Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 271725

Area Forecast Discussion
National Weather Service Topeka KS
1225 PM CDT Tue Oct 27 2020

...Update to aviation forecast discussion...

Issued at 703 AM CDT Tue Oct 27 2020

Did a quick update to increase POPs across Dickinson and Morris
counties as well as east central KS this morning. Latest radar
shows an area of precip moving north through central KS with
reports of -SN and even some -FZRA. The recent HRRR/RAP/NAM
solutions support precip moving up into these areas before moving
east. Mid level warm air advection is expected to cause a warm
nose to develop and snow to mix with sleet and freezing rain. At
this point I only have snow amounts around a half inch or less
with minor ice accumulations. So am not going to expand the
advisory west since snow should remain light. Confidence in mixed
precip is increasing across east central KS where the advisory is
currently in place. Will monitor trends and adjust the advisory
as needed.


.SHORT TERM...(Today and tonight)
Issued at 318 AM CDT Tue Oct 27 2020

Another day of a wintry mix before warmer temperatures make their
return with mostly rain through Thursday - potentially heavy mainly
over east central Kansas.

The upper pattern is like a broken record so far this week.
Persistent and deep elongated positively tilted trough extends
through the Upper MS Valley down through the Four Corners region
with a closed mid level low pressure system slow to move out of
the region as northern stream energy is becoming established once
again to the north as the southern branch of energy is becoming
cut-off. As a result, broad southwest flow regime remains across
the area with surface high pressure over southeastern NE allowing
for a weak anticyclonic flow pattern to be situated over the
forecast area with weak CAA helping to keep morning low
temperatures in a gradual falling trend. Morning lows should
bottom in the middle 20s across most of the area with perhaps some
high teens near the KS/NE border.

Around or soon after sunrise, a subtle H7 vort max looks to be
tracking into the southern portions of KS which would impact mainly
east central areas concerning our forecast boundary extent.  This
energy is emanating from the midlevel low over the Four Corners
that will more directly impact the forecast area Wednesday and
Thursday as it lifts into or just south of the area. For today,
the concern weather wise is still a wintry mix as sounding
profiles suggest a slow warming of temperatures aloft - a warm
nose. What this appears to look like with low level cold air still
in place is that ice pellets may develop over east central areas
shortly after sunrise before eventually changing to more a light
freezing rain type sounding profile with further warming of the
warm nose. As the vort max translates east of the area, this mix
should begin to come to an end by early afternoon. Right now,
confidence in subtle shifts in position of actual precipitation
and timing keep me from changing the winter weather advisory area
or timing. It is possible this area may need northern extension
into the Topeka area and last into mid afternoon. But, would
rather see the trends suggest that before making too much change
to what looks to be an adequate coverage for the threat at this
time. High temperatures today should remain in the 30s.

.LONG TERM...(Wednesday through Monday)
Issued at 318 AM CDT Tue Oct 27 2020

Warming temperatures bring mostly rain to portions of the area on
Wednesday and Thursday before a nice weekend sets up across the

As the cut-off low lifts out of the Four Corners region, some
uncertainty in the actual track is still present in the
deterministic model solutions.  Some hints are that perhaps a more
southern track may be favored.  This uncertainty is typical when
systems are at least partially cut-off from the mean flow.  Another
complication with this suite of model runs is that Hurricane Zeta is
also working toward the southeastern CONUS at this same time.  This
all leads to uncertainty for the forecast area - mainly regarding
position of the upper low and resultant precipitation as well as
overall timing.  What does appear to be the case is that all
solutions favor sufficient warming of the column, so confidence in a
possible short period of mixed precip changing over to all liquid
rain is a very likely scenario.  Flash Flood guidance across the
areas that would likely see the highest rainfall totals into
Thursday are from 2.50 to around 4.00 inches for the 6 hour period.
Since this would be largely stratiform type precipitation, then a
Flash Flood Watch right now will not be issued.

After, this upper system starts to once again phase with northern
stream energy, it should quickly exit the region late Thursday. High
pressure expands into the area under northwest flow aloft.  Very
pleasant conditions set up across the area into the weekend with
highs rebounding to the 50s and 60s.  A weak cold front with a dry
passage passes through Sunday making it feel cooler with dewpoints
in the 30s.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1225 PM CDT Tue Oct 27 2020

VFR conditions are expected. Steady precipitation has continued
to push southeast over the past few hours and expect this trend
to persist. Light surface winds and recent precip give some
concern for BR formation but it appears mid level cloud will be
continual enough to keep this in check.


Winter Weather Advisory until 1 PM CDT this afternoon for



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