Area Forecast Discussion
Issued by NWS Topeka, KS

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225
FXUS63 KTOP 272310 AAA
AFDTOP

Area Forecast Discussion...UPDATED
National Weather Service Topeka KS
610 PM CDT Sat May 27 2017

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Sunday)
Issued at 316 PM CDT Sat May 27 2017

Thunderstorms moved east of the area early this afternoon which
resulted in mesoscale subsidence and drying across northeast
Kansas. This was evident on the 18Z special TOP sounding which was
dry and relatively stable. The airmass may recover enough to
support continued thunderstorm chances with a low risk of severe
weather mainly from large hail. Mid-level lapse rates were around
8.5 C which favored hail if there was enough low-level moisture to
produce storms. What storms we see will likely be slightly
elevated and not surface based. The area of extreme instability
coupled with favorable shear should remain south of our area.
Expect all of the thunderstorms to exit the area by early evening.
Model soundings suggest saturation below the frontal inversion
tonight which supports cloudiness. Recent runs of the HRRR keeps
showers together as they move out of Colorado and across Kansas
late night. Will not alter the forecast based on this due to lack
of confidence, but it is something to watch.

.LONG TERM...(Sunday night through Saturday)
Issued at 316 PM CDT Sat May 27 2017

Overall, the upper air pattern remains PNA with west coast ridging
and an upper trough over the upper Mississippi valley. Cool
Canadian air should move into Kansas tonight and Sunday in
association with a polar high pressure system building south
through the plains. This should result in dry and relatively cool
weather through the balance of the holiday weekend.

The surface ridge eventually moves east by midweek allowing for
return flow and increased moisture and instability. This along
with weak disturbances is enough to support small pops in the
extended forecast. Temperatures should slowly warm to slightly
above normal by the end of the forecast period.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 603 PM CDT Sat May 27 2017

Will keep TAFS VFR at this time with the expectation that any
precip with the southern KS overnight complex will remain south of
the sites given dry advection at 850mb. Only other potential issue
would be some MVFR VIS issues around TOP however at this time
boundary layer mixing and weak dry air advection makes fog
development uncertain at TOP and unlikely at FOE or MHK.

&&

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

$$

SHORT TERM...Johnson
LONG TERM...Johnson
AVIATION...Omitt



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