Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 180534

Area Forecast Discussion
National Weather Service Louisville KY
1234 AM EST Sun Feb 18 2018

.Forecast Update...
Issued at 607 PM EST Sat Feb 17 2018

Several reports of 1 to 2 mile visibilities have been observed
across southern Indiana, Illinois, and western Kentucky. Starting to
see some sites along and north of the Ohio River drop under 3 miles,
so have thrown in some patchy fog everywhere this evening until the
drier air over eastern MO reaches us.

With the drier air in place, we should see a break from the fog
during the overnight hours. However, the fog may redevelop early
tomorrow morning as skies clear and temperatures drop under
radiational cooling. It looks like temperatures should cool enough
to where T/Td spreads would support fog development. With light to
calm winds anticipated tomorrow morning as well as high soil
moisture from recent precipitation, have gone ahead and put in
patchy fog for the whole CWA starting after 09z.


.Short Term...(Today through Monday)
Issued at 320 PM EST Sat Feb 17 2018

Snow has ended across southern Indiana, and rain is quickly winding
down along and west of I-65 in central Kentucky. Temperatures remain
borderline in the Bluegrass region north of Lexington. Additional
light snow will continue through 22z from Franklin County over to
Nicholas County. These areas have seen a dusting thus far and
wouldn`t expect more than that. Could have a few slick spots to
watch out for through this evening in that area. Back across
southern Indiana, roads will likely remain slushy in areas that got
heavier snow today. Moderate rain continues in the Lake Cumberland
region, but that should be winding down around 22z as well. The
Clinton County KY Mesonet site has recorded around 3/4 of an inch of
rain thus far.

A secondary impulse dropping southeast from Illinois could result in
some drizzle this evening north of I-64. Otherwise, high pressure
and dry air punching in from the west will result in improving
conditions after midnight. As skies gradually scatter out from west
to east early Sunday, patchy fog will likely develop. And further
east in the Bluegrass region, low clouds may hold in long enough
Sunday morning to prevent fog formation.

Sunday looks relatively nice as high pressure shifts east of the
area. Expect partly to mostly sunny skies and highs in the 50s.


.Long Term...(Monday night through Saturday)
Issued at 313 PM EST Sat Feb 17 2018

...Increasing Potential For River Flooding Next Week...

Highly anomalous weather pattern is still poised to set up across
the lower Ohio Valley next week bringing threats for heavy rain,
river flooding, and potentially record warm temperatures to parts of
Kentucky and southern Indiana.

The first wave of precipitation will pass by Sunday night into
Monday in association with a warm front. We should see temperatures
rising Sunday night into Monday morning in response to the warm
front, and by Monday afternoon, the front should clear the CWA. The
precipitation will taper off by Monday afternoon, and afternoon
highs will easily climb into the low to mid 70s. Overnight lows
Monday will remain warm, only dropping into the low to mid 60s.

After the precipitation ends Monday, it looks like most of central
Kentucky will see a break from the rain through at least Tuesday
evening. The latest 12z model guidance is in pretty good agreement
of keeping moderate to heavy rain just west of the CWA near a cold
front, with only lighter showers clipping parts of southern Indiana
Tuesday. Should this solution end up verifying, high temperatures
Tuesday could end up being VERY warm by February standards. GFS MOS
is currently predicting 82 for Louisville, 83 for Lexington, and 82
for Bowling Green. Should these high temperatures occur, they would
break the all time record highs for the month of February in
Louisville and Lexington, and come close to tying for Bowling Green.
Given how wet and moist it has been in the lower Ohio Valley, there
are some doubts we could reach temperatures this high as
evapotranspiration effects may limit temperatures from climbing too
high. Still, have gone ahead and bumped up temperatures a bit, with
several areas forecast to reach the 80 degree mark.

By Wednesday, the models show the front moving through Kentucky
bringing widespread rain and possibly a few thunderstorms to the
area. Total rainfall amounts forecast for Monday through Wednesday
continue to come in lower across central Kentucky with totals around
1  to 1.5 inches. Across southern Indiana, especially southwest
Indiana, totals in excess of two inches are possible. Even though
the forecast rainfall has dropped some over the past couple of days,
it will still lead to further rises on small river basins, streams,
and creeks and extend the rises on the main stem of the Ohio River
which is forecast to rise into minor flood stage next week.

More rainfall could fall Thursday into next weekend as models show
another frontal boundary stalling near the region. Still lots of
time to hone in on where the heaviest axis of rain will fall, but
the overall forecast regarding flooding is not very optimistic.


.Aviation...(06Z TAF Issuance)
Issued at 1233 AM EST Sun Feb 18 2018

Stratus has been stubbornly redeveloping over the lower Wabash
Valley over the past few hours, but the larger area of general
cloudiness is still expected to gradually push off to the east over
the next several hours. Dry air associated with high pressure
centered near KPOF at 05Z will help to stave off widespread dense
fog formation. However, shallow ground fog will still be a
possibility, especially at HNB and somewhat at BWG, in the few hours
either side of dawn. Will need to keep an eye out for this and
possible AMDs to the TAFs.

During the daylight hours today that surface high will proceed from
Kentucky to the Delmarva Peninsula, providing the TAF sites with VFR
conditions and southeast breezes near 10 knots.

Tonight scattered warm advection showers are expected to develop,
primarily after this TAF period.




Short Term...EBW
Long Term...DM
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