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Area forecast discussion...updated
National Weather Service Jackson Kentucky
1059 PM EST Fri Nov 24 2017

issued at 1055 PM EST Friday Nov 24 2017

Hourly temperatures have been updated to account for the latest
trends in valley temperatures. A few of the normally cold spots in
the Big Sandy region likely will drop to the freezing mark or just
below before leveling off or even rising late when the clouds
increase and the pressure gradient increases. The increasing
pressure gradient ahead of the approaching cold front is already
evident on top of Black Mountain at the Kentucky mesonet site, where
winds are gusting into the 20 to 25 mph range with sustained winds
near 15 mph there and at the Pike co Kentucky mesonet site at 2770 ft
msl. Winds in these locations should increase further overnight,
into the 15 to 20 mph range, with gusts up around 30 mph per
model trends. Winds and gusts about 2500 feet have been increased
for the duration of the night.

Update issued at 735 PM EST Friday Nov 24 2017

Temperatures were cooling off faster than the previous forecast
in Eastern Valley locations. Hourly temperatures were adjusted for
these trends with min T lowered a few degrees for some of the
normally colder locations. Otherwise, no other changes were needed
at this time.


Short term...(this evening through Saturday night)
issued at 309 PM EST Friday Nov 24 2017

It was a cold start to the day with morning temperatures in the
valleys in the lower to middle 20s. Under abundant sunshine temperatures
have warmed into the lower 60s in much of the area this afternoon.

With dewpoints in the 20s in the north and east, temperatures
will fall quickly in the valleys this evening. A Ridge Valley
temperature difference will develop especially in the east, and
this is depicted in the forecast grids with lows in the middle 30s
in the eastern valleys and in the middle 40s on the ridges. It is
possible this may not be enough of a Ridge Valley difference and
temperatures may need to be further adjusted this evening.

Clouds will increase late tonight in advance of a cold
front. The front will make its way across the area on Saturday.
We will continue with the previous forecast thinking and keep the
sprinkle threat in the forecast late tonight and Saturday. After
the frontal passage on Saturday colder air will work its way back
into the area, though we'll only receive a glancing blow with the
main cold air staying off to our north and northeast.

Long term...(sunday through friday)
issued at 309 PM EST Friday Nov 24 2017

Models are in good agreement until the final 48 hours or so of the
extended. This leads to considerable uncertainty with the mid to
late week storm system we have been watching over the last several
runs. Overall the pattern still looks amplified and progressive. But
model solutions have lacked even a hint of consistency with the
timing, strength, and evolution of troughs and short waves that will
move into the lower 48 by early next week. A center of low pressure
just off the West Coast splits into northern and southern stream
components. An initial southern stream short wave tracks across the
southern Continental U.S. But dampens by the time it reaches the Ohio Valley in
response to a second stronger trough riding eastward a bit further
upstream. The 12z GFS and European model (ecmwf) have switched roles at this point as
the slower GFS shows energy digging further south than the now
faster and less amplified European model (ecmwf). A bit more consistent Canadian
seems to again prefer the middle of the Road with respect to timing
of these features across the nation. For now best bet is to stay
with the model blends until more consistent trends begin to show up
in the solutions.

With the weakening of the initial short wave moving into the region,
sensible weather features a more definitive trend towards warmer
than normal temperatures, climbing into the 60s by mid week. For now
our weather continues to look dry until at least the latter part of
the week where blends ramp best pops up Thursday into Thursday
night. Made the typical minor adjustments to the temperature grids
each night anticipating a small to moderate Ridge-Valley split
during those times when high pressure is centered more directly over
our forecast area.


Aviation...(for the 00z tafs through 00z Saturday evening)
issued at 735 PM EST Friday Nov 24 2017

VFR conditions will prevail through at least the first 12 to 15
hours of the period. Mid and high level clouds will increase
through the night ahead of a cold front, especially during the 6z
to 12z period. Low clouds are then anticipated along and behind
the cold front from generally 15z on. Most of these should be in
the VFR range, but some below 3kft mean sea level cannot be ruled out as
models vary on this. The front may also bring a few sprinkles,
but nothing of significance. Winds ahead of the front will be
south to southwest, and then shift to the west from 14z to 19z as
the front moves through.


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