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Area forecast discussion 
National Weather Service Kansas City/Pleasant Hill MO
630 PM CDT Tuesday Aug 4 2015

Short term...(this evening through Thursday night)
issued at 257 PM CDT Tuesday Aug 4 2015

Shortwave tracking northeast out of southern Kansas will interact with a
stalled frontal/outflow boundary just south of the US 50 corridor
this afternoon and this evening. This interaction will likely lead to
showers and thunderstorms developing across areas near and south of
this boundary through the evening, potentially creeping back north
toward the Missouri River. Airmass across these areas has become
moderately unstable but shear is very weak, so a few short-lived
strong storms can't be ruled out but the overall severe threat this
evening is low. Slow storm motion could favor pockets of heavy rain,
particularly right along the boundary, but modest precipitable water
values and relatively shallow warm cloud depth don't point to
widespread flooding problems with tonight's activity.

A second round of thunderstorms is likely late tonight into Wednesday
with another shortwave dropping out of Nebraska. Interaction of this
feature with the aforementioned boundary and a strengthening low-
level jet could lead to an enhanced risk for heavy rain, particularly
where and if the leading edge of the low level jet becomes aligned with the
boundary. Models have really struggled to pinpoint where this
interaction may occur, bouncing from northern Missouri in earlier
model runs to now southern Kansas into the MO Ozarks. Since most model
runs have now settled on the latter solution, this is the preferred
forecast for heavy rain potential (for now) which may impact far
southern portions of the forecast area including the Butler/Clinton
areas. These locations have been relatively dry recently and can
handle more rain than areas further north, so will not put out a
Flash Flood Watch at this time. However, given the poor model
performance lately, will need to watch how things evolve overnight in
case wednesday's heavy rain potential shifts back north toward areas
that can't handle as much water.

Departure of wednesday's system to the east and modest height rises
across the plains will bring a drying trend to the area on Thursday.
Temperatures will run close to average.

Long term...(friday through tuesday)
issued at 257 PM CDT Tuesday Aug 4 2015

As we head into the weekend, the upper-level pattern places the
region in slight northwest flow. To the north across Canada, a
vigorous shortwave trough is progged to slowly translate across the
southern provinces through the weekend. This will send a few weak
surface fronts through the area and don't look to impact the
temperatures much. To the south and west, a ridge of high pressure
will build over the Southern Plains with a few ridge runners
initiating over the high terrain and riding the ridge into the area
each night/early morning through the weekend. The ridge begins to
build across the inter-mountain west by early next week.


Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 630 PM CDT Tuesday Aug 4 2015

Showers and perhaps a few embedded thunderstorms will continue to
impact all taf sites through the next 1-3 hours, then should begin to
dissipate and shift out of the area for the overnight hours. Another
round of storms is expected to develop early Wednesday morning, but
its exact position is still in question, and may stay south of the
terminals. For now, have included a thunderstorms in the vicinity group for the most likely
period of storms Wednesday morning. Winds will gradually lighten and
back to the east southeast this evening and tonight, and skies will
become VFR after storms exit this evening.


Eax watches/warnings/advisories...


Short term...hawblitzel
long term...pmm

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