717
FXUS63 KLMK 150844
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
344 AM EST Fri Nov 15 2024

.KEY MESSAGES...

*  Dry but mostly cloudy Friday with slightly below normal
   temperatures.

*  Dry/quiet weather expected over the weekend with a moderation in
   temperatures.

*  Another system will bring a chance for rain/storms on Tuesday. A
   transition to a cooler pattern is expected for mid-late next
   week, with increasing confidence in well below normal
   temperatures late next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 344 AM EST Fri Nov 15 2024

The upper low from yesterday`s system is now moving off the mid
Atlantic coast. Meanwhile, progressive upper ridging and surface
high pressure will slowly build into our area through tonight. In
many cases, this type of pattern would yield sunny or clear
conditions, however this won`t be the case in the short term due to
some trapped low level moisture beneath an inversion.

Current nighttime microphysics satellite imagery shows an expansive
stratus deck over much of the Great Lakes region and eastern CONUS.
Time heights also captures the trapped 1000-850mb moisture, although
do vary on just how long the clouds expected to stay across the
area. Generally like to look for thermal ridging in the 1000-850mb
layer to signal hope for some clearing, and best chance for this to
occur would possibly be late afternoon west of I-65. Models show
some potential for clearing there, however any clearing would likely
result in broken stratocu quickly filling back in. As a result, not
very optimistic in a whole lot of sun today, and seeing a consistent
signal for steady N near surface winds confirms that stratus is
likely to persist. As a result, like the idea of another day with
very small diurnal trends. In other words, went below guidance for
today`s highs, and will go milder than most guidance for tonight`s
overnight lows. Have Max T`s in the low to mid 50s, and overnight
lows in the low to mid 40s. Also, hanging onto some patchy drizzle
chances mainly across the NE half of the CWA at least for the first
half of today where the low level moisture remains just deep enough
to squeeze out some liquid. Won`t carry any measurable pops, but do
like the idea of drizzle mention.

The last thing worth mentioning would be a conditional fog threat
for later tonight into Saturday morning. This would only be possible
if we clear out by tonight, and since confidence isn`t high in that
happening, have decided not to carry in the forecast at this time.
If clearing does end up happening, then could end up with a
potential dense fog scenario given the recent widespread heavy
rainfall combined with excellent radiational cooling conditions.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 344 AM EST Fri Nov 15 2024

Saturday through Sunday Night...

An amplified upper level pattern will be in place across North
America during the coming weekend, with troughing across the western
half of the continent and ridging over the eastern half. At the
surface, a meridionally oriented high pressure will start the
weekend over the Ohio Valley and is expected to gradually move east
over and east of the Appalachians by Sunday afternoon. The initially
phased trough out west will split over the weekend as a leading
northern stream wave ejects into northern Ontario while the southern
stream wave digs near the Four Corners region. While the northern
wave will force the development of a sfc disturbance over Ontario
and the Great Lakes, high pressure is expected to remain in control
over the southeastern U.S. through the weekend.

As far as sensible weather is concerned over the weekend, there is
some uncertainty as to how long sfc-850 mb moisture will linger.
With the H85 ridge expected to pass across the region on Saturday,
low-level warm advection should assist in clearing out clouds by
Saturday afternoon. Temperatures Saturday will be dependent on how
quickly we clear out, with low-mid 60s expected for highs across
southern KY while values should range from the mid 50s to near 60
across northern KY and southern IN. With the H85 ridge over the
Appalachians on Sunday, low-level SW flow should help send
temperatures higher. While there will be upper level cirrus on
Sunday, would expected uninhibited warming leading to highs ranging
from the mid 60s to around 70 in most places.

Monday and Tuesday...

As we head from the end of the weekend into early next week, the
southern stream upper wave will begin to eject to the northeast,
with most progs having the system track from extreme west TX Monday
morning to the upper Mississippi Valley by Tuesday afternoon. Sfc
lee cyclogenesis will take place over the southern Rockies early
Monday, with this sfc low moving quickly across the Plains and into
the upper Midwest by Tuesday, occluding over western MN on Tuesday.
Ahead of the sfc low track, strong southerly flow will draw moisture
northward across the Mississippi Valley, though this fetch of
moisture should largely remain west of our area on Monday. However,
as the remnants of a cold front from the northern stream wave
approach the Ohio Valley Monday morning, some of the moisture over
the southern Plains and Ozarks could get stretched eastward, with
clouds expected to increase Sunday night into Monday. While a stray
shower cannot be ruled out across southern IN Sunday night into
Monday morning, most locations should remain dry into Monday
evening. Temperatures will remain above normal on Monday, with highs
remaining in the mid 60s to around 70.

Monday night into Tuesday, as the upper low cuts well to the
northwest of the region, an arcing sfc boundary is expected to move
across the Mississippi Valley, reaching our area during the morning
hours on Tuesday. Showers and thunderstorms are expected to develop
along this boundary well west of our area on Monday, with convection
expected to continue as it moves toward us. However, there is some
suggestion (particularly in the GFS) that the dry conveyor belt will
bisect the better dynamics to the north and better
moisture/instability to the south, limiting precipitation potential.
Also, while the setup is not particularly favorable for significant
severe weather, strong storms cannot be ruled out, with a weak
signal continuing in latest CSU machine learning probabilities.
Behind this boundary, temperatures will not cool off immediately,
with current progs actually showing next Tuesday as the warmest day
in the extended period.

Mid-to-late Next Week...

With the most recent suite of guidance (15/00Z), there has been some
forecast convergence, with the ECMWF solutions trending toward the
GEFS/GEM ensembles for mid-late next week. This suggests a
faster/more east-based trough, bringing cooler air into the region
Wednesday into Wednesday night. Blocking over the north Atlantic
will allow for amplification of an upper level trough over the
eastern CONUS next Wednesday into Thursday, with the upper trough
expected to bring cool and damp weather to the Ohio Valley for much
of the second half of next week. Thermal profiles continue to look
marginal for any kind of wintry precipitation, with a warm near-sfc
layer limiting snowfall potential in spite of unusually cold
temperatures aloft. In general, below normal temperatures with
breezy and showery conditions would be expected for the latter part
of next week.

&&

.AVIATION /06Z TAFS THROUGH 12Z SATURDAY/...
Issued at 1232 AM EST Fri Nov 15 2024

Impacts/Confidence:
- High confidence in MVFR or lower ceilings through much of today.
- Medium confidence in IFR ceilings/timing early this morning at
LEX/RGA/HNB.

Discussion...Lingering low level moisture trapped beneath an
inversion will lead to an extended period of MVFR ceilings overnight
and through much of the day. A period of IFR ceilings does look
likely at LEX, HNB, and RGA, mainly between 06-15Z (confidence in
exact timing of IFR is slightly lower). Ceilings are forecast to
gradually improve from west to east later this afternoon and
evening. Light NW, then N, and then NE winds are expected through
this forecast cycle.

&&

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

&&

$$

SHORT TERM...BJS
LONG TERM...CSG
AVIATION...BJS