Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 110552
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1252 AM EST Sun Dec 11 2016

.UPDATE...
Issued at 1252 AM EST SUN DEC 11 2016

Altocumulus/cirrus should thin out overnight, allowing
temperatures to fall into the low-mid 20s with a few readings in
the teens in the valleys. Would expect a quicker dropoff in the
Lake Cumberland region where clouds should thin earlier, but
points nearer the Virginia border should still see this occur
later on tonight.

&&

.SHORT TERM...(This evening through Sunday night)
Issued at 400 PM EST SAT DEC 10 2016

20z sfc analysis shows high pressure centered over Kentucky with
mostly sunny skies now in place along with light winds. This has
helped our area recover from the chilly start this morning, but
still only made it to the lower 30s for most spots by mid
afternoon. Dewpoints, meanwhile, have held in the teens with even
some values mixing down to near 10 degrees across the south.
Winds have been, and remain, light across the area this
afternoon.

The models are in good agreement aloft through the short term
portion of the forecast. They all depict fast and zonal flow
through the breadth of the nation. This will carry, mainly weak,
packets of energy through the region until Sunday evening. At this
time, amplification to the longwave pattern associated with a
trough moving through the Northern Plains. As this happens, more
energy will start to dive into the Great Lakes and Ohio Valley
along and ahead of the 5h trough axis. Only minor differences are
noted among the models with these key features so a blended
solution looks good. Did favor the solution from the higher
resolution models for the near term portion of the forecast.

Sensible weather will feature a night of increasing and thickening
high clouds, but still likely not thick enough to prevent a
decent ridge to valley difference from showing up. Have added
this distinction into the T grids through the night. The high will
move off to the east on Sunday with low pressure progressing into
the Upper Midwest and a cold front crossing the Mississippi River.
Clouds will lower through the day as temperatures warm up on
southwest winds. This will scour out all the sub freezing air
fairly early in the day before any risk of pcpn moves in late in
from the northwest. The cold front pushes into the state Sunday
night with a slug of soaking rain showers expected to cross the
CWA through the night propping temperatures up into the low to mid
40s most places - keeping everything liquid. Only late in the
night will CAA start to kick in for the northwest parts of the
area with readings starting to fall toward 40 degrees there by
dawn Monday.

Started with the CONSShort and ShortBlend for the grids through
the short term with significant temperature adjustments tonight
for the ridge to valley differences. Also adjusted the PoPs up by
about 10 percent during the fropa Monday night.

.LONG TERM...(Monday through Saturday)
Issued at 405 PM EST SAT DEC 10 2016

The period begins with precip moving out of the region through the
day on Monday. This as a cold front and upper level feature
progress east out of the region. High pressure is poised to build
into the region by Monday evening but the region will remain under
some clouds with low stratus possible based on the latest sounding
data. There is a hint of a southern disturbance getting close
enough to add some slight POPs in the far south, however this will
be fighting with a stronger surface high that will begin build SE.
Overall support is low with the ECMWF being the only advertiser at
this stage and we begin to see more inconsistencies as we move
forward into the rest of the forecast. The next chance of seeing
precip will be Wednesday into Wednesday night and this is where we
see more differences. That said the models have continued to go
back and forth on this system, but the GFS has come in drier this
run. Overall keep best POPs in the east and looks like fairly low
amounts given the speed of this clipper feature.

After this feature we see surface high pressure once again build
into the region and consequently cold temperatures. Highs on Thu
struggle to make it above freezing area wide and most seeing teens
come Wed and Thu night. This surface high progresses quickly east
by Friday and again we begin to see issues with timing on the next
system. The ECMWF is the faster solution and for now given the
uncertainty will stick with the blend. That said there is a chance
of more snow and mixed precipitation Friday night into Saturday
morning if some of the current blend remains the same, but the
uncertainty at this point is high of the evolution of this system.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
ISSUED AT 1252 AM EST SUN DEC 11 2016

VFR conditions will remain in place through this afternoon, before
lowering/thickening clouds arrive this evening complete with rain.
Southerly winds will increase to 5-10 knots or so by late this
morning through this afternoon, with gusts nearing 15 knots at
times. Low level wind shear will become an issue this evening as a
wind maximum aloft moves overhead, producing unidirectional shear
of near 40 knots at FL020. Following this, the arrival of rain
will lead to at least MVFR visibilities/ceilings developing
tonight into Monday morning.


&&

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

$$

UPDATE...GUSEMAN
SHORT TERM...GREIF
LONG TERM...DJ
AVIATION...GUSEMAN



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