LMK issues Area Forecast Discussion (AFD) at Oct 12, 1:46 PM EDT ...Updated Aviation Discussion...560
FXUS63 KLMK 121746
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
146 PM EDT Sat Oct 12 2024
...Updated Aviation Discussion...
.KEY MESSAGES...
* Warmer temperatures today with dry conditions continuing.
* Breezy and very isolated showers along and east of US-127 on
Sunday.
* Turning much cooler next week with widespread frost likely
Tuesday and Wednesday nights.
&&
.UPDATE...
Issued at 949 AM EDT Sat Oct 12 2024
It's another beautiful Fall morning in Kentucky and southern
Indiana. Skies are sunny, though we do have a band of high clouds
just upstream stretching across eastern MO and central IL/IN. These
clouds will spread southeast over southern IN and central KY this
afternoon and evening.
A sfc quasi-stationary boundary extends from near the IA/MO border
ENE through northern portions of IN/OH. Weak convection is noted
this morning along the boundary in northern IN, but the sfc front
will not move a whole lot today as a weak sfc wave develops back to
the west over the IA/MO border. Still expect a dry day in southern
IN and central KY with just a brief uptick in cloud cover during the
second half of the day. Expect a warm afternoon with southwesterly
winds increasing to 5-10+ mph. Afternoon highs are still expected to
be in the upper 70s to mid 80s.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 335 AM EDT Sat Oct 12 2024
Synopsis...
A mid-level shortwave trough over southern Ontario will
quickly eject eastward into the North Atlantic later this morning as
subtle mid-level ridging sets up over the Ohio and Mississippi
Valleys later today. A sfc cold front which was pulled southward by
the aforementioned leading shortwave will stall out near the I-80
corridor, with warm SW flow south of the boundary promoting warm
advection across the Ohio Valley today. Later this evening into
tonight, an initially weak trailing shortwave over the Canadian
Prairies will begin to amplify and dig southward into the upper
Midwest by Sunday morning. Strong upper diffluence ahead of this
disturbance will promote low-level cyclogenesis along the pre-
existing front later tonight, with a strengthening sfc low pressure
system expected to move across the Midwest Sunday morning. A
trailing, strengthening cold front will move toward the Ohio Valley
early Sunday morning, but is not expected to pass through southern
IN and central KY until the daytime on Sunday.
Today and Tonight...
Cool and dry conditions are present once again this morning across
central KY and southern IN, with temperatures ranging from the 40s
in sheltered valleys to the 50s in higher elevations and urban
areas. As we head through the morning hours, mostly clear skies
should continue, with ample sunshine and an overall warmer air mass
overhead allowing for temperatures to ascend quickly after sunrise.
High clouds from the northwest will move across the area during the
afternoon hours, though this should be thin enough for filtered
sunshine to continue. Today looks like the warmest day since last
Sunday across the area, with highs expected to range from the upper
70s east of US 127 to the low-to-mid 80s west of I-65. As the
pressure gradient associated with the developing sfc low begins to
tighten later today, winds should pick up out of the SW, with speeds
generally between 5-10 mph.
Tonight, as the surface low continues to strengthen over central IN,
S/SW winds are not expected to slacken in spite of the expected low-
level inversion setting up after sunset. With that being said, the
inversion should keep most of the momentum of a 45-50 kt LLJ
elevated, though a wind gust of 20 mph cannot be ruled out in
elevated locations early Sunday morning. Persistent S/SW winds of 5-
15 mph will keep low temperatures considerably milder Sunday
morning, with most locations only falling into the upper 50s and low-
to-mid 60s. In spite of the strengthening sfc low and strong low-
level SW flow tonight into Sunday morning, moisture return will be
fairly mediocre, especially in the low levels, so we'll keep silent
PoPs going through the short term forecast period.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 335 AM EDT Sat Oct 12 2024
Synopsis...The mid-level pattern during the medium range will begin
essentially with an amplifying longwave trough over the Eastern US and
anomalous ridge extending across the West and into Canada. The
Eastern trough will feature several embedded shortwave troughs that
will help drive frontal waves and unseasonable cold air to the Ohio
Valley: the leading wave on Sunday and the second one on Tuesday.
Then, the large-scale pattern will become more progressive during
the second half of next week as a Pacific trough pushes the ridge to
the east and the Eastern trough lifts to the Atlantic.
Model Confidence/Evaluation...Overall, model confidence remains
relatively high for this period; however, there are a couple of
windows worth monitoring. First, SPC has started highlight a
possibility of thunderstorms and marginal severe threat for the
easternmost areas on Sunday associated with the frontal passage.
Certainly, the CSU ML guidance support a low chance of severe hail
and wind gusts, but the big question is convective initiation give
the dry airmass in place and lifting strength in the moisture-
deprived warm sector. Such issues are reflecting in the HREF and
RRFS model output given the very isolated nature of the simulated
reflectivity fields. The second item is related to a potential
blocking pattern late in the period as the eastward moving mid-level
ridge builds over the East CONUS and the incoming Pacific energy
cuts off from the jet. GFS, CMC, and AIFS models favor the blocking
while the dynamic ECMWF has trended more progressive and zonal.
Sunday...Mostly dry, warm, and breezy conditions to close the
weekend. A weak surface low is still expected to move across the
Upper Ohio Valley the first half of Sunday while the attendant front
will be delayed to the evening hours. Non-thunderstorm wind gusts of
20-30 mph out of the west-southwest could be reported Sunday
afternoon with a decent chance (higher than 50%) of having 30+ mph
gusts in southern Indiana and north-central Kentucky. As for the
marginal severe concerns along and east of US-127, CAM guidance is
not very supportive of convective initiation in the warm sector
given presence of dry air, capping inversion around 850 mb, and lack
of strong lifting mechanism as the low pressure races to the east.
Nonetheless, strong daytime heating and sufficient moisture will
support a corridor of 1500 J/kg along south-central KY with steep
mid-level lapse rates and enhanced 700-mb flow, so if even isolated
convection is able to realize, a conditional severe threat of hail
and damaging winds could exist in the late afternoon or early
evening hours. Most likely storm mode would be elevated cellular
storms with the potential of a rogue supercellular storm given
effective shear of 30-40 knots and SCP of 4 or higher.
Monday-Wednesday Night...Broad cyclonic flow aloft and surface high
pressure will promote persistent cold air advection regime through
midweek. Monday will still be breezy under NW winds (although not as
breezy as Sunday) with well below-normal highs. A moisture plume
from the Great Lakes will keep a steady stream of clouds on the
forecast. Best chances of widespread frost continues to be Tuesday
and Wednesday night based on temperatures, clear sky conditions and
relaxing winds as the high pressure closes in from the west.
Thursday-Friday...As surface high pressure slowly moves to the
Appalachians, winds will back to the south and slight warming trend
will begin. Otherwise, weather will remain dry and mostly sunny.
There is still a non-zero chance of frost Thursday night but will be
more isolated and confined to the rural areas and sheltered valleys.
&&
.AVIATION /18Z TAFS THROUGH 00Z MONDAY/...
Issued at 146 PM EDT Sat Oct 12 2024
VFR conditions are likely to persist throughout this TAF period. The
main aviation impact will be increasing winds through the lower
levels of the atmosphere. SW winds are briefly increasing to 7-12 kt
this afternoon before diminishing once again this evening with
sunset. Late tonight into early Sunday morning, SW winds aloft in
the lowest 2 kft AGL will gradually increase to 40+ kt as a cold
front approaches from the northwest. Expect LLWS conditions to
develop between 06-09Z Sunday from NW to SE in southern IN and
central KY.
As we move through the Sunday morning hours, we'll see more of that
stronger wind aloft mix to the surface (especially after sunrise).
Gusts to 20-25 kt are likely at the surface from ~14Z.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
UPDATE...EBW
SHORT TERM...CSG
LONG TERM...ALL
AVIATION...EBW
Source:
LMK issues Area Forecast Discussion (AFD) at Oct 12, 1:46 PM EDT ...Updated Aviation Discussion...---------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!
