Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 192336
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
636 PM CDT Wed Jul 19 2017

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Thursday)
Issued at 306 PM CDT Wed Jul 19 2017

Cloud debris from the morning convection continues to linger around
portions of eastern KS this afternoon. This cloud cover has kept the
temperatures cooler by a few degrees, but most locations should
reach their respective high temperatures. regardless the dew points
have been higher than previously thought therefore the heat indices
are still reaching 105-112. Low temperatures tonight will manage the
mid to upper 70s. The nocturnal low level jet increases to around 40
kts and this along with a weak inversion will keep surface winds
from going calm. Therefore there is a chance some locations may stay
in the 80s tonight. Isentropic lift driven showers and storms
should not be an issue tonight as most of the soundings show drier
air in the lower levels. Tomorrow will not be much different from
today besides less clouds and slightly warmer temperatures. The
highs are expected to be around 98-105 with heat indices 105-112
across the entire area.

.LONG TERM...(Thursday night through Wednesday)
Issued at 306 PM CDT Wed Jul 19 2017

Upper ridge axis shifts to the south and east by Friday evening.
Meanwhile the frontal boundary is oriented northeast to southwest
from southeast NE to western KS. Elevated thunderstorms are expected
to form with the LLJ overnight, barely clipping our northern
counties Sat. morning. Cloud debris from these storms could hinder
temps from reaching 100 degrees Saturday afternoon, however believe
most of the CWA should quickly warm into the upper 90s. Areas south
of Interstate 70 are likely to reach the low 100s. Moisture pooling
near the boundary may actually boost dewpoints a few degrees higher
than currently forecast, but overall results in heat indices in the
middle to upper 100s. Convergence along the boundary and an upper
trough entering from the northwest will likely trigger convection by
late afternoon into the evening hours. Wind shear up to 6 km is
around 25 kts or less so do not expect severe weather at this time.
Scattered thunderstorms focus on the boundary on Sunday afternoon as
well, however believe that the GFS has been more consistent between
runs with the placement of the boundary compared to the ECMWF (which
is slower). This would place the best precip chances along and south
of Interstate 35.

From Sunday onward, overall pattern shifts to northwest flow with
weak vorticity lobes translating through the region. Guidance varies
somewhat on frontal placement and where the upper troughs lie, but
based on the active pattern, its at least worth a chance mention of
precip on Tuesday. Overall temps are cooler with highs around 90
degrees.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 634 PM CDT Wed Jul 19 2017

VFR conditions for the 00Z TAFs. LLWS conditions may set up
overnight. Would like to see lower surface winds before
mentioning. Will monitor trends, but with a weak inversion setting
up overnight probably will keep somewhat mixed boundary layer in
place. Winds stay generally south overnight.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning until 8 PM CDT Saturday for KSZ008>012-
020>024-026-034>040-054>056-058-059.

&&

$$

SHORT TERM...Sanders
LONG TERM...Prieto
AVIATION...Drake



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