone forecast product update.


Short term...(today through sunday)
issued at 345 am EDT Sat Oct 10 2015

07z surface analysis shows a cold front slowly moving southeast
through far southern parts of our County Warning Area. This is taking light rain
showers out of the area along with its passage. Post frontal
cooler and drier air is seeping into the northern parts of east
Kentucky on light north to northeast winds. Readings currently
vary from the low to middle 50s in the north to near 60 in the far
south. Dewpoints...meanwhile...range from the upper 40s in the
north to the upper 50s in the south. There are also hints in the
observation and on web cams of some fog starting to form in the
valleys...but not far.

The models remain in good agreement aloft through the short term
portion of the forecast. The all take a shortwave trough through
the Tennessee Valley and off the southeast coast by evening. In
the wake of this...heights will rebound through the Ohio Valley
Saturday night and into the day Sunday. Attention is then drawn to
a developing strong trough moving into the northern plains later
that evening. Given the model agreement have favored the higher
resolution hrrr and nam12 for forecast details.

Sensible weather will feature the light showers ending across the
far south by middle morning with some sunshine returning by
afternoon. The change of air masses today will mean cool high
temperatures in the 60s along with lower humidities in the
afternoon. For tonight...clearing skies will likely provide for
decent radiational cooling across eastern Kentucky along with
patchy valley fog developing by dawn. Look for a small to moderate
ridge to valley temperature split to set up shortly after sunset
this evening and continue through the night. The coldest valleys
may see readings down around 40 degrees or even into the upper 30s
with patchy frost not out of the question...should the skies
stay clear for most of the night.

Again used the shortblend guidance as a starting point for the T
and dew point grids into the evening before going with the superblend
through Sunday. Did make some relative elevation based
adjustments to low temperatures tonight addressing the ridge and
valley low temperature split. As for probability of precipitation...ended up similar to
consensus MOS guidance this morning with near zero values
thereafter...also in line with MOS.

Long term...(sunday night through friday)
issued at 335 am EDT Sat Oct 10 2015

The extended period will begin with an elongate ridge of high
pressure aloft stretched across the southern Continental U.S....with a well
developed trough aloft moving across the Continental U.S. Canadian border. The
ridge will be the primary influence on area weather Sunday night and
Monday...with southerly flow and mostly clear skies on tap. Clouds
will be on the increase beginning Monday an ill defined
and fairly dry cold front moves across the Ohio and Tennessee Valley
regions. The front will represent the surface extension of the upper
trough that will be moving across the Great Lakes region during this
time. The forecast issue at the start of the period will be just how
much moisture will be available for the front to interact with as it
moves across the region. This will also determine how much
precipitation the front will be able to produce. At this time...the
GFS model keeps eastern Kentucky almost completely dry during
frontal passage...with increasing cloud cover being the only
indication that the front is moving through. The European model (ecmwf)...on the
other hand...keeps things dry at first...but then produces a large
area of rain showers Monday night into Tuesday the
front interacts with the terrain across our area. Based on this
uncertainty...decided to use a 50/50 blend of the GFS and European model (ecmwf)
model data to create the pop forecast for the Monday Tuesday time
frame. This blend produced a maximum pop of 30 percent and has eastern
Kentucky rain free by 15z on Tuesday. The rest of the week should be
dry with partly cloudy skies.

Temperatures during the period are on track to be below normal
across the board beginning on Tuesday. A Canadian air mass is
forecast to filter into the area Tuesday and Tuesday a
large dome of high pressure settles over the region. After a near
normal day on Monday...with highs in the low to middle 70s expected...a
steady cool down is anticipated. Daily highs are expected to top out
in the 60s...with overnight lows in the 40s across the area from
Wednesday Onward. Lows Monday morning and Tuesday morning should
be slightly warmer...with min readings around 50 on tap.


Aviation...(for the 12z tafs through 12z Sunday morning)
issued at 755 am EDT Sat Oct 10 2015

MVFR ceilings at a few sites will return to VFR conditions by middle to
late morning as high pressure builds into the region. Fog could be
an issue at the sites later tonight depending on how much drying
takes place this afternoon. expect areas of fog
in the valleys late tonight. Winds will generally be from the
north to northeast at 5 kts or less through the period.


Jkl watches/warnings/advisories...

short term...greif
long term...Arkansas

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