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000
FXUS63 KEAX 132322
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
622 PM CDT Thu Jun 13 2013

.UPDATE...
Issued at 622 PM CDT THU JUN 13 2013

The decaying thunderstorms that moved into northwest Missouri
continue to decay. Lightning activity has come to and end, so updated
the forecast to adjust POPs for current locations still receiving
rain, and to convert the character of the storms from thunderstorms
to rain showers. Still expect there could be an area of showers and
thunderstorms effecting northwest Missouri again around and after
sunrise Friday morning, generally in the same area todays storms are
occurring, as the early morning low level jet focus some lift across
southeast Nebraska and northwest Missouri.

&&

.SHORT TERM...(This Evening through Friday Night)
Issued at 348 PM CDT THU JUN 13 2013

A fairly pleasant day across the area as temperatures have risen
into the lower 80s with lower humidity values than Wednesday.  A
cluster of showers and thunderstorms across eastern Nebraska and
northern Kansas continue to steadily move eastward towards northwest
Missouri.  This activity seems to be rooted on a weak 700mb
shortwave and associated isentropic lift on the 315-320K surfaces.
This activity is expected to dissipate as it enters northern
Missouri this evening thanks to slightly drier low-level moisture
values and waning isentropic lift. However, have increased PoPs
substantially based on recent HRRR/RAP guidance.

Tonight-Friday night: A secondary shortwave lifting northeast out of
Colorado will lead to redevelopment of scattered showers and
thunderstorms over the northwestern third of the CWA. However again
the strongest isentropic lift seems to be focused just north of the
CWA and this activity is not expected to persist though the day.

A series of shortwaves moving through the Rockies will promote the
development of a frontal boundary across eastern Nebraska and
northwestern Kansas by Friday afternoon. Convection may redevelop
along this boundary late in the afternoon as a rich and unstable
environment grows over the low and middle Missouri River valley
region.  The cap may weaken sufficiently along this boundary to
support scattered thunderstorm development in eastern
Nebraska/northern Kansas by late afternoon. This activity will
likely remain relatively disorganized given the poor shear, but
wouldn`t be surprised to see several organized clusters pushed
southward into northern Missouri later in the evening as cold pools
develop. This activity will be pushing into a fairly strong cap as
it moves into Kansas and Missouri, which should lead to waning
severe weather chances south of Hwy 36.

Once initial convection dissipates Friday evening, redevelopment
will likely remain north of the CWA on the nose of the intensifying
LLJ.

.LONG TERM...(Saturday through Thursday)
Issued at 348 PM CDT THU JUN 13 2013

Medium range models continue the same theme of the past 2 days for
the weekend through Tuesday. The weekend and Monday morning will be
marked by a rather active and unsettled pattern with a couple of
shortwaves likely spawning at least a couple rounds of thunderstorms
including the potential for isolated severe weather as well as heavy
rainfall.

Saturday through Sunday night: A moderately strong upper trough
passing through southern Canada and a shortwave lifting northeast
from West Texas through Kansas on Saturday will effectively flatten
the upper ridge migrating east through the region. This will allow
multi-layered subtropical moisture to spill northeast and into the
CWA and result in very warm and humid conditions. Favor the slower
NAM/ECMWF solutions, by about 6 hours, on timing the Southern Plains
shortwave. The 12z GFS has actually slowed down this feature which
supports the slower solution. In addition, a weak quasi-stationary
boundary will likely lie across southern IA on Saturday which would
help focus stronger convection later in the day. This places the bulk
of the CWA within the warm sector and supports near 90F temperatures
and a moderately unstable airmass. Current thinking is Saturday
morning will be rain-free with only low chance PoPs over far
northern MO. Better bet for scattered convection will be in the
afternoon and especially in the overnight hours as the Southern
Plains shortwave interacts with the deep subtropical moisture.
Isolated pulse-type severe storms possible late Saturday
afternoon/evening. Also favor likely PoPs for Saturday night with
potential for locally heavy rainfall as precipitable water values
reach the 1.75 to 2 inch range which approaches the 99th percentile.

Sunday will be a challenge as convection will likely be ongoing in
at least some portion of the CWA in the morning, which makes it more
difficult to determine if/when additional convection could reform
due to the lack of confidence in placing any outflow boundaries. It
is quite possible the afternoon hours could be relatively rain-free
but with considerable cloud cover affecting temperatures. Confidence
increases for another round of thunderstorms with heavy rain Sunday
night as the GFS/ECMWF/GEM models all depict a vorticity lobe/MCS
emanating from CO translating eastward and passing through the CWA.
So once again likely PoPs are warranted.

Monday: Looks like a transition day as residual convection is
possible over the southeast 1/2 of the CWA Monday morning with skies
clearing out by afternoon. A sharp shortwave will dive southeast
through the Great Lakes and the associated cold front will plunge
southward during the day allowing much drier and cooler air to spill
in.

Tuesday-Wednesday: Dry northwest flow and seasonable temperatures
will mark Tuesday into Wednesday. An upper level ridge will once
again build eastward into the Plains by Wednesday.

Thursday: Warm air advection and a hint of elevated convection as
the upper ridge passes east will bring warmer and slightly more
humid air into the CWA.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1136 AM CDT THU JUN 13 2013

Increasing isentropic lift across central Kansas and Nebraska is
beginning to translate into showers and even a few thunderstorms.
More importantly, we`ll begin to see a marked increase in cloud cover
through the afternoon with an outside chance of a shower later in the
day in STJ. By tonight, additional shower and thunderstorm activity
will be possible especially after midnight and through mid-morning as
another shortwave moves into the Plains and the LLJ intensifies. At
this point, feel that the higher chances for thunderstorm activity
(given the orientation of the jet) will be to the north of KC, but
St. Joseph and much of northern Missouri could be impacted. Will keep
a CB mention in the KC terminals and include a PROB30 in STJ.


&&

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

$$

UPDATE...Cutter
SHORT TERM...Dux
LONG TERM...MJ
AVIATION...Dux