LMK issues Area Forecast Discussion (AFD) at Sep 6, 7:44 PM EDT ...Updated Aviation Discussion...665
FXUS63 KLMK 062344
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
744 PM EDT Fri Sep 6 2024
...Updated Aviation Discussion...
.KEY MESSAGES...
* Scattered showers and thunderstorms are expected this afternoon
and evening. Gusty winds will be possible with this activity
through sunset.
* Dry weather is expected for the weekend through at least the
middle of next week.
* Overnight lows Sunday night may dip into the upper 30s in the
favored radiational cooling spots and deeper valley locations.
* Overall worsening drought conditions expected given mostly dry
forecast.
&&
.SHORT TERM /THROUGH SATURDAY/...
Issued at 310 PM EDT Fri Sep 6 2024
Current mesoanalysis reveals a cold front starting to enter our far
northwest CWA. Temperatures were mainly in the upper 80s with a few
spots in the lower 90s. Dewpoints have mixed out a bit with values
in the lower-middle 60s. This yields SBCAPE values of 1000-1500
J/kg with DCAPE values in the 1000-1200 J/kg range, with minimal
inhibition. Radars show a band of broken convection stretching from
just north of the Ohio River southwestward into northwest KY.
Earlier convective models were a bit too slow with the development
but are starting to catch on. Despite decent surface based
instability, overall moisture and moisture quality are not that
great, plus we still have a bit of an weak cap aloft that continues
to erode. Convection was quite robust earlier in western KY with
the Calhoun KY Mesonet site picking up a 47 mph wind gust with the
storm that rolled through. As convection has moved into the LMK
CWA, the effects of the cap aloft are apparent as convection has
become a bit more ragged and outflow dominant.
For the remainder of the afternoon and evening, the surface cold
front entering our northwest CWA will continue to push south and
east. Additional convection will likely develop along the front,
despite overall weak convergence. This activity will push into the
I-65 corridor/Louisville metro in the 3-6 PM time range and then
into the central Kentucky/Bluegrass by early evening. We did bump
up coverage slightly to around 50% with this forecast. Given low-
level dry air and inverted V soundings, gusty winds will be
prevalent with any convection. In sub-severe convection, wind gusts
of 40-50 mph will be common given the relatively high DCAPE values.
For storms that are able to remain a bit more discrete and attain
larger vertical growth, downburst with core collapses may produce
55-60 mph winds in spots. Additionally, frequent lightning, and
brief heavy, but much need rainfall will be possible. Convection is
likely to wane by mid-late evening with the loss of heating and
nocturnal stabilization of the PBL.
With the passage of the front this evening, winds will shift to the
northwest and become quite breezy through the mid-late evening and
into the early part of the overnight. In the post frontal airmass,
we'll see strong cold advection push into the region with
temperatures falling into 60s by the early overnight period and cool
to the lower 50s across southern IN/northern KY by morning. Mid-
upper 50s will be common across the southern part of Kentucky.
For Saturday, tranquil weather is expected as high pressure builds
into the region. We'll likely develop a diurnal Cu field in the
afternoon with breezy northeasterly winds. Wind gusts of 15-25 mph
will be possible through the afternoon hours. Highs on the day will
range from the upper 60s to around 70 across southern IN and the
northern half of KY. Highs in the lower 70s will be confined to
areas mainly south of the Cumberland Parkway.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Issued at 310 PM EDT Fri Sep 6 2024
By Saturday evening, the Ohio Valley will be under the influence of
surface high pressure beneath longwave upper troughing extending
from a closed 5H low over the Great Lakes. This set up will result
in fair skies and cooler than normal temperatures, giving all of us
a sneak peek at Autumn. Sunday morning min temps will bottom out in
the low to mid 40s with some valley locations and typical cool spots
possibly seeing upper 30s, with afternoon highs peaking in the mid
70s.
Fair weather continues into the work week as surface high pressure
slowly advances eastward, though temperatures will gradually
increase back to normal by mid week as upper ridging builds in from
the west. By midweek, models indicate a tropical wave developing
into a closed low at 500mb along the Mexican Gulf Coast. This system
is progged to eventually make its way north into the TN Valley and
possibly bring some well needed rainfall to our southern counties
along the KY/TN border on Friday, but confidence in any details
remains low this far out. Otherwise, dry conditions are expected
throughout the week, likely resulting in worsening drought
conditions. The latest US Monthly Drought Outlook does show
worsening conditions across portions of southern Indiana and the
Commonwealth. Stay tuned for updates, and be sure to check with
local authorities for any burn bans in your county.
&&
.AVIATION /00Z TAFS THROUGH 06Z MONDAY/...
Issued at 743 PM EDT Fri Sep 6 2024
Cold front is currently through HNB and SDF and will continue
through the region, along with showers and storms. Gusty winds and
brief vis reductions due to rain will be possible. Behind the front,
winds will gust out of the northwest in the post frontal wake with
broken cigs around 5-6kft AGL. Clearing will take place late tonight
with winds leveling off. However, winds will pick up out of the
north after sunrise with gusts of 15-20kts at times through the day
on Saturday with VFR conditions.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
SHORT TERM...MJ
LONG TERM...CG
AVIATION...SRM
Source:
LMK issues Area Forecast Discussion (AFD) at Sep 6, 7:44 PM EDT ...Updated Aviation Discussion...---------------
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