Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 251747
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1247 PM CDT Tue Apr 25 2017

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 323 AM CDT Tue Apr 25 2017

Showers and embedded thunder are lifting northeast across the
forecast area at this hour, and are expected to be lifting out to
the northeast not long after sunrise. Warming mid level temps then
cap off the area for much of the morning and into the early
afternoon, before the surface coldfront starts to march
southeastward through the afternoon and evening hours. Have
introduced some chances in the later afternoon, but think better
chances will be near 0z after the cap erodes and the front forces
evening convection.  Sounding at TOP indicates 1500J/kg of cape with
steep mid level lapse rates, and hail/wind remain the primary
hazards as the front comes through. The 3-6Z window may be the best
chance across the far eastern counties based on timing of the front,
although rain chances and possibly some lingering thunder in the far
east look to remain over the forecast overnight as lift continues
ahead of the larger scale trof.

Daytime highs today range from near 60 in the far northwest,
although with the inverted trof developing over the CWA, not certain
the far NW counties will make it out of the 50s today before the
front pushes southeast.  Southeastern counties have a chance for
middle 70s under warm advection for the day and capped off from
precipitation early.  Overnight lows fall into the 40s.

.LONG TERM...(Wednesday through Monday)
Issued at 323 AM CDT Tue Apr 25 2017

On Wednesday the main mid level trough will continue to gradually
track over the northern plains. The associated cold front will
already be east of the area, but the models are forecasting post
frontal showers mainly in the morning. The NAM is particularly
stronger with the southern stream shortwave that passes just south
of the area and therefore hangs precipitation through the evening.
The best chances for precipitation Wednesday appears to be east
central KS with lesser chances across central KS. Most if not all of
the instability will also be east of the area so have almost
completely removed the mention of thunder with the exception of
early in the morning. Behind this system surface high pressure
builds southward Wednesday night. During this time radiational
cooling should allow temperatures to drop into the 30s. The
exception to this would be if any clouds linger behind the departing
system. Frost is possible with in the lower to mid 30s and light
wind especially in north central KS. On Thursday night return flow
develops over the plains and instability tries to lift ahead a
shortwave that will pass overhead. As of now the mucape does not
appear to be much over 500 j/kg so some thunder may be possible.
The mid level lapse rates are relatively steep, but the moisture
quality may be less than the models depict. A much stronger
shortwave is still forecasted to lift over the region this
weekend. The warm sector will remain over the mid MS valley so a
cold rain is expected during this time frame.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1243 PM CDT Tue Apr 25 2017

VFR conditions are expected to continue through the afternoon into
th evening hours. A few showers and an isolated thunderstorm is
possible mainly at the Topeka terminals in the 23-04Z timeframe.
While a rain shower is possible at MHK, the best chances are
east of the terminal. MVFR stratus is expected to arrive at all
terminals in the 02-05Z timeframe. Winds will continue to veer the
the west and northwest throughout the period with sustained 10 to
15 knots and gusts upwards of 20 to 25 knots.

&&

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

$$

SHORT TERM...67
LONG TERM...Sanders
AVIATION...Baerg



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