Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 170900

National Weather Service Jackson KY
500 AM EDT Wed May 17 2017

.SHORT TERM...(Today through Thursday)
Issued at 302 AM EDT WED MAY 17 2017

A ridge of high pressure will continue to be the primary influence
on the weather of eastern Kentucky today, tonight, and most of the
day on Thursday. Sinking air beneath the ridge will continue to
warm, bringing well above normal temperatures to the area the next
couple of days. Highs todays should easily top out in the mid to
upper 80s, and in the mid 80s on Thursday. Tonights low
temperatures will likely fall into the lower 60s in the valleys,
and in the upper 60s on the surrounding ridges. We may see a few
showers and storms popping up across portions of the area late in
the day on Thursday, as the ridge finally begins to break down
and an area of low pressure approaches from the Great Plains.

.LONG TERM...(Thursday night through Tuesday)
Issued at 500 AM EDT WED MAY 17 2017

The models are in fair agreement aloft through the extended period
of the forecast. They all depict ridging holding on over the
southeast parts of the nation as a lead, and now open, trough
lifts into eastern Canada on Thursday and another large and deep
closed one settles into the Southern Rockies. The model agreement
with this latter trough starts to suffer as the work week comes
to an end, though. They do agree that some energy manages to
break free and work east into the Ohio Valley during this time
while the CMC lags the other two main medium range models. The
energy will pass through Kentucky Friday into Friday night as the
ridging over eastern Kentucky further breaks down heading into
Saturday. The now open, full latitude trough will press further
northeast into the the Upper Midwest as the southeast ridge works
off shore. The bulk of the energy associated with the trough will
move into Kentucky on Sunday along with some moderate height
falls. Broad troughing then looks to be in place through Tuesday
- centered well to the north of the state. This whole process has
slowed with subsequent model runs so have trended that way as well
with this issuance, otherwise favored a general model blend to
account for the uncertainty without a clear trend.

Sensible weather will feature summer-like weather through the
first part of the weekend with warm temperatures and daily chances
for showers and thunderstorms as eastern Kentucky will be
generally in the warm sector of a large sfc lows to our northwest
for much of this time. We will need to watch the wiggles of a
frontal boundary that will be established itself just north of the
area through Saturday night. A cold front arrives on Sunday and
slowly moves through the CWA into Monday - slowest in the GFS
toward which the forecast was nudged. Cooler temperatures with the
rain on Monday will limit the instability so chose to keep
thunder out of the forecast after Sunday night. Seasonably cool wx
then sets up for Tuesday in the wake of the main system, though
another batch of pcpn will not be far away - likely inbound from
the west beneath the large trough settling into the area aloft.

Again made some adjustments to lows each night through Sunday
morning based on at least a small temp split between ridges and
valleys. As for PoPs, did continue to beef them up a bit more
from the SuperBlend for Sunday and Sunday night as model agreement
for this to be a time frame is fairly consistent - upping


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

VFR conditions are expected to prevail through the forecast
period. A few non TAF site valley locations may experience some
IFR or MVFR reductions due to fog through 12Z. However, crossover
temperatures at LOZ and SME suggest fog in those locations in not
likely, but cannot be completely ruled out briefly before 12Z. As
the axis of the ridge of high pressure moves east, winds aloft
will begin to increase with an increasing gradient especially in
the west. Therefore, some non-convective low-level wind shear
remains possible at LOZ and SME during the 8Z to 13Z period.
Otherwise, after light winds to begin the period, gradient winds
develop from the southwest reaching between 10 and 15 kt by 14 or
15Z this morning.




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