Area Forecast Discussion
Issued by NWS Paducah, KY

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000
FXUS63 KPAH 141735
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
1132 AM CST Sun Dec 14 2014

.UPDATE...
Updated aviation section for 18z tafs

&&

.SHORT TERM...(Today through Tuesday night)
Issued at 239 AM CST SUN DEC 14 2014

A few adjustments made in the short term to address ongoing and
projected items with the Monday system.

Firstly, dropped mention of drizzle for the pre-dawn and morning
hours this Sunday. Measurable isentropic lift and upglide over
warm front to the southwest appears to be lacking and no longer
warrants a mention of drizzle in next forecast package.

Secondly, with the Monday system, best forcing and lift will be
over the western 1/3 of the WFO PAH CWA during the morning hours.
Beyond that time, main forcing lifts off to the northeast, with
the best elevated instability shifting of to the southeast with
time. Gradually reduced PoPs starting in the 15z-18z (9am-Noon)
time frame on Monday. Also added a small differential PoP mention
of Thunderstorms to the extreme southern Purchase and Pennyrile
area during the early/middle afternoon hours on Monday. Due to the
short duration of thunderstorm potential, its mention will likely
only show up in the fine resolution forecast products versus long
term text products issued by this office.

Other than very subtle tweaks in timing/location of rain chances
and frontal passage and subsequent temperature falls, little
significant change in ongoing short term forecast package.

.LONG TERM...(Wednesday through Saturday)
Issued at 239 AM CST SUN DEC 14 2014

The overall trend during the long term period will be toward
increasing precipitation. The models are in good agreement that a
moist southern branch of the jet will ensure at least one
organized precip event. As usual, the devil is in the details. The
timing of the event (or events) and the type of precip are highly
variable from model run to model run.

Wednesday should be a dry day, as a chilly 1030 high pressure system
ridges southeast through the MS River Valley. Highs will probably no
top 40 degrees in many locations north of the Ohio River.

On Wednesday night and Thursday, models are in better agreement this
morning that h50 flow will become more zonal to wswly...and weak
overrunning may develop over the sfc ridging. Precip type could be
just about anything in the north, and most likely rain or a mix in
the south.

Thursday night and beyond, there is strong agreement that a moist
upper level shortwave will eject east from the Plains. However, the
track and timing of the system varies considerably from model to
model. For example, the new 00z ecmwf is slower with the timing
compared to the 00z operational GFS, and digs the shortwave much
farther south into the srn Plains by Friday night. This would
actually create a significant winter weather event Friday night into
Saturday over much of the forecast area, whereas the GFS solution is
quicker in timing, and also much warmer with the upper low tacking
nw of the region. This would result in mostly liquid over our area.
A blend of the solutions seems to be in order for the time
being...yielding partially or mostly snow northwest of the Ohio
River, and a mix or just rain south.

&&

.AVIATION...
Issued at 1132 AM CST SUN DEC 14 2014

At the kevv/kowb sites, cigs and vsbys were stuck in the lifr
category all morning. It now appears possible these sites could stay
ifr through the entire taf period, per the latest gfs lamp mos
guidance. However, the forecast will maintain the improving trend
but at a much slower pace, as shown by the nam mos. This means
tonight and most of Monday morning should be mvfr.

At the kcgi/kpah sites, the clearing line has been surprisingly fast
across southeast Missouri. It now appears kcgi will be mainly clear
through this evening. The clearing line looks like it will stall
near kpah late this afternoon, so the forecast is very tough there.
Will maintain a forecast of vfr cigs there tonight, but mvfr vsbys
are likely late tonight. Both sites will go ifr in the morning as
rain arrives.

&&

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

$$

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







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