Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 221156

556 AM CST Mon Dec 22 2014

Issued at 556 AM CST MON DEC 22 2014

The AVIATION section has been updated for the 12Z TAF issuance.


.SHORT TERM...(Today through Wednesday)
Issued at 352 AM CST MON DEC 22 2014

There is much more clarity in forecast this morning. The model
initializations apparently are latching onto the energy that will
carve out the large trough over the mid-section of the country
over the next 24-36 hours.

The 00Z models in general pivot the initial upper trough northeast
through Missouri this afternoon and evening, resulting in an area
of showers mainly over southeast Missouri and southern Illinois
today. This will also force the cold front into the region, and
there should be a nice north-south band of showers/rain over areas
east of the Mississippi River this evening. This will be pushed
eastward rather quickly, as a dry slot noses northeast through the
region. Overnight may very well be dry, and most, if not all, of
the area should be dry Tuesday, as the second upper low gets
organized over the southern Plains.

The 00Z GFS and ECMWF are in very good agreement with the second
system Tuesday night and Wednesday. They push the surface low
northeast through central/eastern KY/TN late Tuesday night and
Wednesday. The low-level flow in our region will transition from
southwest to north Tuesday afternoon and evening, and that should
keep any thunder threat to the southeast of the region.

They both bring the upper low north northeast across southeast
Missouri and southern Illinois Wednesday. The deformation zone
precipitation will be dragged slowly across most of the forecast
area. This could result in some fairly persistent banding through
the day, leading to some fairly heavy rain or snow. There is little
low-level cold air being drawn into this system, so temperatures
are expected to stay in the mid and upper 30s Wednesday. If it
changes over to snow and comes down hard enough, accumulations
could be possible. For now will be very conservative and just
throw in a few tenths right along the northwest border of the
region, where temperatures will be coldest. The banding potential
keeps this worth watching. Maybe some areas could eek out a white

.LONG TERM...(Wednesday Night through Sunday)
Issued at 352 AM CST MON DEC 22 2014

A progressive and less amplified upper-level flow pattern is
expected during the long term period. Following the departure of the
storm system on Christmas Eve, a series of relatively weak frontal
systems are forecast during the long term.

As far as the daily details...
On Wednesday night, some light rain or snow showers may linger
during the evening until the passage of the weakening 500 mb trough
axis. Partial clearing is likely later Wednesday night as mid-level
ridging builds eastward from the Plains.

Christmas Day will be dry as the 500 mb ridge axis passes overhead.
Increasing southwest low-level winds will dry out the low levels,
which should translate into plenty of sunshine.

Christmas night into Friday will be dominated by southwest flow at
the surface and aloft ahead of a frontal system over the Plains.
Temperatures should reach the 50s in most areas on Friday.

On Friday night, the cold front will move eastward into the Lower
Ohio Valley. Most of the upper-level shortwave energy will be
shunted north and west of our region. For this reason, precipitation
is expected to be sparse along the cold front. Forecast pops will
remain only in the slight chance category.

On Saturday, there may be some lingering rain or snow showers with
the cold front in the morning. However, most of the day will be dry
with temperatures struggling to reach 40.

Saturday night and Sunday, the forecast will remain dry as the model
consensus indicates high pressure will move east across the
Mid-Mississippi Valley. The 00z ecmwf will be discounted for the
time being, since it is the first run of any model to lift a storm
system northeast across the Lower Ohio Valley. There is little or no
evidence of such a system in the 00z gfs, its ensemble mean, or
previous runs of the ecmwf and gfs. However, the new 00z ecmwf
ensemble mos does support the high pops indicated by the operational


Issued at 1156 PM CST SUN DEC 21 2014

Deteriorating conditions are expected today, as an upper-level
storm system swings by just northwest of the area. Scattered
light showers this morning will become more numerous and heavier
from west to east this afternoon and evening. MVFR ceilings are
currently developing across the region, and they should lower to
IFR or LIFR levels this afternoon. Southeast winds will also be on
the increase, and some gusts into the upper teens and lower 20 kts
will be possible. The winds will veer to southwest tonight, and
skies may try to scatter out in the west, but that is unlikely in
the east. Definitely played the forecast pessimistically tonight.




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