Area Forecast Discussion (AFD)
Issued by Louisville, KY (LMK)
000
FXUS63 KLMK 180602
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
102 AM EST Fri Jan 18 2019
.Forecast Update...
Issued at 1046 PM EST Thu Jan 17 2019
Forecast is in pretty good shape tonight. Radar is showing some
drizzle and we received a report of drizzle along Interstate 65 in
the Elizabethtown area, so went ahead and added some patchy drizzle
to the forecast for the next few hours, primarily east of I-65.
Drizzle chances should diminish overnight as the depth of the
available moisture decreases and a cold front over central Kentucky
pushes eastward.
Looking ahead...low pressure coming out of the Ozarks tomorrow
night, with a warm front arcing along the length of Kentucky, will
bring widespread rain to the region after midnight. Precipitable
water amounts of 1.1" will be near record levels for the date,
though QPF during the overnight hours should remain well below 6-
hour FFG values. Isolated elevated rumbles of thunder will be
possible with 850mb theta-e ridge/60kt jet, primarily west of I-65
and south of the Ohio River.
&&
.Short Term...(This evening through Friday)
Issued at 300 PM EST Thu Jan 17 2019
A weak surface low is passing just to the north of the Ohio River
with a cold front set to move W to E across the area later this
evening. Isentropic lift aided by a 20-30 knot low level jet is
causing light rain over much of the area, especially along and north
of I-64. This rain is expected to end later this evening as the LLJ
pushes east and the frontal boundary pushes through. Temps have
pretty much peaked in the low to mid 40s across the area, and will
fall back into the 30s tonight mainly on a light cold advection
component. The cold air is not expected to catch up to the moisture
in time to create any p-type issues, so will continue with rain
ending messaging for early tonight. Cloudy skies will continue to
prevail as 1000-850 mb moisture is trapped beneath an inversion.
We'll see a continued cloudy, but dry day on Friday as surface high
pressure and dry zonal flow aloft briefly control the pattern. Highs
look to struggle again to the low and mid 40s with some of the
southern Indiana counties likely staying in the upper 30s.
.Long Term...(Friday night through Thursday)
Issued at 250 PM EST Thu Jan 17 2019
...Plenty of Changing Weather Saturday and Saturday Night...
Saturday a potent low pressure system will cross the southern
Commonwealth, bringing a variety of weather. Rain should be moving
into the region in the morning. With a warm front somewhere across
the state in the morning, we cannot rule out a wintry mix in our
southern IN and northern Bluegrass counties, especially should that
front end up a little farther south than in the current forecast.
This package will keep the forecast as all rain. Rainfall totals
have come down just a tad with this suite of models. Still think
areawide we will see 1-2 inches of rain through Sunday morning.
Higher amounts go over our southern and eastern counties, which do
have some lower flash flood guidance. Ensemble river forecast
guidance gives a chance for the Green River and possibly the other
quick risers in Boston and Peaks Mill. Given we are not expecting
widespread flooding, will continue to hold off on any kind of a
flood watch.
Winds will become more light and variable as the low moves through,
but then the back side we will see some strong cold air advection.
We should see light rain switch over to snow in the evening hours.
Models continue to depict an area of enhanced snow in a region with
a coupled jet structure somewhere over Indiana. Should this band
make it into our southern Indiana counties, we would see more snow
than what this forecast depicts. Didn't stray too far from the
previous package, with most of the area seeing at least a half inch
and our northern counties up in the 1-3 inch range.
Precip should come to an end during the nighttime hours, from west
to east across the region. Temperatures will be crashing hard
though. Strong winds will help dry our roads some, but would not be
surprised to see slick spots develop as temperatures by daybreak
Sunday drop to the upper teens to mid 20s, likely close to the highs
for the day.
After a very cold start to the work week, lows in the single digits
likely in most of southern Indiana and parts of north central
Kentucky, we should start warming up a little. High pressure will
move east of the region Monday afternoon. By Tuesday morning, we'll
see some warm air advection bring in more precipitation. We could
see some wintry precip at onset, depending on starting temperatures.
Then with gusty southerly winds, we'll get back to plain rain
Tuesday. Precip should continue until another cold front crosses the
region sometime Tuesday night or Wednesday. Once again, we could see
some back side switch over to snow. High pressure should move in for
Thursday, but CMC is an outlier showing another low crossing the
Appalachians. Will discount for now and lean more for the
ensemble/GFS/Euro solutions.
&&
.Aviation...(06Z TAF Issuance)
Updated at 1259 AM EST Fri Jan 18 2019
Dry weather will dominate through the next 24 hours, but IFR/Fuel
Alternate stratus will linger throughout the period. RH overviews
and forecast soundings show some ceiling improvement during the
afternoon, perhaps enough for SDF at least to rise above 2 kft.
Slightly reduced vsbys due to light fog/mist between 06-12z. 5-7 kt
NW wind early this morning will become light and variable after
sunrise with sfc ridging building across the region today.
Tonight, winds will turn easterly and increase as a strong storm
system ejects out of the southern Plains. Widespread rain will
spread into HNB/SDF/BWG between 06-12z Saturday. The bulk of the
rain looks to hold off until after 12z at LEX. Expect heavy rain and
poor flying conditions on Saturday.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...13
Short Term...BJS
Long Term...RJS
Aviation...EBW