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Area forecast discussion 
National Weather Service Topeka Kansas
558 PM CDT Wed Aug 20 2014

..aviation update...

Short term...(this evening through thursday)
issued at 333 PM CDT Wednesday Aug 20 2014

A broad upper level ridge axis will continue to amplify across the
lower and mid MS River Valley over the next 24 hours.

A minor upper level trough was located across northeast OK and
southeast Kansas this afternoon, on the western edge of the 500 mb ridge
axis, and will move northeast across southeast Kansas into western MO
this afternoon through early this evening. A shower did pop up
across southern Coffey County but did dissipate. This minor 500 mb
trough may provide just enough lift for an isolated shower or
thunderstorms along and southeast of I-35 through the late afternoon
and early evening hours. I will keep probability of precipitation at 14 percent due to the
very isolated coverage.

During the evening hours scattered thunderstorms will develop across
western Kansas and eastern Colorado. Most of the thunderstorms will lift
northeast into NE but the trailing edge of any thunderstorm complex
may move across portions of north central and northeast Kansas late
tonight and through the mid morning hours of Thursday. At this time
any thunderstorm complex that develops across western Kansas tonight
should be decaying through the early morning hours of Thursday, thus
the thunderstorms will not be severe as they move northeast into a
less favorable environment across northeast Kansas.

Thursday will be mostly sunny as the 500 mb ridge axis amplifies across
the southern and mid MS River Valley. Thunderstorms should remain
well west and north of the County Warning Area during the daylight hours. Highs will
warm into the mid to upper 90s once again. A few locations across
the southwestern counties of the County Warning Area may reach the 100 degree mark.
Heat indices will warm into the 100 to 104 degree range during the
afternoon hours. Some isolated areas across east central Kansas may see
heat indices reach around 105 degrees.

Long term...(thursday night through wednesday)
issued at 333 PM CDT Wednesday Aug 20 2014

The mid-level flow will remain fairly unchanged through the end of
the week into the weekend with a broad ridge remaining in place
across much of the central and eastern U.S. And a trough positioned
over the western U.S. Thursday night through Saturday the models are
in good agreement with the mid-level trough currently over the
Pacific northwest digging southward along the western rockies with
the ridge amplifying further northward toward the Great Lakes
region. This pattern will keep southwesterly flow aloft across the
region, which will continue to support warm air advection through
the end of the week and into the weekend with 850mb temperatures
reaching into the 23c-26c degree range. Hot and humid conditions are
expected during that period as temperatures become unseasonably warm
with highs reaching into the middle to upper 90s Friday and
Saturday. These high temperatures combined with dewpoints reaching
into the mid 60s to low 70s will result in afternoon heat indices
soaring into the 100f to 104f degree range Friday and near 100f
degrees on Saturday. We will continue to monitor these conditions
closely to see if a heat advisory is needed for Friday. During this
period, surface low pressure will become anchored across much of
the northern and Central Plains with a fairly stationary front
situated near north central Kansas. There doesn't appear to be much
in the way of forcing along this boundary, however there may be
scattered chances for precipitation from late week through the early
weekend, especially across north central and northern Kansas. At
this time, the better chances for precipitation look to be during
the evening and overnight hours as the low-level jet increases over
the region.

Saturday night and Sunday, models show a strong embedded shortwave
trough lifting northeastward across the northern rockies and into
the northern plains. This advancing shortwave should be enough to
slowly push the stationary front eastward through the region Sunday
night and Monday, so have more widespread chance pops during that
period. This cold front may lift back northward across the area as a
warm front, however there is model uncertainty with regards to how
far north this warm front will lift, so confidence is low with
precipitation chances Monday night through Wednesday. At this time
have slight to low-end chance pops through that period.

The frontal passage Sunday night into Monday will cause winds to
shift to the north, providing a bit of relief to the heat with highs
dropping into the middle 80s to low 90s Monday. Temperatures are
more uncertain for Tuesday and Wednesday depending upon where the
warm front is located and whether or not the region is situated
within the warm sector, so have highs remaining in the upper 80s to
low 90s at this time.

&&

Aviation...(for the 00z tafs through 00z Thursday evening)
issued at 558 PM CDT Wednesday Aug 20 2014

Organized convection appears to be a pretty low probability this
evening with models showing the nose of the low level jet mainly
north and east of the terminals. However will keep an eye on the
convection off the higher terrain to the west and see if it is able
to hold together once the boundary layer begins to cool. As for
wind shear, think chances are to small to keep the mention of low level wind shear
at top. Rap and NAM soundings are not as strong with the nocturnal
inversion as the indicated last night and models prog a decent
pressure gradient persisting through the night helping to keep the
boundary layer from completely decoupling.

&&

Top watches/warnings/advisories...none.

&&

$$

Short term...gargan
long term...hennecke
aviation...wolters

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