LMK issues Area Forecast Discussion (AFD) at Apr 18, 1:54 AM EDT240
FXUS63 KLMK 180554
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
154 AM EDT Fri Apr 18 2025
.KEY MESSAGES...
* Breezy with unseasonably warm temperatures beginning Friday.
* Shower and thunderstorm chances over weekend. A few stronger
storms are possible in southern Indiana Saturday afternoon and
evening. Stronger storms may again be possible very late Sunday
night into Monday morning.
&&
.UPDATE...
Issued at 938 PM EDT Thu Apr 17 2025
WAA regime will remain in place overnight, thanks to the combination
of warm return flow from a sfc high just off the Atlantic Coast, as
a strengthening southwesterly LLJ moving in ahead of a sfc low
pressure system over the High Plains. A mild night is in store, with
temps currently ranging from the upper 50s to upper 60s. Portions of
western Kentucky are still around 70 at this hour. Lows tonight will
remain in the 50s, which will end up being around 10 degrees warmer
than normal. Mostly to partly clear skycover is forecast tonight,
with a scattering of high clouds possible.
Overall forecast is in good shape for tonight. Warm and breezy
conditions still expected for tomorrow, with winds picking up in the
morning. Highs for tomorrow are forecast to hit the low 80s, with
cloudier skycover west of I-65.
&&
.SHORT TERM /THROUGH SATURDAY/...
Issued at 338 PM EDT Thu Apr 17 2025
Tonight, the axis of upper ridge with a slight positive tilt will
slowly ease over southern Indiana and central Kentucky. At the
surface, a tight pressure gradient running north-northeast to south-
southwest sits over the CWA between a low cutting northeast through
the Midwest and a high just off the Atlantic Coast. This will keep
skies mostly clear as 10-15 mph winds veer from the southeast to
south. Gusts could reach to 25 mph into Friday morning. WAA will
limit lows to the 50s with a few areas along the western edge of the
CWA remaining in the low 60s.
Tomorrow, the upper ridge continues off to the east as a cold front
approaches from the northwest. This will allow the surface pressure
gradient over the Lower Ohio Valley to shift more to the northeast
to southwest. Southern winds around 15-20 mph and gusting to 30-35
mph will usher in warmer temperatures, climbing into the upper 70s
to low 80s. Skies will remain mostly sunny with some added cloud
cover over the western side of the CWA.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 338 PM EDT Thu Apr 17 2025
Friday Night - Monday...
Looking for a fairly active weekend as we sit in the SW flow between
SE CONUS ridging and central Plains positively tilted trough. A
surface low over eastern Canada will drag a cold front toward our
region on Friday night, and then stall as the boundary becomes
nearly parallel to the upper flow. Could see some showers and storms
sneak into our N/NW CWA by late Friday night, and again through
Saturday. SPC has maintained a marginal risk for those time periods
across our N CWA, but uncertainty in placement, instability, and the
lower level speed shear profiles makes strong to severe storms
pretty low confidence at this point.
By late weekend, the stalled frontal boundary will lift back north
as a warm front as a potent southern Plains disturbance ejects out
into the mid Mississippi River Valley. This should bring one final
round of storms later Sunday night into the first part of Monday
ahead of the front. Since this last system looks to occur mainly
during the diurnal minimum, instability looks to be in question.
That being said, plenty of shear for this setup, so if some
instability is realized then some strong storms would be on the
table. Could see our area ending up being outlooked for the late
Sunday/early Monday time frame.
Overall QPF for the weekend into Monday looks to range between .5"
and 1.25" across southern IN. Meanwhile, KY should see a half an
inch or less through this stretch. NW has been the overall trend
with this setup, so wouldn't be surprised if parts of KY end up even
drier. Look for mild days through the weekend with 70s north, to low
80s south. Monday is cooler behind the cold front with highs back in
the upper 60s and low 70s for most.
Monday Night - Tuesday Night...
Cold front slides through by later Monday and hangs up to our south.
We'll stay under drier zonal flow aloft and high pressure at the
surface through Tuesday night. This will keep us dry and cooler.
Highs recover back into the low and mid 70s by Tuesday, with lows
each night in the upper 40s to around 50.
Wednesday - Thursday...
Lower confidence by this time period, but chances for showers and
storms will likely increase again as another disturbance lifts out
of the southern Plains, and helps to drag that stalled frontal
boundary to our south back over our area. This will set the stage
for more rounds of showers and storms by mid to late week.
&&
.AVIATION /06Z TAFS THROUGH 12Z SATURDAY/...
Issued at 152 AM EDT Fri Apr 18 2025
VFR expected through the TAF period with only cirrus ceilings and
the occasional mid deck below it. This forecast cycle is mainly a
wind forecast given the tightening gradient, and a LLWS forecast
with the stout southerly LLJ.
Winds initially just under 10 kt out of the SSE, but just 2000 feet
off the deck we are seeing 40-50 kt per LVX and HPX VAD wind
profiles. As that keeps up through the night we will start to feel
some of it at the sfc, so did take the gusts up closer to 20 kt
before sunrise.
Low-level jet mixes out late in the morning, with a solid 15-20kt
and 25-30 kt gusts through the afternoon. Direction will veer
slightly from overnight, settling into S or maybe SSW by midday.
Sustained wind speeds and gusts will diminish slightly after sunset,
but stay up through the night with the gusts just shy of 20 kt.
Precip shield stays to our north and west, but did opt to include a
mid-level cig at SDF.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
UPDATE...CJP
SHORT TERM...KDW
LONG TERM...BJS
AVIATION...RAS
Source:
LMK issues Area Forecast Discussion (AFD) at Apr 18, 1:54 AM EDT---------------
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