Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 192333
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
533 PM CST Sun Feb 19 2017

...AVIATION UPDATE...

.SHORT TERM...(This evening through Monday)
Issued at 121 PM CST Sun Feb 19 2017

The primary issue in the very short term is the impact of an area
of low cloud cover on near term temperatures. This stratus deck
has been advancing northeast while also eroding from the sides. It
has not been particularly deep but has been deep enough to limit
sunshine and keep temperatures cooler. On the other hand, as it
continues to advance it will keep temperatures warmer overnight.

Precipitation chances become the focus after 9 PM as an elongated
neutral-tilt upper trough is moving across the plains. Upper flow
overhead is quite meridional with ample deep moisture advection
into the region. Several short wave troughs were moving toward the
NNE out of the main longer wave trough. One of particular interest
was evident over the Big Bend region of TX in WV imagery. This
appears that it may be the first piece of lead energy to provide
focused ascent for precipitation locally. Model guidance has
generally increased the expectation for precipitation late this
evening into early Monday largely tied to the trajectory of this
energy. Hi-Res guidance such as recent runs of the HRRR and RAP
support the larger-scale model theme, and seem to focus the
optimal timing for precip in the local forecast area between
midnight and 8 AM with a gradual SW to NE precip transition. There
is some potential to linger a bit longer in the far east as the
upper trough slowly moves east and another slight chance for
precip mainly in far northern KS late in the day as the surface
front eventually moves into the area.

PWAT values are forecast to flirt with record values for this time
of year with some forecast values approaching 1.3-1.5". There
should also be some modest elevated instability, and the
combination of the two features may allow for a few areas of
decent rainfall to materialize. Duration will not be very long
with the progressive waves of energy, but wouldn`t be surprised to
see precip amounts range from very light in north central KS to
potentially a half inch or more where better convection develops.

.LONG TERM...(Monday night through Sunday)
Issued at 121 PM CST Sun Feb 19 2017

Conditions will dry out for Monday night through Thursday morning.
Expect quite a bit of sunshine through Tues/Wed with dry air just
above the boundary layer likely to mix to the surface. Similar
conditions in recent days have led to warmer and drier than
expected conditions so at this time have been forecasting a bit
warmer and a bit drier but will want to monitor for any potential
to go warmer and drier yet. Luckily wind speeds are unlikely to
exceed 20 mph either day so explosive fire conditions are
unlikely although MinRH could fall below 20% each day.

On Thursday, model agreement is still strong in a strong jet
streak crossing into KS with surface cyclogenesis in southeast
Colorado. Expect a strengthening frontal zone to extend across
northern KS by late Thursday with cold air being pulled into north
central KS by Thursday evening. Guidance remains split on how soon
and how impressive the intensification of the upper low will be
but the overall message remains generally the same. Expect windy
conditions with the strengthening surface low, and continue to
see decent potential for snow over mainly northern KS northwest
of a Minneapolis to Clay Center to Marysville line but this could
obviously change substantially between now and the end of next
week. If snow develops, some accumulation is possible but expect a
sharp gradient in accumulation and could very well end up nearly
snowless especially with the warm ground temperatures.

Colder air overtakes the entire region for the weekend, but even
while it is much colder than the current airmass it will still be
fairly close to normal values. Another very weak system will bring
precip chances for Sunday with rain or snow possible, and the
active weather pattern looks to continue into the following week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday)
Issued at 533 PM CST Sun Feb 19 2017

Models are in good agreement with the good surge of moisture
moving across eastern KS along with some PVA. Forecast soundings
even show around 500 J/kg of elevated instability overnight. With
the moisture advecting northeast, MVFR CIGS are expected to return
along with some 3SM to 5SM BR. Timing of this is a blend of
available guidance and the timing of the precip is based largely
off the HRRR. By Monday afternoon, models push the deep moisture
axis east of the area and shift winds more to the southwest. This
should allow for the low level moisture to scour out and conditions
to improve to VFR.

&&

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

$$

SHORT TERM...Barjenbruch
LONG TERM...Barjenbruch
AVIATION...Wolters



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