000
FXUS63 KPAH 291737
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
1137 AM CST Thu Jan 29 2015

.UPDATE...
Issued at 1137 AM CST THU JAN 29 2015

The AVIATION section has been updated for the 18Z TAF issuance.

UPDATE Issued at 905 AM CST THU JAN 29 2015

The forecast has been updated to catch up to the cloud and
temperature trends. Much of west Kentucky will have highs greater
than forecast late this morning. Also, the latest HRRR has no
precipitation over the area through the day, so removed all
measurable PoPs. Would not rule out some patchy drizzle across the
Evansville Tri State region this afternoon, but will add that in
once it becomes more obvious.

&&

.SHORT TERM (Today through Saturday)...
Issued at 255 AM CST Thu Jan 29 2015

A well-defined cold front will move quickly southeast across our
region this morning. A small line of showers developed well ahead
of the front from kowb to khop early this morning. Cannot rule out
another small line until the front passes to our east. For most of
the forecast area, this will be a dry frontal passage.

Behind the front, winds will shift into the northwest and become
rather gusty today. Some gusts around 25 knots are likely. NAM and
GFS 925 mb rh progs indicate widespread low cloudiness will arrive
behind the front and persist through the afternoon. Low level cold
advection and widespread cloudiness should result in a steady or
slowly falling temperature trend this afternoon. Highs will be in
the morning. A period of sunshine prior to the arrival of low
clouds could push temps up from their 08z readings in the mid 40s
to lower 50s.

The main forecast issue for tonight is when and if the low clouds
will clear out. 925 mb rh forecasts from the 00z nam and gfs are
quite moist all night, especially east of the Mississippi River.
The forecast will show partial clearing from west to east tonight,
but at a slower rate than previous forecasts. Lows will be in the
mid to upper 20s.

Friday still looks mostly sunny, although there may still be some
morning low clouds in southwest Indiana and northwest Kentucky.
Winds will decrease as surface high pressure reaches the mid and
upper Mississippi Valley. Highs should be quite cold considering
the amount of sun, ranging from the mid 30s to lower 40s.

Friday night and Saturday...mid and high clouds will gradually
increase ahead of the next system. The low levels will be
extremely dry, which should make it very difficult for precip to
reach the ground. Will keep in a slight chance of showers in the
Ozark foothills of southeast Missouri. Despite the clouds, highs
should be mainly in the lower and mid 40s due to southerly winds.

.LONG TERM (Saturday night through Wednesday)...
Issued at 300 AM CST Thu Jan 29 2015

Main forecast challenge in this time frame comes with the storm
system that looks to be impacting the region over the weekend,
especially Sunday. Forecast confidence remains fairly low at this
time regarding precip types.

As we begin the period, split mid/upper flow pattern should be in
place...with nrn branch trof digging se into the Plains and a nearly
stationary srn branch low in place over the Baja of CA. It now looks
as though the srn branch low will feed pacific moisture into the nrn
branch...leading to fairly widespread precip shield over the mid MS
River and Ohio Valleys Saturday night and esp Sunday as sfc low
pressure develops over the Gulf Coast states. As mentioned, the main
uncertainly at this time lies with precip type. The latest 00z runs
of the operational GFS and ECMWF are now in decent agreement that
the sfc low and inverted trof will remain farther south over
MS/AL...as a 1040 mb sfc high presses south into the nrn Plains.
This would result in a colder thermal profile than we were thinking
yesterday. Snow would be the main precip type over all except our
far southern counties, with some potential for a few inches, esp
along and north/west of the Ohio River. On the other hand for
example, 00Z NAM/GEM both bring the sfc low farther north, and are
thus much warmer in their thermal profiles. For this package, will
keep much of the nrn half of the forecast area mostly snow, and go
with rain/snow for now over much of wrn KY and se MO. Again,
uncertainty is still quite high and things are likely to change one
way or another as we get closer to the event.

Very cold air will follow in the wake of the system as Canadian high
pressure moves se into the region. Most locations will fall into the
teens later Sunday night and Monday night. Highs Monday will likely
remain below freezing. Of course, things could be even colder if any
areas manage to get a fresh layer of snow on the ground. The next
clipper system Tue/Tue night is expected to stay much farther north
and cross over the Great lakes region. May be some light precip as
it drags another cold front across the region, but most impacts with
this low are expected to remain north of the forecast area.

&&

.AVIATION...
Issued at 1137 AM CST THU JAN 29 2015

A large mass of MVFR ceilings is overspreading the region behind a
cold front late this morning. Given the expanse of the MVFR clouds
at this time, would not expect them to depart any time soon.
Definitely went on the pessimistic side of guidance with scattering
or lifting not until Friday morning. Northwest winds will continue
to gust well above 20kts this afternoon, but they should subside
some by sunset. Winds will remain around 10kts through the
remainder of the period.

&&

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

$$

UPDATE...DRS
SHORT TERM...MY
LONG TERM....GM
AVIATION...DRS