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

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217
FXUS63 KEAX 191745
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
1145 AM CST Mon Feb 19 2018

.Discussion...
Issued at 415 AM CST MON FEB 19 2018

A rather amplified upper level system, currently centered over
the northwest U.S., will provide us with multiple chances for
precipitation this week. It will take a while for the trough
itself to push through the central U.S., but it will eject a few
rounds of upper level energy our way, providing the support for
precipitation.

The first round is setting up at the moment, with a surface
low and associated cold front moving east across KS/NE. The timing
of this system has kept temperatures above normal tonight, and
actually started increasing temperatures after midnight. In
addition, the pressure gradient has tightened, resulting in
increased wind speeds. With the projected path of the surface low,
the strongest winds should be limited to areas in south-central MO.
These southwesterly winds are forecast to be between 25-30 MPH with
gusts up to 45 MPH. Therefore, a Wind Advisory has been issued for
Linn County in KS and Bates and Henry Counties in MO until noon
today.

This system also has already brought us scattered storms across the
eastern half of our forecast area this morning. Scattered storm
chances will continue for everyone today as the surface low and
cold front approach and move through the area. No severe weather
is anticipated with this activity at this time. All of the models
are depicting rather high PWAT values for this time of year. This
coincides with the Total Precipitable Water imagery, which shows
ample moisture moving into our area from the Gulf of Mexico. This
means the showers and storms that develop should be rather
efficient rain-makers. This is welcome considering we are well
below normal for precipitation this winter. Precipitation chances
continue tonight as well, as the front stalls across MO. However,
there is some uncertainty on where the front will stall, and
therefore, how cold surface temperatures get tonight. This is
important because the temperatures will dictate what precipitation
type falls. In general, models agree the front will stall across
central MO, allowing temperatures to drop to 32 degrees F or below
tonight in northwest MO and northeast KS, resulting in a change
over from rain to freezing rain. Freezing rain is the expected
winter precip type due to a lack of ice crystal introduction and
strong warm nose near 850 mb. The GFS is the outlier for this
situation, stalling the front across central MO but having it then
push back north near the MO/IA border. This solution limits the
cold surface air, which in turn limits the amount of freezing rain
possible. Have decided to go with a blend of the models, but am
leaning more on the NAM/ECMWF, as the RAP and HRRR are starting to
show a similar story. With that said, freezing rain is expected
tonight across northwest MO and northeast KS with up to 0.20 of an
inch possible. Therefore, a Winter Weather Advisory is in effect
from 9 PM tonight through noon Tuesday. Hazardous travel is
expected, so extra caution needs to be taken if driving during
that time.

We will see a break from the wintry precipitation during the day
Tuesday, but the cold front is slated to finally push through
Tuesday night. This will provide a chance for a wintry mix in
central MO before the precipitation finally exits the forecast
area early Wednesday. A few more rounds of precipitation are
possible at the end of the work week into the weekend, as the
aforementioned upper level trough ejects more pulses of energy
this way with additional surface low development. As of right now,
it looks like the upper level trough will finally push through
the area by the end of the weekend.

&&

.Aviation...(For the 18Z TAFS through 18Z Tuesday Afternoon)
Issued at 1139 AM CST MON FEB 19 2018

Overcast skies will dominate through this TAF period with low
ceilings and sporadically reduced visbys causing high impacts to
aviation interests. Additionally, cold front currently traversing
through the terminal areas will usher in sub-freezing temps by
later this afternoon into this evening, allowing for any drizzle
or showers that occur to freeze on surfaces. The huge challenge
for this forecast period will be the fact that the front is
looking to make a brief retreat back northward, allowing for
warmer temps to move back into the terminal areas. However, the
front will make its final push through by midday tomorrow, with
precip chances looking to head on out with it.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...Winter Weather Advisory from 9 PM this evening to noon CST
     Tuesday for KSZ025-102.

MO...Winter Weather Advisory from 9 PM this evening to noon CST
     Tuesday for MOZ001>005-011-012-020.

&&

$$

Discussion...Grana
Aviation...lg



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