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

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FXUS63 KEAX 160824

National Weather Service Kansas City/Pleasant Hill MO
324 AM CDT Tue May 16 2017

Issued at 324 AM CDT TUE MAY 16 2017

A more active pattern for the central Plains is beginning to take
shape, as a series of shortwave troughs carve out a persistent
longwave trough across the western CONUS. On-and-off storm chances
will begin late this evening, and will continue beyond the end of
the forecast period.

The complex of showers and storms off to our west early this AM
will continue to dissipate and lift northeastward as the lobe of
surface low pressure associated with their development shifts off
to the northeast. Warming cloud tops in IR imagery and radar
trends indicate that the area of precipitation near Salina will
disintegrate before reaching far northwestern portions of the CWA,
but have included a brief window of light showers or sprinkles
across very far northwest MO early this morning, and accounted for
slower morning temperature rises as cloud cover associated with
the complex translates eastward.

Robust convective initiation is anticipated across western KS this
afternoon, as the upper wave currently over the Four Corners
region pushes quickly east and pushes another center of surface
low pressure out into the Plains. The dryline, which has retreated
to the KS/CO border early this morning will begin to push eastward
again this afternoon, serving as a focus for DCI and fueling
convection that will eventually reach the forecast area tonight.
Most hi-res models show storms growing upscale across central KS
in an environment with up to 3000 J/kg MUCAPE and 30-50 kts of
deep layer shear, but also show trends of weakening/dis-
organization as the storms separate from the low-level forcing
and surface-based instability decreases diurnally after sunset
this evening. However, steep midlevel lapse rates translate
eastward as the trough ejects into the central Plains this evening,
while both 0-1 km shear and 6-10 km shear increase along/ahead of
the upper trough, providing an environment supportive of MCS
development and maintenance across eastern KS and western MO
tonight. Upper-level steering flow turns from SW to almost due
south as the upper trough becomes negatively tilted, which could
hamper MCS development and may take storms mainly north of the
CWA tonight, but the supportive environment and near-certainty of
convection to our west this evening raises concern for strong to
severe winds with any storms that reach western portions of the
forecast area tonight into early Wednesday morning.

Additional storm development is also possible across OK or south
central KS tonight near the base of the upper trough, but is a bit
more uncertain as the nose of the low-level jet surges well to the
north and isentropic lift weakens. These storms, if they develop,
would be a bit further behind the first round and thus would
encounter more unidirectional (but still strong) deep-layer shear
and generally lower elevated instability, cut off from the
coldest temperatures in the low- to midlevel trough. The strong
shear is still enough to raise an eyebrow if the storms can
develop and persist long enough to reach the forecast area early
Wednesday morning, but have a lower overall potential to become

The pacific front/diffuse dryline will continue to push eastward
on Wednesday as the increasingly stacked low occludes and wraps
northward, possibly serving as a focus for additional storm
initiation in our forecast as early as midday Wednesday. Location
of any storms that develop will depend on how quickly the boundary
pushes eastward on Wednesday and any additional outflow boundaries
from overnight convection, as well as how much instability is able
to develop with lingering convection/cloud cover in the morning.
Shear will remain strong and shear vectors will begin to orient
back to the southwest to even WSW as the negatively-tilted trough
axis swings into southern portions of the CWA, promoting very fast
storm motions to the northeast. Strong surface-based instability
seems unlikely due to the morning cloud cover and diminishing low-
level convergence as the boundary becomes more diffuse, but
elevated supercells are not out of the question if convection does
initiate over the CWA Wednesday. In that scenario, both hail and
wind would be a threat for a few hours before storms would race
out of the CWA.

The weakening surface boundary will stall across the forecast
area Wednesday night, and while convergence will be too weak along
the front to support storm development on its own, it will set the
stage for additional storms later this week. The next wave is
expected to move over the parked boundary Thursday night into
Friday morning, and another will follow in its wake by Friday
night or early Saturday. Although rain amounts are potentially
high due to the multiple rounds of convection and high PWATs, the
convective nature of rainfall means that QPF is likely overdone
in some areas. Will continue to monitor the potential for flooding
if all rounds of storms come to fruition, but many pieces will
have to fall into place before flooding becomes a consideration.

Temperatures will be highly dependent on storms/cloud cover
through the week, but in general highs should be cooler than the
last several days in the more active/wetter pattern.


.Aviation...(For the 06Z TAFS through 06Z Tuesday Night)
Issued at 1205 AM CDT TUE MAY 16 2017

Low clouds will form during the day on Tuesday but not expecting
any flight restrictions with this SCT/BKN deck around FL040. Winds
will become quite gusty, generally residing in the 20 to 30 knot
range, but could see a few gusts approaching or exceeding 35
knots. Winds will gradually come down a bit after sunset, but not
expecting a steep decrease in winds Tuesday night.




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