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Area forecast discussion
National Weather Service Topeka Kansas
631 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 relative humidity
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 European model (ecmwf) and Gem push the front into North Texas and Arkansas.
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 00z tafs through 00z Friday evening)
issued at 627 PM CDT Thu Sep 21 2017

Expect VFR conditions through the next 24 hours. This evening a 40
to 45 knots southerly low-level jet will increase across the
terminals. This will cause low-level wind shear to develop within
the lowest 2000 feet once the surface winds diminish slightly
through the mid evening hours and will continue through until
after sunrise on Friday.


Top watches/warnings/advisories...

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