232
FXUS63 KLMK 020721
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
321 AM EDT Tue Jul 2 2024

.KEY MESSAGES...

*   Hot and humid Wednesday afternoon and evening with heat index
    values peaking around 100-105.

*   Unsettled weather expected Wednesday afternoon through Friday
    with daily chances of showers/storms.  Strong storms will be
    possible each day. Isolated damaging wind gusts, torrential
    rainfall, and intense lightning will be the primary hazards.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 321 AM EDT Tue Jul 2 2024

High pressure centered over New York and ridging down much of
the East Coast will provide us with a steady south breeze today as
upper ridging builds into the region from the southwest. Though
moisture around 4-6k` will lead to some scattered cumulus
development, there will be plenty of sunshine, combined with the
south breeze and rising heights, to reach maximum temperatures
around 90 degrees this afternoon. Moisture pulled northward from the
Southeast will result in dew points increasing from the mid 50s this
morning to the 65-70 degree range by late afternoon.

Tonight the East Coast surface ridge will remain in place while a
slowly weakening cold front advances from the northwest, reaching a
Michigan-Missouri-Texas Panhandle line by Wednesday morning. This
will allow the south breeze, around 5 to 10 mph, to continue through
the night, leading to a very warm night. Low temperatures will range
from around 70 in the eastern and southern Blue Grass to the low/mid
70s along and west of I-65, which is a few degrees below record warm
lows for July 3. Any precipitation associated with the cold front
will hold off until during the day Wednesday (see below).

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 321 AM EDT Tue Jul 2 2024

Wednesday - Wednesday night...

Strong ridging aloft will remain centered over the Southeast on
Wednesday as a low pressure system lifts northeast across northern
Ontario. Sfc high pressure slowly slides east off the East Coast. A
long trailing cold front will extend southwest through the Great
Lakes and Mid-MS Valley. Earlier convection is forecast to dissipate
upstream over MO/IL Tuesday night, with the weak frontal boundary
forecast to sag southeast through IL/IN on Wednesday. As a very
moist, humid airmass heats up and destabilizes, convective
development appears likely over the Lower OH Valley Wednesday
afternoon and evening.

Exact mesoscale evolution is still somewhat uncertain. Tuesday night
convection could blow debris clouds southeast over portions of
southern IN and central KY Wednesday morning, which could modulate
daytime heating to some degree. At this time, however, some early
day sun looks possible with the morning hours remaining dry. That
should allow temps to surge into the lower 90s by mid-afternoon. A
few of our typically warmer spots may touch the mid 90s. Heat index
values of 100-105+ are forecast during the afternoon and early
evening hours.

HREF and LREF data point to 1000-2000 J/kg SBCAPE and a very moist
airmass characterized by PW values exceeding 2 inches. Scattered
convection will be possible in the afternoon and evening hours,
particularly across southern IN and northern portions of central KY.
The stronger winds aloft will remain well to our north, and deep-
layer shear will be limited to 20-25 kts. With a very warm, moist
environment, the hail threat looks very low. The main threats with
any stronger storms will be localized damaging winds, torrential
rainfall, and frequent lightning. Relatively slow storm motions may
increase the risk for localized flooding should multiple storms
impact the same area.

Loosely organized multicell clusters may linger into Wednesday night
as the cold front sinks further southeast. It will be a warm, humid
night with lows in the low to mid 70s.

Thursday - Friday night...

A hot, humid airmass will remain in place for the Fourth of July.
Remnant convective outflow boundaries may be lingering from late
Wednesday activity. In the upper levels, subtle shortwave impulses
will continue to stream ENE through the stronger flow across the
Midwest and Great Lakes. We do see a subtle uptick in W/SW flow
aloft for Thursday afternoon and evening, which will result in
slightly stronger deep-layer shear of 30-35 kts. Scattered to
numerous showers and storms will be possible, though confidence in
timing of individual waves remains very low.

Increased cloud cover and precip chances relative to Wednesday
should help suppress temps a bit, with highs ranging from the mid
80s to lower 90s. Thursday night will again be quite warm with lows
in the low to mid 70s.

A stronger upper level trough is forecast to rotate over the Upper
Midwest Friday, which will help force a stronger cold front
southeast through the forecast area. Expect at least one more round
of showers and thunderstorms before cooler, less humid air arrives
Friday night in the wake of the cold front.

Saturday - Monday...

The weekend looks dry and not as hot as weak sfc high pressure
builds in behind the cold front. Highs in the mid 80s look likely
for Saturday, with upper 80s/possibly near 90 in some spots on
Sunday. Low rain chances return early next week as upper level
troughing deepens to our west.

&&

.AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1235 AM EDT Tue Jul 2 2024

The pre-dawn hours will be quiet with light winds and mostly clear
skies thanks to high pressure over the Appalachians. During the
daylight hours today that high will slide eastward to the coast,
causing our winds to come in from the south around 7-10kt.
Increasing moisture flowing northward from the Gulf will support
scattered afternoon cu. Tonight the high will stay put while a cold
front approaches from the west, sustaining a south breeze here
through the night.

&&

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

&&

$$

SHORT TERM...13
LONG TERM...EBW
AVIATION...13