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000
FXUS63 KEAX 181117
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
617 AM CDT Sat May 18 2013

.SHORT TERM...(Today through Sunday)
Issued at 300 AM CDT SAT MAY 18 2013

For today, dry conditions are likely as a fairly stout elevated
mixed layer spreads over the region. This should inhibit convection
despite increasing moisture streaming into the region leading to a
moderately unstable airmass by this afternoon. High temperatures
should be able to climb into the mid to upper 80s across the area
today, but may be offset some by possible cloud cover that may
linger into the afternoon hours or if thicker diurnal cu can build.

For tonight, a strong low-level jet will develop and broad
isentropic ascent may lead to showers and storms developing during
the late evening hours and then spread north across northern
Missouri late tonight. The strongest pressure gradient on the 305K
surface, and resultant more concentrated lift looks to be across
northern Missouri by midnight or so so think the best coverage will
be across the northern half of the forecast area. This focus should
shift northward by daybreak. Given the amount of instability, which
may be around 3000J/kg, strong storms are likely and a few severe
storms can not be ruled out. Although the strongest shear will move
into the region later, most likely after the convection has lifted
north of the forecast area.

The threat of severe thunderstorms looks to dramatically increase by
Sunday afternoon and evening. The finer scale details still can not
be resolved with much confidence, but the larger scale pattern will
be very favorable for severe thunderstorm development. Widespread
convection will likely be ongoing during the overnight across
central to possibly eastern Kansas. This will likely spread cloud
cover over the area through the morning hours which lead to weaker
instability. But with such a humid air in place, breaks in the
clouds by early afternoon should result in a rapid destabilization
across the area with potential instability likely to be 2500 to 3500
J/kg by late afternoon or early evening. Strong convergence and lift
along the advancing cold front will be enough overcome any cap and
initiate convection. With 0-6km shear likely greater than 40 kts,
and strong instability in place, storms should quickly become severe
across eastern Kansas. Steep lapse rates, particularly in the hail
growth area should lead to a very large hail potential across eastern
Kansas and possibly western Missouri, if storms can remain discreet
as the move east. The orientation of the shear would favor more
persistent discreet storms in southeast Kansas where storms are more
likely to move away from the initiating boundary. Further north, the
orientation looks more parallel to the boundary which may keep the
storms closer to the boundary and suggests that the northern portions
of convection would form more quickly into a linear complex of
storms. So think that by the time the storms begin to impact our
forecast area they may be transitioning to that more linear mode.
All hazard types are possible across extreme eastern Kansas and
western Missouri as this transition occurs but damaging winds and
large hail will become the main threats as the evening progresses and
storms move east southeastward.

.LONG TERM...(Monday through Friday)
Issued at 300 AM CDT SAT MAY 18 2013

Monday into Monday night will see the potential for additional
active weather over portions of the area, but greater uncertainty
exists during this period based on Sunday night`s unknown convective
evolution and model discrepancies. Current model consensus suggests
a temporary break of widespread convection over the CWA during
portions of the day on Monday, with the surface boundary placed over
east central Kansas northeastward to north central Missouri by late
afternoon. If sufficient insolation can occur during the day, then
moderate instability would likely develop across the warm sector.
Directional shear is not particularly impressive and the winds
through the storm depth layer are expected to remain largely
parallel with the surface boundary over the CWA. This may tend to
seed downstream convection and favor an evolution to a linear mode.
Of course, this far out with the unknown convective evolution from
earlier days and the eventual position of key surface/upper air
features, much uncertainty remains. The takeaway message is that
severe weather will once again be possible on Monday afternoon and
night, especially over the southeast two-thirds of the CWA, with
large hail and damaging winds the primary severe weather concerns.

The upper low across the central CONUS will slowly move east away
from the area Tuesday into Friday with an upper ridge building into
the central CONUS by the end of the work week. The end result will
be near seasonal temperatures and slight chances for showers or
thunderstorms during the period.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday Morning)
Issued at 616 AM CDT SAT MAY 18 2013

Scattered to broken low VFR clouds were spreading northward into the
terminals. These clouds should arrive by the time the forecast
becomes valid. The bases should lift some during the day settling to
around 5k ft by late morning/early this afternoon. Cloud cover looks
to remain at this level through the remainder of the forecast
although the could vary from scattered to broken. There may be a few
storms to develop in the vicinity of the terminals within a few hours
after sunset tonight. The best chances should be across northern
Missouri so have just mentioned a VCTS group for now. Winds should be
fairly consistent from the southeast at around 10 to 15 kts from
later this morning through the remainder of the forecast.

&&

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

$$

SHORT TERM...CDB
LONG TERM...Blair
AVIATION...CDB