000
FXUS63 KTOP 111734
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1134 AM CST Wed Dec 11 2013

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 332 AM CST WED DEC 11 2013

At 07Z the mid level shortwave was progressing eastward through
NE and IA and has pushed a front southward into the region that
will bring another shot of cold air to northeast KS. The current
surface analysis depicts that cold front bisecting the forecast
area from northeast to southwest, which is forecast to slide
southeastward through the early morning hours exiting the area by
10Z. The winds behind the front shift to the north increasing to
around 15 mph with gusts up to 25 mph. Winds increase after
sunrise and stay gusty until around noon especially in east
central KS. High temperatures today will range from the upper 10s
in far NE KS to the mid 20s in SE KS. Low level clouds have formed
behind the front currently across eastern NE and parts of far NE
KS and are forecast to continue to progress southward. Boundary
layer mixing later this morning may help to maintain the clouds
until early afternoon. There are also mid level clouds associated
with the advancing shortwave stretched across the area that should
dissipate later. Surface high pressure not far behind the front
enters the area around mid day allowing the winds to become light
through the evening hours and skies to clear out. That high
pressure slides south of the area later tonight causing winds to
slightly increase and shift to the south southwest. Overnight low
temperatures range from the mid 0s in far NE KS to the low 10s in
central KS.

.LONG TERM...(Thursday through Tuesday)
Issued at 332 AM CST WED DEC 11 2013

Thursday and Thursday night, an upper level trough, off the CA
coast, embedded within the southern branch of the jet stream will be
kicked east-northeast into the lower and central high plains late
Friday night by an upstream upper level trough moving onto the
pacific northwest coast.

Increasing mid level winds over the central Rockies will cause a lee
surface trough to deepen across the central and southern high plains
on Thursday. The low-level winds will become southwesterly, which
will help to warm high temperatures on Thursday into the mid and
upper 30s, with the southwest counties reaching the lower 40s.

The southerly winds will continue Thursday night. Overnight lows may
occur in the evening hours with temperatures remaining steady or
slowly rising into the upper 20s during the early morning hours.

Friday, Southwesterly 850mb winds will advect residual moisture
northward from north TX and OK. The big question will be,  will
temperatures warm enough above freezing before the isentropic lift
causes light rain to develop across east central KS after 12Z
Friday. The ECMWF, GFS and GEM forecast that temperatures may only
be in the upper 20s to lower 30s as the rain develops from south to
north across east central KS after 12Z Friday. Surface dewpoints may
also lead to wet bulb cooling which could offset the WAA at the
surface. At 850mb, temps will warm above 4 deg C after 12Z. Thus the
precip will be in a liquid form that may start out as a light
freezing rain with surface temperatures in the upper 20s to lower
30s. Eventually the WAA should cause surface temperatures to warm
above freezing during the late morning hours. The 6Z NAM model does
not show any QPF across the TOP CWA on Friday and keeps the better
isentropic lift and rain to the south across southeast KS and MO. At
this time the NAM model looks to be the outlier and even if it does
verify we could still see freezing drizzle in the morning hours of
Friday that should turn over to drizzle with periods of light rain
through the the afternoon hours as surface temperatures warm above
freezing.

The 00Z ECMWF solution has the most amplified solution showing the
H5 trough moving east-northeast across southern KS and northern OK
by late Friday Afternoon. The large scale ascent and frontogenetical
forcing would begin to cool the warm layer between 850mb and 700mb.
This would cause the light rain during the late afternoon hours to
mix with snow and ice pellets. Both the GEM and GFS are not as
amplified and actually show the upper level trough filling a bit as
it lifts east-northeast across OK and southern KS.

Friday Night, the more amplified ECMWF solution shows a TROWAL
developing with good mid-level frontogenetical forcing and negative
EPV, thus the potential would be there for a band of heavy snow to
develop somewhere across east central KS during the evening hours of
Friday and slowly move east into western MO during the early morning
hours of Friday. If the ECMWF model were to  verify, the I-70
corridor from MHK to MKC could see 4 to 8 inches of snowfall Friday
Night. The GFS and GEM show may be 1 to 2 inches across east central
KS through the night. While the NAM shows only snow flurries.

Saturday through Sunday, the H5 trough will lift northeast into the
mid MS river valley. The upstream kicker H5 trough will dig
southeast into northern Mexico and move east across southern TX by
Sunday. Eastern KS will be under northwesterly flow aloft. It now
looks as if the cold Arctic airmass will dig southward across the
upper Midwest and into the OH valley, with the coldest air remaining
well east of the CWA. Highs on Saturday will range from the mid 20s
across far northeast KS with lower 30s across the southwest
counties. Sunday will be a bit warmer with mid to upper 20s across
northeast KS and upper 30s across the southwest counties.

There may be a slight warm up into middle of next week as the
amplified longer wave length trough shifts eastward into the eastern
US. Expect Highs in the mid to upper 30s across northeast KS and
lower to mid 40s across the southwest counties of the CWA.

Both the ECMWF and GFS show an intense upper level trough developing
across the western US in about 10 days. Initially there could be a
continued warm up through late next week with perhaps a possible
snowstorm for portions of the plains after December 20th. Any one
with travel plans before the Holiday`s will need to monitor the
development of this intense upper level trough.

&&

.AVIATION...(For the 18Z TAFs through 18Z Thursday Afternoon)
Issued at 1132 AM CST WED DEC 11 2013

High pressure will move southeast across eastern Kansas this
afternoon and evening. North winds will go to light and variable
by late afternoon and evening. As the high pressure moves off to
the southeast overnight, winds will shift to the south. Expect
mostly clear skies and VFR conditions through the forecast.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Sanders
LONG TERM...Gargan
AVIATION...Phillips