Shelbyville, Kentucky 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

790
FXUS63 KLMK 211156
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
656 AM EST Thu Nov 21 2024

...Updated Aviation Discussion...

.KEY MESSAGES...

*  Snow showers will be possible this morning through Friday
   morning. The best chance for any local minor impact will be from
   southeast Indiana to the Bluegrass region of Kentucky.

*  Gusty winds today through Friday, with some gusts around 30 to 35
   mph. The strongest gusts likely today.

*  Gusty winds during snow showers will likely result in brief
   periods of reduced visibility.

*  Much colder weather today and Friday with wind chill values in
   the 20s and 30s.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 333 AM EST Thu Nov 21 2024

Our first real taste of winter is expected today through tonight. As
an upper low currently over the Great Lakes and its associated sfc
low bring snow showers to the area, especially from late afternoon
into the evening hours. The strong upper low is currently over the
Great Lakes and will work to the southeast across the Ohio Valley
towards the Mid-Atlantic coast by tomorrow morning. Deepening 994mb
sfc low currently over the far northern tip of the Lower Peninsula
of MI will rotate southward around the upper low along Lake Michigan
and into central/southern IN this evening and overnight before
phasing out as a new sfc low develops over Long Island. This will
send a couple of embedded shortwaves through the area. The first one
will arrive this morning right around daybreak. This one is the
weakest of the two and will likely produce just a few light snow
showers/flurries given the relatively shallow moisture layer between
850-700 mb. Snow seems to be the primary precipitation type given
the current CAA over the area this morning and today. A good portion
of the shallow moisture layer is within the DGZ. Other than seeing a
fine dusting on roofs and other elevated surface from Madison, IN
into the northern Blue Grass (Georgetown, Cynthiana, Carlisle, etc.
temperatures will be too warm at the surface for any real impacts
from this initial wave.

Winds will increase as the aforementioned sfc low drops south over
Lake Michigan and tightens the pressure gradient over the region.
Mixing due to the CAA will also help to enhance some gusts to
between 25-35 mph. This will add to the impacts of the light snow by
causing reduced visibility. The gusty winds will make it very
blustery with wind chill values feeling like they are in the 20s.

After a lull in the precipitation this afternoon, the second and
stronger of the shortwaves will dive into the area late this
afternoon and early evening. Steepening lapse rates in the CAA and
good saturation through the column into the DGZ will increase the
snow showers over the area from around 4pm to 7pm EST coming in from
the north to the south. While road and ground temperatures are above
freezing and surface temperature will hover above to around freezing
later this evening and overnight, went ahead and issued a Winter
Weather Advisory for the Blue Grass and up into Jefferson Co, IN.
This will go into effect later this afternoon and continue
overnight. Overall impacts are minimal, but given that this is our
first snow of the season and we could have a few moderate to heavy
snow showers heading into the evening commute along I-64, I-75 and
the Lexington Metro. Decided a Winter Weather Advisory was
warranted. Winds will also be gusty adding to potential travel
hazards from reduced visibility from blowing snow. Locations within
the advisory will likely see snow accumulations of around an inch
with a few locations getting upwards of 2 inches. The main challenge
will be the above freezing ground and surface temperatures. Areas
outside of the Winter Weather Advisory should expect to see a slushy
accumulation of a half inch or less, mainly along and east of I-65.

Snow will start to taper off from north to south after midnight with
a few lingering flurries by morning. Wind gusts around 20 mph are
still possible and with lows overnight around or even a few degrees
below freezing, wind chill values will be in the low/mid 20s to
start the day on Friday.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 333 AM EST Thu Nov 21 2024

By Friday morning, most of the snow fall will be ending with only
flurries lingering across portions of southern Indiana and the
Bluegrass Region. As the upper low slowly edges eastward, wrap
around moisture will result in another cold and cloudy day of light
rain and drizzle with afternoon highs only reaching the mid 40s.

Rain will end early Saturday across the Bluegrass Region as high
pressure builds in across the Gulf States and northward into the OH
Valley. Upper ridging will erode quickly as shortwave passes through
the Great Lakes, resulting in zonal flow across most of the US. Dry
and cool conditions are expected for the weekend with morning lows
in the 30s and highs in the 50s.

Aforementioned zonal flow aloft will allow for unsettled weather
next week as multiple shortwave disturbances propagate through the
large scale pattern. Monday will see a shortwave move across the
Great Lakes inducing a SWrly 40-45kt LLJ over the Commonwealth, as
subsequent lift taps into abundant Gulf moisture ahead of a cold
front pushing in from the west. NCEP IVT shows an impressive stream
of moisture over the OH Valley, as PWATs around 1.30" surpass the
90th percentile of sounding climatology. So, expect a wet beginning
to the work week with showers and possibly a rumble of thunder
across south central KY. Resultant WAA from southerly flow will push
afternoon temperatures into the low to mid 60s.

Confidence begins to decrease moving into the mid week timeframe as
global models begin to diverge in solutions. Using a blend of
models, it appears we`ll experience a lull in rainfall Tuesday
before showers return Wednesday into Thursday. Temperatures will
also fall behind Monday`s cold FROPA, with morning lows potentially
falling to the upper 20s and low 30s by mid to late week. This
forecast continues with rain as the main precip type, but model
soundings are showing saturation within the DGZ. So we`ll be keeping
a close eye on whether or not more snow is in store later next week.

&&

.AVIATION /12Z TAFS THROUGH 18Z FRIDAY/...
Issued at 655 AM EST Thu Nov 21 2024

The first of two shortwave disturbances are working into the area
with mid-level CIGS already coming in for HNB/SDF. Light snow was
also being reporting upstream across central IN at BMG. With this
first wave, we could see some light rain or even light snow but
temperatures will be above freezing. Could see a brief period of
MVFR for CIG of VIS but right now snow confidence this morning is
not that high with this first wave. Winds will continue to increase
and become gusty. Gusts of 20-25kts are possible with even some
higher gusts mainly out of the west. This is in response to the sfc
low currently over Michigan dropping south and tightening the
pressure gradient over the area. Wave number 2 will arrive around 20-
23z this will have a much bigger impact with CIG becoming IFR below
1000ft and even periods of heavy snow bringing VIS down to 1 to 3
miles, especially for SDF, LEX, RGA. Winds will also remain gusty.
Snow is expected for several hours before diminishing from the north
to the south. Might see a return to MVFR into the early morning.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Winter Weather Advisory from 4 PM this afternoon to 7 AM EST
     Friday for KYZ031>037-039>043-047>049-055>057-066-067.
IN...Winter Weather Advisory from 4 PM this afternoon to 7 AM EST
     Friday for INZ079.

&&

$$

SHORT TERM...BTN
LONG TERM...CG
AVIATION...BTN