Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 160544

National Weather Service Jackson KY
1244 AM EST Thu Feb 16 2017

Issued at 1244 AM EST THU FEB 16 2017

Forecast still on track so far tonight. Cloud cover will continue
to gradually fill in from north to south across the area, with
broken low level clouds expected by around 9Z this morning. The
latest obs were ingested into the forecast grids to establish new
trends, but no other changes to the forecast were required.

UPDATE Issued at 1042 PM EST WED FEB 15 2017

Hourly grids have been freshened up based on recent observations
and trends. Some of the valleys in the Big Sandy Region and the
Kentucky River basin have begun to decouple over the past hour or
so and have opted to lower min T in these locations a couple of
degrees. Some of the colder spots in the Cumberland basin have
also decoupled. Otherwise, there were no substantial changes at
this time.

UPDATE Issued at 710 PM EST WED FEB 15 2017

Mostly clear to clear skies were currently observed across the
area with a few high clouds passing by from time to time. Drier
and colder air will continue to advect into the area tonight with
850 mb temps expected to bottom out near dawn. The pressure
gradient between the deep low pressure system off the Northeast
U.S. Coast and a ridge of high pressure centered over the Southern
Plains building toward the area is expected to be strong enough
to keep the atmosphere a bit mixed overnight. Also, later on
tonight, mid and high clouds will increase from the northeast to
southwest. Valley locations are currently not expected to decouple
or what decoupling that does occur should be balanced somewhat by
the cold air advection and increase in clouds late, limiting the
range in low temperatures. The previous forecast generally appears
on track with mainly just some updates at this time to hourly
temperatures, dewpoints, and winds based on recent observation and
short term model trends.


.SHORT TERM...(This evening through Thursday night)
Issued at 329 PM EST WED FEB 15 2017

Quiet weather has settled over the area. Cold air advection is
ongoing as a surface ridge builds in from the west. The air mass
is dry enough that low level moisture has already eroded and left
mainly clear skies behind.

The clear skies will last into tonight, but will be interrupted
over the northeast part of the area. A jet streak rotating around
a large northeastern CONUS trough/upper low will bring an increase
in clouds late tonight, and lasting into Thursday morning. Models
do not indicate any precip with it locally, just a slight increase
in upslope precip further to our northeast. This feature departs
on Thursday, and clouds should be on the decrease in the
afternoon. Meanwhile, at the surface, high pressure ridging will
slip away to our east on Thursday. This results in the return of
warm air advection, which subsequently will support ridge/valley
temperature differences on Thursday night.

.LONG TERM...(Friday through Wednesday)
Issued at 329 PM EST WED FEB 15 2017

The highlight of the long term portion of the forecast is
unseasonable warmth. In fact temperatures are forecast to average
close to 15 degrees above normal for the Friday through Wednesday
period. This will continue to help boost our 2016-2017 average
winter time temperature, and with above normal temperatures expected
to prevail through the end of February it is possible both Jackson
and London may experience their warmest December to February periods
on record. Average temperature for December 1, 2016 to February 14,
2017 has been 41.2 at Jackson and 41.1 at London. The warmest
December to February on record is 41.6 at Jackson in 2011-2012, and
41.5 at London in 1991-1992. Records at Jackson date back to 1981
and at London to 1954.

The forecast period begins with upper level ridging extending from
the southeast U.S. through the western Great Lakes. An upper level
low will move northeast from Texas and weaken as it moves through
the TN and OH valleys this weekend. There is good model agreement on
this scenario. This will result in a chance of rain mainly across
the southern and central parts of the area from Saturday into Sunday

As we move into next week upper level ridging from the Gulf of
Mexico into the Great Lakes will once again be the dominant feature.
Monday looks to be the warmest day of the period with maximum
temperatures around 70 Monday afternoon, or 20-25 degrees above
normal. Another upper low which will be over northern Mexico at the
start of the week will drift east northeast through midweek while a
weak short wave trough moves through the northern stream helping to
damp out the high amplitude ridging. As to be expected there is less
model agreement with the evolution of the overall upper air pattern
next week but at this point it appears that rain chances will return
Tuesday night and continue into Wednesday with mild temperatures


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)

Although an increase in high and mid clouds is expected later
tonight across the northeastern two thirds of the area, VFR
conditions are expected to prevail throughout the period with
surface high pressure dominating. Northwest to west winds should
generally remain light and out of the west through around 10Z this
morning, before increasing to around 7Kts by around 15Z today. The
clouds should begin to scatter out by 16Z or so at LOZ and SME,
with BKN middle level clouds persisting everywhere else.




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