472
FXUS63 KLMK 051700
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1200 PM EST Thu Nov 5 2026

...Updated Aviation Discussion...

.KEY MESSAGES...

* Areas of frost are expected Friday night, with freezing conditions
  possible (20-30% chance) over southern Indiana. A more widespread
  freeze is forecast Saturday night.

&&

.DISCUSSION...
Issued at 309 AM EST Thu Nov 5 2026

*** PATCHY FOG EARLY THURSDAY MORNING ***

At 245am Thursday morning, clouds are gradually pushing east of the
I-65 corridor as drier air attempts to work its way into the region
behind a weak cold front. This has allowed patchy fog to develop in
rural, low-lying areas where light winds have permitted temperatures
to sink like a rock - into the mid 40s in spots. I lowered
temperatures and added some patchy fog to the forecast through 8am
to account for this, but it should quickly dissipate thereafter as
surface heating eradicates PBL saturation. Also helping disperse any
residual morning fog will be increasing winds which mixing
techniques via Bufkit forecast soundings suggest may gust up to 20
mph late morning into the afternoon across northern Kentucky and
especially southern Indiana. Temperatures this afternoon will climb
into the low to mid 60s, which, though cooler than we`ve become used
to recently, is near normal for early November in the Bluegrass
state.

*** FROST AND FREEZE THIS WEEKEND ***

Cloud cover will increase again from the north tonight into tomorrow
morning as a cold core low dives southeast towards the area.
Consequently, highs will run a few degrees cooler tomorrow,
particularly across areas near and north of the I-64 corridor where
the Rapid Refresh Ensemble Forecast System (REFS) mean brings 850mb
temperatures to < -2 degC. In addition, the RAP shows 0-1km RH >
90%, light QPF, and a 0% probability of cloud ice tomorrow morning
into the early afternoon - implying we may see some patchy drizzle,
if not true rain showers over the Bluegrass where weak diurnal
instability will develop by early afternoon. Highs in the upper 50s
to low 60s will give way to Saturday morning lows in the 30s -
coolest over southern Indiana where clouds should depart by
midnight, allowing patchy frost to form.

Cool advection will continue through the day on Saturday, confining
highs to the 50s despite partly to mostly sunny skies. Then, with
enough clearing, Saturday night lows will take a sharp dive,
particularly with high pressure settling over the area to promote
light-calm winds. The result will be area-wide frost and in some
locations, a freeze. NBM probabilities for sub 32 degF lows are
highest (60-90%) along two corridors: one over southern Indiana west
of the Louisville Metro, and another across the Bluegrass. It is
this second area where a hard freeze may also be achieved, primarily
in low-lying rural areas; NBM probabilities for such (< 28 degF)
temperatures are 30-50%. While the horticulture growing season is
over, such freezing temperatures promote prussic acid formation in
certain plants - suggesting possible livestock impacts in the
absence of protective action. As a result, we will likely need
frost/freeze headlines to highlight this potential beginning
tomorrow night and again on Saturday and/or Sunday nights.

Dry and mild weather is expected going into next work week, with
afternoon highs in the 60s following crisp mornings in the 30s.

&&

.AVIATION /18Z TAFS THROUGH 00Z SATURDAY/...
Issued at 1200 PM EST Thu Nov 5 2026

VFR conditions are ongoing this afternoon across the region. A weak
cold front is expected to arrive tomorrow, though precip chances
remain below 20%. Biggest impact with this frontal passage will be
lowering cigs, which are forecast to drop to MVFR for all terminals
during this forecast period. Expect lowering cigs first at HNB by
09z tomorrow morning, followed by SDF, then LEX/BWG and then finally
at RGA by 16z. For the extended SDF forecast, should see VFR return
by tomorrow afternoon beyond 18z. Otherwise, sfc winds will switch
around from a SW flow today to a NW flow behind the front tomorrow.

&&

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

&&

$$

DISCUSSION...JRB
AVIATION...CJP