Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 070243

Area Forecast Discussion
National Weather Service Louisville KY
943 PM EST Fri Dec 6 2019

.Forecast Update...
Updated at 925 PM EST Fri Dec 6 2019

Sharp northern edge of the cloud shield is roughly along or just
north of Interstate 64, and making slow southward progress. Overall
forecast is on track, but have tweaked hi-res products for sharper
clearing overnight and a bit quicker rise in temps Sat morning.


.Short Term...(This evening through Saturday)
Issued at 250 PM EST Fri Dec 6 2019

A cold front continues to move south through central Kentucky
tonight. Behind the front, a line of low level clouds follows
overhead. Northeast winds, driven by post-frontal high pressure,
will stay between 5 to 10 mph. These winds advect temperatures in
southern Indiana down to the mid to upper 20s with areas in south
central Kentucky dropping to the mid 30s by morning.

Tomorrow to start the day, southern Indiana and north central
Kentucky will see mostly clear skies. It will take a little longer
to thin the clouds out of southern Kentucky. Winds will veer towards
the east as the surface high moves from northern Indiana towards New
England. Highs will reach the mid to upper 40s in southern Indiana
and the low 50s in southern Kentucky.

.Long Term...(Saturday night through Friday)
Issued at 230 PM EST Fri Dec 6 2019

Saturday Night - Sunday...

Dry and zonal flow will dominate the upper pattern for the latter
half of the weekend. Meanwhile, surface high pressure will retreat
off the mid Atlantic coast. Dry conditions will persist although a
notable S-SW wind will take hold. This will result in the slightly
milder temps on Saturday night, mostly in the mid to upper 30s. A
few of the typical cool and decoupled spots will drop into the low
30s. Increasing sky cover toward dawn will also help to keep temps
overall milder. Highs on Sunday will also be notably warmer given
the southerly flow. Look for most spots in the low to mid 50s. Winds
will be a bit gusty at times, but pretty heavy cloud cover should
limit deeper mixing potential a bit.

Sunday Night - Tuesday...

A subtropical impulse will nose into the area with good isentropic
lift overspreading the area on a 40 knot low level jet. Light rain
chances begin Sunday night, however will increase in coverage by
Monday morning with widespread steady rainfall lasting through the
day on Monday and likely into Monday night. During this time, an
impulse in the polar jet will quickly nose into the area, and phase
with the subtropical impulse helping to add a stronger
frontogenetical component. This looks to occur sometime later Monday
night into Tuesday, so will continue with likely chances for
precipitation at least into late Monday evening. Precipitation
coverage and intensity begins to diminish into Tuesday, however
enough lingering low level moisture may still be around to change
over p-type given the cold air coming in behind the system.

It is worth noting that winds look pretty gusty on Monday as surface
low pressure develops to our north. Overall, rain totals look to be
in the .5 to 1" range for the event with the higher totals expected
to be in the farther south and east you get. Temps will be quite
mild Sunday night on good southerly flood and plenty of cloud cover.
Temps will only drop to the 45 to 50 degree range. Temps should
surge into the upper 50s and low 60s on good warm advection. Did
include some small t-storm chances later Monday evening. Temps fall
off Monday night back into the 30s, with a raw day mainly in the 30s
for Tuesday.

Tuesday Night - Friday...

Canadian high pressure at the surface and zonal flow aloft will
dominate the region for the remainder of the work week. Expect dry
conditions and cold temps during this stretch. After Tuesday night
lows in the upper teens and low 20s, Wednesday highs likely don`t
make it above freezing in many spots. Wednesday night will be the
coldest as the surface high settles very near the region. Lows in
the mid to upper teens will be common.

Temperatures will likely remain in the 30s in most spots on Thursday
and then trend toward moderating by Friday.


.Aviation...(00Z TAF Issuance)
Updated at 622 PM EST Fri Dec 6 2019

Winds have come around to north at all the TAF sites, with post-
frontal stratus creating MVFR ceilings for SDF, LEX and HNB. Expect
the lower ceilings to spread into BWG by late evening as the cloud
shield progresses southward, but aside from LEX it should stay above
fuel-alternate. Even LEX only warranted a TEMPO for fuel-alternate
in the first couple hrs.

Skies will clear ever so slowly from north to south, with HNB
scattering out by mid-evening, SDF around midnight, but LEX will
hold on to stratus for much of the night.  BWG might not even
scatter out until after daybreak. Light N-NE winds overnight will
veer to easterly by morning.  Return flow and warm advection clouds
ahead of the next system will hold off even beyond the planning
period at SDF.




Short Term...KDW
Long Term...BJS
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