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Area forecast discussion 
National Weather Service Topeka Kansas
638 am CDT Tuesday Jul 28 2015

..update to aviation forecast discussion...

Short term...(today and tonight)
issued at 310 am CDT Tuesday Jul 28 2015

An amplified upper level trough was lifting northeast across the
northern and Central High plains early this morning. The stronger
ascent and isentropic lift across western and central South Dakota has caused
a large complex of thunderstorms to develop. The complex of storms
will move east-southeast across Minnesota and Iowa through the the day.

At 7z a surface cold front extended from eastern ND...south-
southwest into northeast Colorado.

Expect another hot day today. Forecast soundings by 21z show deeper
mixing across the County Warning Area. The forecast sounding for top mixes the
boundary layer up to 837mb by 21z...with around 825mb at emp and
abi. Dewpoints may mix down into the middle and upper 60s across much
of the County Warning Area. The extreme eastern and northeast counties may not mix as
deep and could keep lower to middle 70s through the afternoon. Highs
will be around 100 degree across the southwest counties with middle to
upper 90s across the remainder of the County Warning Area. Heat indices will range
from 102 to 106 degrees along and south of a Minneapolis to Hiawatha
line. Therefore, i'll keep the current heat advisory in effect for
this afternoon.

As the 500 mb trough moves east across the northern plains this
morning...stronger cold air advection across the northern and Central Plains will
help push the cold front southeastward into western and central Kansas
later this afternoon. Surface convergence ahead of the front will
allow scattered thunderstorms to develop from north central Kansas
southwestward into southwest Kansas. The thunderstorms will congeal into
a line of storms early this evening and slowly move southeast across
the County Warning Area. The 0-6km effective shear will increase to 20 to 30 kts as
MLCAPE will be around 2500 j/kg across the County Warning Area. Some of the storms
in the line may become strong to severe given the parameters of weak
vertical windshear and moderate values of MLCAPE. Precipitable waters will range
between 1.4" to 1.6" across the cwa, but any type of training could
lead to isolated flash flooding across the western half of the County Warning Area
this evening. The primary hazard would be damaging winds and heavy
rainfall. If any of the embedded updrafts in the line of storms can
sustain middle level rotation then there could be a brief large hail
threat.

The WRF solutions all show an outflow boundary racing ahead of the
line of storms after 6z as they move southeast across northeast and
east central Kansas. This may cause the line to fall apart with updrafts
weakening after 6z. The thunderstorms could all weaken before
reaching east central Kansas after midnight. For now I leaned more with
the NAM which kept the line or complex of storms together through 9z
but as the 500 mb trough shift east into the upper Midwest and middle MS
River Valley...the synoptic scale subsidence may increase across
eastern Kansas and allow any line or complex of storms to weaken after
9z.

Long term...(wednesday through monday)
issued at 310 am CDT Tuesday Jul 28 2015

By Wednesday morning the cold front should be south of the forecast
area as surface high pressure begins to build into the area.
Although there may be some lingering showers behind the front during
the morning hours mainly south of I-70. Clouds will gradually
diminish through out the day as cooler and drier air filters in from
the north. High temperatures will only reach the lower to middle 80s
with dew points in the upper 50s middle 60s. This is when the upper
level pattern will begin to transition to northwest flow. Not before
a few weak disturbances move along the northern periphery of the
upper high. These waves will bring a chance for elevated showers and
perhaps storms Wednesday night mainly across south central Kansas. The
models agree that several weak shortwaves will traverse through the
northwest flow aloft into early next weak. As now now there is no
agreement as to where the associated precipitation will fall due to
tracking and timing issues of the waves. High temperatures look to
stay near 90 through the extended for most areas with the exception
of Sunday when it might be a bit warmer. Low temperatures are
forecast to be around 70 with the exception of Thursday and Friday
morning when they will be in the low to middle 60s as the area remains
under the influence of surface high pressure.

&&

Aviation...(for the 12z tafs through 12z Wednesday morning)
issued at 634 am CDT Tuesday Jul 28 2015

Expect VFR conditions at the terminals through most of the next 24
hours. South-southwest winds will pick up after 15z to 12-15 kts
with some gusts up to 22 kts through the afternoon. A cold front
will bring a chance for thunderstorms across the terminals
tonight. Mhk may see the best chance this evening form storms.

&&

Top watches/warnings/advisories...
heat advisory from 1 PM this afternoon to 8 PM CDT this evening
for ksz011-012-022>024-026-035>040-054>056-058-059.

&&

$$

Short term...gargan
long term...Sanders
aviation...gargan

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