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199
FXUS63 KTOP 222323
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
623 PM CDT Tue Aug 22 2017

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Wednesday)
Issued at 224 PM CDT Tue Aug 22 2017

19Z water vapor imagery shows the mean westerlies across the
northern tier of the country with an upper trough over the great
lakes and another off the British Columbian coast. There were also a
couple areas of low pressure noted off the TX/LA gulf coast and off
the CA coast. At the surface, obs show high pressure over the
northern plains building south with the cold front stretching from
southern MO into northern OK.

Quiet weather is forecast for tonight and Wednesday. Surface ridging
should continue to build south with much drier air moving into the
region. Combined with no obvious shortwave within the northwest flow
aloft, precip chances are pretty slim. Biggest concern may be
whether ground fog develops Wednesday morning. Forecast soundings
show boundary layer moisture remaining very shallow with models
bringing dry air in from the north, so they are not showing any fog
in the progs. However clear skies with light and variable winds are
forecast overnight. Models could possibly be overdoing the dry air
advection and boundary layer moisture could end up being deeper
considering this morning`s rainfall totals across east central KS.
Since there is no guidance showing fog, will leave it out of the
forecast and let later shifts monitor trends. If it does develop, it
would likely be confined to the usual low lying places along rivers
and streams. Lows tonight could feel a little chilly with readings
expected to fall into the middle 50s. Highs Wednesday should rebound
into the lower and middle 80s with good insolation and the boundary
layer mixing to 850.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 224 PM CDT Tue Aug 22 2017

By Wednesday night, a mid-level trough will be stretched across the
northeastern U.S. with a mid-level ridge over the Northern Rockies,
resulting in northwesterly flow aloft across the central U.S.  With
surface high pressure centered just east of the forecast area
through the end of the week, conditions will remain dry across much
of the area.  The only exception may be across far north central KS,
where models continue to show an embedded shortwave developing over
the NE/KS border within the northwesterly flow aloft.  While much of
the precipitation from this shortwave should remain focused across
western KS, there is a slight chance for it to extend into portions
of north central KS late Thursday night into Friday morning.
Beginning Friday night and continuing into early next week, models
show a large mid-level ridge building across the western CONUS, with
the ridge axis actually extending into Canada.  As this ridge axis
begins to build, it will push the embedded shortwave hovering near
the KS/NE border northeastward toward the Great Lakes region late
Friday night into Saturday.  As a result, some scattered showers and
storms may skim across far north central to far northeast KS.  As
the ridge builds across the western U.S., the mid-level flow will
become more northerly with models showing additional embedded waves
developing Sunday into Monday within the mid-level flow, producing
additional chances for scattered showers and storms.

Temperatures through early next week will remain fairly steady and a
few degrees below the seasonal normals, with highs in the low 80s
and low temperatures ranging from the upper 50s to mid 60s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 618 PM CDT Tue Aug 22 2017

VFR prevails through the forecast period with light northerly
winds veering to the east southeast as high pressure builds into
the region. There is a slight chance for shallow MVFR fog at KTOP
towards sunrise, however confidence is not high enough at this
time based on the drier air moving into the region.

&&


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

$$

SHORT TERM...Wolters
LONG TERM...Hennecke
AVIATION...Prieto