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Area forecast discussion
National Weather Service Topeka Kansas
538 PM CST Sat Dec 7 2019

..update to aviation forecast discussion...

Short term...(this evening through sunday)
issued at 137 PM CST Sat Dec 7 2019

A positive tilt upper level trough across the western US will
continue to shear apart with the northern stream 500 mb trough moving
east across the northern High Plains Sunday afternoon. The southern
stream section of the 500 mb trough will dig southeast across Arizona into
western nm.

A Lee surface trough across the central and southern High Plains
will slowly drift east across west central Kansas and southward across
western OK. South-southwest surface winds will gradually advect
modified Gulf moisture northward across eastern OK into southeast
Kansas tonight. The weak isentropic lift ahead of the moisture return
will cause a stratus deck to develop across southern Kansas late
tonight, which will overspread the County Warning Area during the morning hours.
Tomorrow will become mostly cloudy but south-southwest surface
winds should still allow high temperatures to reach the the lower
to mid 50s. If we see more breaks in the cloud cover Sunday
afternoon, then the planetary boundary layer will mix a bit deeper, allowing highs to
reach into the upper 50s to around 60.

Long term...(sunday night through saturday)
issued at 137 PM CST Sat Dec 7 2019

Sunday night through Monday night, the northern stream upper level
trough across the northern High Plains will shift east across the
northern and Central Plains into the upper Midwest through Monday
night. Strong low-level cold air advection across the northern plains will cause a
surface cold front to move southeast across the area late Sunday
night into Monday morning. 850mb and surface winds will veer more to
the west-southwest as the surface trough shifts east across Kansas
and northern OK. At this time the stronger isentropic lift will be
confined to southeast Kansas and southwest MO, where drizzle or light
rain may develop but the light rain or drizzle will probably
remain southeast of the County Warning Area.

Once frontal passage occurs late Sunday night into Monday morning, surface
winds will switch to the north-northwest and increase to 15 to 25
miles per hour with higher gusts through the morning hours of Monday and
will continue through Monday afternoon. The strong low-level cold air advection
will cause afternoon temperatures to fall through the 30s. Highs
across east central Kansas may reach the lower 40s before noon on
Monday but fall through the 30s during the afternoon hours. As the
southern extent of the 500 mb trough moving east-southeast across the
northern and Central Plains passes east across northern KS, there
may be enough ascent for light snow or flurries to develop across
the northern half of the County Warning Area during the day on Monday. I don't
expect any snow accumulations, since the stronger q-g forcing
will remain well northeast of the County Warning Area.

Monday night the center of the cold surface ridge will build
southeast across eastern Kansas. The surface winds will diminish through
the night and with skies clearing overnight, overnight lows will
fall into the mid teens to around 20 degrees.

Tuesday through Wednesday, the upper trough across the eastern US
will deepen as if slowly shifts east towards the eastern Seaboard.
The central and Southern Plains will remain under northwesterly flow
aloft. Highs will only reach into the 30s both Tuesday and
Wednesday. The minor perturbations embedded with the northwest flow
will remain northeast of the cwa, so I expect a dry but cold
forecast. Overnight lows will drop into the teens Tuesday night.

Wednesday night through Saturday, the upper flow will become more
zonal across the central and Southern Plains. This will help high
temperatures to moderate back into the 40s on Friday with upper 40s
to lower 50s Friday and Saturday. A mid-level perturbation embedded
within the zonal flow will move east across the Central Plains and
may provide enough ascent for light rain late Friday afternoon
into Friday evening. The light rain may mix with snow later Friday
night before ending. Any precip accumulations look light at this
time.

&&

Aviation...(for the 00z tafs through 00z Sunday evening)
issued at 527 PM CST Sat Dec 7 2019

No significant changes to the going forecast for the 00z tafs. The
primary hazard will be the low level wind shear conditions and a strong
southwesterly low level jet strengthens across the area overnight. Still
uncertain in stratus deck as the best moisture still looks to far
southeast of the area in the low levels. But, will need to watch
trends on overall moisture advection into the terminals to better
refine this part of the forecast.

&&

Top watches/warnings/advisories...
none.
&&

$$

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