Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 021108
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
508 AM CST Fri Dec 2 2016

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 246 AM CST Fri Dec 2 2016

Quasi-zonal flow aloft will continue today as a surface high
pressure slides across the northern plains and upper Midwest. An
area of confluence at 700 mb has lead to clouds over portions of
east central KS. This has inhibited the radiational cooling that
the rest of the area is experiencing under clear skies and light
wind. Therefore temperatures under the cloud cover have remained
in the 30s while elsewhere have dropped into the 20s. Those clouds
should move off to the east later this morning. Today highs should
generally be in the 40s with light wind. Tonight a mid/upper level
low pressure will track over the southwest US, which will lead to
more southwest flow aloft. Mid level clouds should overspread the
region as that wave approaches. Towards sunrise the mid level
moisture and lift may support precip although the lower levels
will start off dry. The lower levels may become saturated allowing
precip to reach the ground. Of course all of this will depend on
the strength of the mid level lift. Temperatures are forecasted to
be right around freezing during this time frame therefore either
rain and or snow could not be ruled out. As of now most of the
precip holds off until after sunrise. Also, the expansive cloud
cover could prevent the temperatures from cooling into the lower
30s.

.LONG TERM...(Saturday through Thursday)
Issued at 246 AM CST Fri Dec 2 2016

By 12z Saturday morning, light precip expands from the southwest
into the forecast area as an upper shortwave moves across the
Central to Northern Rockies.  Along with the precip comes warmer
temperatures in weak warm advection ahead of the wave, which by the
noon hour has light precip type as rain.  Until then, could see a
light wintery mix, but very little would be expected to accumulate.
The colder air stalls near the northern and western borders for the
evening hours and overnight, and as the base of the shortwave trof
swings over and through, areas generally west of Topeka that fall
below freezing could get another chance for a light wintery mix,
while rain remains in the east.  Very little accumulation is
anticipated with the potential mix overnight as well, although
eastern counties could pick up a few tenths of an inch of rainfall.

Sunday into Monday brings a break from precip and clouds and a boost
in temperatures with highs back into the upper 40s to low 50s.
Keeping an eye on an upper trof moving out of Texas and quickly into
Missouri and Illinois, but track is consistent between tonights
model runs. Could see some rain in the southeast counties Monday
afternoon and into the evening as this system traverses to our
east. The next incoming large scale upper trof is advancing into
the western counties by late Monday evening, with some light
chance for rain or a rain/snow mix. Worth noting that the EC keeps
western counties dry. By early morning Tuesday, the GFS has below
freezing temps at 850mb, with -3 to -10c across the entire area
by late day Tuesday. EC is slower with the cold air, with the
freezing mid level temps about 6-12 hours behind.

Main wave in the GFS sweeps over the eastern part of the state by
afternoon on Wednesday. Sounding profiles keep types as snow, with
Bufkit giving some accumulations across the area by Wednesday
afternoon, with best chances midnight to Noon. The slower EC is
also slower with the potential for snowfall, with latest run
bringing accumulations into the west by early morning, into the
east by Noon, with best chances in the afternoon when the better
lift moves in. This would keep chances for snow across the east
into Wednesday late evening. Timing will have impacts on commutes,
etc, so will see how model solutions evolve over the next few
days. Its a bit early for specifics on timing or amounts given
model differences, but worth noting that is potential for some
accumulating snow on Wednesday.

Although there are some differences in how the larger scale upper
trof moves over the central states into Thursday, both EC and GFS
draw some of the coldest air so far of the season into the area.
Highs on Wednesday in the 20s to lower 30s fall into the 20s as
the cold air drives southeastward into Thursday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 505 AM CST Fri Dec 2 2016

VFR conditions expected through the taf period. Clouds will
overspread the area and gradually lower through out the day.
Ceilings could drop to around 5 kft by the end of the period.

&&

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

$$

SHORT TERM...Sanders
LONG TERM...67
AVIATION...Sanders



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