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Area forecast discussion 
National Weather Service Kansas City/Pleasant Hill MO
1145 PM CST Fri Jan 30 2015

Short term...(this evening through Sunday night)
issued at 318 PM CST Friday Jan 30 2015

For tonight, mainly quiet conditions are expected out ahead of the
system that will be the main focus of this forecast package. Lows
tonight will occur before midnight, then steady to gradually rising
temperatures are expected through the remainder of the night as
southerly winds draw warmer air into the region ahead of the
approaching system.

The forecast remains on track for wintry precipitation this weekend
throughout the forecast area. Precipitation type is still expected
to start out as mainly rain, unless light precipitation develops
where dry low-level air is still present and wet-bulb effects can
reduce near-surface temperatures enough for a brief rain/snow mix.
Either way, no snow accumulations are expected during the daytime
hours on Saturday as light to moderate rain spreads across the
region. A half an inch of rain is possible prior to any mix with or
transition to snow, especially across the western half of the County Warning Area.
Temperatures should sit in the upper 30s to lower 40s during the day
as southerly winds continue but thick cloud cover overspreads the
region.

After sunset, dynamical cooling will start to reduce temperatures
across far northern and northeast MO as the 850 mb low lifts into
northeast Kansas/northwest MO, the northern stream shortwave trough
heads into southern Iowa, and lift from a departing jet streak all
become superimposed with the aforementioned features. Snowfall rates
should become high enough to overcome the wet/warm ground in far
northern and especially northeast MO, and snow will begin to
accumulate quickly between 8 PM and midnight. Near-surface cooling
will support a gradual transition to snow from north to south during
the nighttime hours, but it may take quite a bit longer for snow to
accumulate where rates aren't quite as high. Snow totals overnight
will be in the 4-6 inch range across far northern and northeast MO,
but will likely remain less than an inch elsewhere.

On Sunday, cold air and strong northerly winds on the back side of
the surface low will force temperatures quickly into the teens and
20s, freezing wet/slushy roads and making the entire temperature
profile supportive of snow. Additional precipitation wrapping around
the back side of the system will combine with light precipitation
associated with the northern shortwave trough, resulting in an
additional half to one inch of snow during the day Sunday. The
highest amounts are again expected in northeast MO, but up to a half
inch is possible across the entire County Warning Area as the shortwave trough digs
into central MO. Total snow accumulations will range from 5-7 inches
in far northern and northeast MO to less than an inch along and SW
of a line from the far northern edge of the kc Metro to Boonville.
Blowing snow is also possible on Sunday in the areas that receive
several inches of snow, as northerly winds gust between 20-30 mph.
Light snow will taper off from west to east Saturday afternoon and
evening, ending altogether by midnight. Existing cold air will be
reinforced by frigid air behind the shortwave trough, knocking
temperatures into the single digits by early Monday morning as
surface high pressure moves over.

Long term...(monday through friday)
issued at 318 PM CST Friday Jan 30 2015

Sunday night's high pressure will quickly slide to our east on
Monday. This will allow southerly flow to return to the area Monday
afternoon, but not soon enough to allow temperatures to rise any
higher than the middle or upper 20s. A weak impulse could bring a
few light snow showers to northern and northeast Missouri Monday
afternoon but this activity will have to fight rather dry air in the
lower and middle layers of the atmosphere. That should keep any
snowfall amounts minimal, if anything at all.

Southerly flow continues into Tuesday bringing temperatures well
into the 40s before another cold front slides through the region
Tuesday night. Can't rule out a few light rain or snow showers
behind the front but again this will have to battle drying air
moving in from the north. In general the chances for measurable
precipitation look low for most of next week.

&&

Aviation...(for the 06z tafs through 06z Saturday night)
issued at 1123 PM CST Friday Jan 30 2015

VFR conditions are prevailing currently at all four terminals and
will continue to prevail for the next few hours. However, as the
rain and lowering ceilings migrate in from the west, MVFR and IFR
conditions will take over. For much of Saturday, expect overcast
skies and periods of rain to affect the terminals. By later
Saturday, better rain chances move into the region with much
colder air beginning to filter down from the north. This colder
air will force a changeover from rain to snow with stj being the
first terminal to see a mix in the evening hours to snow
overnight. The transition at stj currently looks to occur sometime
after around 23z or so but have left out the mention at this time
given the uncertainty in how quickly or slowly the colder
temperatures moves in. The remaining three terminals likely won't
see a changeover until beyond this taf period.

&&

Eax watches/warnings/advisories...
Kansas...none.
MO...Winter Storm Watch from Saturday evening through Sunday
afternoon for moz003-005>008-015>017-024-025.

&&

$$

Short term...Laflin
long term...hawblitzel
aviation...lg

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