Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 140547

Area Forecast Discussion
National Weather Service Paducah KY
1147 PM CST Fri Jan 13 2017

Issued at 1147 PM CST Fri Jan 13 2017

Updated aviation discussion.


UPDATE Issued at 1122 PM CST Fri Jan 13 2017

Killed two birds with one update. As the measurable precipitation
has ended at least temporarily in the Freezing Rain Advisory, have
cancelled it an hour early. In its place, sort of, have issued a
Dense Fog Advisory for much of west Kentucky, along and south of
Highway 13 in southern Illinois, and adjacent portions of
southeast Missouri through 9 AM Saturday. Visibility has dropped
to 1/2SM or less over much of that area, and it should continue to
worsen until the next batch of rain arrives later tonight. It may
very well be cancelled well before 9 AM depending on the impact of
the rain.

UPDATE Issued at 853 PM CST Fri Jan 13 2017

Showers have persisted in a zone along and north of I-64 this
evening, but they should diminish through midnight. Temperatures
have not changed much, so will have to keep the Freezing Rain
Advisory going for now. Still thinking that we will be able to let
it go at midnight.

The latest guidance continues to bring a rather large area of
rain eastward into the region just before 12Z. Through daybreak
this should only impact southeast Missouri, where temperatures
should be just above freezing. This will have to be watched
closely. If there is enough evidence of the rains arriving with
temperatures at or below freezing, the Advisory may need to be
continued, or a new one issued for what should be a small area
from possibly Carter and Wayne through Bollinger and into Perry
county. That will most likely have to be determined by the
midnight shift.

South of the showers, drizzle and fog will be the story for the
rest of the night. We are currently down to 1/2SM in FG at the
office, and this has been a steady downward trend. Easterly winds
over much of west Kentucky are trying to advect warmer and
moister air into the Lakes through the Purchase Area and the
southern tip of Illinois. Not sure if it will go to 1/4SM or less,
but will keep an eye on it. Added areas of fog to the forecast
for the rest of the night, but may need a Special Weather
Statement or possibly a Dense Fog Advisory if it gets any worse
over this area.

UPDATE Issued at 613 PM CST Fri Jan 13 2017

Have decided to extend the Freezing Rain Advisory basically along
and northwest of a line from Marble Hill Missouri to Mt Carmel
Illinois. That line approximates the freezing line as of 00Z.
While the tangible rains are confined to the north of I-64, METARs
reveal 2-5SM visibilities reflective most likely of freezing
drizzle back to KMVN and KMDH. With the loss of solar input would
prefer to keep the headline going where temperatures have not
climbed above the freezing line. Short term guidance continues to
show a slow westward push of the freezing line, so hopefully, the
entire area will be above freezing by 06Z. Will continue to re-
evaluate through the evening for additional adjustments to the

The AVIATION section has been updated for the 00Z TAF issuance.


.SHORT TERM...(Tonight through Sunday)
Issued at 226 PM CST Fri Jan 13 2017

Event diminishing this afternoon on schedule. Things seemed to pan
out ok, with 0.05-0.20" glaze most areas, maybe a tad more parts
of southern IL. Impacts more so on elevated surfaces, not so much
roads. Cannot rule out some lingering freezing drizzle in the wake
of the NE moving precip area. Will continue the Advisory til 6
p.m. and the evening shift can go from there.

Will have a lull this evening. Again, may see some drizzle at
times. Maybe a slight chance of rain. Temps should be above
freezing nearly all areas by shortly after dark. Exception area
may be from a Marble Hill, MO to Mount Vernon, IL line and points
west. Rain should pick up again after midnight. Temps will be very
close to 32F Perry County MO to Perry County IL. Will have to
monitor. For now, no new headlines. Rain chances to continue
Saturday and Saturday night. Models seemed a bit low on QPF
overall past 24-30 hours. Will have to monitor for standing water
issues Saturday, mainly parts of SEMO, southern IL. Rain chances
to continue Sunday. Basically followed the NAM/EC solutions,
especially for temps.


.LONG TERM...(Sunday night through Friday)
Issued at 226 PM CST Fri Jan 13 2017

The long-term period will be highlighted by a moist southwest flow
aloft over our region. The 500 mb longwave trough position will
remain over the western states. A series of shortwaves will eject
northeast across the central states. The models are in relatively
poor agreement on the timing of these shortwaves, especially
compared to yesterdays model runs. This makes it difficult to
forecast dry weather on any day in the long-term period.

The models remain in good agreement that the strongest system will
affect our region early in the week, bringing the potential for a
widespread soaking rainfall. The 12z gfs has abruptly sped up the
system compared to previous guidance. The slower 12z ecmwf is
consistent with previous runs of both the ecmwf and gfs, and the
forecast will be heavily weighted toward the ecmwf timing. This
means rain is likely Monday night and Tuesday, along with a slight
chance of thunderstorms. The models continue to indicate 850 mb
southerly flow will be near 50 knots ahead of the cold front,
bringing some weak elevated instability. Forecast rainfall amounts
have come down slightly, and they now average 1 to 2 inches for the
event. Temps will generally be in the 50s and 60s in the mild
southerly flow Monday through Tuesday.

Rain will taper off from west to east Tuesday night. The best chance
of dry weather appears to be Wednesday and Wednesday night in the
wake of the departing low pressure system. Winds will turn into the
west Tuesday night, bringing slightly cooler air. Highs on Wednesday
will be in the 50s.

Thursday into Friday, there is a large range of model solutions.
Once again, the faster gfs and gfs ensemble mean are not preferred
due to their lack of consistency. The 12z gfs camp brings two
moisture-laden shortwaves northeastward into the Ohio Valley late in
the week. The ecmwf is drier, but it also indicates some qpf with a
weak shortwave on Friday. Due to the moist southwest flow aloft, a
small chance of rain seems warranted from Thursday into Friday,
regardless of model preference. Temps will turn milder, with highs
in the 60s due to returning southerly surface winds.


Issued at 1147 PM CST Fri Jan 13 2017

Ceilings across the region will remain LIFR throughout the 06Z TAF
period as a disturbance aloft approaches the region overnight. Vsbys
are expected to continue to deteriorate overnight as fog (and
drizzle) becomes more likely, and LIFR vsbys in fog may occur at
some terminals. The aforementioned disturbance will result in an
area of rainfall around daybreak, which will move west to east,
probably keeping vsbys at least IFR for much of the day. Surface
winds, while light, should back somewhat Sat morning for at least a
few hours.


IL...Dense Fog Advisory until 9 AM CST Saturday for ILZ085>094.

MO...Dense Fog Advisory until 9 AM CST Saturday for MOZ087-110>112-

KY...Dense Fog Advisory until 9 AM CST Saturday for KYZ001>017-021-



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