Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 181845 AAC
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
145 PM EST Sun Feb 18 2018

.UPDATE...
Issued at 112 PM EST SUN FEB 18 2018

Hourly grids have been freshened up based on recent observations.
This led to no substantial changes at this time.

UPDATE Issued at 1125 AM EST SUN FEB 18 2018

Surface and upper level high pressure will remain in control of
the weather today. A few fair weather cumulus will be present
through early to mid afternoon until the low levels dry out
further, with high clouds increasing late ahead of a warm front. A
window of clearing and light winds should support decoupling of
eastern valley locations and development of a nocturnal inversion.
A moderate ridge/valley split in low temperatures late this
evening should occur with min T near midnight for eastern valley
locations. Although COOP MOS lows are probably a bit too low, min
T should easily fall below blended guidance for tonight. It also
appears that showers should generally hold off until the 4Z to 6Z
period for the southwest part of the area and then spread
northeast as a warm front approaches. Adjustments to pops for
timing trends have been made accordingly.

UPDATE Issued at 626 AM EST SUN FEB 18 2018

The forecast is looking good so far this morning. The latest obs
were ingested into the hourly grids to establish new trends. No
update is planned at this time.

&&

.SHORT TERM...(Today through Monday)
Issued at 303 AM EST SUN FEB 18 2018

A ridge of high pressure will keep the weather across eastern
Kentucky dry today. Winds should be generally light and variable
with partly cloud skies on tap as well. The weather will become
wet again tonight, as an area of low pressure moving northward
through the Great Plains, drags a warm front across the Tennessee
and Ohio Valley regions. The rain should begin around 0Z tonight
and will likely be coming to an end by late Monday afternoon.
Rainfall amounts should be light, so no flooding issues are
anticipated from this rainfall. Temperatures are going to be well
above normal in the short term, as strong southerly flow along the
west edge of a strong area of high pressure sets up across the
region. Highs are expected to be in the mid to upper 50s today,
and in the lower 70s for Monday. Tonights lows will only fall into
the mid to upper 40s for most locations.

.LONG TERM...(Monday night through Saturday)
Issued at 415 AM EST SUN FEB 18 2018

Similar to last night, the models are in pretty good agreement
with the overall longwave pattern aloft through the extended as
they all depict persistent and strong ridging through the
southeast and troughing to the west. This sets up a near
continuous deep layer flow of warm and moist air from the
southwest direction - off the western Gulf - up through the Ohio
Valley. The ridge expands enough into the southern Appalachians
early in the long term to likely protect eastern Kentucky from
any impulses sliding by well to the north. This does change on
Wednesday, though, as the ridge retreats to the southeast in all
models with energy packets rolling east northeast along the Ohio
River. Clusters of energy will continue to use this route into the
upcoming weekend with Kentucky under the gun for the effects of
mid level waves strafing by the state from Wednesday on through
Saturday. More dissension is introduced into the models by the
weekend as the trough to the west comes east quicker and flatter
in the GFS than the ECMWF. However, for Kentucky there will be
little distinction in the pattern with southwest flow holding
pat. Given the overall model agreement will favor a blended
solution for the grids after accounting for local effects -
favoring the ECMWF for differences late.

Sensible weather will feature anomalous warmth through Wednesday
with the precip chances to the northwest during the bulk of this
time. Strong southwest flow will support unseasonable - record
setting (possibly for the entire month) - temperatures for the
area Tuesday and Wednesday. The sfc high pressure to the east
responsible for the summer-like temperatures will shift further
east on Wednesday allowing a cold front to move into the area and
stall out. In addition to a threat of periods of excessive
rainfall from this lingering boundary sfc based instability should
be enough for some thunder chances Wednesday into Wednesday
night. Surges of moisture will then seep northeast along the front
from Thursday through Saturday with more showers expected - though
indications are that the heavier rains will more likely
concentrate in locations closer to the Ohio River and just to the
north as the southeast high helps to shield eastern Kentucky from
the direct storm track for much of the time. We will need to
watch this situation, though, as plenty of moisture will fall and
should it be further south than anticipated flooding concerns will
be renewed and extended through the upcoming weekend.

Again made some significant adjustments to temperatures at night
for expected ridge to valleys splits Monday and Tuesday nights
along with Friday night. Did also tweak the PoPs through the
period to better match the 00z ECMWF surges late in the period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
ISSUED AT 125 PM EST SUN FEB 18 2018

VFR conditions will prevail across the region through 5Z as high
pressure departs to the east. A warm front will approach the area
this evening and move north of the area during the last 6 hours
of the period. High clouds will increase during the first 6 to 9
hours of the period with mid and low level moisture increasing
from around 3Z. Clouds will move into the area or develop at those
levels shortly thereafter with ceilings decreasing to MVFR in the
southwest near KSME around 6Z. This will gradually spread north
and east with at least 3 to 5 hours of MVFR CIGS and VIS
anticipated in rain showers at all locations through 12Z.
Ceilings should increase back to VFR from the south and southeast
as the warm front lifts north of the area during the last 6 hours
of the period. Winds should be generally 10kt or less through the
period, with higher sustained speeds and gusts above 2500 feet
near the VA border.

&&

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

$$

UPDATE...JP
SHORT TERM...AR
LONG TERM...GREIF
AVIATION...JP



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