Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 220543

Area Forecast Discussion
National Weather Service Topeka KS
1143 PM CST Sun Jan 21 2018

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Monday)
Issued at 257 PM CST Sun Jan 21 2018

A surface low continues to trek eastward towards northeast Kansas
with a surface boundary bisecting the CWA from the southwest to
northeast. In the warm sector, dewpoints have risen into the low 50s
with high temperatures reaching the upper 50s to low 60s.  Models
indicate 100-300 J/kg of MUCAPE overspreading east central Kansas up
towards very northeastern Kansas in the early evening.  Showers and
a few thunderstorms are expected to form later this afternoon with
peak heating near the surface low and advance northeastward.  With
the RAP indicating roughly 200 m2/s2 of helicity coupled with a
boundary in the area, this leaves the concern for some rotating
thunderstorms to form near this boundary.  If storms do form in this
area, there is a chance that pre-existing vertical vorticity along
this boundary may induce a weak, brief tornado.  Isolated wind gusts
with storms may also be a hazard.  This whole scenario is highly
dependent on whether or not a cap that has overspread northeast
Kansas breaks this afternoon.  In east central Kansas, models break
this cap between 5-8 PM, leaving this time the most probable if any
severe weather was to occur.

Showers and any storms will come to an end by late night as the low
continues to push into the area, along with a dry slot which will
give a break between this activity and the coming deformation zone
progged to reach northeast Kansas in the early morning.  With
temperatures in north central Kansas slightly above freezing as this
precipitation moves into the area, rain will first be observed
before temperatures continue to fall and mixed precipitation
eventually transitions to snow.  Snow is likely across most of the
area from a line from Hiawatha to Emporia with the highest amounts
upwards of three inches confined to very north central Kansas.  A
Winter Weather Advisory has been issued for areas where the highest
snowfall is likely. Very eastern counties may see some mixed
precipitation, but overall rain will be the prominent precipitation
type.  Precipitation will eventually change back to rain across
northeast Kansas and temperatures on Monday rise into the upper 30s
and low 40s.

On top of the precipitation Monday, winds will be strong behind this
departing low with sustained speeds in central Kansas up to 30 mph
with gusts up to 40 mph.  Elsewhere, gusts up to 35 mph are
expected.  This may cause blowing snow, especially in north central
and central Kansas where the greatest snow totals are forecast. With
this, expect extremely reduced visibilities and hazardous travel
conditions.  Gusty winds continue through the afternoon keeping this
a hazard through all of Monday.

.LONG TERM...(Monday night through Sunday)
Issued at 257 PM CST Sun Jan 21 2018

Snow continues move out to the northeast through Monday evening
and clears most of the CWA by around the midnight hour, as the
upper low move into the Ohio Valley. Lows fall into the 20s as CAA
continues overnight.

Pattern across the Central US moderates behind the system rather
quickly with the coldest air well north of the forecast area. The
westerly flow that transitions over the week to more southwesterly
brings a gradual warm up in temperatures, with 40s Tuesday to
upper 40s Wednesday, then into the mid to upper 50s by Thursday
and Friday. The next chance for rain is progged to move into the
area possibly late Friday into early Saturday as the next more
amplified upper trof moves out of the Rockies into the Central
Plains. Highs on Saturday are currently forecast back down into
the 40s, but could be higher if the system slows its eastward


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1143 PM CST Sun Jan 21 2018

Only minor changes to the previous forecast. Have kept limitations
to MVFR with RA and SN with marginal temperature profiles along
the terminals. Strong northwest winds accompanying snowfall could
bring visibilities to IFR range but too little confidence in that
actuality at this point.


Winter Weather Advisory until 3 PM CST Monday for KSZ008-009-020-



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