Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion...updated 
National Weather Service Topeka Kansas
1218 PM CDT Wednesday Jul 29 2015

..update to aviation forecast discussion...

Short term...(today and tonight)
issued at 303 am CDT Wednesday Jul 29 2015

Today through tonight...an amplified upper level trough was moving
east across Minnesota early this morning. The southern extension of the
upper trough axis extended south-southwest into northeast Kansas.
Isentropic lift north of the front was causing elevated showers and
thunderstorms to develop and move northeast across the central and
northeast counties of the County Warning Area. As the front shifts south the
elevated convection may try to develop farther southeast across east
central Kansas. Though, I think the coverage will decrease as the
southern periphery of the Midwest 500 mb trough begins to shift east
into northern MO. I'll keep low chance and slight chances for
showers and thunderstorms across east central Kansas from 12z through
about 18z...and will linger the slight chance in the extreme
southeast counties through the the afternoon hours.

The skies will gradually become mostly sunny across north central Kansas
with partly to mostly cloudy skies across the remainder of the County Warning Area
today. Northeast surface winds will advect a slightly cooler and
drier airmass southwestward across the County Warning Area. Highs today will only
reach the lower to middle 80s across much of the County Warning Area.

Tonight...the surface front will become nearly stationary across the
OK/Kansas border and may begin to lift northward across southwest Kansas
through the night. Easterly 850mb winds across southern and central
Kansas will begin to veer more to the southeast. The NAM and GFS models
show enough isentropic lift at the 300 k Theta surface for scattered
showers and perhaps an isolated thunderstorms developing late
tonight across the southern and western counties of the County Warning Area. The WRF
solutions show the isentropic lift remaining south and west of the
County Warning Area which would keep the showers and thunderstorms chances late
tonight across southern and central Kansas. I leaned more with the arw
version of the WRF and placed slight chance for showers and
thunderstorms across the southwest and extreme southern counties of
the County Warning Area after 9z Thursday.

Long term...(thursday through tuesday)
issued at 303 am CDT Wednesday Jul 29 2015

Thursday morning showers and thunderstorms will likely be ongoing
across central and southeast Kansas in response to a weak shortwave
moving along the northern periphery of the upper high. Both the NAM
and GFS show isentropic lift will provide ascent through the late
morning hours. At the surface high pressure will settle across the
area bringing in cooler and drier air. Therefore some precipitation may
have trouble reaching the ground especially further north in east
central and northeast Kansas. That area of precipitation and the surface high
pressure will gradually progress southeastward through out the day.
High temperatures on Thursday will only reach the middle to upper 80s
with dew points in the 60s. Most of the daytime hours on Friday will
be dry but a weak shortwave within the northwest flow aloft is
forecast to push another front into the area. Models are showing
possible storm development along this front in NE before moving
towards northern KS, although these chances are relatively low at
this point. Large scale forcing appears fairly weak and the front is
not well defined so low level convergence may also be an issue. A
slightly stronger wave may track across the Midwest that will send a
more potent front close to the area during the Saturday night Sunday
time frame. With the upper ridge centered more over the s0uthwest US
the pattern does not look to change much through middle week. This will
keep US in northwest flow aloft and the waves will continue to bring
chances for precipitation.

&&

Aviation...(for the 18z tafs through 18z Thursday afternoon)
issued at 1216 PM CDT Wednesday Jul 29 2015

Surface high pressure building in will cause light NE surface winds today
with VFR ceilings and visible conds expected. Winds will become calm or
variable and light overnight. Visible and ceilings should remain VFR as
better forcing for precipitation should remain south of taf sites
tonight.

&&

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

$$

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

National Weather Service Glossary of Abbreviations