Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO

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FXUS63 KEAX 291728

1228 PM CDT Fri Aug 29 2014

Issued at 1012 AM CDT FRI AUG 29 2014

Quick update this morning to account for latest radar and satellite
trends. Fairly potent upper-level wave inbound this morning as
seen on latest water vapor imagery. Ahead of this feature...upper-
level pressure along the 1.5 PVU surface showing a nice "treble clef"
signature with latest RUC analysis showing the trop undulation down
to almost 500-mb...not bad for this time of year! Pressure advection
in advance of this feature combined with decent upper divergence
aloft should continue to support organized shwrs and thunderstorms.
As this feature continues sliding east this morning...expect a
gradual increase in precip chances from west to east which should
result in very beneficial rainfall for a good portion of the area. In
general...QPF totals will likely range from a quarter to half
inch...with localized higher amounts possible with thunderstorm
activity. Pop/wx grids updated to reflect a slightly delayed arrival
time...but overall fcst trends remain unchanged.


.SHORT TERM...(Today through Sunday)
Issued at 326 AM CDT FRI AUG 29 2014

For today, areas of scattered thunderstorms will continue to develop
along and ahead of an eastward-moving shortwave trough, resulting in
slowly increasing chances of precipitation this morning into the
evening across the CWA. The best chance of storms will spread from
early afternoon across eastern KS and far western MO to late evening
in central MO. Afternoon temperatures will be held down by clouds
and precipitation, keeping highs mainly in the 80s and the highest
readings in central MO where storms will be later to arrive. Not
much instability is expected to develop today with clouds arriving
early and temperatures aloft and no real significant temperature
perturbation along the trough to increase lapse rates, so do not
expect much of a strong/severe storm threat this afternoon or this
evening. However, if areas of central MO see a few peeks of sun
through early afternoon, an isolated more robust storm could develop
and could produce briefly gusty winds.

Precipitation will generally clear out from northwest to southeast
on Friday night, but may linger into Saturday across portions of
central MO as a second weak shortwave trough rides up over central
MO, especially if the weak surface boundary associated with today`s
shortwave trough can stall over the region and support convective
initiation on Saturday. High temperatures should be several degrees
warmer for Saturday and especially Sunday as skies clear, southerly
surface flow returns, and 850 hPa temperatures remain in the 18 to
21 C range.

The next round of thunderstorms is expected to be a bit more robust
Sunday night into early Monday morning along a southeastward moving
cold front. General model consensus brings the front through the CWA
between midnight and 9 AM Monday morning, although timing could
change a bit. MUCAPE values in the 1000-2000 J/kg range and bulk
shear values as high as 40 kts could support organized, potentially
strong multicell storms especially across northwest MO. Heavy rain
is also a threat with PWATs climbing to around 2 inches and bulk
shear vectors orienting parallel to the front to support training
storms. The overall severe threat will depend on timing of frontal
passage as storms should become elevated with time and instability
will decrease, but is expected mainly across northwest and northern
MO where upper-level forcing and flow is a bit stronger.

.LONG TERM...(Monday through Thursday)
Issued at 326 AM CDT FRI AUG 29 2014

A complex of showers and thunderstorms will likely be ongoing over
portions of the forecast area Monday morning as a cold front settles
into northwest Missouri. While not an optimal diurnal time for
severe weather with only modest instability forecast, will need to
monitor potential as dynamics from the large upper trough over the
northern tier of the country will yield moderate shear in advance of
the cold front. The upper trough will gradually deamplify, leaving
the surface cold front largely stationary Monday into Tuesday across
the northern half of the CWA. Periodic thunderstorm chances will
remain possible through Tuesday night as the region remains on the
southern periphery of strong upper dynamics and associated embedded
shortwave troughs traversing the area. A few storms may be strong
with moderate shear and instability, especially during the afternoon
and evening hours. With the boundary layer winds expected to remain
weak, the primary threat would be brief periods of damaging wind
gusts and hail to quarter-size. Pinpointing the timing and
specific locations of highest precipitation potential remains
challenging at this stage with convective details that will play
some role in frontal position and windows of strongest ascent both

The surface boundary is expected to retreat northward as a warm
front by Wednesday as heights begin to rise across the region. Only
a slight chance of thunderstorms is anticipated on Wednesday, with
dry conditions for the remainder of the work week. Likewise,
temperatures will return to above normal readings, with afternoon
highs in the upper 80s to lower 90s.


.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
Issued at 1227 PM CDT FRI AUG 29 2014

Complicated fcst this afternoon as large scale upper trough and
associated cold front will move through the area this
afternoon/evening. That said...latest radar trends showing a decent
swath of rain inbound to MCI with upstream obs over eastern KS
supporting a tempo IFR mention out of the gate. As this activity
clears to the north by 20z or so...attention then shifts to areas
upstream which are now destabilizing thanks to mostly clear skies. As
result...expect renewed shwr/storm activity later this afternoon with
a second tempo group added at all sites to account for this
possibility. Skies to slowly clear from west to east overnight which
should give rise to developing VSBY and low CIG restrictions. For
now...IFR restrictions offered at STJ with MVFR elsewhere.




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