Area Forecast Discussion
Issued by NWS Topeka, KS

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707
FXUS63 KTOP 171121
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
621 AM CDT Thu Aug 17 2017

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 303 AM CDT Thu Aug 17 2017

A mid level trough is currently tracking northeastward over the
Great Lakes region, and is responsible for the surface cold front
pushing through the area this morning. Drier is filtering into the
area behind the front with dew points dropping into the 60s by
sunrise for most locations. A band of clouds associated with the
front still stretches from Wichita to Kansas city, which could
prevent any further cooling this morning. Surface high pressure is
expected to slide across the area today with highs in the mid to
upper 80s. Later tonight the high pressure retreats to the southeast
and return flow develops over western and central KS. Also another
mid level trough digs across the northern plains, which will aid the
moisture return. Models are depicting convection forming along the
resulting front over the high plains. Some of this activity will try
to reach portions of north central KS towards sunrise tomorrow.
Also, a shortwave tracking over SD will support a possible complex
which could track southeastward across eastern NE, but it should
remain north of the area through sunrise. Lows tonight will range
from the lower to mid 60s.

.LONG TERM...(Friday through Wednesday)
Issued at 303 AM CDT Thu Aug 17 2017

For Friday, models are in general agreement for a couple
opportunities for precip. The first is for some elevated storms
Friday morning within a low level warm air advection pattern.
Isentropic surfaces shows some decent lift, but saturation is a
little questionable. Nevertheless most guidance suggest a
potential for precip. Then Friday afternoon and evening shortwave
energy is progged to amplify as it moves through the mid MO river
valley clipping northeast KS and bringing a frontal system through
the area. There are location differences among the various model
solutions, so confidence is about average for a summer time
convective event and only have some chances POPs at this time.

Saturday looks to clear out with weak surface ridging over the
area. However this appears to be short lived as return flow sets
up for Saturday night and Sunday. The pattern for Sunday and heading
into the beginning of the work week is for a flat upper ridge
along the Gulf Coast as shortwave energy generally remains north
across the northern plains. So models keep a semi-zonal flow
across the forecast area with the potential for subtle
perturbations to move through the flow. Low level moisture is also
expected to return by this time. By the middle of next week, an
upper ridge amplifies to the west of the Great Plains with
northwest flow setting up overhead. Again models suggest the
potential for subtle waves within the pattern. So with models
showing a conditionally unstable airmass over the forecast area,
there is some probability for showers and storms just about
everyday from Sunday through Wednesday. Although with the lack of
a strong surface feature or obvious shortwave, precip chances are
likely to be driven more by mesoscale details which makes nailing
down specifics a little tricky and only have POPs in the 20 to 40
percent range.

For Monday and the eclipse specifically, it`s hard not to see some
cloud cover over the region with models showing the low level
moisture axis over eastern KS. Based on GFS forecast soundings,
there should be some diurnally driven CU. And while there are
some small POPs in the forecast, the model progs suggest any
precip would be scattered in nature with no one location favored
over another due to a lack of a focusing feature for storm
development.

Haven`t made any significant changes to the temps forecast through
the period with seasonable readings expected. There doesn`t appear
to be any period of strong temperature advection so highs are
forecast to be in the mid 80s to mid 90s while lows range between
the mid 60s and mid 70s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 617 AM CDT Thu Aug 17 2017

VFR conditions expected through the taf period. High pressure will
slide across the area causing a shift in the winds from northwest
to more south to southwest by tonight. There is a very slight
chance for ground fog mainly at TOP around sunrise tomorrow.

&&

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

$$

SHORT TERM...Sanders
LONG TERM...Wolters
AVIATION...Sanders



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