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

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FXUS63 KEAX 101722
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
1122 AM CST Wed Jan 10 2018

.Discussion...
Issued at 341 AM CST WED JAN 10 2018

Large-scale upper low spinning over the Desert Southwest this
morning, with plenty of low-level moisture remaining fixed
downstream over the lower Missouri Valley in a strengthening warm
air advection regime. Out of the gate this morning, all reporting
stations highlighting low stratus across the region, with
persistent southerly winds of 8-12 mph resulting in limited fog
formation across the area. Despite this, low clouds look to hang
around for a good portion of the morning and possibly through the
afternoon, which will likely damper max heating potential despite
warming 850 temps aloft. For now, have played the middle of the
road with respect to high temperature fcst as model spread is
lower than yesterday`s. For now, expect temps to top out in the
lower to middle 50s for most this afternoon, with breezy south
winds of 15-20 mph.

Fcst becomes increasingly complex late tonight as aforementioned
low starts lifting through the Southern Plains and eventually into
the upper Mississippi Vly by late Thursday afternoon. With plenty
of moisture available, along with strong dynamical forcing
resulting from a compact PV anomaly approaching from the
southwest, precip should have little problem forming after
midnight tonight; initially in the form of rain. Main concern
associated with this feature will arrive later Thursday morning as
a strong arctic cold front plows through the region, supporting a
changeover to a wintry mix, before finally changing over to all
snow. As was highlighted in previous discussions, fcst soundings
and time sections show a general lack of saturation in the main
snow growth region through the duration of the event, suggesting
the likelihood for rain changing over to freezing rain as surface
temperatures rapidly cool behind the cold front. That said
however, icing potential looks to be rather short-lived in nature
as the boundary-layer cold dome increases in depth through the
late morning and afternoon hours. As a result, the additional
possibility exists that liquid precip may refreeze into sleet as
the depth of the cold dome increases, before finally changing
over to all snow. Considering the slightly faster progression of
the system as compared to yesterday`s model runs, its hopeful the
bulk of precipitation will be east of the KC Metro by the
afternoon rush hour. That said however, lingering impacts
resulting from light ice and snow accumulations may still be felt
through the evening rush...

Further north, fcst models again show a secondary frontogenesis
band setting up across southeast Nebraska, southwest Iowa, and far
northwest Missouri. With the prospects for cold air being firmly
entrenched by sunrise, along with better ice crystal
availability, snowfall accumulations of 1 to 2 (and potentially
higher) exist over these areas. Initial thoughts this morning
suggest that a winter wx advisory will be needed over this area
for snow accumulations, with additional extension south and east
to account for light icing and minor snow accumulations across
remaining portions of the fcst area. Considering we`re still 24+
hours out from expected impacts, will allow the dayshift the
opportunity to issue any needed headlines after 12z model guidance
is inspected. Overall, this system will likely bring minor issues
to the area with larger impacts being reserved for areas well off
to our north and east.

Beyond this, attention quickly changes over to the cold as the
arctic airmass takes firm grip of the area. Temperatures through
the weekend look to only rise in the 20s for daytime highs with
lows falling into the single digits to lower teens. Models
continue to highlight a weakening clipper system arriving by
Saturday morning, however moisture availability looks rather poor,
as is the case with these types of systems. A slightly stronger
system may impact northeastern portions of the fcst area Sunday
night into early Monday, however initial impressions suggest our
area will only receive a glancing blow. Beyond this, dry but cool
weather looks to dominate through the remainder of the fcst
period.

&&

.Aviation...(For the 18Z TAFS through 18Z Thursday Afternoon)
Issued at 1122 AM CST WED JAN 10 2018

Transition to VFR expected in the next 1-2 hours, with MVFR stratus
returning around midnight. IFR conditions expected by early morning
with chances for rain before a cold frontal passage brings much
colder air and the potential for light freezing rain.

&&

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

$$

Discussion...32
Aviation...Blair



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