Area Forecast Discussion
Issued by NWS Topeka, KS

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912
FXUS63 KTOP 210444
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
1144 PM CDT WED JUL 20 2016

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Thursday)
Issued at 211 PM CDT WED JUL 20 2016

Tonight through Thursday, a broad upper level ridge will continue
across the southern and central plains. Expect the hot and humid
conditions to continue with any thunderstorm chances remaining well
west and north of the CWA.

The 850mb temperatures warm about 2 degrees tomorrow afternoon and
will range from around 24 degrees C across the eastern counties to
28 degrees C across the western counties. Forecast soundings show
the boundary layer mixing up to 850mb across northeast and east
central KS which will allow high temperatures to reach the upper
90s. Afternoon dewpoints will be in the lower to mid 70s across
northeast and east central KS. Slightly deeper mixing across the
western counties of the CWA will result in dewpoints mixing down
into the mid 60s, though highs will reach the 101 to 104 degree
range. Given the combinations of high temperatures and dewpoints,
afternoon heat indices on Thursday will reach 105 to 110 degrees
across much of the area with the extreme northeast counties getting
to around 112 degrees. An excessive heat warning will continue
across the CWA through 7 PM Saturday.

Overnight lows will only drop down into the mid 70s to around 80
degrees.

.LONG TERM...(Thursday Night through Wednesday)
Issued at 211 PM CDT WED JUL 20 2016

Overall, very little change to the ongoing forecast. Upper ridge
over the central CONUS early in the forecast period is flattened
by a shortwave move through the northern plains and upper midwest
this weekend. The 12z ECMWF/GFS/CAN all sink a cold front into
northeast Kansas by Sunday in association with the before
mentioned upper wave. The upper ridge amplifies over the western
CONUS late in the period allowing weak WNW flow to develop over
Kansas. Once the surface boundary reaches the area, it is forecast
to remain in the vicinity for the remainder of the forecast
period.

Before the frontal boundary arrives, see no reason to change the
ongoing hot forecast. 850 mb temperatures slightly increase in
time. Mixing and lower dewpoints during the afternoon may also
occur, especially on Saturday. With respect to the apparent
temperatures, a decrees in dewpoints should correspond to an
increase in temperatures. Apparent temperature forecasts during
the day of 103-110F through Saturday are likely. Therefore, will
not change the ongoing Extreme Heat Warning with this forecast.
The warning might need to be extended in time depending on the
eventual timing of the front into the area.

Once the boundary arrives, temperature should be cool enough to
end the heat headlines. With the boundary in the area and the
weakened cap due to the flattened upper ridge, a small chance of
thunderstorms seems reasonable early next week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1138 PM CDT WED JUL 20 2016

VFR prevails with southerly winds at or just below 10 kts this
evening, increasing during the afternoon with occasional gusts to
20 kts. LLWS remains marginal through 12Z. Latest short term
trends are showing stronger sfc winds at KMHK, therefore lowering
the potential.

&&

.TOP Watches/Warnings/Advisories...
Excessive Heat Warning until 7 PM CDT Saturday for KSZ008>012-
020>024-026-034>040-054>056-058-059.

&&

$$

SHORT TERM...Gargan
LONG TERM...Johnson
AVIATION...Prieto



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