657
FXUS63 KLMK 060519
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
119 AM EDT Sat Jul 6 2024

...Updated Aviation Discussion...

.KEY MESSAGES...

*   Drier, slightly cooler, and less humid conditions are expected
    for the weekend.

*   Remnants of tropical cyclone Beryl may affect the Ohio Valley by
    late week.

&&

.UPDATE...
Issued at 839 PM EDT Fri Jul 5 2024

Cold front is making slow but steady progress eastward across the
Ohio Valley. Deep moisture is already rapidly declining with east-
central Kentucky still showing PWAT values of even 1.5 inches. As a
result convection has really struggled with just a few isolated
showers south and east of Lexington, and between Louisville and
Cincinnati.  Expect that to dissipate and/or exit within the next
hour or two, leaving us with a dry and increasingly less humid
night.

Will update shortly to clean up evening precip mentions, while hi-
res products are already updated for hourly trends.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 247 PM EDT Fri Jul 5 2024

Main morning wave now is well east of the region at this time. Still
have a fairly juicy airmass in place, especially along and east of I-
65, where GOES Sounder places precipitable waters above 2 inches.
Values still are fairly high to the west of that, but there`s a
clear shut off behind the front that`ll bring an end to any precip
chances later this afternoon and evening...from west to east.

In the mean time, we are seeing a few showers develop with heating
behind that morning wave and clearer skies. Most of these are in
western IN, but expect isolated to widely scattered storms to
develop across south central IN and central KY this afternoon. GOES
also shows a weaker link along a Hodgenville to Shelbyville line.
These can bring brief heavy rains and gusty winds...also cannot rule
out isolated damaging winds, especially the longer into the
afternoon it takes for those storms to get here. At the current pace
for that dry line, looks like it makes it to Louisville by 8 PM
tonight and then to Lexington by Midnight. Thus will time end of
storm chances in Louisville to that 7-8 PM time frame and then
Lexington will be more like 9-10, more for the loss of heating.

That drier air will continue pushing into the region, allowing lows
tonight to fall into the lower 60s west of I-65 and through southern
IN. Given the later fall off in humidity, expect points along and
east of I-65 in central KY to stay in the mid 60s. Saturday should
temperatures a little below normal, with highs generally in the mid
80s.

&&

.LONG TERM /TONIGHT THROUGH FRIDAY/...
Issued at 247 PM EDT Fri Jul 5 2024

Saturday Night through Monday Night...

Surface high pressure beneath unremarkable SW flow aloft will
continue through the weekend. As a result, dry conditions continue
into Monday morning across the area. Plenty of sunshine on Sunday
will allow for high temperatures to reach up around 90, just
slightly above normal for this time of year. Look for comfortable
lows in the 60s each night to end the weekend.

As we get into Monday and Monday night, mostly dry conditions are
still expected however will continue the trend of some shower and
storm chances returning to the area, most likely across southern KY.
A weak surface low pressure will move into the mid Mississippi River
Valley and upper Midwest, and a weak warm frontal boundary will set
up over or near our area in response to that. Subtle low level
jetting and the associated isentropic lift may be enough to force
some convective parcels. Looking at soundings, there is enough of an
inversion between 850-700 mb that it will take some pretty good
forcing to get a parcel to the LFC, so these are conditional
chances. Overall, think that Monday/Monday night will also be more
dry than not, but enough data to support at least some shower and t-
storm chances, especially by Monday evening. We do get pretty warm
on Monday with highs peaking into the low 90s, however dew points
look to mostly stay in the mid to upper 60s.

Tuesday through Friday...

A more active stretch of weather looks to be in play for the mid to
late week time frame as an upper trough axis swings through Tuesday
& Tuesday night, and then we potentially get the deep moisture plume
from the remnants of Beryl by Thursday or Friday. Like the previous
forecast of keeping the highest pops for the Tuesday/Tuesday night
period. After a relative lull in the upper pattern through Wednesday
(still some low chances for a shower/storm), we`ll ramp pops back up
later Thursday into Friday. Models are still trying to resolve how
the prevailing westerlies over the central US will interact with and
pick up Beryl over eastern Texas, and until then can`t have too high
of confidence in the exact track of the moisture plume.
Nevertheless, it seems that increased pops are a good bet into the
late week time frame. Should the path cross directly over our area,
then a few concerns would come into play like heavy rainfall, and
potential for some rotating cells (NE quadrant) that are typical
with remnant tropical systems.

&&

.AVIATION /06Z TAFS THROUGH 12Z SUNDAY/...
Issued at 118 AM EDT Sat Jul 6 2024

Through the rest of the night tonight, light westerly winds will
continue behind the departing cold front. While primarily high level
clouds are expected through sunrise, transient lower level clouds
will be possible, with areas of clouds with 4-6 kft bases currently
being observed near LEX and HNB. With drier air in the low levels
being slow to push eastward, a brief period of MVFR visibilities
cannot be ruled out at LEX/RGA; however, confidence in this is still
fairly remote, so will refrain from inclusion in the forecast at
this time.

Later today, VFR conditions will continue as westerly winds will
increase but remain modest during the late morning and afternoon
hours, with wind speeds generally between 5-10 kt. SCT-BKN cirrus
and FEW-SCT cu are expected during the daytime hours, with VFR
ceilings expected. Winds will go light and variable quickly after
sunset tonight, with VFR conditions continuing through the remainder
of the forecast period.

&&

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

&&

$$

UPDATE...RAS
SHORT TERM...RJS
LONG TERM...BJS
AVIATION...CSG