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Area forecast discussion
National Weather Service Topeka Kansas
535 PM CST sun Feb 26 2017

..update to aviation forecast discussion...

Short term...(this evening through monday)
issued at 253 PM CST sun Feb 26 2017

Morning light precip has moved off and dissipated with clearing
skies in weak subsidence behind the northern branch shortwave over
the Great Lakes. Midday visible satellite imagery suggesting a
narrow band of snow fell over southern Dickinson County which has
quickly melted with temps into the upper 40s and lower 50s.

Overnight period is quiet with light winds and clear skies. South
winds do increase late in the night as warm air advection ramps up
in the mid levels. This wind appears to be strong enough to keep fog
formation in check but will need to be watched as the night passes.
Have kept with small precip chances for much of the area Monday
afternoon as warm air advection develops on down ahead of the
surface warm front. Models do vary quite a bit with depths and
timing of lower level saturation and could see some sprinkles or
perhaps drizzle nearly anywhere, but best saturation continue to
look focus in the southeast. 850-925mb temps rise about 5c from
today and should still support highs at least a few to several
degrees warmer despite thickening cloud.

Long term...(monday night through sunday)
issued at 253 PM CST sun Feb 26 2017

A shortwave trough is still expected to move across the Central
Plains mainly Tuesday night with some mid level frontogenesis
developing across the area. But models have trended weaker with
the surface low and are a little more progressive pushing the
system to the east of the forecast area. With the more
progressive trend in the models, have ended precip chances by the
daytime hours Wednesday. Additionally there continues to be a
lack of cold air with the system and models start to push the
precip east as the column cools down enough for snow. The NAM
appears to be an outlier with the system with a deeper surface low
and slower to lift it east. So have relied on the GFS/ECMWF/Gem
consensus. There may still be some minor accumulations of snow
early Wednesday morning across northeast Kansas. But at this time, the
majority of available guidance is pointing towards amounts less
than in inch simply because the precip looks to be coming to an
end as temps get cold enough for snow. Models continue to show
some modest surface based instability flirting with Anderson
County Tuesday afternoon. There may be a short window for some
thunder across east central Kansas Tuesday evening, but since models
keep the main axis of instability to the south and east have not
included a mention of thunder.

For Wednesday night through Saturday night, dry weather is
expected to persist with northwest flow aloft and ridging to the
west slowly moving east over the plains. There are a couple weak
shortwaves progged to move through the northwest flow. But the
energy from these waves appears to be remain northeast of the
forecast area. They should help a modified Canadian airmass move
through the region Thursday. So temps are forecast to remain a
little closer seasonal normals. A warming trend should be in full
swing by the weekend as return flow develops on Friday with low
level warm air advection. Have highs in the 60s and near 70s for
Saturday and Sunday. And this may be on the cool side as 925mb
temps from the GFS and European model (ecmwf) would argue for mid 70s by Sunday.

The GFS shows another upper trough approaching the Central Plains
on Sunday. However the European model (ecmwf) and Gem have different solutions on
timing and generally keep any shortwave energy to the north of the
state. Therefore confidence in any given solution is pretty low
and have continue with a dry forecast.


Aviation...(for the 00z tafs through 00z Monday evening)
issued at 525 PM CST sun Feb 26 2017

VFR conditions should prevail through the period. Have kept out
reduced visible potential at this point near the 12z time frame as
moisture may be too shallow to cause much reduction. Will need to
watch trends into the 06z time frame. Remains small potential for
showers near the very end of the period, but chances mainly near
the ktop/kmhk terminals too small to mention that far out.


Top watches/warnings/advisories...


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