415
FXUS63 KLMK 010538
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
138 AM EDT Wed May 1 2024

.KEY MESSAGES...

*   Chance of fog tonight in the Lake Cumberland and Bluegrass
    regions.

*   Dry and warm Wednesday and Thursday with highs in the 80s.

*   Showers and thunderstorms likely Friday, with a chance of rain
    lingering over the weekend. Forecast confidence in detailed
    timing remains low.

&&

.UPDATE...
Issued at 916 PM EDT Tue Apr 30 2024

Sfc high centered just to our southeast will keep skies clear and
winds light overnight. Quiet and comfortably cool weather for the
overnight. The only concern for the overnight remains the
possibility of some fog from around the Lake Cumberland region
stretching into the Bluegrass and even along the KY/TN border by
morning. No changes have been made to the forecast at this time.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 328 PM EDT Tue Apr 30 2024

Currently, we have mostly zonal flow above with high pressure at the
surface. With a surface high sitting off to our southwest over
western Kentucky and extending down the Mississippi Valley, surface
winds are staying out of the northwest over southern Indiana and
central Kentucky through the rest of the day. Skies are clear over
much of Indiana, but scattered cumulus begins to increase across
southern Indiana and central Kentucky. Skies become broken and
overcast over eastern Kentucky. The clearing trend will continue
through the afternoon and evening hours.

Tonight, winds will go calm as the surface high passes east over the
CWA. Calm wind and clear skies will help increase radiative cooling,
resulting in fog in areas with high ground moisture. Believe the
best chance of fog will be over eastern Kentucky, but fog is
expected to extend westward through the Lake Cumberland Region
towards Bowling Green and into the eastern Bluegrass. Basically the
worst of any fog development is expected to remain along and
southeast of a line from Bowling Green to Lexington. Low
temperatures are expected to dip down into the low to mid 50s.

Tomorrow, on the backside of the surface high, winds will begin the
day out of the south, and as the high slides to the east, winds will
veer towards the southwest as they increase to 5-10 mph. Skies are
expected to remain dry for the most part, but as a weak cold front
approaches from the northwest early in the day, a few very light
showers/sprinkles could affect parts of southern Indiana before
dissipating. A near surface dry layer will also help to limit
precipitation from reaching the ground. Most areas will only see
some scattered mid-level clouds overhead from this front. Highs are
expected to reach the low to mid 80. A few on the eastern edge of
the CWA will likely only reach the upper 70s.

&&

.LONG TERM /TONIGHT THROUGH TUESDAY/...
Issued at 328 PM EDT Tue Apr 30 2024

========== Long Term Overview ==========

Mainly a zonal flow in the upper levels with lower level ridging
will be at play for Wednesday night and into Thursday. Sfc high
pressure will be centered somewhere to our southeast, which will
promote a WAA regime. Dry and hot expected for Thursday as we are
deep within the warm sector of a large low pressure system. That
upper low pressure system over the High Plains will extend a cold
front far south through much of the central US. This cold front will
bring shower and storm chances for Friday. Cold front should push
east of the region Saturday, which may result in drier weather by
the afternoon hours for most. Confidence remains limited, but
guidance appears to be in somewhat better agreement today. After a
short break in precip activity on Saturday, another wave within the
primary upper trough looks to spin through, bringing another shot of
precip for Sunday or into early next week.


========== Heat Concerns for Thursday ==========

Temperatures surge for Thursday with subsidence aloft and sfc high
pressure across the area. Southerly wind component will add to the
WAA pattern in place. Deterministic guidance generally has good
agree on 1000-850 mb thicknesses that support at least mid-80s
Thursday afternoon. However, 50% of the NBM v42. members suggest
seeing temps exceed 90F Thursday afternoon for areas west of US-127.
Upper 80s look like a sure bet, with the urban islands possibly
closer to 90F. It does not appear we`ll threaten the high
temperature record at SDF (94F in 1959) or BWG (93F in 1901), but
LEX may be in jeopardy. Their record high for May 2 is 88F (1959).

If you`re planning to spend alot of time outdoors on Thursday, be
sure to practice heat safety be staying properly hydrated and taking
breaks indoors if possible. Our experimental HeatRisk index
highlights minor impacts for Kentucky. Minor impacts affects
primarily those individuals extremely sensitive to heat, especially
when outdoors without effective cooling and/or adequate hydration.


========== Thunder Concerns for Friday ==========

Adequate moisture and forcing ahead and along an approaching cold
front will drive increasing precip chances for Friday. PWATs could
exceed 1.5", which would be above the 90th percentile for sounding
climatology. While rain is not a main concern for any outdoor events
taking place in the state this week, lightning and thunder are
concerns. Model soundings show skinny CAPE profiles, with sfc based
instability generally above 1000 J/kg by the afternoon hours. If
there`s any good news, it`s that we lack any substantial shear for
severe storms. Certainly see the possibility for some strong storms
with heavy rain rates given the instability profiles and available
moisture, but overall coverage should be numerous to widespread
showers with scattered/embedded thunderstorms.

Cold front is expected to pass through Friday night or early
Saturday morning, resulting in lower PoPs as we get into the
weekend. QPF for Friday is a broad-brushed 0.25-0.50" of rain, with
some locally higher amounts possible given the convective nature.

========== Uncertainty for Saturday ==========

Still expect to have a brief period of drier conditions in the wake
of FROPA, which perhaps persists deeper into the afternoon hours.
Ensembles sill show considerable spread, but deterministic runs show
drier conditions for Saturday afternoon. Will stick with the NBM
general 30-40% chance, though could see these chances decrease in
future forecast packages when data comes into better agreement.

&&

.AVIATION /06Z TAFS THROUGH 12Z THURSDAY/...
Issued at 137 AM EDT Wed May 1 2024

VFR conditions will prevail through much of the period. Fog will
likely impact visibility briefly this morning at RGA, but confidence
in any impacts from fog is much lower at the other terminals. RGA is
most likely to see IFR/LIFR vis in dense fog through sunrise. LEX
may see some brief vis reductions after 08Z, most likely in the MVFR
range. Cannot rule out brief IFR, however. SDF/BWG/HNB appear likely
to remain VFR.

Calm to very light southerly winds are expected through sunrise,
with winds veering southwesterly and increasing to 5-10 mph by late
morning. A SCT cu field will take shape across southern IN and the
northern half of central KY late this afternoon and evening as
moisture pools along a weak cold front. There is a 10% chance for an
isolated shower/storm near HNB after 20Z. Otherwise, dry weather
will continue.

&&

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

&&

$$

UPDATE...BTN
SHORT TERM...KDW
LONG TERM...CJP
AVIATION...EBW