545
FXUS63 KLMK 101727
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
127 PM EDT Mon Jun 10 2024

.KEY MESSAGES...

* Below normal temperatures and humidity through Tuesday.

* A warming trend with hot and dry conditions likely for late
  this week into next weekend.

&&

.UPDATE...
Issued at 1120 AM EDT Mon Jun 10 2024

Earlier fog across south central Kentucky has dissipated, leaving
mostly sunny skies across the Ohio Valley. Cold advection stratus
shield now near a line from Vincennes to Cincinnati, and will spread
through most of southern Indiana and the northern portion of central
Kentucky early this afternoon. However, given that it continues to
modify as it progresses southward, confidence really diminishes in
terms of getting extensive cloud cover south of I-64. Partly cloudy
forecast for this afternoon seems to be in good shape, though
temperatures could struggle north and east of Louisville. No changes
to the previous forecast.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 258 AM EDT Mon Jun 10 2024

Latest fog product view on satellite is showing an area along and
south of the KY Parkway system with some fog development where
recent rainfall occurred Sunday.  A special weather statement has
been issued for locally dense fog and rapidly changing visibilities
this morning for travelers.

Dry frontal passage today and associated upper level trough of low
pressure will keep conditions on the cool side of normal with highs
in the mid to upper 70s, which is between 5 and 10 degrees below
normal for mid June.  Some afternoon clouds may pop up in the
afternoon, but mainly sunny skies will prevail with lots of dry air
in place (PWs based on sounding climo between 10th and 25th
percentile today and tonight).  Outside of a few clouds, the only
other sensible weather will be an occasional NNW wind gust up to 15
mph.  Some patchy valley fog is possible overnight into the early
morning hours Tuesday, but any impact will be minor and limited to
low lying areas.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 258 AM EDT Mon Jun 10 2024

The extended forecast period from Tuesday through next weekend is
expected to feature a lot of dry weather and a big increase in
temperatures as a dome of hot temperatures gradually builds across
the central and eastern portions of the CONUS. At the beginning of
the period on Tuesday, mid and upper-level troughing will still be
located over the east coast while broad ridging will abound along
and west of the Rockies. At the surface, high pressure is expected
to be located near the confluence of the MS/OH River, with the air
mass overhead being somewhat cooler and considerably drier than
normals for mid June. Both the NAEFS and EPS Ensemble Mean PW
values, ranging from 0.4" to 0.6" across the area, are below their
respective model climatology`s 5th percentile. For reference, the
10th percentile PW value in observed soundings on June 11th is 0.57"
at ILN and 0.76" at BNA. This dry air mass will stick around into
the middle and latter portions of the week with modest moisture
return expected, allowing for large diurnal temperatures ranges even
with an overall warming trend.

Wednesday into Thursday, the synoptic pattern will transition to
flat, broad ridging with the primary baroclinic zone being shoved
into the northern U.S. and southern Canada as the heat dome spreads
eastward. Low-amplitude troughs will ride along the top of the
building ridge, with associated moisture and precipitation chances
remaining well north of the Ohio Valley. Increases in 850 mb
temperatures from Tuesday (9-10 deg C) to Thursday (16-18 deg C)
will be a good proxy for rises in daytime highs given continued dry
air through the column. This would translate to a roughly 15 deg F
increase in expected temperatures, which would take us from readings
in the mid-upper 70s on Tuesday to a few degrees either side of 90
by Thursday. Fortunately, dew points should remain low enough to
keep heat indices in check.

By Friday, a more substantial shortwave will try to cut into the
northeastern flank of the upper ridge, bringing a cold front with it
as it moves across the Great Lakes and into the northeastern U.S. By
the time the front reaches our vicinity, it will have lost much of
its upper level support as the aforementioned trough progresses
quickly eastward. While there will be an area of increasing moisture
ahead of the front and some lift associated with FROPA, the
dilapidated state of the boundary should limit shower/storm chances.
For what it`s worth, the GEFS does depict a more robust
trough/front, which would favor more widespread precipitation
chances, while the EPS and GEPS families have a weaker front and
less in the way of precipitation. At this time, think most areas
will experience little more than a few extra clouds and a wind shift
Friday into Friday night.

If the front makes it through the region Friday night, slightly
cooler temperatures would be expected within a low-level NE flow
regime on Saturday. However, this should be short-lived as the upper
ridge builds quickly back to the east Saturday night into Sunday. At
this time, Sunday into early next week has the potential to be
rather hot, although increasing moisture from the Gulf of Mexico
early next week may limit diurnal temperature ranges and increase
cloud cover/precipitation chances.

&&

.AVIATION /18Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 126 PM EDT Mon Jun 10 2024

VFR expected through the valid TAF period. Look for NNW winds
gusting just shy of 20 kt in the cold advection regime this
afternoon, along with strato-cu ceilings around 5k feet. Will keep
it scattered at BWG and RGA where there is less cold pool influence.

Winds will lay down gradually this evening, so we`ll keep a window
of light NW winds and scattering/mid-level clouds through mid-
evening before the boundary layer decouples. Will be light/variable
with clear skies by midnight. Not expecting any fog in the terminals
overnight with a very dry boundary layer, but there could be some
valley fog east of BWG.

&&

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

&&

$$

UPDATE...RAS
SHORT TERM...MCK
LONG TERM...CSG
AVIATION...RAS