Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 230203
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
903 PM EST Mon Jan 22 2018

.Forecast Update...
Issued at 900 PM EST Mon Jan 22 2018

Most of the cells across the region are not bringing down stronger
winds, with just a few showing pea-sized hail and one that got tall
enough for a warning.  The back edge of the precip is where the
strongest winds have been so far this evening, with gusts around 50
mph at FTK, SDF, and LOU in the last hour. There must be just enough
of a mix down occurring along that back edge to allow some of the
stronger winds aloft to get down to the surface. Otherwise, the
automated gauges and Kentucky Mesonet sites are not showing stronger
winds at this time. Will have to continue watching storms along this
back edge for any rotations, as that would bring a better chance to
get it to the surface.

Issued at 655 PM EST Mon Jan 22 2018

Line of showers and a few thunderstorms embedded forming a little
farther west than the HRRR anticipated. The NAMNest, which has been
doing a great job in the near term the last several weeks, has
picked up on the location better, and thus have leaned toward this
model in the near term, as well as current observations from radar.
Environment appears supportive for some low-topped supercells, and
have seen a couple form along our western forecast area, near
Lewisport, KY and Tell City, IN. Have seen some good rotation with
these storm, and will continue to monitor trends. Otherwise, seeing
wind gusts of 30-40 mph out there, and we may see a few storms with
stronger gusts the rest of this evening.

&&

.Short Term...(This evening through Tuesday night)
Issued at 301 PM EST Mon Jan 22 2018

...Gusty Showers Expected This Evening...

GOES East imagery shows an impressive and mature cyclone over the
upper Midwest. Today`s widespread rainfall associated with the warm
conveyor portion of the cyclone has continued to weaken as it pushes
east, however still expect everyone to get some rain so likely to
categorical pops continue east of I-65 for another couple of hours.
The focus then shifts back to the west as an impressive dry slot
begins to work into western KY. Hi-res models have been pegging
redevelopment of showers (and perhaps an isolated T) somewhere along
or W of I-65 late this afternoon and early this evening. This would
occur as the approaching cold front (still back over the mid
Mississippi River Valley) combines with exit region dynamics to kick
of sct-numerous showers. Given that the low level jet will still be
around 45-50 knots, worried that the steepening lapse rates will
help some stronger gusts get down to the surface with the showers.
At this point, thinking some Special Weather Statement worthy gusts
of 40+ mph are possible. Still not all that confident on exactly if
the showers will redevelop to the magnitude that the HRRR shows, but
if they do am more confident that we will see some pretty healthy
gusts. Think this would be better handled by short fused SPS`s than
any Wind Advisory product given the expected convective and short-
lived nature. Still, synoptic winds outside of any showers could
still gust up to 35 mph through the overnight.

Later tonight, low level moisture associated with the comma head of
the mature cyclone moves into our CWA, with deep enough moisture to
squeeze out some measurable light showers and sprinkles, mainly
across our northern CWA. Temps fall off into the upper 30s and low
40s through Tuesday morning, but think thermal profile stays warm
enough for rain. As we move deeper into the day on Tuesday, will
continue to keep low chances for a measurable shower and/or
sprinkles. Also think we could see a few ice pellets mix in given
some positive area (steep low level lapse rates) extending well
above the freezing level.

Low level moisture still looks to linger into Tuesday night where
temp profiles begin to be cold enough to possibly support some
flurries. Lows should drop into the mid and upper 20s.

.Long Term...(Wednesday through Monday)
Issued at 301 PM EST Mon Jan 22 2018

Wednesday - Friday...

A secondary shortwave will slide through on Wednesday. Low level
moisture should remain trapped through this time, so added ascent
from the passing shortwave could be enough to kick off some
continued flurries or sprinkles. Will keep a dry forecast (from a
measurable standpoint) but may have to mention chances for a
sprinkle or flurry through Wednesday night. Highs should struggle
into the low 40s.

Dry NW flow aloft and surface high pressure will then dominate
through Thursday night, keeping us dry with steadily moderating
temperatures. Highs by Thursday will be in the upper 40s to low 50s.
After Wednesday night lows in the mid 20s, Thursday night lows
should trend milder to around freezing.

Progressive upper ridge axis slides through on Friday, and will
bring another dry and warmer day. Look for highs in the mid 50s.

Friday Night - Saturday Night...

Models have trended less amplified and faster with the weekend
system, which will bring shower chances in by Friday night. The bulk
of the rainfall should be on Saturday as deeper moisture pools ahead
of the upper trough axis, along the surface cold front. Given the
faster and less amplified trend, it`s going to be harder for any
cold air to catch up to lingering moisture on the back side of the
system. So, think a mostly rain forecast is still the way to go.
After a milder Friday night in the mid 40s, Saturday highs will also
be in the mid 50s, with temps falling off Saturday night behind the
front.

Sunday - Monday...

Dry NW flow and surface high pressure then control for the remainder
of this forecast cycle. Slightly cooler temps take hold with lows
just below freezing and highs in the 40s.

&&

.Aviation...(00Z TAF Issuance)
Issued at 620 PM EST Mon Jan 22 2018

Have some pretty gusty winds out there now, as a potent low pressure
system drags a cold front across the region. Also seeing a few
showers pop up with some isolated thunder. This rain will not last
long, but we could see some gusts to 35 knots either with or without
the rain. A clear slot will come behind these showers before we
should get socked in with lower clouds by daybreak Tuesday. For now
time-height sections indicate these should stay MVFR, but that they
should persist through the rest of the day. Wind gusts will persist
through the period as well.


&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&

$$

Update...RJS
Short Term...BJS
Long Term...BJS
Aviation...RJS



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