Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 232313
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
613 PM CDT SAT JUL 23 2016

...AVIATION UPDATE...

.SHORT TERM...(This Evening through Sunday)
Issued at 317 PM CDT SAT JUL 23 2016

An area of scattered to broken mid and upper level cloud cover is
currently moving over the forecast area. This has keep the
temperatures cooler than previously forecasted. There are some breaks
in the clouds, which have allowed a temporary rise in the
temperatures. The dew points have ranged from the mid 60s to the mid
70s. Heat indices are generally between 100 and 105, although a few
locations may peak near 110 for a brief period this afternoon. The
coolest temps have been across northern KS, but that area will
receive more sun in the next few hours. For now have decided to keep
the excessive heat warning in effect through the afternoon.

Later this evening the models are forecasting an increase in the
isentropic lift in the mid levels. The flatted upper ridge has
allowed monsoonal moisture to spread over KS. Also, isentropic
showers have been fairly persistent each night over the past week
across northern KS. This isentropic lift my linger into the late
morning hours similar to today. At the same time a surface front
moves southeastward through the forecast area. During the overnight
and morning the environment should remained capped from any low
level lift associated with the front. Later in the day surface
heating may erode the cap and allow showers and storms to develop.
The front should be located somewhere near I-70. A main concern will
be the elevated showers and the associated cloud cover that may
prevent warming ahead of the front. This will dictate whether or not
the cap will break to allow surface based storms along the front.
The GFS keeps most areas capped, while the NAM and ECMWF develop
storms. The forecasts for the different models ranges from 1000 to
3000 j/kg, so consensus would be around 2000 j/kg. Strong wind gusts
could be possible tomorrow afternoon and evening if a surface based
storm could tap into this potential cape. The highest chance for
this will be along and south of a line from Abilene to Holton. As of
now highs tomorrow range from the upper 80s in northern KS to the
upper 90s in east central KS. Therefore the highest heat index
should only reach up to 105.

.LONG TERM...(Sunday Night through Saturday)
Issued at 317 PM CDT SAT JUL 23 2016

Sunday night through Tuesday, The broad upper level ridge across the
southern plains will retrograde a bit farther west-southwest into
the portions of the Southwest US and southern high plains. The upper
level flow will become west-northwest across eastern KS, though the
stronger upper level jet will remain across the northern plains.

Sunday night, The weak surface front will push southeast across east
central KS during the evening hours of Sunday. Any Scattered showers
and thunderstorms that develop along the front earlier in the
afternoon hours of Sunday should move southeast of I-70 during the
early evening hours and move south of the CWA by midnight Monday.
Most of the CWA should remain dry through the night.

Monday, showers and thunderstorms that develop north of the surface
boundary across northwest KS late Sunday night will slowly move
southeast and may move across the western counties of the CWA during
the mid and late morning hours of Monday. The NAM and GFS show a
surface ridge of high pressure building southwest across the
northeast counties during the morning, then across the CWA during
the afternoon hours. The front will remain nearly stationary along
the OK and KS border where afternoon thunderstorms will develop
across northeast OK, well south of the CWA. Frontolysis will occur
across western KS and upslope flow will advect deeper gulf moisture
northwest into eastern CO. Northeast to easterly surface winds will
keep high temperatures cooler with highs in the lower to mid 90s.

Monday night through Tuesday, As the deeper moisture advects
northward across KS into central NE, isentropic lift combined with
ascent ahead of a weak H5 trough will cause numerous showers and
thunderstorms to develop across central and eastern NE late Monday
night. The southern edge of this complex of thunderstorms may
propagate southeast across northeast KS around sunrise and continue
through the mid morning hours of Tuesday before shifting southeast
into MO. After the chance for morning storms, mainly across
northeast KS, the remainder of the afternoon across the CWA looks to
be dry. The next H5 trough will be digging southeast cross west
central NE and northwest KS where showers and thunderstorms will
develop during the afternoon hours of Tuesday.

For Tuesday night through Saturday, upper level northwest flow is
forecast over the northern Central Plains.  With several shortwaves
propagating through the mean flow, precipitation chances remain
through the entire period.  For now, looks like Wednesday night and
Thursday night have the better chances to see some overnight
complexes of storms.  With chances through most of the week next
week, flooding concerns are possible.  Temperatures will be near
climatological values with highs near 90 and lows in the lower 70s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday)
Issued at 613 PM CDT SAT JUL 23 2016

Area of virga continues to move off to the southeast. With no
obvious forcing for storms noted, VFR conditions should prevail
through the night. Have removed the mention of LLWS from the
forecast. Models have backed off on the strength of the low level
jet with 850MB winds only around 30KT. So confidence in LLWS is to
low to keep it in the forecast. With the boundary in the area
during peak heating Sunday, there could be some storms pop up
around the terminals. Forcing is still not obvious, but models
show enough instability with little or no inhibition. Therefore
introduced a PROB30 for the end of the forecast period.

&&

.TOP Watches/Warnings/Advisories...
Excessive Heat Warning until 7 PM CDT Sunday for KSZ021>024-026-
034>040-054>056-058-059.

Excessive Heat Warning until 7 PM CDT this evening for
KSZ008>012-020.

&&

$$

SHORT TERM...Sanders
LONG TERM...Gargan/Heller
AVIATION...Wolters



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