LMK issues Area Forecast Discussion (AFD) at Feb 26, 10:04 PM EST523
FXUS63 KLMK 270304
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
1004 PM EST Wed Feb 26 2025
.KEY MESSAGES...
* Warm into this evening. A narrow band of light to moderate
showers will move across the region this evening and overnight.
An isolated thunderstorm will be possible.
* Mostly dry weather returns for Friday into the weekend.
* Another chance of rain arrives next Tuesday into Wednesday.
Thunderstorms, including strong to severe storms, are possible
next Tuesday night into Wednesday.
&&
.UPDATE...
Issued at 1003 PM EST Wed Feb 26 2025
A cold front will cross the region from west to east tonight
accompanied by a corridor of showers and an isolated thunderstorm or
two. No significant adjustments are needed to the going forecast for
tonight other than to introduce showers a little earlier than
previously planned in the Bowling Green region. A few of the showers
have managed to produce 30-40mph wind gusts in dry sub-cloud air.
Tomorrow may be an interesting weather day. A sharpening 5H
shortwave trough will bring in CAA aloft as it digs from the upper
Midwest in the morning to the upper Ohio Valley by evening. By the
time of peak heating (albeit only in the mid-upper 50s) there will
be moderately steep lapse rates, sufficient deep layer shear for
organized convection, and stronger instability than what we saw
today ahead of the aforementioned cold front. Moisture will be very
limited, with PWAT only around half an inch, limiting coverage of
any showers/storms. With very low freezing heights and low RH in
much of the column, some of the cells could produce hail that would
survive to the ground, though hail size would be small. Dry sub-
cloud air, with surface dew point depressions on the order of 15-20
degrees, could support a few enhanced wind gusts with the healthier
cells. The best chance for a stronger cell should be north through
east of Lexington.
And speaking of wind, sky cover tomorrow will be an important factor
in how breezy we get. If more sun is realized than is currently
expected, non-thunderstorm gusts of 30-40 mph are well within the
realm of possibility.
&&
.SHORT TERM /THROUGH THURSDAY/...
Issued at 335 PM EST Wed Feb 26 2025
This Evening and Tonight...
A mid-level shortwave trough will swing east across IL/IN/OH this
evening and tonight. At the surface, a 1008 mb sfc low currently
over northern IL will also move east across northern portions of
IN/OH tonight, dragging a cold front southeast through southern IN
and central KY. A warm, breezy afternoon is in progress with gusty
SSW winds in the warm sector ahead of the cold front. Temperatures
are overachieving relative to pretty much any model data.
Temperatures currently range from the mid/upper 60s north of I-64 to
the lower 70s in south-central KY. We do finally have a bit more mid
cloud spreading east into central KY, but temps could increase
another 2-3 degrees through late afternoon.
Dry weather remains likely through 23-00Z this evening, at which
time shower chances will ramp up in southern IN. A band of light to
moderate showers will develop along the front in southern IN and
northern portions of central KY between 23-03Z. This relatively
narrow band should then progress ESE across the rest of central KY
through the overnight hours.
As the mid-level trough swings in from the northwest, colder air
aloft will support max mid-level lapse rates slightly exceeding 7
C/km. Weak (100-250 J/kg MUCAPE) elevated instability will support
an isolated risk for a thunderstorm. The overall thermodynamic
environment is very marginal, and the severe weather risk is quite
low. Low-level moisture return into this evening is modest at best
ahead of the cold front. But a convective shower or possible storm
could produce very brief heavy rainfall. Overall QPF remains limited
due to limited moisture and very brief residence time of any
moderate or heavier rainfall rates. Around 0.10-0.25 inches is
possible in most areas, with localized amounts near a third of an
inch not out of the question.
Thursday and Thursday Night...
The showers exit prior to daybreak, and cooler air streams into the
region behind the front. Thursday morning lows will range from near
40 in the southern IN to the mid 40s in south-central KY. Thursday
will be noticeably cooler than today with cool NW flow. Expect
partly to mostly cloudy skies. The mid/upper level trough rotating
overhead will steepen lapse rates through a deep layer. This will
promote an additional chance for scattered showers in the afternoon,
along with gusty winds. Scattered shower chances increase after 2
PM, especially across the northeastern half of the area (highest
rain chances from SE IN through the KY Bluegrass). Temperatures will
be in the 40s and 50s during the day. Winds will also increase in
the afternoon, with gusts of 25-30 mph likely. Peak gusts up to 35
mph will be possible.
The sharp shortwave trough quickly swings east of the area Thursday
night, with ridging building in behind it. Conditions will dry out,
with skies becoming partly cloudy to mostly clear. It will be a
chilly night, with lows in the upper 20s to lower 30s.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 335 PM EST Wed Feb 26 2025
Friday through Sunday Night...
Northwest flow aloft will be present across most of the lower 48 as
we close out the month of February. The upper trough which is
bringing a chance for showers tonight will be exiting the Carolina
coast Friday morning as another coupled surface/upper wave begins to
descend from the Canadian prairies toward the northeast US. 988 mb
sfc low over the Great Lakes will create a fairly strong pressure
gradient across the Ohio Valley, with 50+ kt of flow at 850 mb
expected Friday evening. While the heart of this stronger jet core
will still be north of I-70 during peak mixing hours on Friday,
still think that some higher momentum could mix down to the ground,
and Friday should be a windy day, especially along and north of I-
64. Sustained SW winds of 10-20 mph with gusts of 25-35 mph are
likely, and there is a 10-20% chance in NBM guidance of exceeding 40
mph gusts north of the I-64 corridor Friday afternoon.
Expect these SW winds combined with mostly sunny skies to send
temperatures surging once again Friday afternoon. Have gone quite a
bit warmer than NBM guidance given the setup, with highs ranging
from near 60 along the I-75 corridor to the mid-60s west of I-65.
While most of the forcing associated with the upper trough axis and
sfc cold front will slide to the northeast of our area Friday night,
the front should still make it through the area, with cold advection
overspreading the region from the NW Saturday morning. As the front
passes, a stray shower or two cannot be ruled out across the
Bluegrass region; however, coverage and confidence in any showers is
low enough to keep silent PoPs for now. Cooler temperatures are
expected for the day on Saturday as NW flow continues off of the
Great Lakes. Low-level moisture will likely help to produce a
stratus deck or stratocu field over the region, with more clouds the
farther north and east you go. Highs should be around 15 degrees
cooler across the area on Saturday.
The mid- and upper-level trough axis will eject east of the
Appalachians Saturday night into Sunday, with a modified cP air mass
and sfc high pressure settling into the region during the day on
Sunday. This should bring dry and cool weather to the region for the
second half of the weekend.
Early to Mid Next Week...
An upper trough ejecting into the western CONUS on Sunday will lead
to a phase shift in the upper wave pattern across North America for
early next week as upper ridging spreads over the eastern half of
North America Monday into Tuesday. As upper heights increase and sfc
high pressure shifts east of the Appalachians, warm return flow will
lead to increasing temperatures through the middle of next week.
Moisture will also increase via deep S/SW flow, with both ECMWF and
NAEFS ensemble mean precipitable water exceeding the 90th percentile
of model climatology next Tuesday into Tuesday night. As the upper
level wave over the west coast ejects into the central and eastern
CONUS Tuesday into Wednesday, a strong area of sfc low pressure is
expected to develop across the southern Plains.
There is still considerable spread in medium-range guidance as to
where this system tracks and how strong it will be; however, it is
looking more likely that it will take a track that could put the
Ohio Valley in a favorable zone for thunderstorms which could be
strong or severe. With both NAEFS and ECMWF ensemble mean 850 mb
wind speed exceeding the 90th percentile of model climatology,
strong wind shear will be present across the Ohio Valley.
Instability is a bit more uncertain; however, the ECMWF ensemble
mean now shows the strongest signal for anomalously low MSLP across
the Wabash Valley Tuesday night, which would suggest a track
favorable for surface-based convection across central KY and
southern IN.
Machine learning convective hazard guidance has the highest
probabilities of severe weather over the lower MS valley next
Tuesday into Wednesday. However, until recent runs, much of the
GFS/GEFS members were supporting a more suppressed/southerly track,
so would expect these probabilities to increase in subsequent runs.
With all this being said, this is still 6-7 days away; however,
continue to monitor the latest forecasts later this week and through
the weekend.
&&
.AVIATION /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 641 PM EST Wed Feb 26 2025
A cold front will cross southern Indiana and central Kentucky
tonight from west to east, accompanied by a band of showers. There
will be about a 5-hour window of shower chances, and a few rumbles
of thunder can't be ruled out just ahead of the front. Have
accounted for this with as PROB30 at SDF and HNB...chances are too
low at the other airports to include in the TAFs at this time. WSW
winds ahead of the front this evening will gradually veer about 50
degrees to W behind the front and become gusty.
Tomorrow a sharp upper trough will slide toward us and spark
scattered showers and thunderstorms in the afternoon, especially at
SDF/LEX/RGA. At this time it looks like there will be quite a bit of
cloud cover, but if we get more sunshine than currently expected
gusts could become rather strong in the afternoon, out of the west.
For now will stick with values around 20-27kt.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
UPDATE...13
SHORT TERM...EBW
LONG TERM...CSG
AVIATION...13
Source:
LMK issues Area Forecast Discussion (AFD) at Feb 26, 10:04 PM EST---------------
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