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

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FXUS63 KEAX 202347

National Weather Service Kansas City/Pleasant Hill MO
547 PM CST Sat Jan 20 2018

Issued at 304 PM CST SAT JAN 20 2018

SW flow and WAA dominate the region this afternoon as a low pressure
over eastern Colorado continues to deepen as a result of an
approaching shortwave trough over the SW US.  Surface temperatures
warmed rather quickly this morning mixing into the WAA aloft much
more aggressively than most of the model guidance suggested.  This
lifted and thinned the lower cloud deck shutting off most of the
drizzle chances that were expected this afternoon. Another impact to
these warmer temperatures and the developing warm frontal boundary
over our southern CWA is to start scattering out some clouds
resulting in temps into the 60s just south of our CWA.  As the upper
level shortwave ejects into the plains there will be rapid
cyclogenesis over eastern KS helping to intensify frontogenesis
along the warm front over our CWA.  This added lift is expected to
thicken the cloud deck overnight and allow some drizzle form up over
the region, mainly north of the Missouri River initially before it
back builds further south by morning. Temperatures will remain above
freezing Sunday morning keeping all precipitation liquid over
northern Missouri. The main forcing for actual rain showers and
possible isolated thunderstorms will come along the developing cold
front as the surface low tracks to the NE through central KS. This
frontal boundary will be mainly elevated with a weak temperature
gradient on the surface but strong CAA aloft associated with a
closed low aloft. This cold air will lift and erode the strong
subsidence inversion in place and allow some elevated showers and
thunderstorms to form along and ahead of the cold front, mainly east
of the KS/MO border Sunday evening. Models are indicated MUCAPE
values between 100-400 J/kg with effective shear in the 20-30kt
range, indicating the potential for severe weather will be low. The
front will progress quickly moving from the KS/MO border from sunset
on Sunday to east of our CWA by midnight.  The rapid movement of
this front will keep any significant accumulations from occurring
with less than 0.25" expected over the region. A significant dry
slow will develop behind the cold front clearing most of the area
out of any precip chances overnight Monday with some drizzle and
rain starting to push back into NW Missouri Monday afternoon as the
backside of the occluded boundary pushes through. Temperatures are
expected to stay above freezing through the afternoon and into the
evening as this occlusion passes through Monday. Temps will
eventually cool down below freezing overnight Monday as colder air
dips into the region with strong NW flow of 20-25mph gusting into
the mid 30s.  This will cause the tail end of the front to
transition from rain to snow with some patches of freezing
rain/drizzle expected as the drier air aloft inhibits ice crystal
growth.  A trace of snow accumulation is possible along the IA/MO
border as this feature finally pushes to the east.

Little to no colder air will build in on the backside of this system
as ridging and increasing upper level heights quickly move into the
region by the middle of the week.  Tuesday looks to be the coolest
of the days with temperatures still above average in the lower to
mid 40s with a progressive warm up each day as the warmer air mass
and SW winds build into the region.  By the end of the week
temperatures will feel more like early March than the end of January
with high temps in the mid to upper 50s possible.  The next chance
for precipitation will be Saturday as a shortwave trough exits into
the central plains developing a low pressure system over Minnesota
and trailing cold front down through our area. Models are in fair
agreement for this far out into the forecast period with all precip
expected to stay in the form of liquid and little to no instability
available for severe weather.


.Aviation...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 546 PM CST SAT JAN 20 2018

The low cloud deck continues to move north, leaving the southern
half of the forecast area with mostly clear skies, while the
northern half remains under MVFR ceilings. The cloud deck should
move north of MCI shortly after the top of the hour. It could
reach STJ before the clouds fill back in overnight but it doesn`t
look likely at this point. Around midnight, ceilings should start
to drop to IFR across much of the area. Drizzle is possible with
these clouds, but most high res models are now keeping the
greatest chance for drizzle along and north of HWY 36. However, it
won`t take much to squeeze some moisture out of this cloud deck
so have kept the mention for areas south of HWY 36. With the
chance of drizzle, creates a good chance of lower visibilities;
therefore, have drop visibilities to MVFR during this time.
Ceilings (and visibility) should lift to MVFR around noon tomorrow
for the remainder of the TAF period.




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