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

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FXUS63 KEAX 161014

414 AM CST Tue Dec 16 2014

Issued at 413 AM CST TUE DEC 16 2014

Northwest SFC flow continues to usher cold air into the forecast
area as a fairly strong anticyclone persists off to the west. Low
level moisture appears to be abundant enough to keep the stratus deck
in place for at least a good portion of the day. The moisture layer
does appear to be rather thin, so it`s conceivable that there could
be a period of sun through the late morning and early afternoon. The
temperatures forecast for today reflects more on the side of clouds
sticking around, and subduing any appreciable warm up through the
day. Should the clouds burn off for a few hours this afternoon max
temperatures might need to be adjusted up a few degrees. At any rate
the cold air advection behind the northwest surface winds will keep
things rather chilly through the day. As the large trough continues
to trek eastward its final influences, in the form of light scattered
snow showers and patchy drizzle/freezing drizzle across far northern
and eastern Missouri will wane through the day. Expect a period of
dry conditions through the day on Tuesday and likely Wednesday as
well before the next weather maker reaches the area for Wed night
into Thursday. The surface high will make slow eastward progress
through the middle part of the week, so its influence will remain
over the area for a few days. The result will be continued chilly
conditions with highs in the 30s across the entire area.

The focus then shifts toward Wednesday and Thursday, when warm air
advection in the lower levels will bring some moisture back into the
Central Plains and lower Missouri River Valley. Cold air should be
in place as the aforementioned surface high continues to influence
the area. As the low level warm air moves into the area it will
ascent primarily via isentropic lift. A weak trough will be off to
the west, with a SW flow component over the area. Mid level
vorticity will move into the area as well, which should help out
with some mid level ascent. All told it appears that there will be
between 5 to 10 -ubars/sec of Omega across most of the forecast area
Wednesday night. Light precipitation will likely result, especially
south of the HWY 36 corridor. At this point the thermal profile
looks to be cold enough for snow to be the primary precipitation
type for Wednesday night. For now, have around a tenth to a quarter
inch of QPF in for that time period, and with the thermal profile
looking to be in the wheel house for climatologically normal snow
ratios, went with an even 12:1 ratio to obtain a preliminary snow
total for the first few hours of this event. Generally, for the area
with expected snow on Wed night we could be looking at 1 to 2 inches
of accumulation before sunrise on Thursday. High temperatures on
Sunday will likely get above 0C, so any lingering precipitation
through the day could change over to rain, or maintain a wintry mix.
At any rate, the early snow fall might not stick around for very
long, especially if daytime highs reach the upper 30s and rain falls
on top of the fresh snow. As the best lift and moisture move out of
the area for Thursday night, the thermal profile will drop to below
0c once again (including SFC temps), so light freezing drizzle or
perhaps snow flurries could occur during the overnight hours on

By Friday a more significant system will likely be moving across the
I-40 to I-20 corridor, and we should remain too far north to see the
main brunt of its impact. Perhaps the southern row of counties could
see some light rain/snow mix as the system moves through Fri/Sat,
but the most likely area for any precip will be south of I-70. Model
runs have been fairly consistent with this system staying well south
of the forecast area, so confidence is growing that it will stay
south and not impact our area strongly. Mid range modeling fairly
consistent regarding a persistent west coast ridge and a Central
Plains trough, which should keep the area more seasonably chilled
for the extended forecast. Precipitation that far out is uncertain,
but given the general mid level pattern it appears there could be
several chances of rain and/or snow into early next week.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday Night)
Issued at 1133 PM CST MON DEC 15 2014

Low clouds, strong/gusty northwest winds and patchy light
precipitation main concerns for this forecast.

Wrap around MVFR cigs extend westward into southwest NE and central
KS. Large cyclonic circulation tied to eastern IA low will result in
slow clearing. Should see back edge of these clouds clear west
central MO around 18Z with clearing from southwest to northeast.
Short range models suggest clearing of MVFR cigs will stall over
northern MO by early Tuesday evening and then begin to bleed back to
the south overnight.

Patchy light rain with some sleet occasionally mixed in will linger
for several more hours over west central MO with flurries or very
light snow over far northwest MO. Patchy light rain over north-
central and northeast MO will be replaced by the light rain and sleet
mix through around 10z.

Strong and gusty northwest winds will prevail through the night and
gradually diminish from west to east in the afternoon.




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