923
FXUS63 KLMK 021742
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
142 PM EDT Sun Jun 2 2024

...Updated Aviation Discussion...

.KEY MESSAGES...

*   Shower and storm chances Sunday and each day Tuesday through
    Thursday. A few strong to severe storms may form Tuesday, with
    slightly better chances for a few severe storms later Wednesday.

&&

.UPDATE...
Issued at 142 PM EDT Sun Jun 2 2024

Current VWX radar continues to show scattered light rain showers
pinwheeling around the southern edge of a low pressure system
currently located over Indiana. Latest surface analysis reveals a
weak warm front stretching NW-SE across the Commonwealth with a cold
front draped along the MS River. Expect to see these conditions
persist until the low stratus advects to the east allowing for some
breaks in the clouds, currently evident on GOES-16 imagery over SW
Indiana. Once we get some breaks in the clouds, temperatures should
be able to meet or surpass convective temps, upon which we could
start to see isolated showers and thunderstorms begin to develop.
All of this is covered well by this morning`s forecast, with no
major changes needed at this time.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 313 AM EDT Sun Jun 2 2024

Weak sfc low will continue to push northeastward across southern
Indiana today and towards Lake Erie, with the upper shortwave
weakening by this evening. Scattered light showers will continue
within a weak WAA axis this morning, but overall rainfall amounts
will be manageable. A good amount of cloud cover will continue
through this morning, though southerly flow will still allow temps
to reach the low to mid 70s by lunchtime.

Model agreement has remained consistent for this afternoon, which
still calls for isolated to scattered pulse thunderstorms.
Temperatures will peak in the upper 70s and near 80 this afternoon,
which will help us realize marginal instability in a humid airmass.
We could actually see some breaks in the cloud cover this afternoon
as the upper wave shifts to our east, which would influence
differential heating boundaries to fire up some convection. HREF
paints the greater probability for SBCAPE over 1000 J/kg east of I-
65, which is where we will have the slightly higher PoPs this
afternoon. We`ll likely see an axis of 1000-1500 J/kg of SBCAPE
between I-65 and I-75 this afternoon. Model soundings show very weak
flow in the column, so storm motions will be pretty slow. With a
lack of shear, pop-up storms will be unorganized and short-lived,
likely collapsing on itself not long after towering up. Soundings do
show some dry air aloft, which could get brought down to the sfc.
Not expecting any severe storms, but perhaps we could get some
strong gusts under some storms later today.

Around or after sunset, any remaining convective activity will
dwindle with the loss of daytime heating. It`ll be a dry night as
upper ridging approaches from the west overnight. Expect another
normal night with temps in the mid-60s.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 313 AM EDT Sun Jun 2 2024

Monday - Thursday...

Looking for a mostly dry Monday/Monday night as a brief period of
upper ridging builds over the area. Deterministic models do try to
paint some light qpf in spots just ahead of the upper ridge axis,
but tend to lean on the majority of data and upper pattern
supporting a dry period. Highs on Monday should be notably warmer
and solidly in the mid 80s. Expect mild overnight lows in the
mid/upper 60s.

The upper ridge axis begrudgingly slides east on Tuesday, allowing
shortwave energy to try and impinge on our area from the west by
Tuesday afternoon and evening. Highs will likely reach mid to upper
80s given the mostly dry first part of the day. Forecast soundings
show a deeply moist and moderately unstable atmospheric profile
ahead of this next shortwave. Overall deep layer shear isn`t that
impressive, but suppose a few marginally organized updrafts would be
possible across our NW CWA. The majority of storm modes would likely
be more pulse in nature. Outside of any wet microburst threat, would
also be concerned about some locally heavy rainfall potential as
efficiency would be high and motion would be relatively slow.

The Wednesday/Thursday timeframe continues to be the most intriguing
of the long term forecast, at least with respect to strong/severe
storm chances. Anomalously strong troughing will develop
southeastward from central Canada down toward the Great Lakes region
through this time frame. As a result, a cold front extending from
this system is expected to move through our region sometime later
Wednesday into Thursday. Ahead of that cold front, forecast
soundings show us becoming strongly unstable, with increasing deep
layer shear in the NW flow regime over our area. Details on timing
are a bit lower confidence at this point given some inconsistency in
model timing, however the best chance for any strong to severe
weather would likely be later Wednesday afternoon into Wednesday
night. 02/00z GFS has a much slower cold front passage, and
redevelops storms on Thursday afternoon, but this seems to be on the
slow side of the guidance envelop for now.

Thursday Night - Saturday...

Lower confidence for the late week into the weekend timeframe. The
anomalous closed low is expected to remain quasi-stationary over the
northern Great Lakes region, and we`ll likely have a drier period
of post frontal and dry NW flow aloft setup. Will have to keep some
shower and storm chances in the forecast heading back into Saturday
as models disagree how far south the front makes it, and how much
southward influence the closed upper low has on our region. Overall
temps should be a bit cooler late week into the weekend as highs
fall back into he mid to upper 70s for most.

&&

.AVIATION /18Z TAFS THROUGH 00Z TUESDAY/...
Issued at 142 PM EDT Sun Jun 2 2024

Latest surface analysis reveals low pressure over Indiana with a
weak cold front stretching south across the TN Valley, while current
radar shows scattered showers moving generally west to east across
the region. Breaks in the cloud cover will allow for increased
diurnal heating, which will help spark additional showers and
possible thunderstorms this afternoon. AMDAR soundings out of SDF
continue to show light wind columns with meager lapse rates, which
adds to low confidence in thunderstorms. Tonight, expect winds to
slacken and clouds to clear leading to potential fog development by
early Monday morning. VFR conditions are expected shortly after
sunrise.

&&

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

&&

$$

UPDATE...CG
SHORT TERM...CJP
LONG TERM...BJS
AVIATION...CG