LMK issues Area Forecast Discussion (AFD) at Nov 13, 12:41 PM EST ...Updated Aviation Discussion...060
FXUS63 KLMK 131741
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
1241 PM EST Wed Nov 13 2024
...Updated Aviation Discussion...
.KEY MESSAGES...
* Widespread moderate rain expected this afternoon into tonight,
with locally heavy rain rates expected at times. Rainfall totals
of 1-2" expected in general, with swaths of 2-3" likely.
* Dry through the weekend. Temperatures remaining at or above
normal through next Tuesday.
&&
.UPDATE...
Issued at 1001 AM EST Wed Nov 13 2024
After a chilly morning in the mid 30s to low 40s for most,
temperatures have warmed up to the 50s taking advantage of the still
unblocked solar radiation and ESE winds. Although cloud coverage
will be on the rise today, there is still a small window through the
early afternoon for temperatures to continue rising to the 60s.
Furthermore, some light to moderate radar echoes and isolated
lightning are noted moving up the Mississippi River. This activity
is associated with convergence and moisture advection on the leading
edge of a narrow 850-mb jet and upper divergence ahead of the mid-
level shortwave trough. Previous forecast remains on track as rain
chances will not increase across the western half of the forecast
area until later this afternoon. Rest of the forecast remains
unchanged.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 325 AM EST Wed Nov 13 2024
This morning, dry weather and cool temperatures are present across
central KY and southern IN, with latest obs generally in the low to
mid 40s. Nighttime microphysics satellite imagery shows a few upper
level clouds passing overhead, with the cirrus shield doing a fairly
good job of outlining the upper level ridge which is over the region
at this time. These upper clouds are coming from convection over the
central Plains which is associated with the system that will bring
widespread rain to our area this afternoon into tonight.
Dry conditions should continue through the rest of the morning as
the antecedent air mass hangs on for a few more hours. A plume of
low-to-mid level moisture which can currently be seen over the
Mississippi Delta on satellite will approach the area from the
southwest during the late morning and early afternoon hours, with
upper level clouds gradually building downward throughout the day.
How quickly we can get lower clouds into the region will be the
primary factor controlling temperatures today, with areas east of I-
65 likely to experience more warming as the lower moisture remains
to the west. Highs should be in the 60s in most locations today,
with the southern Bluegrass counties and Lake Cumberland area
favored to make it into the mid-to-upper 60s.
As far as rainfall is concerned, there are several factors which are
expected to come together to support a decent soaker across the Ohio
and Tennessee valleys this afternoon into tonight. First, the
moisture should be plentiful as HREF 50th percentile PW values
tonight approach 1.3-1.5". For context, BNA sounding climatological
max PW is 1.58" for 11/14, with 90th percentile being 1.19". This
moisture will arrive, in part, due to a 50-60 kt LLJ bringing warm,
humid Gulf of Mexico air up into the Ohio Valley. On the leading
edge of this LLJ, 850-700 mb warm frontogenesis and isentropic
upglide could help to enhance precipitation totals, and hi-res
guidance does show enhanced bands moving through the region tonight.
As we get further into the evening and overnight hours tonight, the
mid-level trough and vort max will move into the mid-Mississippi
Valley, providing upper dynamic support for additional waves of
rain. While a strong near-sfc inversion will hinder sfc-based
instability, the strong dynamic support and reasonably steep lapse
rates aloft could support one or two rumbles of thunder in the
most robust showers tonight.
Through the short term forecast period (Thursday 7 am), widespread
rainfall amounts of 1-2" are likely across the area. HREF localized
probability-matched mean QPF reaches 2-3" across portions of central
KY, indicating the possibility for locally heavier amounts. While 6
hr FFG is generally between 2.5-3" across most of the FA, localized
minor flooding issues can't be ruled out where the heaviest rain
rates occur, especially in poor drainage areas.
Temperatures tonight will be mild thanks to warm advection, low
clouds and precipitation. Lows should only fall into the upper 40s
and lower 50s.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 325 AM EST Wed Nov 13 2024
Thursday - Thursday Night...
Anomalous shortwave trough and its associated surface low will
rotate through the lower Great Lakes and Ohio River Valley region
through Thursday, then off the mid Atlantic Coast by Friday. The
upper trough axis will be rapidly pushing eastward of I-65 by
daybreak, effectively shutting off the deep moisture and forcing as
it does so. The trailing surface cold front will also be pushing
through our area W to E. Forecast soundings show low level lapse
rates steepening through the day, and this combined with the
lingering 1000-800 mb moisture will allow for lingering scattered
showers through Thursday. Overall, coverage and intensity will be
notably lower than what occurred previously overnight. Additional
QPF values are mostly expected to range in the .05" to .25" range.
Looks to be a fairly raw day given the lingering showers, heavy
cloud cover, and cool advection component. Would like to go a little
below guidance here given the lack of opportunity to warm up too
much. Time heights show pretty solid low to mid level cloud cover,
so don't expect too many peaks at the sun. As a result, expecting
most highs to be in the 55 to 60 degree range, overall a pretty
small diurnal range from the mild lows ahead of the front.
We look to dry out by sunset on Thursday evening, with cool
advection and some lingering clouds likely to keep temps from
bottoming out too bad by Friday morning. Looking for values mostly
in the low to mid 40s here.
Friday - Monday...
High confidence in a dry stretch of weather from late week, through
the weekend. Medium confidence for that dry stretch to continue into
the first part of next week. This will occur as surface high
pressure and upper ridging dominate our pattern. Temperatures near
normal values in the upper 50s and low 60s are expected on Friday,
and then a gradual warming trend is expected through the weekend.
Well above normal temps in the mid and upper 60s look like a good
bet by Sunday and Monday. It's possible we might be able to go
warmer here if we can keep sky cover in check. Models are having
some timing difference by early next week that could bring the next
system in a bit quicker, but for now like the idea of a dry forecast
with a lean toward milder temps.
Monday Night - Tuesday...
Decent model agreement in the next weather making system ejecting
out of the central Plains to the upper Midwest. Have chances for
precipitation beginning by this time with continue mild/above normal
temperatures ahead of the approaching cold front.
&&
.AVIATION /18Z TAFS THROUGH 00Z FRIDAY/...
Issued at 1240 PM EST Wed Nov 13 2024
Impacts/Confidence:
- High confidence in MVFR/IFR ceilings tonight into Thursday morning
- High confidence in MVFR visibility with heavier showers
- Medium confidence in LLWS at BWG and RGA tonight
- High confidence in breezy non-thunderstorm winds starting tonight
Discussion...Current VFR weather conditions will gradually
deteriorate tonight as a low pressure system and attendant warm/cold
fronts move through the area. Warm air advection showers are
currently moving over western Kentucky and within a few hours will
start light rain activity over the western terminals. Cloud base
will slowly lower to MVFR levels as more moisture is transported
into the region and heavier rainfall sets in. A 50-knot LLJ will
develop over central Kentucky tonight promoting LLWS at BWG and to a
lesser extent RGA. Confidence is too low at the moment to include
SDF/HNB/LEX due to a more marginal shear forecast. Heaviest rainfall
is expected between 14/0-9Z when IFR visibilities are also possible.
Thereafter, IFR ceilings, breezy southerly winds, and light rain
will be the main impacts. Finally, rain will let down from west to
east late in the morning while winds turn to the west behind the
cold frontal passage; however, IFR/MVFR ceilings will
probably continue into the afternoon.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
UPDATE...ALL
SHORT TERM...CSG
LONG TERM...BJS
AVIATION...ALL
Source:
LMK issues Area Forecast Discussion (AFD) at Nov 13, 12:41 PM EST ...Updated Aviation Discussion...---------------
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