NWS Area Weather Forecast Discussion
Louisville, KY

FXUS63 KLMK 040023

Area Forecast Discussion
National Weather Service Louisville KY
723 PM EST Thu Dec 3 2020

.Forecast Update...
Issued at 715 PM EST Thu Dec 3 2020

Light band of precip associated with weak warm advection and a sfc
trof now pushing across central Kentucky.  We`re just cool and dry
enough to be mixing in a few pellets of sleet or graupel at the
onset of precip, based on ground truth reports and some bright-
banding noticeable on radar. Expect any mixed precip to be brief,
and temps are warm enough that it won`t be impactful. Have issued a
Special Weather Statement to highlight the potential for a brief
period of sleet/graupel. Otherwise the forecast remains on track.


.Short Term...(This evening through Friday)
Issued at 300 PM EST Thu Dec 3 2020

A mid-level low pressure center is slowly advancing eastward from
the Oklahoma/Missouri border. While at the surface, a low pressure
trough, ahead of the mid level low, is following the Mississippi and
Ohio River Valleys northward. This trough is giving moisture a
channel to be isotropically lifted, and as the system moves east, the
CWA can expect increasing low level moisture which will result in
lowering clouds and rainfall. A few radar returns have already moved
over parts of the area, but with dry low levels, virga resulted.

The better rain chances will begin to move into the southwestern
parts of the CWA around 0z tonight. The heaviest rain will arrive
after 6z and slowly work its way east out of the area tomorrow
evening. Areas east of Interstate 65 and south of the Kentucky
Parkways are expected to see the most rain. Overall, this will be a
light rain event with many in southern Indiana and around Louisville
seeing less than a tenth of an inch total. Areas near Clinton
County, Kentucky will do much better as they are expected to see
close to an inch.

.Long Term...(Friday night through Thursday)
Issued at 245 PM EST Thu Dec 3 2020

Rain showers will begin tapering off Friday evening as our system
pushes eastward. It appears at this time that the cold air will lag
behind just enough to prevent any wintry precipitation from
developing, so currently advertising just a cold rain to wrap
things up.

Dry conditions should persist through the weekend as high pressure
builds in from the west. We could see some very isolated, light
showers develop late Sunday into Monday as a fast moving clipper
diving out of Canada interacts with a slow moving upper level low
that will push from the southern Plains into the Tennessee Valley. A
few models depict some light QPF falling ahead of these systems, but
a quick look at forecast soundings shows very little moisture in the
column, and most of it reserved to the lowest 2km. Should
precipitation develop, temperature profiles could be cold enough to
support something wintry, but with moisture lacking, any
accumulations would be minimal.

Flow aloft will remain northwesterly through much of the early and
mid parts of next week and generally devoid of any fast moving
clippers or systems beyond Monday. As a result, expect dry
conditions to end the period, with some slight warming as an upper
level ridge begins to advance toward the region.


.Aviation...(00Z TAF Issuance)
Issued at 635 PM EST Thu Dec 3 2020

Low-level saturation is just getting underway with very light rain
falling out of a mid-level ceiling at SDF and BWG. Once this initial
warm advection wing moves through, look for a dry period before the
low-level jet punches up into BWG and LEX after midnight.  Greatest
operational impact will be ceilings dropping into IFR and staying
there for at least the morning. By mid-afternoon, the upper low
pushes into the Tennessee Valley, shunting the best moisture feed
off to the east, with winds picking up out of the west and ceilings
recovering to MVFR. However only HNB will come up above 2000 feet
Friday afternoon.

SDF will stay VFR with light winds for much of the night, but cigs
will drop into MVFR just before daybreak Friday and go below 2000
feet by mid-morning. Fuel-alternate conditions will persist at SDF
until around sunset, then lift to VFR.




Short Term...KDW
Long Term...DM

Forecast Discussion from:
Script developed by: El Dorado Weather
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