Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
FXUS63 KEAX 131451
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
851 AM CST Fri Dec 13 2013
Issued at 850 AM CST FRI DEC 13 2013
12Z KTOP sounding confirms just how poorly the models have been
resolving the incoming storm system, and why the forecast challenge
has been so difficult even in closing time steps. 800mb temperature
of a whopping +9C makes precipitation type now a no-brainer for the
first half of the event.
Strong warm advection, occurring ahead of a lead sub-synoptic low
just west of Kansas City, began to overspread the area around 12Z.
This forcing will continue to spread northeast through this morning,
generally impacting areas southeast of a St. Joseph to Trenton to
Kirksville line. An initial band of moderate-heavy rain, followed by
more showery precipitation will continue through this morning. The
greatest immediate term impacts appear to be from Marshall to Moberly
to Boonville along the I-70 and highway 63/65 corridors. With surface
temperatures still in the upper 20s to lower 30s, we have seen insta-
glaze conditions develop literally within a couple minutes of the
onset of freezing rain, even with QPF amounts of a few hundredths of
We are urging people to remain off the roads with accidents too
numerous to count at this time.
The silver lining is that given the incredible magnitude and depth of
warm air aloft, rain falling through that layer will acquire those
thermal conditions and steadily warm the surface and boundary layer
above freezing. As such, freezing rain showers will become rain
showers from south to north this morning. However, in areas that have
already glazed over, it may take every bit of 35-36F to remove the
existing ice given overcast conditions and the extremely low sun
Updates on the second half of the event, in terms of snowfall
potential, will come after 12Z model data has been ingested and
.SHORT TERM...(Today and Tonight)
Issued at 414 AM CST FRI DEC 13 2013
Main concern in the short term continues to revolve around
precipitation type and snowfall amounts. This is associated with a
upper level shortwave over the four corners region early this
morning, which will move out into the central Plains this afternoon.
WAA is ongoing ahead of this system keeping overnight temperatures
in the mid 20s to near 30 CWA wide. Mid-level moisture is streaming
northeastward out of Oklahoma this morning with light returns on
radar. This moisture is expected to move into the southern CWA this
morning between 12Z-15Z. Temperatures profiles suggest that despite
a warm nose between 900mb-700mb precipitation will fall as liquid
but with surface temperatures hovering near or just below freezing,
freezing drizzle/rain will be possible. Only light ice accumulation
is expected before surface temperatures move above freezing. Through
the late morning hours and the afternoon areas south of Hwy 36 will
mostly see rain as temperatures move into the mid to upper 30s.
Along and north of Hwy 36, where temperatures are near freezing and
moisture is not as deep, freezing rain or sleet is the more likely
Tonight we will see a change of rain/mixed pcpn over to all snow
generally from north to south. This will occur as an 850mb low moves
south and then east of the area and ushers in cold northerly winds
in behind it. There is some concern of a deformation band setting up
over the eastern portion of the CWA which may drive up snow totals
there. Model sounding indicate by early tomorrow morning we lose ice
crystals with the layer of moisture being shallow and, precipitation
may end as light freezing drizzle. Right now we are looking at
snowfall amounts of 2"-4" along and east of Interstate 35 which
generally 1"-2" across eastern Kansas and western Missouri. As such
have replaces the Winter Storm Watch with a Winter Weather Advisory.
.LONG TERM...(Saturday through Thursday)
Issued at 414 AM CST FRI DEC 13 2013
Any lingering snow across central Missouri Saturday morning will be
quick to exit the area with little if any additional accumulation.
Steady cold air advection through the day will keep thick clouds
around through the afternoon which will keep temperatures nearly
steady or slowly falling through the 20s during the day.
Low-level ridge axis moving into the area Saturday night will allow
skies to clear and will likely cause temperatures to quickly fall
into the single digits especially for any areas with snow on the
ground. This ridge axis will move east of the area on Sunday
bringing winds around from the south and initiating a gradual
warming trend into the upper 30s and lower 40s by Monday and
Tuesday. Broad northwest upper flow to the north of the area will
maintain these near-average temperatures through mid week while
conditions remain dry. Next chance of precipitation will arrive late
in the week as troughing redevelops to the west.
.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
Issued at 522 AM CST FRI DEC 13 2013
Conds are expected to deteriorate at the terminals by late morning.
VFR conds this morning are expected. Radar as of 11Z this morning
shows light echoes producing light rain across southeast Kansas.
These returns are expected to move north into the terminals between
15Z-17Z with vsbys reduced to 5SM. MVFR cigs across northern Texas
this morning are also streaming northward and are expected to move
into the terminals between 18Z-19Z. Rain is expected to gradually
change over to snow this evening between 22Z-00Z when there may be a
period of rain mixing with snow before changing over to all snow.
After 00Z expect precipitation to be in the form of light snow with
IFR cigs and reduced vsbys between 1/2SM-2SM. The heaviest of snow
will fall before midnight with 1-2 inches of snow possible at the
terminals. Light snow will be possible after midnight however
cigs/vis will lift back to IFR conds.
KS...WINTER WEATHER ADVISORY until 9 AM CST Saturday FOR KSZ025-057-
WINTER WEATHER ADVISORY until 9 AM CST Saturday FOR KSZ102.
MO...WINTER WEATHER ADVISORY until 9 AM CST Saturday FOR MOZ020>025-
WINTER WEATHER ADVISORY until 9 AM CST Saturday FOR MOZ004>008-