Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 262343

Area Forecast Discussion
National Weather Service Topeka KS
643 PM CDT Mon Jun 26 2017

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Tuesday)
Issued at 235 PM CDT Mon Jun 26 2017

As of 19Z, an upper level trough continues to slowly push
eastward across the Great Lakes region. Its position continues to
reside the central and northern Plains within northwest upper and
mid level flow. At the surface, early morning convection spawned
an outflow boundary that has pushed through the majority of the
outlook area. As of 19z the OFB was positioned from roughly
Concordia southeastward to near Emporia. With south to
southwesterly surface flow to the south of the OFB, sufficient
convergence along the boundary has allowed for a thunderstorm to
develop south of EMP. This trend will continue through the
afternoon hours, although the best chances will shift southward as
the OFB continues to push south and westward. We then turn our
attention northward to a weak synoptic front aligned from south
central NE into central IA. These areas have destabilized through
the late morning and early afternoon hours. Mesoanalysis reveals
upwards of 1500 J/KG of MLcape. Sufficient effective shear
approaching 40 knots could suffice for large hail. Low level wind
fields are weak, therefore expect the wind threat to remain
limited. Thunderstorms have began to develop along the boundary.
All of that said, given the lack of upper support expect coverage
to remain isolated through the afternoon and evening hours. As the
front pushes through the area overnight, the shower and storm
chances will temporarily push south of the area. Cloud cover is
expected to rapidly decrease behind the front, therefore given
clear skies expect temperatures to dip into the 50s overnight.

Tuesday: high pressure will push into the Mississippi Valley by
midday Tuesday, allowing return flow for the southern and central
Plains. Dew points will surge into the low and middle 60s. High
temperatures will rebound into the lower and middle 80s. Southerly
winds to gust as high as 25 MPH during the afternoon, especially
across central and north central KS. By the afternoon, an upper
trough will begin its push towards the northern and central Plains.
Thunderstorms look to develop in the foothill of the Rockies along a
weak cold front. These thunderstorms look to impact the outlook
area after 00z Wednesday.

.LONG TERM...(Tuesday night through Monday)
Issued at 235 PM CDT Mon Jun 26 2017

Not certain about southern extent of thunder chances overnight
Tuesday night into early Wednesday morning, as better LLJ
convergence interacts with shortwave just to our north into NE and
IA - although the GFS is slightly farther southward than the NAM
as of this run. Could see storms continue through the eastern
counties toward sunrise, and even if storms are farther north and
east would still likely see an outflow boundary move westward into
the CWA for Wednesday. This will aid in focusing instability and
could intersects incoming frontal boundary for the afternoon.
Given abundant CAPE and shear over the state, storms that do form
may be potentially large hail and wind producers. Again much will
depend on how overnight/early morning convection pan out, and what
they leave behind, as well as speed of the incoming front. For
now have thunder chances focused west then spreading to the east,
with broader chances for the evening. Highs still reach toward 90
as warm advection returns.

As we go into the late evening and overnight hours, depending on
where the boundary sets up across our area, eastern Kansas could
become the potential target for downstream propagation of MCS
activity rolling off the high terrain and eastward into our area.
GFS keeps convection initiation over eastern KS, but develops MCS
right over, so either case brings thunder chances. Another
northern shortwave slides across the front along the KS/NE border
on Thursday, and brings yet another chance for storms Thursday
afternoon. May catch a break for all or part of Friday and into
Saturday behind this shortwave trof. Next in the series of systems
progged to move through on Sunday and into Monday morning. EC
solution is similar to the GFS, although much mesoscale influence
at play in this extended forecast. Main takeaways are several
chances for strong to severe storms, and potential for locally
heavy rainfall if storms keep training over the same areas for
days in a row.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 643 PM CDT Mon Jun 26 2017

Expect isolated tsra through 02Z at TOP and FOE and through 01Z at
MHK or sooner. VFR conditions are expected outside of any
convection this evening. Northeast to east winds less than 10 kts
will veer to the southeast by 14Z and increase to around 10 kts.




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