Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 200824
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
324 AM EST Tue Feb 20 2018

.Short Term...(Today through Wednesday)
Issued at 249 AM EST Tue Feb 20 2018

High pressure off the East Coast will pump very warm air northward
ahead of a cold front stretching from Texas to the Great Lakes
today. South winds will once again gust to 30-35 mph. There will be
plenty of cirrus today, plus some cu development this afternoon
especially in Kentucky. However 5H heights will be a little higher
today and 850 temps similar to or maybe a bit warmer than yesterday.
For MaxT will add 2 or 3 degrees onto yesterday`s readings,
resulting in highs in the upper 70s to around 80.

Tonight that cold front will begin to move eastward as high pressure
crossing the northern Plains gives it a push. Showers, with a few
embedded rumbles of thunder, will enter the Ohio Valley from the
northwest after midnight. The leading edge of the showers should be
in the vicinity of, or just south of, the Ohio River by 12Z Wednesday
morning.

Primarily post-frontal showers, and a few rumbles of thunder right
along the front, will cross the region through the day on Wednesday
as the sharp cold front marches across the area. Temperatures will
fall behind the front, dropping into the 40s in southern Indiana
while the Lake Cumberland region manages to maintain 60s until
around sunset (after highs in the low 70s). Rainfall amounts will
range from 0.75-1.00" in southern Indiana and north central Kentucky
to less than 0.25" at Lake Cumberland. This shouldn`t cause any
flooding problems but will help to keep the ground moist ahead of
rains coming in later this week.

&&

.Long Term...(Wednesday night through Monday)
Issued at 302 AM EST Tue Feb 20 2018

...SIGNIFICANT RAINFALL LIKELY FROM MID-WEEK AND INTO THE WEEKEND...

The trough west/ridge east pattern will stay in place through this
weekend, though it will start to flatten late in the week. The main
corridor of heavy rains will be from Texas through the Ohio Valley
to the eastern Great Lakes, with frequent waves of showers moving
along that pathway in the static pattern.

The front that moves through on Wednesday will get hung up as it
bumps into the eastern ridging, and after less shower coverage on
Thursday (compared to Wednesday) renewed shower and isolated
thunderstorm activity is expected Thursday night into Friday.

Surface cyclogenesis is expected over the southern Plains Friday
night/Saturday, with the low heading northeast into the Great Lakes
Sunday. This would push a warm front through our region Friday
night/Saturday and pull a cold front through here Saturday night,
with widespread showers and scattered thunderstorms. The best chance
for storms will be Saturday evening.

High pressure then should move in and dry us out to end the weekend
and begin the new week.

Operational runs of the GFS and ECMWF are still suggesting 3-5"
rainfall totals through the weekend, which is in good agreement with
the GEFS ensemble mean and with what the data were indicating
yesterday. If this QPF does come to fruition, moderate flooding
would be likely by this weekend on the Ohio River from Louisville
downstream, as well as on smaller streams in southern Indiana and
central Kentucky. People with interests along rivers need to keep an
eye on the forecast for the next few days. remember that river
forecasts are available via the "Rivers and Lakes" link on our
webpage at weather.gov/lmk.

&&

.Aviation...(06Z TAF Issuance)
Issued at 1218 AM EST Tue Feb 20 2018

Wind gusts and wind shear will continue to be the main issues for
this TAF forecast. The region remains solidly in the warm sector
with south-southwesterly winds expected through the TAF period. A
low level jet has begun to develop tonight. The latest AMDAR
soundings show around 40 knots at 2000 feet and some strengthening of
this LLJ is expected over the next couple of hours, so will continue
to carry low level wind shear overnight. This should weaken by mid
morning as surface winds begin to increase. Wind gusts through the
daytime tomorrow will be 25-35 knots again. Scattered to broken cu
will develop during the afternoon as well. A cold front will
approach SDF late in the planning period and will bring with it rain
and lower ceilings.

&&

.Hydrology...
Issued at 318 AM EST Tue Feb 20 2018

Minor flooding is in progress on the Ohio River at Tell City,
Cannelton, and Louisville. The Green River is just below flood stage
at Rochester but is already in flood downstream from there.

Fortunately we`ll have another dry day today. However, the latest
forecast suggests that a heavy rainfall event is still expected to
occur from Wednesday into the weekend. Widespread rainfall amounts
of 3-5 inches will be possible across southern Indiana and central
Kentucky between late tonight and Saturday night.  Some locally
higher amounts will be possible depending on where the heavier axes
of precipitation develop. This rainfall combined with already
saturated soils will lead to flooding problems in low-lying areas
near rivers/creeks, and the typical flood prone areas.

Ensemble river forecasts suggest that some of our rivers could rise
into the moderate flood range by the end of the week, including the
Ohio from Louisville downstream. River forecasts are highly
dependent on where the heavy rainfall actually occurs, though.

Residents of southern Indiana and central Kentucky should remain
alert this week for flooding.  Stay tuned for the latest forecasts
and updates through the week.

&&

.Climate...
Issued at 323 AM EST Tue Feb 20 2018

Today`s forecast highs will smash the records for this
date, and threaten the records for the all-time warmest February
day.

          Today         Feb All-Time
SDF     76 (2016)       81 (2/24/2017)
LEX     72 (2016*)      80 (2/23/1996)
BWG     76 (2017)       83 (2/28/1918)
FFT     73 (2016)       80 (2/24/2017 & 2/10/1932)

Record warm lows will occur today. Here are the current
records:

SDF     55 (1994)
LEX     54 (1994)
BWG     55 (1994)

* and previous years

&&

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

$$

Short Term...13
Long Term...13
Aviation...EER
Hydrology...13
Climate...13



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