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000
FXUS63 KTOP 071011
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
411 AM CST Fri Mar 7 2014

.SHORT TERM...(Today and Tonight)
Issued at 410 AM CST FRI MAR 7 2014

Early Friday morning, a short wave trough and associated jet max
were making their way into the central Rockies while a second short
wave trough was tracking across south central Canada. At the
surface, a cold front extended from far northwest Kansas into
eastern South Dakota The front will surge south this morning,
eventually slowing but still moving south across the area through
this evening. The cold front is expected to be through Concordia by
around 10 AM, and Topeka closer to 4 PM. Ahead of the front, the
airmass will be warm and temperatures will likely climb well into
the 50s and perhaps approach 60 degrees. Even behind the front, deep
cold advection will be lacking, especially during the day, and
fairly deep mixing should allow temperatures to still climb well
into the 40s or low 50s. Through tonight, the coldest airmass will
be rather shallow, 2-3 thousand feet, and expect moderate to strong
frontogenesis in the low levels to produce 6 to 12 hours of low
level vertical motion. At the same time, while there is some mid and
upper level moisture associated with the incoming trough, all
indications suggest that it will not be sufficient to create ice in
the cloud, at least initially, except for those areas near the
Nebraska border. Moistening is expected with time, but for areas
southeast of an Abilene to Hiawatha line, there could be 3 to 6+
hours of strong low level vertical motion amidst a low level
saturated layer with no ice growth in the cloud above. This would
suggest potential for drizzle, possibly turning to freezing drizzle
as temperatures fall through the evening. Moisture profiles in the
vertical will be key as the -8C and colder layer is not super dry,
and slightly more moisture would mean rain or snow rather than
drizzle, and the boundary layer is on the dry side for drizzle
production in north central KS. But, as the forecast stands, would
expect some freezing drizzle during the late evening and early
morning hours with some glazing possible if conditions come together
prior to a change over to very light snow. Confidence is on the low
end at this time in terms of how it will all play out, but freezing
drizzle would be the highest impact potential scenario to play out
through tonight.


.LONG TERM...(Saturday through Thursday)
Issued at 410 AM CST FRI MAR 7 2014

By Saturday morning, models show a positively-tilted mid-level
trough stretching from the southern Rockies northeastward across the
Central Plains and toward the Great Lakes region. The cold front
with this system will have already tracked just southeast of the
area with surface high pressure advancing southward into the Central
Plains. Models still show some modest lift present in the low to
mid-levels of the atmosphere over the area Saturday morning before
gradually diminishing during the afternoon hours. The 00z
GFS/ECMWF/GEM are in pretty good agreement in having some light
precipitation across the southeastern two-thirds of the forecast
area Saturday morning. By the afternoon hours any lingering
precipitation should generally be focused along and southeast of the
I-70 corridor. In these solutions, the model soundings do not show
deep saturation profiles over the area as some drier air may be
working its way into the mid-layers by late morning or early
afternoon. As a result, would not expect much QPF from this system.
However, the 00z NAM is not only a much different solution from the
other models but also a much different solution from its previous
runs. This latest run shows much more moisture with the system,
especially over east central and southeast Kansas on Saturday, with
its soundings showing a deeply saturated profile in which
temperatures near the surface and further aloft would be cold enough
to support all snow. This scenario would lead to a few inches of
accumulating snowfall over portions of east central Kansas. Have
considered the NAM an outlier with this forecast and have gone with
more of a blend of the GFS/ECMWF/GEM solutions. The northerly winds
behind Friday`s frontal passage will usher some cooler air into the
region for Saturday, however this caa won`t be too strong compared
to some of our recent storm systems. With the cloud cover in place
from the lingering light precipitation through the day on Saturday,
have trended a bit cooler with temperatures (primarily across east
central Kansas) with highs ranging from the mid/upper 30s in eastern
Kansas to the lower 40s over north central Kansas. However, if the
cloud cover is able to clear out quicker over north central Kansas,
temperatures may end up being a few degrees warmer. With
temperatures starting off near or below freezing and only gradually
warming up into the mid/upper 30s, have the mention of rain or snow
through the day on Saturday before drying out by Saturday night.

Saturday night into Sunday, surface high pressure will track over
the region and progress into the southeastern U.S. As a result,
southwesterly flow will return to the region on Sunday, supporting
decent waa into the area as a modest thermal ridge develops across
much of western Kansas. High temperatures for Sunday look to range
from the middle 50s over east central Kansas to the low/mid 60s over
north central Kansas. This southwesterly flow and thermal ridge will
remain in place through Monday with further waa helping to boost
temperatures into the mid/upper 60s and possibly into the low 70s
over north central Kansas.

Zonal mid-level flow will set up over much of the northern conus on
Monday, however models show the next mid-level trough advancing into
the Pacific Northwest and progressing towards the Rockies Monday
night into Tuesday. This advancing trough will help to push another
cold front through the region, however there is still a great deal
of uncertainty with how progressive this trough will be and, thus,
when it will move the cold front into the area. In general, the
models seem to be a bit slower with the frontal passage, with it
currently progged to move through sometime during the day on
Tuesday. The exact timing of this frontal passage will have an
impact on when the winds shift to the north and what sort of high
temperatures can be expected. At this time have a range of low 50s
to near 60 degrees, however the temperature spread may end up being
greater across the area. There are very notable differences amongst
the models in how they handle this mid-level trough as it progresses
through the central U.S. mid-week. The GFS/GEM are most similar in
trending with a weaker trough and some light, scattered post-frontal
precipitation. The ECMWF on the other hand has a mid-level low
closing off over southern Kansas and brings an abundant amount of
moisture to the region Tuesday night through Wednesday. Due to the
low confidence with this system, have only slight to very low-end
chance PoPs in for Tuesday through Wednesday. The northerly flow
behind this frontal passage will result in cooler conditions on
Wednesday with highs dropping into the 40s, however have conditions
rebounding by Thursday with temperatures back in the 50s.

&&

.AVIATION...(For the 06Z TAFs through 06Z Friday Night)
Issued at 1130 PM CST THU MAR 6 2014

Vfr conditions will persist at all terminals through 18z with only
high clouds expected and south winds 7-13 kts...although some
brief mvfr vsbys in hz/br are possible at the KTOP terminal.
As a cold front moves in from the north aft 22z mvfr cigs will
overspread the terminals as winds switch to the north by 00z/08
with some gusts aoa 20kts through the remainder of the fcst.


&&

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

$$

SHORT TERM...Barjenbruch
LONG TERM...Hennecke
AVIATION...63