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

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FXUS63 KEAX 280458

National Weather Service Kansas City/Pleasant Hill MO
1158 PM CDT Tue Jun 27 2017

Issued at 323 PM CDT TUE JUN 27 2017

High pressure over the Ohio Valley has kept the area fairly nice
with partly cloudy skies, temps in the low 80s, and a light breeze
from the SE over the region.  This benign weather will end tonight
as a lee side trough develops over eastern Colorado in response to
an incoming shortwave.  This low pressure will help to develop a very
strong LLJ overnight through the central plains of 50+kts shortly
after sunset. This strong push of warm air will lead to the
development of elevated thunderstorms over central Nebraska which
currently appears to develop into an MCS overnight. This MCS is
expected to track to the E-SE and push into the region after 3:00CDT
as a line of elevated thunderstorms with strong winds possible along
the gustfront as it enters. Lack of instability will be a limiting
factor as this feature pushes into the area decreasing the threat of
severe weather. The extent of precipitation and remnant clouds from
this morning MCS will be a crucial piece of the puzzle come
Wednesday afternoon convection.  Currently guidance has this feature
dissipate by late morning with strong southerly flow of 20-30kts
allowing warmer temperatures to mix down and also advect in higher
dewpoints.  The main axis of higher dewpoints will lie near NW
Missouri just to the west of a weak surface boundary extending down
from Iowa. There is some uncertainty as to the placement of the
initial afternoon convection with GFS and ECMWF firing up over NW
Missouri and then along the boundary with NAM delaying convection
until right along the boundary. This uncertainty has lead to lower
PoPs overall but more coverage to account for this variability. The
environment where storms do form will be primed for potential severe
weather with SBCAPE values 2000-2500J/kg and 0-6km bulk shear of 35-
40kts.  Large hail and damaging winds will be the main threats but
the possibility of a tornado is not zero along the boundary. With a
decent LLJ over the region tomorrow these storms may become elevated
and last into the night longer than they typically would after
sunset and may even propagate further south early Thursday morning.

The active pattern does not let up Thursday as a deepening low over
SW Oklahoma will help to re-intensify the boundary over northern
Missouri and lift it north with more warm frontal characteristics
Thursday afternoon. Where this boundary finally sets up will be the
focal point for the second round of potential severe weather.
Currently most of the guidance has the boundary setting up 30-60
miles south of the MO/IA border. A strong LLJ with 40+kts will help
fuel strong lifting along and north of the warm front in an
environment very conducive to severe weather possibilities.  SBCAPE
values will be 3000+J/kg, 0-6km bulk shear of 35-40kts, 0-1km shear
of 25kts, and 0-1km SRH 200+ leave all modes of severe possible with
large hail and damaging winds having a higher chance but isolated
tornadoes can not be ruled out along that warm frontal boundary.
another threat with this system will be flooding as multiple rounds
of precipitation will help to saturate northern Missouri with
training storms possible Thursday evening with storm motion parallel
to the warm frontal boundary. As the low over Kansas tracks to the
NE frontogenesis will occur on the backside along the cold front
toward sunset providing another forcing mechanism to develop a more
linear mode of convection over southern NE and eastern KS.  This
line of convection is expected to push through our region overnight
with plenty of instability and 0-3km shear to produce potential
damaging winds as it moves through early Friday morning.

Weak high pressure will build into the region behind this cold
frontal boundary allowing the active pattern to somewhat settle down
for a few days.  All precipitation appears to stay mostly south of
our area Saturday with this weak boundary coming back up into our
region as a warm front Sunday night into Monday. This boundary
stalls in our southern CWA creating the chance for a fairly rainy
Monday, especially early in the day.  This boundary will also
increase the chances of PoPs on the 4th of July early in the day
depending on where it finally settles down.


.Aviation...(For the 06Z TAFS through 06Z Wednesday Night)
Issued at 1158 PM CDT TUE JUN 27 2017

Line of storms over Nebraska will encounter a drier and more
stable airmass over northern KS and northwest MO and is unlikely
to make it much further south than its current southern extent.
This stable airmass should keep most of Wednesday dry until
another potential round of storms late Wednesday evening,
although it`s uncertain if this round can make it much further
south than far northern Missouri.




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