466
FXUS63 KLMK 060040
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
840 PM EDT Fri Jul 5 2024

.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 SATURDAY/...
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 /SATURDAY NIGHT 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 /00Z TAFS THROUGH 06Z Sunday/...
Issued at 736 PM EDT Fri Jul 5 2024

Cold front just knocking on the door of HNB and will make its way
eastward across the terminals this evening. No impact to the TAFs
however, as the deep moisture has already been lost, limiting precip
to a few showers that are moving across northern Kentucky while
southern Indiana and central Kentucky remain dry.

Winds from the west will slack off with the loss of boundary-layer
mixing after sunset, but still expect speeds around 5 kt through the
night at SDF and LEX. Modest advection of cooler and drier air
during the mixy part of Saturday will help push speeds back up near
10 kt, and bases of diurnal Cu near 5-6K feet. VFR conditions will
persist through and beyond the TAF period.

&&

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

&&

$$

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