Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 170802
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
202 AM CST Wed Jan 17 2018

.SHORT TERM...(Today and tonight)
Issued at 201 AM CST Wed Jan 17 2018

An upper trough continues to rotate east of the forecast area per
the 08Z water vapor imagery. This has allowed an upper ridge to move
into the plains while a closed upper low remained well off the west
coast. At the surface, the arctic surface high was centered over
northeast OK and continues to move south of the area.

The forecast for today and tonight remains dry with below normal
temps persisting. Models are in agreement that a there really isn`t
any moisture return today even though southwesterly low level winds
will develop on the back side of the surface ridge. This is because
the high has pushed all the way into northern Mexico and should keep
the gulf closed off. Forecast soundings show little if any mixing
today and as a result tend to keep highs in the lower and mid 20s.
However think sunny skies and a southwesterly wind will help bump
highs a little warmer than this into the upper 20s and lower 30s.
This is supported by the MOS guidance. Lows tonight should fall back
into the teens. A weak pressure gradient should help keep a light
surface wind overnight keeping lows from bottoming out.

.LONG TERM...(Thursday through Tuesday)
Issued at 201 AM CST Wed Jan 17 2018

Surface high pressure anchored across the southeastern U.S. on
Thursday will remain in place into the weekend, resulting in
south/southwesterly winds supporting decent WAA across the area.
Thursday into Friday, a mid-level trough will begin to track into
the Pacific Northwest, and this advancing trough ultimately will
help to push surface low pressure over the Rockies further eastward
toward the High Plains.  The resultant increased pressure gradient
over the CWA will support increasing southerly winds, and stronger
WAA. As a result, models are trending a bit warmer for temperatures
late week into the weekend, with highs in the 40s on Thursday and
into the 50s by Friday. However, by Saturday, models show a cold
front associated with the advancing low pressure sliding southward
into northern KS through the day, resulting in high temperatures
ranging from the upper 40s/low 50s to upper 50s from northwest to
southeast across the CWA. This front looks to pivot over the CWA
Saturday night into Sunday, becoming more southwest-to-northeast
oriented. In general, models are trending a bit further west with
the placement of this pivoting front by Sunday morning, resulting in
more of the CWA remaining in the warm-sector initially before the
front tracks eastward through the afternoon hours.  There are still
some timing and tracking discrepancies in the models with this
frontal passage Sunday into Sunday night, however the models are in
agreement in delaying the onset of precipitation until mid to late
morning due to dry air aloft that will need to be overcome. Due to
this delayed start to precipitation, the precipitation type should
be predominantly in the form of rain through the daytime hours, with
an initial mix of rain and snow possible across north central KS
before temperatures rise into the low 40s across that area. The
frontal passage will likely result in a large temperature spread,
with highs possibly reaching into the upper 50s across east central
KS. Expect some dry periods through the day as models continue to
show the dry slot nosing into the area before the wrap-around
precipitation on the back-side of the low skims across much of north
central to northeast KS Sunday night.  Models have trended a bit
further south with the coverage of this deformation zone, and with
low temperatures dropping into the 20s, expect this precipitation to
transition over to snow during the evening hours. As a result, light
snow accumulations will be possible Sunday night before this system
exits to the east by around sunrise Monday morning.

Dry conditions are expected for the start of next week as surface
high pressure moves in behind the exiting front.  With fairly zonal
westerly mid-level flow setting up behind this system, do not expect
much in the way of CAA with high temperatures in the low/mid 40s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1115 PM CST Tue Jan 16 2018

VFR conditions are expected through the TAF period. Southerly
winds will increase to 5-10 kts by 16-17Z at all terminals.


&&

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

$$

SHORT TERM...Wolters
LONG TERM...Hennecke
AVIATION...Baerg



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