Area Forecast Discussion
Issued by NWS Paducah, KY

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382
FXUS63 KPAH 142031
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
231 PM CST Sat Jan 14 2017

.SHORT TERM...(Tonight through Monday night)
Issued at 225 PM CST Sat Jan 14 2017

Have allowed winter/fog headlines to expire this afternoon as
vsbys have improved and surface temperatures have crept just above
the freezing mark over nw counties with precip shifting south
toward the OH River. Could be another batch or two of very light
rain or drizzle overnight tonight at many locations as the lower
atmosphere remains quite saturated. Not much forcing to work with
though, so any QPF should be quite light. Temperatures not
expected to fall off much during the night, but it would not take
much of a drop to get our northern/western counties of srn IL/se
MO back to near or just below freezing. Will need to monitor to
see how precip/temp trends go this evening up in those locations
for possible quick advisory for some freezing drizzle/light
freezing rain possibilities.

Weak mid level ridging on Sunday will also serve to keep any
significant amounts of precip out of the region, though will need
to leave some chance for a bit of very light precip, especially
along/north of the I-64 corridor. Again, would not be surprised to
see a touch of freezing precip in that corridor early in the day,
but will hold off on headlines at this time and handle with
HWO/possibly an SPS.

Next high chance of rain/isolated thunder looks to hold off until
later Mon/Monday night time frame as the next surface front and
associated H50 short wave approach from the west. Not too excited
at this time on strong/severe threat given overall lack of
instability. More likely just a few isolated rumbles of thunder
here and there. Could be some decent widespread rain amounts up
over 1/2 inch tho.

.LONG TERM...(Tuesday through Saturday)
Issued at 225 PM CST Sat Jan 14 2017

The northern hemispheric pattern has the center point of the wave
pattern shifted toward the Arctic circle northwest of Alaska at the
start of the extended forecast period, with the most dominant
meridional wave extending from the pole to east of Greenland and a
low amplitude, split trough over the Northern Pacific. The evolution
of the primary stable five wave pattern (per the ECMWF and GFS
guidance) into a 3-4 unstable wave pattern, suggest a more dynamic
and chaotic flow over the U.S. during the extended period. However,
the dominance of the mean trough east of Greenland/Northern
Atlantic, may mean greater heights upstream over the eastern U.S.,
pushing systems to the west of the WFO PAH forecast area further to
the west and north.

Although the GFS and ECMWF similarly handle the ejection of the Baja
California low into the western Great Lakes through Tuesday, the
similarity begins to wane with time, especially late in the week.
The 12z Saturday ECMWF is a little warmer aloft, but cooler at the
surface than the 12z Saturday GFS.  A blend of ECMWF/GFS seems to be
a more realistic solution.

For the WFO PAH forecast area, this would be mean that the weather
system on Tuesday should exit a little quicker, with the system
moving from the southwest Thursday into Friday should be shifted
more to the east with time in a more progressive flow.

Blended max/min temperatures upward slightly from the cooler ECMWF
values, but still lower than the GFS. In addition, kept PoPs in
place closer to the slightly faster and more eastern ECMWF than the
warmer and more unstable GFS.  There is lesser forecaster confidence
in the late week solution (40-50%) than the Tuesday weather system
(60-70%).

Otherwise, no significant changes in the other sensible weather
elements through the forecast period.

&&

.AVIATION...
Issued at 225 PM CST Sat Jan 14 2017

Expect low IFR cigs to be the rule for much of the 18z TAF cycle.
Also will need to monitor for some more IFR vsbys to form of areas
of drizzle/fog can get going sometime tonight. Winds will continue
light north/northeast less than 7 knots for the most part.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&

$$

SHORT TERM...GM
LONG TERM...Smith
AVIATION...GM



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