Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 220802

Area Forecast Discussion
National Weather Service Louisville KY
302 AM EST Mon Jan 22 2018

.Short Term...(Today through Tuesday)
Issued at 255 AM EST Mon Jan 22 2018

Bowling ball upper low making its way across Kansas will catch up to
its sfc reflection later today, and the system will become
vertically stacked over NW Missouri this evening before heading ENE
into the Great Lakes tonight. Warm conveyor belt is well established
from the ArkLaTex up into the Ozarks, and will translate eastward
across the Ohio Valley today.

Have gone with categorical POPs across the region for today, with
the best precip chances late this morning into early afternoon along
and west of I-65, and later in the afternoon farther east into the
Bluegrass region and along the Cumberland Escarpment. QPF for this
event is fairly modest, averaging around a quarter inch. Thunder
remains a low probability, but there is some weak elevated
instability so we will include a slight chance for embedded thunder.
Not a huge difference in probabilities when all is said and done,
but confidence is a bit higher south of the Western Kentucky and
Bluegrass Parkways.

Temps will be reltively flat through the day today, staying in the
50s to lower 60s. Bigger story will be the wind later this afternoon
and tonight, as the wind fields are fairly robust. However, with the
strongest cold advection aloft coming during the night, that will
limit the gustiness, but still could see gusts in the 30-40 mph

Not much temp recovery is expected on Tuesday under lingering upper
trofiness behind the departing cyclone. Most of the wraparound
moisture will stay to our north, but held on to slight chance POPs
over the Bluegrass region late in the day as the low-level flow
turns more northwesterly.


.Long Term...(Tuesday night through Sunday)
Issued at 255 AM EST Mon Jan 22 2018

Fairly progressive pattern through the middle of the work week.
Initially deep cyclonic curvature could keep some lingering precip
over the Bluegrass into Tuesday night, and that could end as
flurries if it persists long enough. However little or no impact is

Temps near seasonal normals Tue night and Wed, with a warming trend
for the latter half of the week as we trend into low-amplitude upper
ridging, and southwesterly low-level flow behind a departing sfc

Next precip chance ramps up Fri night and stays with us for much of
the weekend as the pattern amplifies enough to get a good Gulf
moisture tap. Temps are mild enough for this to be an all-rain
system, but moist adiabatic profiles are too stable for any thunder
threat. Capped precip chances in the likely category mainly to
account for timing uncertainties. Otherwise rain at some point
during the weekend is close to a slam-dunk. GFS and ECMWF both
currently show a "clean" frontal passage, but other runs have shown
the potential for a secondary sfc wave that could hang the front up
enough for precip to persist longer and perhaps even end as snow.
Sunday forecast will mention mixed precip, but it`s a low-
probability forecast at this point.


.Aviation...(06Z TAF Issuance)
Issued at 1245 AM EST Mon Jan 22 2018

Lower clouds have been pushed well north of the TAF sites tonight by
a steady southerly breeze. Ceilings will remain VFR for the next
several hours, with south winds increasing toward daybreak. LLWS
remains a concern tonight and early Monday at HNB/SDF/BWG. A 45-50
kt SSW low-level jet is developing as low as 1500-2000 ft AGL.
Closer to 12z, more of that wind will reach the surface, ending

Expect gusty south winds throughout Monday, with 25-30 kts certainly
possible at times. A band of moderate showers associated with a cold
front will march west to east across the TAF sites, reaching HNB
around 14-15z, SDF/BWG by 16-17z, and LEX by 18z. A narrow plume of
low level moisture along and behind the rain band should drop
ceilings to MVFR for up to a few hours. Visibility may also briefly
drop in moderate rain. Thunder looks unlikely at this time.

Dry air punching in behind the cold front will end the steady rain
rather abruptly Monday afternoon and evening. Gusty southwest winds
are forecast to increase Monday evening and overnight. Scattered
light precip will remain possible into early Tue, esp at the
northern sites.




Short Term...RAS
Long Term...RAS
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