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

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FXUS63 KEAX 131720
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
1120 AM CST Sat Jan 13 2018

.Discussion...
Issued at 411 AM CST SAT JAN 13 2018

Satellite imagery this morning shows an amplified pattern in place
across the Nation, with a northwest flow currently prevailing across
the Plains States. This has kept temperatures rather cold since the
northerly flow blasted a cold front through the region Thursday.
However, temperatures will recover a little ahead of a little
clipper system that will bring some snow to the region late this
weekend into the beginning of the work week, but not today as highs
will be in the teens in most areas.

Attention early this morning is on a shortwave trough, currently
shifting southeast into the northern provinces of Canada, as this
feature will be responsible for a couple of chances at snow Sunday
and Monday along with another shot of cold air. Models continue to
advertise this shortwave zipping southeast this weekend, inducing a
bit of isentropic lift/warm air advection along it`s leading edge as
it dips into the Central Plains, which will ultimately result in
afternoon highs near freezing by Sunday, but not before likely
inducing some light precipitation in the morning hours. Current
thermal profiles indicate that snow will be the only precipitation
type to worry about Sunday. Available moisture in the northwest flow
will be limited Sunday morning, but should be sufficient to overcome
any surface dry layer. Add in the the cold temperatures in place
ahead of this trough, and expectations are that snow ratios will be
rather high, even if snow totals are rather low; in the 15:1 to 20:1
range. This should result in some light snowfall accumulations
between 1 to 2 inches in areas near the Kansas-Missouri border
between midnight and noon Sunday. Areas farther east, in central or
north central Missouri, will have to wait till early Monday morning
before they have a chance at the secondary round of snowfall
expected from this trough.

The leading isentropic lift induced snow will exit to the southeast
during the early afternoon hours Sunday, with a secondary surge of
cold air following the trough inducing sufficient frontogenic
forcing to bring a widespread swath of snow that night. Timing on
this secondary band of snow currently indicates that light snow will
move into areas near the Iowa border late Sunday evening, sweeping
south overnight into southern Missouri by noon Monday. Snowfall
amounts with the secondary snow will be highly dependent on the
antecedent conditions from the activity earlier in the day, thermal
profile and available moisture, but currently an additional inch of
snow looks possible. This secondary surge of cold air will also
stick around for a few days, resulting in potentially dangerous wind
chill values across much of the region by Tuesday morning, with
afternoon highs on Tuesday likely in the single, and low double,
digits. Temperatures will then moderate towards the end of the work
week with afternoon highs expected to peek above freezing by
Thursday.

&&

.Aviation...(For the 18Z TAFS through 18Z Sunday Afternoon)
Issued at 1117 AM CST SAT JAN 13 2018

Light snow expected to move into the terminals early Sunday
morning, and persist through at least the mid morning, and perhaps
into the early afternoon. The heaviest period of snow will likely
be in the 13z to 18z time frame, when CIGS and VIS could drop to
below MVFR/IFR thresholds. Could see a brief period of LIFR Sunday
morning, but likely not for more than short periods at a time.
Snow should move out of the terminals around or shortly after 18z
Sunday.

KSTJ will continue to be NIL until weather observation data is
restored at the terminal, which at this point is expected to be
Tuesday.

&&

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

$$

Discussion...Cutter
Aviation...Leighton


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