Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 242047
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
247 PM CST Fri Feb 24 2017

.SHORT TERM...(This evening through Saturday)
Issued at 245 PM CST Fri Feb 24 2017

20Z water vapor imagery shows an upper level trough over the upper
Midwest and middle MO river valley. Another upper trough was noted
over the Pacific Northwest coast with a quasi zonal flow in between.
At the surface, a ridge of high pressure continues to build south in
the wake of a surface low lifting into the Great Lakes. Radar shows
an area of light snow moving across northeast KS while some more
convective snow showers moved across east central KS. Any minor
accumulations seem to be confined to north central KS and along the
Neb state line with road cameras indicating mainly wet roads across
northern parts of the forecast area.

For tonight, models take all of the forcing associated with the
upper trough to the east of the area as surface high pressure
continues to build into the area. With dryer air moving in, precip
should come to an end across northeast KS around 6 PM with improving
conditions through the night. Latest guidance supports the going
forecast of lows in the upper teens and lower 20s tonight. The only
thing to watch out for regarding temps might be the cloud cover, At
this point clouds should scatter out enough to allow temps to fall
into the teens and 20s. If the clouds hold on through the morning,
lows could be a couple degrees warmer.

Saturday looks to be another relatively cold day with highs in the
lower and mid 40s. Models show the surface ridge axis passing to the
southeast with little if any moisture advection into the forecast
area through the day. This combined with the quasi zonal upper flow
should lead to dry weather prevailing. Forecast soundings mix the
boundary layer to around 850MB supporting the forecast highs in the
lower and middle 40s. There may be some potential for afternoon
highs to be a little warmer with MOS guidance a little warmer than
my forecast. At this point think increasing high clouds may limit
insolation some.

.LONG TERM...(Saturday night through Friday)
Issued at 245 PM CST Fri Feb 24 2017

A 140 kt zonal polar jet will be positioned across the southern
CONUS Sunday morning. while at the surface, a 1020 mb high will
be shifting into the southeast U.S. Increasing 285-290K isentropic
ascent coupled with modest synoptic lift ahead of a shallow H500
wave may be enough to generate some light snow/rain across eastern
Kansas on Sunday morning. Despite a stiff southerly flow, Gulf
moisture will remain over TX and OK as the system pushes through
and overall accumulation amounts should be light. Model trends
with the Monday system remain quite variable and the blended
solutions, which factor in older model runs, are still carrying
POPS across the south and east during the day. However, the
latest runs of the NAM/GFS/EC push the precip well south of the
CWA. Did not adjust the blended solution too far towards these
latest 12Z runs, but if this trend continues for the next few
model cycles, look for a reduction in the forecast precip for
Monday. Also did not incorporate any top-down p-type techniques
into the weather grids on Monday owing to the poor model run
consistency and having FZRA/IP mentioned in such a low confidence
forecast did not seem justified.

An upper wave currently along the west coast of Alaska will track
south and east downstream of a decaying omega block over the NE
Pacific Ocean and amplify as it drops into the Pacific NW early in
the day on Monday. Increasing SW flow ahead of this trough will aid
in pushing temperatures back above average on Monday into Tuesday,
though recent guidance is not nearly as bullish with the strength of
the H850 warm nose. Confidence in the timing and strength of
attendant surface cyclone on Tuesday into Wednesday is less than
average, though most solutions are locked onto a track not too
dissimilar to our currently departing weather system. The middle
to latter part of the week looks dry with at least slightly above
normal temperatures as a broad longwave ridge builds over the
western CONUS.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1129 AM CST Fri Feb 24 2017

MVFR ceilings and visibilities are expected through the afternoon
and early evening.  VCSH may cause brief IFR/LIFT conditions when
passing.  Northwest winds will pick up this afternoon with gusts
nearing 25 knots.  Gusts will end after sunset near 01-02Z.
Conditions are expected to reach VFR by 01-02Z and prevail for the
rest of the period.


&&

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

$$

SHORT TERM...Wolters
LONG TERM...Skow
AVIATION...Heller



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