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000
FXUS63 KTOP 041113
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
513 AM CST Tue Mar 4 2014

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 341 AM CST TUE MAR 4 2014

Early this morning, surface high pressure progressed east of the
area, resulting in surface winds shifting to the south/southwest.
Despite having mostly clear skies over the region from this passing
high, this southerly component to the wind was enough to help keep
overnight low temperatures a few degrees warmer in the teens to
upper single digits. With these conditions in place, wind chills
values around sunrise are expected to range from -1 to -6.

Surface winds will remain out of the southwest today. Skies will be
mostly sunny this morning with model soundings showing some high
clouds developing this afternoon into this evening as a system
approaches the region. These conditions will help to push high
temperatures today above the freezing mark with readings ranging
from the mid 30s over east central Kansas, which has the better
snowpack, to the lower 40s over north central Kansas.

Water vapor imagery early this morning showed a weak shortwave
moving into northern California. Models are in good agreement in
having this shortwave progress eastward into the central Rockies
late this afternoon into early this evening and deepening as it
advances into Kansas and Oklahoma overnight into Wednesday morning.
Ahead of this wave, a weak cold front will shift toward the
Kansas/Nebraska border this evening and continue to track southward
over the area overnight into Wednesday morning. The better moisture
and lift look to be behind the boundary and associated with the
mid-level shortwave, with a slight chance for some light
precipitation to start developing over north central and far
northeast Kansas after 09z Wednesday. Model soundings show
saturation in the dendritic growth zone and increasing low-level
saturation through the overnight hours with a dry layer roughly
between 850mb-650mb. Several models show a warm nose present within
the dry layer into Wednesday morning. While any precipitation that
develops early Wednesday morning should be in the form of light
snow, cannot rule out the potential for some sleet to develop as
well with that warm nose present. Winds overnight tonight will
become light as the weak boundary tracks through the area before
shifting more to the north. These light winds combined with
increasing cloud cover will limit how far temperatures will drop
with lows Wednesday morning likely in the low/mid 20s.

.LONG TERM...(Wednesday through Monday)
Issued at 341 AM CST TUE MAR 4 2014

Mid level trough will continue to move southeast across the Central
Plains on Wednesday and favored the GFS, ECMWF and UKMET and
ensembles over the 00Z NAM run for precipitation. The above
mentioned models all show similar solutions and cluster well.
Forecast soundings suggest that the predominate precipitation type
will be snow as the warm nose in the mid levels goes away in the
northeast. Across parts of east central Kansas there may be a brief
period of rain and snow mix at the onset. However evaporative
cooling to the wet bulb will bring temperatures below zero through
the column and yield all snow. Cross sections show mid level
frontogenesis and lift through the dendritic ice crystal layer
diminishing in the afternoon from northwest to southeast. May see
some light snow chances continue south of I-35 for a couple hours
Wednesday evening. Highs Wednesday in the lower to upper 30s are
expected with the warmer temps southeast of I-35.

Warm advection will develop across the Central Plains with heights
rising through the day ahead of a trough moving from the Great Basin
and into the Rockies on Thursday. A nice warmup is expected with
highs reaching the mid 40s in the far northeast to the lower 50s
near central Kansas.

The aforementioned upper trough will move southeast into southwest
Texas and Mexico. There is some phasing of energy with a northern
stream wave moving southeast out of the Northern Plains and into the
Great Lakes. Thermal profiles from ECMWF and GFS suggest rain and
snow initially for the area then becoming cold enough for all snow
for much of the area after 06Z Saturday and continuing into Saturday
with the far southeast parts of east central Kansas continuing with
a rain and snow mix. Amounts are light and do not expect much
accumulation with this system. After a day in the 30s on Saturday
temperatures will rebound with warm air advection Sunday into Monday
with temperatures warming into the upper 40s to mid 50s Sunday and
in the 50s to lower 60s Monday. A frontal boundary will approach the
CWA late in the day and should move into north central Kansas by 00Z
Tuesday.

&&

.AVIATION...(For the 12Z TAFs through 12Z Wednesday Morning)
Issued at 512 AM CST TUE MAR 4 2014

For the 12z TAFs, VFR conditions are expected through the day with
southerly winds at less than 10kts and mid/high clouds building into
the area by this afternoon. As a shortwave trough advances toward
the region overnight into Wednesday morning, should see increasing
saturation in the low-levels with the development of MVFR cigs.
Winds are expected to become light and variable overnight as a weak
boundary passes over the area, which could result in some MVFR vis
toward the end of the period due to the support of some expected
snow melt today.


&&

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

$$

SHORT TERM...Hennecke
LONG TERM...53
AVIATION...Hennecke