LMK issues Area Forecast Discussion (AFD) at Sep 11, 12:47 AM EDT ...Updated Aviation Discussion...842
FXUS63 KLMK 110447
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
1247 AM EDT Wed Sep 11 2024
...Updated Aviation Discussion...
.KEY MESSAGES...
* Unseasonably warm temperatures and continued drying conditions
through Wednesday.
* The remnants of Francine will bring chances for tropical rain
showers and storms to the region beginning Thursday and continuing
into the weekend.
* Rainfall amounts between 1-3 inches, with locally higher amounts,
possible between Thursday and Sunday.
&&
.UPDATE...
Issued at 825 PM EDT Tue Sep 10 2024
Another quiet night in store with mostly clear and cool conditions
expected. Low expected mostly in the low and mid 50s, although a few
upper 50s possible. Starting to see the first hints of the upper
cloud shield from Francine spinning into southern KY, however not
much more to it than a neat satellite image.
&&
.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 307 PM EDT Tue Sep 10 2024
Sfc high pressure over the Upper Ohio Valley will continue to drift
east toward New England, but the gradient overhead remains weak,
resulting in continued light winds. Dry column with sfc dewpoints
near 50 will allow for favorable radiational cooling, and another
chilly early fall night.
The same dry conditions will make for an unseasonably warm
Wednesday. Low-level thickness progs suggest max temps will run
about 5 degrees warmer than this afternoon, so 90 is on the table
for quite a few spots.
&&
.LONG TERM /TONIGHT THROUGH TUESDAY/...
Issued at 1246 AM EDT Wed Sep 11 2024
===== Wednesday Night - Thursday =====
Upper level ridging will be building across the Great Lakes region
as an upper shortwave digs over the Pacific Northwest. Francine is
expected to have just made landfall in Louisiana, and will continue
its northward trajectory following the Mississippi River. While our
weather will still be dry for Wednesday night, can expect to see
cloud cover increasing from south to north as the tropical system
spins inland. This increase in cloud cover will limit radiational
cooling overnight, and should help keep temperatures in the 60s.
On Thursday, the remnants of Francine will continue to push
northward into the Tennessee Valley, thanks to a weak shortwave
trough helping to push it along. While dry conditions are expected
for the first half of the day, precip chances will be increasing
from south to north by Thursday afternoon and evening. Areas north
of the I-64 corridor could end up remaining dry until sunset or
later. Temperatures for the day will vary from north to south,
dependent on cloud cover and any rain showers. Expected the warmest
temperatures in the forecast area to actually be north of I-64, with
low to mid-80s expected. To the south, upper 70s are mostly
expected.
Shower activity will continue to expand Thursday night and into
Friday morning as Francine looms closer. The moisture transport axis
will be strongest Thursday night into Friday morning, rising PWATs
to more than 1.5 inches and above the 90th percentile for most. A
few thunderstorms may be embedded, but overall model soundings
suggest a high shear low CAPE regime for Thursday night.
===== Friday - Weekend =====
The aforementioned upper shortwave that was steering Francine looks
to weaken on Friday, resulting in the tropical system essentially
parking itself over the Mississippi/Ohio River confluence and within
the upper ridge. Throughout Friday, the upper level organization of
Francine will begin to deteriorate, with not much steering expected
through the weekend either. The system will meander across the
Tennessee Valley through the weekend.
Friday serves as the best chance for numerous shower and storm
chances. We'll take any precip chances we can get, especially when
looking at the US Drought Monitor. Almost all of our forecast area
is experiencing abnormally dry conditions (D0), though some areas
have escalated to moderate drought (D1). A good chunk of western
Kentucky is experiencing D1 conditions, which will fortunately have
the best chances for the highest QPF in the Commonwealth. However,
it remains to be seen if this round of precip will bring any
considerable improvements to the Drought Monitor. With the low
continuing to remain in the region through the weekend, additional
shower and storm chances will linger throughout the weekend.
As for rainfall amounts, still appears the highest QPF will be
across western Kentucky and south-central Kentucky. The 100 member
LREF-NH ensemble has strong indications that many in our CWA will
receive more than an inch of rain between Thursday and Sunday.
Roughly 80 of the 100 members suggest this for an area south of a
line stretching from Tell City to E-town to Tompkinsville. That same
area has roughly 50% probability of receiving over two inches of
rain, with high probs pointing to the southwest. In general we are
looking at 1-3 inches of rain, with the high amounts focused on our
southwestern corner of the CWA. Of course, with tropical showers and
storms, localized higher amounts will remain possible as well, but
those finer details cannot be predicted with the coarse resolution
of ensembles.
As for severe potential, there certainly will be a low-end
potential, as we usually end up seeing with any tropical depression
making its way into the Ohio Valley. The Euro deterministic appears
a little more excited about thunderstorm potential on Friday than
the GFS, with slightly more favorable soundings for some quick spin-
ups. SPC SREF plumes suggest the best instability will still be to
our south, but perhaps could get between 250-500 J/kg of MLCAPE
across south-central Kentucky. The concern continues to be initially
strong mid-level flow will provide ample shear profiles, though this
too will weaken as the storm loses intensity Friday into Saturday.
&&
.AVIATION /00Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1246 AM EDT Wed Sep 11 2024
Surface high pressure drifting very slowly eastward across the
northeastern United States will continue to provide the region with
dry low/mid levels and a light wind coming in from the east and
southeast. Cirrus will be the main cloud type, gradually spreading
from south to north ahead of TC Francine.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
UPDATE...BJS
SHORT TERM...RAS
LONG TERM...CJP
AVIATION...13
Source:
LMK issues Area Forecast Discussion (AFD) at Sep 11, 12:47 AM EDT ...Updated Aviation Discussion...---------------
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