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

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000
FXUS63 KEAX 052355
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
655 PM CDT Tue May 5 2015

.DISCUSSION...
Issued at 409 PM CDT TUE MAY 5 2015

Active pattern will continue through the rest of the week, and into
the weekend. Perhaps the quietest of the next several days will be
this afternoon. Warm and muggy conditions persist across the area
today, with temperatures in the middle 70s to lower 80s, with
dewpoints in the upper 50s to lower 60s. RAP soundings indicate that
the atmosphere is uncapped, which has allowed for the CU field to
form across the area. However the lack of any appreciable forcing
has prevented much in the way of thunderstorm development. That
being said, with the uncapped environment there is enough weak
forcing to get a few storms to form across central Missouri. These
storms will generally be pretty scattered in nature across the area,
but coverage will not be very great. Any shower will likely be
rather brief in nature. No strong or severe weather is anticipated
with any of these storms outside of a wind gust or two near the
storm. These diurnally driven showers will likely fall apart and
diminish around sunset.

Over the next several days several shortwave troughs will be rolling
through the area, bringing several chances of rain. The first
appreciable chance for rain will be during the morning to early
afternoon hours on Wednesday as a vorticity lobe will swing through
the area, bringing some scattered convection. While there will be
some instability in the area, on the order of 500 to 1000 J/kg the
amount of instability will be somewhat meager. Deep layer shear will
also be on the low side, with 20 to 30 kts of 0-6 km shear. So given
those particular CAPE/shear parameters it doesn`t look like severe
weather will be the main story for Wednesday, but some of those
morning and afternoon storms could be strong, to perhaps isolated
severe. With the instability axis generally lined up to the west,
the farther east any storms form will have a lessor chance to be
severe.

For Thursday another area of low pressure will eject through the
area, and perhaps be accompanied by convection rolling eastward off
the High Plains. This should kick off another round of convection
across the area. Thursday will likely bring quite a bit more
instability with ML CAPE values approaching 1000 to 2000 J/kg, but
shear will still be on the low end, with 0-6 km layer shear in the
20 to 30 kt range. Even though the CAPE/shear values are not
incredibly high they will be ample to possibly produced some
organized rotating cells, and perhaps an isolated supercell or two
across the area. Once again, the main threats will be hail and wind
for

Friday brings a slightly different story, as a surface boundary will
sag southward, and basically bisect the forecast area E-W. Friday
looks to be a little more capped than the previous couple of days,
and that convective inhibition is a bit more influenced by some
moderate height rises across the Plains for that time period. With
good turning in the atmosphere, characterized by veering-with-height
wind profile deep shear will be a bit higher, and instability will
be in the 1000 to 2000 J/kg range any storm that is able to go up on
Friday has a chance to be severe. If a storm does latch itself to
the boundary, which will be somewhere near I-70 it could get a
little extra low level turning, which would make any storm in that
area even stronger. Synoptically speaking Friday doesn`t seem to
bring much in the way of severe weather potential, but the mesoscale
forecast closer to the event might reveal some potential for some
isolated to scattered severe storms.

By Saturday, the chances for severe weather start to synoptically
increase. A very large trough, off to the west, will eventually take
on a negative tilt and move through the Central Plains this weekend.
Saturday still looks to be a little too far west to bring much in
the way of widespread severe weather to the area. But during the
overnight hours on Saturday night into Sunday morning the convection
that occurs over the western and central plains will likely roll
through the area. Convection during this overnight period would
likely not be as organized, but it could roll through as an
organized MCS, bringing a low end hail threat, but a larger wind
threat Saturday night into Sunday morning.

While this time period is still quite a way out, and much will
depend on how things pan out closer to the event, Sunday is looking
to be the day to watch as far as widespread severe weather across
eastern Kansas and western Missouri is concerned. Recent runs of the
GFS and ECMWF indicate a very potent mid level trough moving through
the area Saturday night and Sunday. At the surface there will likely
be a dry line somewhere between KDDC and KEMP. Where exactly the dry
line sets up will dictate whether heightened concern for significant
severe weather is warranted on Sunday. Should the dry line set up
farther west, as is indicated by the GFS, then the area might be
spared the brunt of the severe weather.  But if it sets up near KEMP
or even a little farther east, then this area could see a rather
significant severe weather day on Sunday. But again, despite the
synoptic signal, and with the timing so far out, and with mesoscale
features playing a big roll in how convection plays out it`s much
too early to get super concerned about severe weather this weekend.

Also, despite the uncertainty regarding the timing, location, and
severity of the thunderstorm activity through the rest of the week
and into the weekend, there is also a very strong signal to support a
prolonged period of multiple rounds of heavy rain. Some areas could
see higher amounts, and some locations could see lower amounts, but
generally speaking there appears to be a good signal for several
inches of rain (perhaps up to 5 inches in some areas) through the
next 5 to 7 days.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 655 PM CDT TUE MAY 5 2015

Isolated shwrs and storms moving north through eastern KS at 00z should
largely remain west of most terminals. The only exception will be IXD
where periodic VIS/CIG restrictions will be possible for the next
hour or two. Otherwise...concerns overnight will transition to LLWS
as the low-level jet strengthens aloft. Big question remains whether
the boundary layer will have the opportunity to decouple overnight.
For now...have included a LLWS mention at STJ who likely stands as the
best candidate to see decoupled conditions during the early morning
hrs. Will have to evaluate other locations for the 6z TAF package.
Otherwise...shwrs/storms expected to increase in areal coverage after
12z tomorrow as main upper-level disturbance begins moving through
the area. Periodic restrictions will be possible under the heaviest
activity.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&

$$

DISCUSSION...Leighton
AVIATION...32







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