Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 132124
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
324 PM CST Fri Jan 13 2017

.SHORT TERM...(This evening through Saturday)
Issued at 320 PM CST Fri Jan 13 2017

Currently the upper level low pressure is located over the coast of
southern CA, while at the surface high pressure was centered over
the upper Midwest. Mid level flow out of the southwest has set the
stage for an overrunning situation. The challenge in the short term
is the chances for freezing drizzle across portions of the area this
evening and overnight. The soundings show that saturation is
relatively deep over east central KS and there may be periods of
lift. There is also a thin layer of drier air near the surface that
could potentially limit freezing drizzle from reaching the surface.
Also, a few of the models suggest enough lift for isolated to
scattered freezing rain showers tonight. The chances for this are
low and confined to locations along and south of I-35. If any
freezing rain falls tonight the amounts will generally be light, but
may cause travel issues.

Overnight the surface high pressure will be reinforced over the
northern plains and upper Midwest. This will help maintain the
northerly to northeast surface winds, which will support the sub
freezing air mass in place. A band of freezing rain is forecasted to
move over portions of southeast KS tonight and into tomorrow
morning. As the upper level low pressure tracks over northern Mexico
another surge of moisture will flow northward around the periphery
of the sub tropical high over the southeast US. That round of
precipitation is forecasted to lift into KS mid day Saturday. Models
are still in agreement that surface temperatures will be sub
freezing with warm air aloft for northeast KS. Late Saturday into
Sunday the ice accumulation is expected to increase across most of
the area depending on the actual width of the band of precipitation.
Current radar over southwest MO showed that the band of freezing
rain today was relatively narrow like 2 to 3 counties wide. If this
were to occur then icing would be highly localized. The NAM is
suggesting this could be a possibility late Saturday into Sunday,
while the GFS and ECMWF are predicting more widespread
precipitation.

.LONG TERM...(Saturday night through Friday)
Issued at 320 PM CST Fri Jan 13 2017

The more significant icing is expected to occur late Saturday into
Monday morning. On Sunday models agree that surface temperatures
will gradually warm to around or just above freezing. A few degrees
will mean the difference between rain and freezing rain.
Precipitation rates may also play a role in mixing down those warmer
temperatures from above the surface. So you could have transitions
of rain vs freezing especially across east central KS depending on
the rain intensity. Temperatures are forecasted to be slightly
cooler over northern and north central KS so Sunday into Sunday
night these areas could receive significant icing. This is when
the upper level low pressure lifts out over the plains, which
means the warm air advection will increase and will be fighting
the sub freezing temperatures. Again, a few degrees will make a
huge difference so large potential for lots of ice or not much
ice. Cooler warm nose temperatures may also cause sleet to mix
with freezing rain. From late Saturday through Monday morning most
locations should receive some ice with amounts around one quarter
to three quarters of an inch. This will likely cause travel issues
and possibly scattered to widespread power outages. Again, there
is also the possibility of much lesser ice amounts. Warmer
temperatures will definitely move into the area on Monday with
highs in the 40s and 50s. Melting will help improve the lasting
effects of any ice accumulations, although recovery time is tough
to predict and depends on many non meteorological factors.

A brief period of mixed precipitation may linger for a few hours
over north central into northeastern KS mainly along the hwy 81 and
hwy 36 corridor Monday night as the storm system departs the area
associated with some wrap around areas of precip. The rest of the
period should remain dry and rather uneventful weather wise as much
of the Central Plains remains in between a split flow pattern as a
broad upper level ridge builds over the region. Temperatures for mid
to late week will warm and be quite pleasant and once again well
above normal for this time of year into the 50s and 60s by Thursday
and Friday.  A bit early to tell, but the next upper level weather
system may start to encroach on the area by late Friday with the GFS
most aggressive on the evolution of upper level features with a
closed upper low and negatively tilted trough lifting into the
region.  Meanwhile, the EC keeps the system further west still over
the Southern and Central Rockies.  Based on temperature profiles,
both models indicate that any precipitation would be all liquid.
But, again, this remains too far out in the forecast to have too
much degree of confidence.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1123 AM CST Fri Jan 13 2017

MVFR ceilings have moved over TOP/FOE while MHK may stay VFR through
the period as ceilings moving in from the west are still above 4kt.
Believe that TOP/FOE will remain MVFR through the period.  There is
a small chance for FZRA late in the period, but chances are too low
to include in this TAF issuance.


&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Ice Storm Warning from 6 PM Saturday to midnight CST Sunday
night for KSZ024.

Ice Storm Warning until midnight CST Sunday night for KSZ026-
038>040-054-055.

Ice Storm Warning from 6 PM Saturday to noon CST Monday for
KSZ008>012-020>023-034.

Ice Storm Warning from 6 AM Saturday to midnight CST Sunday
night for KSZ035>037.

Ice Storm Warning until noon CST Sunday for KSZ056-058-059.

&&

$$

SHORT TERM...Heller/Sanders
LONG TERM...Drake/Sanders
AVIATION...Heller



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