000
FXUS63 KTOP 080930
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
330 AM CST Sat Mar 8 2014

.SHORT TERM...(Today and Tonight)
Issued at 329 AM CST SAT MAR 8 2014

Early Saturday morning, a short wave trough with an axis strongly
tilted in the positive extended from Iowa into northern New Mexico.
A cold front that passed through the area on Friday has since
progressed well into Oklahoma. Several individual weaker upper
disturbances were pinwheeling around within the base of the trough
over the general 4 corners region and then ejecting some of that
energy across Kansas. Water vapor imagery indicates a fair amount of
mid level moisture throughout the trough, although soundings
throughout the region indicate dry air embedded in portions of the
vertical column. Locally, the lowest 5k feet were rather dry this
evening, even after a fairly strong cold frontal passage. The 00Z
DDC sounding indicated some rather dry air at and above 700 hpa. So,
while a fairly broad area of weak to moderate mid and upper level
ascent has been in place across the region, it has not necessarily
developed a lot of precipitation. However, through Saturday
afternoon, expect some more persistent ascent as one of the stronger
disturbances move across southeastern Kansas. Most of this will be
focused only as far north as east central KS, but a band of
frontogenetical forcing will also drift south across the entire
forecast area this morning...although likely weakening beyond mid
morning. Forecast soundings continue to support potential for
periods of drizzle and freezing drizzle early this morning, owing to
the occasional dry air intrusions aloft, but do expect the full
column to saturate with time to support ice within the cloud layer.
Snow would likely become the dominant precip type, although
temperature profiles especially in east central KS suggest periods
of sleet possible as well while rain seems unlikely. Precipitation
amounts will be light, with most areas barely seeing a trace of
snow. However, locations south of I-35 could approach an inch of
snow/sleet with higher amounts just to the south in southeast KS.
Precipitation should come to an end by sunset with clearing skies
and light winds through much of the night. This should allow
temperatures to drop off pretty well initially but will also see
some warm advection aloft through the night so after daytime highs
only in the upper 30s to lower 40s, expect overnight lows to hold in
the lower to middle 20s.


.LONG TERM...(Sunday through Friday)
Issued at 329 AM CST SAT MAR 8 2014

By Sunday morning, the mid-level trough that contributed to this
weekend`s light precipitation will be progressing into the
northeastern U.S. As surface low pressure expands across the
Northern Plains, it will help to push an area of surface high
pressure further south into the southeastern U.S., resulting in
southwesterly surface winds over the area. This southwesterly flow will
result in decent warm air advection through the day with a thermal
ridge developing over eastern Colorado and western Kansas. These
increasing winds along with sunny skies should lead to high
temperatures reaching into the upper 50s/low 60s over eastern Kansas
to the middle 60s across north central Kansas. Models show this
thermal ridge expanding eastward across Kansas for Monday as
southwesterly winds persist across the region. A nose of 12C to 14C
850mb temperatures looks to stretch into eastern Kansas, so have
continued the trend of warmer temperatures for Monday with highs in
the upper 60s to low 70s. It is worth noting that models are showing
the potential for a weak boundary to stretch near the
Kansas/Nebraska border, which could cause winds to shift more toward
the west or northwest and result in slightly cooler temperatures
than the current forecast. At this time, the boundary looks to stay
just north of the area but it`s something to keep an eye on in
future model runs.

Monday into Tuesday models show a mid-level trough developing over
the Pacific Northwest and shifting eastward across the northern
Rockies toward the Northern Plains. This advancing trough will help
to push a cold front southward through the region on Tuesday. There
are still model discrepancies with the exact timing of this front
through the day, but there`s pretty good agreement in having the
front southeast of the area by mid-evening Tuesday. With the
uncertainty in the timing of the front, that leads to further
uncertainty in when the winds will shift to the north and what sort
of spread we can expect with the temperatures through the day. At
this time, the GFS/NAM seem to be the most progressive with the
front while the ECMWF/GEM are slower with it`s southward track. Have
trended a bit more toward a blend of the ECMWF/GEM which would keep
much of east central Kansas in the warm sector through the day,
resulting in high temperatures in the low/mid 60s with cooler
conditions near the Kansas/Nebraska border in the mid 50s. The GFS
continues to show very little post-frontal precipitation with its
more progressive system, while the GEM is falling more into line
with the ECMWF that has consistently been showing more widespread
precipitation chances Tuesday afternoon into Wednesday morning. Have chance
PoPs in for Tuesday night with the system likely progressing east of
the area by Wednesday. With the warmer conditions in place,
precipitation should start out in the form of rain, but low
temperatures Tuesday night look to drop into the low/mid 30s so
could see a transition over to light snow as this system exits the
area. Northerly winds on Wednesday will usher some cooler air into
the region with highs dropping into the mid/upper 40s. However,
these cooler conditions will be short-lived as southwesterly surface
winds return by Thursday with high temperatures likely reaching back
to near 60 degrees for Friday.

&&

.AVIATION...(For the 06Z TAFs through 06Z Saturday Night)
Issued at 1127 PM CST FRI MAR 7 2014

Low level dry is complicating the taf forecast this evening
especially over MHK. The chances for any drizzle overnight is
looking less likely. Have kept the mention at TOP/FOE where there
is more low level moisture and smaller dew point depressions. The lift
associated with this system may be too weak and short lived to
fully saturate. With increasing mid level lift later this morning
there is a slight chance for a light snow shower although it
appears several dry layers may be present. Have adjusted the the
taf sites to clear out much earlier.


&&

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

$$

SHORT TERM...Barjenbruch
LONG TERM...Hennecke
AVIATION...Sanders