Area Forecast Discussion
Issued by NWS Topeka, KS

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829
FXUS63 KTOP 220422
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1122 PM CDT Thu Sep 21 2017

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Friday)
Issued at 256 PM CDT Thu Sep 21 2017

Feels a lot more like June out there than September, with highs
in the western counties in the middle 90s and around 90 in the
east, with dewpoints 70 degrees west to middle 70s east. This
makes for heat indices from the middle 90s to low 100s. Breezy
south winds likely helping little for much cooling. Shortwave
lifting out of Oklahoma across eastern Kansas having little impact
on the area except to continue mixing and moisture advection into
the state. Wave lifting out of the Panhandles may generate a few
storms out over the dryline but atmosphere not supporting keeping
those chances continued up into our area and have kept rain
chances out of the forecast.

Forecast for tonight into tomorrow is nearly identical, with
overnight lows only falling into the 70s and highs once again rising
to near todays numbers. Breezy conditions also continue into Friday,
as well as higher dewpoints. This will make for another day of heat
indices around 100.  Fire danger is also elevated, but higher RH
should will continue to help temper fire danger.

.LONG TERM...(Friday night through Thursday)
Issued at 256 PM CDT Thu Sep 21 2017

The main focus of the extended forecast is a high amplitude upper
trough progged to move slowly west to east across the plains for
the first half of next week. The overall trend with the models has
been to slow the progression of the upper trough and surface front
through the plains. It now looks like the front moves through late
Monday and Tuesday morning. So the forecast shows the higher POPs
in for Monday through Tuesday morning. There remains some timing
differences with the frontal passage so the POPs are still
somewhat broad brushed through this period. Also with the slower
trends in the models, have held onto some chance POPs, mainly
south of I-70, through Wednesday as the GFS hints at some
potential for overrunning. Although there is also some uncertainty
in this as the ECMWF and GEM push the front into north TX and AR.
So think there is some fine tuning to due in the POP forecast
before all is said and done.

Temps are expected to gradually cool through the weekend as the
models show 1000-500 MB thicknesses lowering and 850 MB temps
cooling. Although highs are still anticipated to be in the mid
80s and around 90. And a southerly surface wind should keep lows
in the mid to upper 60s. Temps for Monday and Tuesday are the
more uncertain of the forecast due to the uncertainty in the
frontal timing. By Wednesday low level cold air advection should
bring a bigger cool down.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1119 PM CDT Thu Sep 21 2017

Expect VFR conditions at all terminals through the next 24 hours.
the 40 to 45 KT low-level jet about 1000 ft to 1500 ft will
continue through sunrise. Therefore expect periods of low-level
wind shear within the lowest 2000 feet through 13Z.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...67
LONG TERM...Wolters
AVIATION...Gargan



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