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

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FXUS63 KEAX 140855

National Weather Service Kansas City/Pleasant Hill MO
355 AM CDT Mon Aug 14 2017

Issued at 353 AM CDT MON AUG 14 2017

A shortwave and associated low level isentropic lift along the
leading edge of a LLJ have helped develop a line of elevated
convection across IA and NE currently.  This wave is expected to
move east while storm motion will be more SE creating the chance for
some storms to make it to the MO/IA border near sunrise lasting
possibly through the early afternoon.  Low level WAA into the area
will bring temperatures up towards normal for this time of year in
the mid to upper 80s with heat index values back into the 90s. Warm
temperatures over central KS will help to provide the set up for a
strong LLJ over KS Monday night into Tuesday kicking off another
round of nocturnal convection.  The WAA will develop a warm frontal
boundary over central NE and IA which provide the forcing mechanism
for storms to initiate after sunset.  As the LLJ tilts to the east
these storms will start to advect SE into NW MO early Tuesday
morning providing chances of precipitation down the KS/MO border.
There is a slight chance of storms reforming Tuesday afternoon, but
most of the forcing will be up near the warm frontal boundary along
the IA/MO border and down towards the southern CWA on the convergent
axis of the LLJ.

A relatively broad shortwave will enter into the Rockies Tuesday
night helping add lift for nocturnal development over the central
plains and developing a LLJ that extends from TX up into MN.  The
majority of the forcing and convection will be over central NE but
enough isentropic lift does occur over our CWA to kick off some
elevated storms as we approach midnight.  With the main focus of WAA
being to the NW of our area the likelihood of severe weather looks
to be lower than it has with the previous guidance.  MUCAPE values
will still be near between 1500-2000J/kg so some strong storms can
not be ruled out.  As the upper level shortwave ejects from the
Rockies a surface low over the northern plains develops helping to
form a cold frontal boundary that extends down into KS with the warm
sector over our CWA Wednesday afternoon. this push of warmer moist
air will allow heat index values to reach into the middle 90s. A
capping inversion appears present for the early part of Wednesday
but will as significant lift moves into the region it helps to
stretch the column and erode this feature by the afternoon.  The
main area of initial development looks to be north of the MO River
that will then progress to the SE with the frontal boundary.  This
feature will provide a nice swath of precipitation leading to
widespread 1-2" with higher totals locally possible.

High pressure will build into the area Thursday which should keep
the area dry through most of the day Friday.  The NW surface flow
will also decrease the dewpoints and drop heat index values back
down into the 80s.  A weak shortwave ejects out of the southern
Rockies Friday helping to produce a round of storms along an area of
WAA near the OK/KS border that may help produce some storms over our
southern CWA Friday afternoon into the evening. A shortwave will
move into the northern plains Friday and quickly push through the
region Saturday morning.  This may help develop some showers over NE
MO and keep showers and storms over out southern CWA Saturday

Upper level ridging will start to build into the plains Sunday
allowing a southerly return flow of warmer temperatures at the
surface.  This increase in temperatures will be crucial to the
Eclipse forecast as it will provide a significant enough temperature
gradient to develop a LLJ Sunday night over central KS.  This LLJ
will be the focus of nocturnal convection over eastern KS and could
provide cloud coverage over Missouri early on Monday.  More details
on this specific forecast can be found in the Solar Eclipse section
of this AFD.


.Specifics for the Total Solar Eclipse on August 21st...
Issued at 353 AM CDT MON AUG 14 2017

GFS, Canadian, and ECMWF all indicate upper level ridging building
into the central plains Sunday into Monday. The GFS and Canadian
have the closest solutions with a shortwave over west-central
Canada helping to enforce this ridge in place. Both of these
models also indicate southerly flow and warmer temperatures over
KS Sunday afternoon which develops a LLJ and nocturnal convection
Sunday night into Monday morning. Both models have this feature
weaken quickly after sunrise, but the main question will be
whether or not the cloud coverage will dissipate in time for the
eclipse to occur. The signal for afternoon convection seems to be
north of our area along a convergent boundary ahead of that
approaching upper level shortwave. Both these models are starting
to come in line with the ECMWF providing some added confidence
that if the morning cloud coverage can dissipate and the upper
level cirrus advect to the SE there will be clear enough skies to
view the eclipse over our area.


.Aviation...(For the 06Z TAFS through 06Z Monday Night)
Issued at 1238 AM CDT MON AUG 14 2017

IFR and LIFR ceilings have developed over southern Missouri and
are expected to slowly move northward with southerly winds in
place over Missouri. These ceilings will move into the region just
before sunrise with lower visibilities possible as well with how
low the ceilings will be. There could be a period where ceilings
drop down to near 300ft right near sunrise itself. This cloud deck
will be very shallow, only a few hundred feet thick, so it will
not take much heating to help burn them off. There will be a quick
rise from LIFR to VFR between sunrise and around 10-11AM with VFR
conditions expected once the clouds and fog dissipate.




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