Area Forecast Discussion
Issued by NWS Louisville, KY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KLMK 220535
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
135 AM EDT Sun Apr 22 2018

...Updated Aviation Discussion...

.Forecast Update...
Issued at 855 PM EDT Sat Apr 21 2018

Current forecast remains on track this evening.  Skies will continue
to cloud up through the overnight hours as plentiful mid-high cloud
cover spreads east across the Ohio Valley.  In the near term, we
expect tranquil conditions with a light northeasterly wind across
the region.  Temperatures are currently in the upper 50s to the
lower 60s and are forecast to steadily fall into the low-mid 50s
during the early overnight hours with minimum readings dropping into
the mid-upper 40s over the Bluegrass region and upper 40s to around
50 elsewhere.  Some light rain showers are still likely to impact
our southwestern areas toward dawn.

&&

.Short Term...(This evening through Sunday night)
Issued at 232 PM EDT Sat Apr 21 2018

Upper level ridging over the Ohio Valley and a 1032mb surface high
near Lake Erie are currently responsible for the beautiful and
comfortable weather we are currently enjoying. Surface observations
across southern Indiana are reporting temperatures in the lower 60s,
while southern Kentucky is seeing temperatures closer to the 70
degree mark. Some cirrus is moving in from the west, but it is
fairly thin and many folks are enjoying mostly unfiltered sunshine.

All good things have to come to an end around here, and
unfortunately gloomy skies are on the horizon. A strong upper level
low (ULL) currently over the southern Plains will begin tracking
toward the lower Ohio Valley Sunday. Out ahead of it, we`ll see
clouds increase in coverage this evening, and rain beginning to fall
as soon as Sunday morning across southwestern Kentucky. The 12z
guidance has slowed down the arrival of rain by just a little bit,
so have trimmed back PoP timing. Still looks like a good chunk of
the CWA will not see rain during the day Sunday, and it may not be
until early Monday morning that parts of southern Indiana and
northern Kentucky see any rainfall.

.Long Term...(Monday through Saturday)
Issued at 244 PM EDT Sat Apr 21 2018

The upper level low (ULL) begins to slow down and take a slight jog
northward on Monday. Widespread showers look like a pretty good bet
on Monday as good forcing, moisture and lift are in place north of
the ULL. The ULL will move over the state of Kentucky Tuesday, and
drier air wrapping into the ULL could limit precipitation coverage
during this period.

Overall rain amounts through Tuesday afternoon vary quite a bit
among model guidance. The GFS and NAM paint 2-3 inches across south
central Kentucky, gradually dropping to an inch or less as you get
into southern Indiana. Meanwhile, the ECMWF and Canadian generally
have less than 1.5" across south central Kentucky, and less than a
half inch up toward southern Indiana. Leaning more toward the
ECMWF/Canadian for current forecast, as QPF from the GFS has been
inconsistent the last few runs, and we`re just starting to get into
the NAM`s 84hr forecast range with this event. Should the wetter
solutions verify, though, some streams and rivers could begin
running high across south central Kentucky.

An approaching trough from the west will finally rid us of the pesky
ULL late Tuesday night into Wednesday. There remains some
disagreement amongst models as to whether the approaching trough
will bring additional moisture to the region. The GFS is among the
"wettest", though overall amounts typically stay below 0.25". The
Canadian and ECMWF remain mostly dry.

Another trough/surface cold front could impact the region during the
Thursday night to Friday timeframe. Some timing differences with
models preclude any higher chance PoPs in the forecast, but it does
look like we will see some rain with that system. Drier weather
should be in store for the weekend.

&&

.Aviation...(06Z TAF Issuance)
Issued at 135 AM EDT Sun Apr 22 2018

A broad upper level low now over Oklahoma will spin its way into the
Tennessee Valley late tonight. A surface warm front will develop
east of it, allowing for enough forcing for light rains at BWG by
late morning, getting into the MVFR range by early afternoon. These
rains should stay south of the other terminals, but a strengthening
wind field around the system will mean steady 10-15 kt gusts with
perhaps stronger gusts. Rain shield will lift north by the end of
SDF`s period, bringing MVFR conditions there by daybreak Monday.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&

$$

Update...MJ
Short Term...DM
Long Term....DM
Aviation...RJS



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.