Area Forecast Discussion
Issued by NWS Jackson, KY

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778
FXUS63 KJKL 151532
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1032 AM EST Thu Feb 15 2018

.UPDATE...
Issued at 1033 AM EST THU FEB 15 2018

A few isolated showers are started to exit eastern Kentucky with a
lull in precipitation expected into this afternoon. Additional
showers could push through areas north of the Mountain parkway
later on today, but moisture and lift is limited through 00z.
Thus, nothing more than isolated coverage is expected at this
time. Brought down pops across the board today and increased them
late tonight with rain expected to move south into the area with
the cold front. Winds will be gusty today with some wind gusts up
to 35 mph possible, especially in the Lake Cumberland region and
bluegrass counties. Should be just shy of our wind advisory
criteria, but may consider a lake wind advisory if winds get
strong enough. For now, going to stay put and wait to see how
things trend into this afternoon.

UPDATE Issued at 657 AM EST THU FEB 15 2018

Overall forecast is on track so far this morning. Llvl moisture
in place is keeping ongoing drizzle and light rain showers across
portions of eastern Kentucky this morning. Expect light precip to
continue through much of the morning, which is already reflected
in the ongoing forecast. The current combination of cloud cover
and precip is keeping temperatures mild and rather steady, so not
much to update in the forecast compared to the ongoing conditions.
Loaded in the latest observations for winds into the near term
forecast as well, which were a bit lighter than forecast, though
off and on gusts are ongoing. Expect that as we continue to head
into the daytime over the next couple of hours, these SW winds
will start to pick up and get more in line with the forecast.
Still expecting gusts between 20 and 30 knots in some locations by
this afternoon.

&&

.SHORT TERM...(Today through Friday)
Issued at 439 AM EST THU FEB 15 2018

Southwest flow and a warm front located just to our north has
allowed for warm moist air to continue making its way into the
state. Most of this moisture is confined to the llvls, leading to
patchy light rain and drizzle across much of the CWA this morning.
Based on the latest NAM12 forecast soundings, this llvl moist layer
could remain in place through much of the day and result in light
precip chances, so kept in 30 to 40 pops across much of the CWA. By
this afternoon, as temperatures peak near 70 degrees, some drier air
will work in near the surface in the south, but clouds will remain
in place here. Any drying will be short lived, however, as our
attention turns north of Kentucky. A surface low pressure system
will be tracking northeast just north of the Ohio River this
afternoon, making its way into New England by tonight. From this low
pressure system will span a cold front, which is expected to reach
the Ohio River during the first part of the overnight tonight, then
quickly transitioning southeast across the CWA during the overnight
hours, finally exiting Friday morning.

The global models are in better agreement about the precip
associated with this cold frontal passage, though there is still
some discrepancies about the amount of QPF. There is less agreement,
however, in the CAMS for both extent and placement. Sticking with a
blend of both CAMS and global models, this shows precip starting to
impact our northern CWA by this afternoon. A band of moderate to
heavy rain is expected to set up along and just ahead of the cold
front overnight, aided by the moist SW flow in place. It appears
that the heaviest rainfall associated with this band will remain
along the Ohio River and points north overnight, with Fleming county
probably seeing the highest rainfall for our CWA. As the frontal
system transitions SE into our CWA we will lose some of the highest
QPF tonight into Friday, though moderate to heavy rainfall at times
is still expected across the region 0.75. While Fleming county could
see around between 0.75 and 1 inch from this afternoon through the
first part of Friday, the rest of the CWA is expecting generally
between half an inch and 3 quarters of an inch.

Given the ongoing flooding concerns across eastern Kentucky over
past days, it is possible that this rainfall, especially during
heavier showers, could lead to further isolated flooding concerns.
However, the heaviest rainfall with this system will be affecting
the far northern CWA, which was the least affected from this last
event. And elsewhere, 0.75 inches or less of rainfall throughout the
course of a day is not going to be enough to really impact most of
the rivers or cause widespread flooding/flash flooding concerns. ILN
did decide to go with a flood watch north of us, joining the ongoing
flood watch by RLX, but they will also be in the heavier axis of
rain. Given the above mentioned conditions, did not think impacts
would justify issuing a flood watch for our CWA, so opted out.

The cold front will quickly shift southeast of the CWA by Friday
afternoon, with drier northerly flow taking hold at the surface.
This will effectively cut off the moisture flow into the region, and
subsequently the precip chances as we head into Friday evening.
Highs on Friday will be much cooler than that of today, generally in
the 50s across the board.

.LONG TERM...(Friday night through Wednesday)
Issued at 535 AM EST THU FEB 15 2018

An overall wet and mild period is expected. A generalized upper
trough should persist over the western CONUS, with flow over the
southeast CONUS tracing back to the subtropical east Pacific. In
the lower levels, Gulf of Mexico moisture will make periodic
surges northward.

One such intrusion will be on the way out at the start of the
period as a cold front sinks through the southeast CONUS. A few
light showers could be lingering into Friday evening in the
southeast part of the forecast area, but will give way to dry
weather as high pressure passes by to our north on Friday night.
The front and overrunning moisture will make a push back to the
north on Saturday as a broad low amplitude trough passes through
the upper level flow. This will bring another round of rain. It
will already move out on Saturday night, and dry weather will make
another brief return for Sunday. The longwave pattern amplifies
early in the week, and northward flow off the Gulf increases
again. This will bring another potential for rain Sunday night
into Monday. The amplified pattern will result in another cold
front slowly pushing across KY Tuesday and Wednesday, with still
more rain potential. Heavy rainfall can`t be ruled out with some
of these episodes, but there is a lack of confidence as to
when/where it would occur.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 702 AM EST THU FEB 15 2018

TAF sites are varying between IFR and MVFR this morning, with off
and on light rain showers and drizzle being reported at most
sites. Expect these conditions to persist through the first part
of the day at least. Gusty SW winds will be picking up throughout
the morning, with 15 to 25 knots possible across all TAF sites
by this afternoon. A cold front will approach the region from the
NW late this afternoon, reaching the Ohio River and quickly tracking
SE across eastern Kentucky overnight, before exiting Friday
morning. This frontal system will bring widespread rainfall to
northern Kentucky by this evening, spreading southward overnight.
Rain could be moderate to heavy at times, causing VIS to possibly
fluctuate in and out of categories. Given uncertainty this far out
of exact timing and impacts, will keep with MVFR mention for now.
CIGS should remain MVFR during this time, though some IFR could
occur at times as well. Winds will continue to be gusty
throughout the night, becoming more Wrly by the end of the
forecast period.

&&

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

$$

UPDATE...KAS
SHORT TERM...JMW
LONG TERM...HAL
AVIATION...JMW



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