Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 302324
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
624 PM CDT TUE AUG 30 2016

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Wednesday)
Issued at 334 PM CDT TUE AUG 30 2016

This afternoon, similar to previous afternoons, scattered
thunderstorms have developed and continue to move very slowly
primarily to the northeast but also having some storms be driven
by outflow and even backbuilding. This has resulted in very small
areas of heavy rainfall with rates approaching and possibly
exceeding 2 inches per hour. The atmosphere remains primed for
these heavy rainfall rates to continue this evening although the
peak rates may wane a bit as instability weakens. However, the
moisture content is likely to continue to increase with widespread
PWat values of 1.9-2.2 inches. This along with the slow storm
motion continues to support at least some flash flood potential
and have extended the flash flood watch until midnight while also
pulling it into Abilene and Geary counties where heavy rain has
fallen this afternoon.

Some high-res convective allowing model guidance continues to
indicate the heavy rain rates continuing overnight, but confidence
is not exactly on the high end at this point. While we have not
extended the watch overnight, a further extension may be needed.
However, with so much uncertainty in how it will evolve, wanted to
be able to further monitor this evening and allow the evening
shift to consider later extension through the overnight hours.
There appears to be a couple of more focused areas of vorticity
set to move across the area and these may locally enhance rainfall
rates and convective coverage. However, the main focus looks to be
from north central KS to the southeast so have removed the far
northeast KS counties from the watch at this point. This likely
convective complex will continue a slow trek to the southeast into
Wednesday before gradually moving out of the area and weakening
through the day. Bottom line is an expectation for pockets of 2+
inches of rain through Wednesday with some localized areas
possibly approaching 4 inches. However, exactly where and when
those heaviest rain amounts fall remains very much in question.

.LONG TERM...(Wednesday Night through Tuesday)
Issued at 334 PM CDT TUE AUG 30 2016

By tomorrow night northwest flow aloft will push a surface high
pressure into the area and clear out the precip. Dry air will filter
in behind this push causing dew points to drop into the 50s. The
pattern will remain quiet through at least Saturday. On Saturday
night the southwest flow aloft becomes more established allowing
potential shortwaves to track over the central plains. This will
increase the chances for precip within this warm advection pattern.
Next week a frontal zone looks to anchor over NE for a few days
before pushing southward towards the area late in the period. The
position of this front may change over time.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 624 PM CDT TUE AUG 30 2016

Storms continue to move from west to east across northeast Kansas
bringing a chance for VCTS to all terminals through the period. VCTS
should reach MHK by 01Z with storms ending near 06Z.  Model
consensus on the current storms is varied so have opted to exclude
VCTS from TOP/FOE for the evening storms due to less than average
confidence of storm evolution.  Another round of storms from 09-11Z
are expected to reach sites in the early morning.  MVFR ceilings are
looking more probable so have included them in this time frame
accordingly.  Reduced conditions may last until early afternoon, but
will need to monitor closely as conditions evolve this evening.

&&

.TOP Watches/Warnings/Advisories...
Flash Flood Watch until midnight CDT tonight for KSZ008>010-
020>023-034>036.

&&

$$

SHORT TERM...Barjenbruch
LONG TERM...Sanders
AVIATION...Heller



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