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271
FXUS63 KTOP 181920
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
220 PM CDT Tue Jun 18 2024

.KEY MESSAGES...

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- Line of thunderstorms will form across KS this afternoon. Strong
winds and large hail are the primary threats.

- Heavy rainfall will be possible, but the rainfall forecast continues
to trend downward.

- Above average temperatures will stick around into the weekend and
next week.
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&&

.DISCUSSION...
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Issued at 219 PM CDT Tue Jun 18 2024

This afternoon, the surface analysis shows a 997 mb low in SW
Kansas and a 997 mb low in E South Dakota, connected by a cold front
which roughly runs from Smith Center KS to Scott City KS.
Convergence is increasing, and storms are beginning to fire on the
front in Nebraska very quickly.

Current mesoanalysis indicates that surface based CAPE values range
from 2000 to 4000 J/Kg, which is quite significant and will result
in rapid storm development further west on the aforementioned
boundary. Effective bulk shear ranges from 20-30 kt ahead of the
front, which is quite low. Current thinking is that thunderstorms
that form on the front will become linear and grow upscale rather
quickly, due to strong convergence in the low levels, weak shear,
and storm motion parallel to the boundary.

The storms are forecast to enter the area by roughly 6 pm tonight in
the NW portions of the area, and reach the KS/MO border roughly by
midnight. These storms will have the potential for strong winds and
large hail, as well as heavy rainfall. The severe weather threat
will diminish from west to east as instability weakens and an
inversion begins to form at the surface.

One significant short term change to the forecast is in the QPF
field, which now shows less rainfall than previous iterations of the
forecast. Generally speaking, the boundary which was expected to
stall around the KS/NE border, now appears that it is stalling
further south. Additionally, there is stronger convergence further
SW in Kansas, and most models are indicating the heaviest rainfall
in southern Kansas.

Forecasts have been adjusted to account for this trend, and the axis
of heaviest rainfall in our area now runs across central portions of
the area. A majority of the area will likely fall in the 1-2" range.
With this southward shift in the guidance, totals have increased a
bit along the turnpike, closer to 1", with lower amounts south.

Scattered thunderstorms will continue overnight and into Wednesday.
The widespread storms and cloud cover means that temperatures will
fall well below normal, with some areas along the Nebraska border
struggling to reach 80. More normal temperatures will be realized
further south, where the boundary won`t reach all the way.

The upper level ridge builds significantly to the west on Thursday,
and the boundary finally leaves the area. Warmer and drier weather
are likely to return for the end of this work week, and temperatures
will return to the 90s across much of the area. A trough further to
our north will likely bring back a chance of storms Saturday
afternoon and evening, and daily storm chances will likely continue
into the start of next week.

Taking a minute to look at the long term forecast, it does appear
that we will be warming up yet again next week. The NBM temps are
approaching 100 across portions of the area, with heat indices well
into the 100s for Monday and Tuesday. For a 6 or 7 day forecast,
this is just a sign that above average temperatures are likely to
be the norm for the majority of the period.
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&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1239 PM CDT Tue Jun 18 2024

This afternoon, southerly winds were gusting as high as 30-35 mph.
Dense cu have formed, with bases high enough for VFR. This evening,
a strong line of thunderstorms is forecast for MHK, which will lead
to temporarily strong winds and vsby reductions. Confidence is lower
in the line of storms reaching TOP/FOE, so no TEMPO group at this
time. Towards sunrise, MVFR cigs are forecast across the area, with
IFR cigs possible at MHK. Cigs should lift through the morning, but
timing is uncertain for now.

&&

.CLIMATE...
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Issued at 220 PM CDT Tue Jun 18 2024

Record Warm Low Temperatures

June 18

               Record       Low as of 2 PM
Concordia     80 (1953)         77
Topeka        81 (2021)         79
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&&

.TOP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Montgomery
AVIATION...Montgomery
CLIMATE...Montgomery/Reese