Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 160521
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1121 PM CST Sat Nov 15 2014

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Sunday)
Issued at 311 PM CST SAT NOV 15 2014

The first upper level trough that brought minor snow accumulations
across the CWA was currently lifting northeast across southeast NE
and western MO. The accumulating snow has shift northeast into IA
and MO.

A more amplified and sheared out upper level trough extended from
the upper Midwest, west-southwest across the northern high plains
into the eastern plains of OR. Both the northern and western
sections of the sheared out upper level trough will amplify. The
first trough will amplify across the northern great lakes while the
western section of the H5 trough will dig southeast across the
southern high plains. Most of the upper and mid level
frontogenetical forcing will occur southwest and south of the CWA as
the western half of the sheared upper level trough digs southeast
across the southern high plains into OK through the day Sunday.

Another amplified upper level trough across north central Canada
will dig southeast into the upper great lakes and mid MS river
valley and phase with the upper trough moving east out of OK. This
will result in strong low-level CAA across the plains bringing down
a cold airmass from north central Canada.

The cold front will move southeast across the CWA during the late
evening and overnight hours. Winds will shift to the northwest and
increase to 15 to 20 MPH and continue through the day on Sunday with
higher gusts. As the positive tilt H5 trough axis moves southeast
across the CWA there may be enough ascent for light snow to develop
across the north central KS this evening. The light snow band will
be weakening as the mid and upper level frontogenetical forcing
intensifies across the TX PNHDL and northwest OK. The western
counties of the CWA could see a dusting or up to a half inch of
snowfall this evening. Through the morning hours of Sunday a band of
light to moderate snow will push east-northeast from northwest OK
into south central and southeast KS. The southeast counties may get
brushed by the northern end of this snow band. The accumulating snow
should remain across southeast KS and southwest MO. The remainder of
the CWA should see clearing skies. Even with insolation across most
of the CWA during Sunday, highs will only reach the mid to upper
20s. Any light snow across the extreme southeast counties should
move east of the area during the afternoon hours.

.LONG TERM...(Sunday Night through Saturday)
Issued at 311 PM CST SAT NOV 15 2014

By Sunday night, the deep mid-level trough axis will be centered
over the central U.S. and will gradually shift eastward through the
early part of this week. With strong northwesterly flow aloft and
breezy northwesterly surface winds as high pressure spreads eastward
into the region, caa will prevail and keep temperatures well below
normal through Monday night. In fact, temperatures for Monday will
be the coldest of the week with highs only reaching into the 20s and
possibly only the teens near the Nebraska border, and low
temperatures Monday night plunging to near record low readings in
the single digits. With light northwesterly winds persisting Monday
night, expect frigid conditions by Tuesday morning with wind chill
values likely dropping into the negative single digits.

Temperatures start to gradually moderate upward by Tuesday as the
mid-level trough advances further east of the area and surface high
pressure shifts southeast toward the Gulf of Mexico, shifting winds
to the southwest. As a result, should see highs in the upper 20s to
mid 30s on Tuesday. Models show an embedded shortwave trough
developing over the Northern Plains within the broad mid-level
trough and sliding to the southeast Tuesday night into Wednesday.
This passing wave will help to push a weak cold front through the
area early Wednesday morning, however expect conditions to remain
dry with only some mid-level clouds developing from this frontal
passage.

Models show more of a mid-level zonal flow developing by mid to late
week with surface high pressure gradually spreading eastward across
the entire central U.S. As a result, expect dry conditions through
the end of the week with high temperatures gradually moderating into
the mid 30s to low 40s and low temperatures into the teens and 20s.
However, it`s worth noting that model discrepancies in the mid-level
and surface flow become more noticeable by Friday and through the
weekend, which is resulting in 10-15F degree temperature
differences for forecast high/low temperatures between the
GFS/ECMWF. Due to these large temperature discrepancies, have stayed
with the consensus blend solution for Friday and Saturday. Despite
the significant model differences, both GFS/ECMWF are showing a
surface low passing south of the forecast area over the weekend in
which a front may extend northward toward the region and result in
some light precipitation developing, so have slight chance PoPs in
for Saturday.

&&

.AVIATION...(For the 06Z TAFs through 06Z Sunday Night)
Issued at 1120 PM CST SAT NOV 15 2014

Multiple cold fronts and light snow potential highlight this
forecast. Will keep TEMPO from earlier update for the next few
hours with mainly MVFR impacts anticipated. Stratus and gust
potential also exists early with the first front`s passage early
in the TAFs with confidence on both being persistent somewhat
limited. Next front arrives around the end of this forecast.

&&

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

$$

SHORT TERM...Gargan
LONG TERM...Hennecke
AVIATION...65





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