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Area forecast discussion...updated 
National Weather Service St Louis MO
1242 PM CST sun Feb 14 2016

Update:
issued at 1235 PM CST sun Feb 14 2016

Canceled portions of central MO from winter wx advisory as
precipitation has come to an end there. Otherwise, updated pops,
snowfall amounts etc. As system is exiting rather quickly. May be
able to cancel rest of advisory by afternoon zone issuance time.
Snowfall amounts have generally been between 1 and 2 inches with
some locally higher amounts.

Byrd
&&

Short term: (through late this afternoon)
issued at 417 am CST sun Feb 14 2016

Focus will be precip today.

Overall, not a lot has changed with the forecast for today. What has
changed is increased amount of ice pellets expected across the srn portions
of the County Warning Area. Expect precip to begin as ice pellets across srn portions of the
cwa, with cooling expected later in the morning as the trof arrives.
Area of precip over ern Kansas is expected to reach cntl MO around
sunrise and also expected to begin as ice pellets. However, as it moves ewd,
the area of precip shud expand nwd, but be largely snow further north.
This transition from ice pellets to snow is expected to occur along the County Warning Area
boarder.

Elsewhere, snow is expected to overspread the region this morning and
quickly move ewd. Latest indications are that the bulk of the snow
will fall in a window of only a 3 or 4 hours, but will have high
snowfall rates for at least a couple of those hours.

Precip shud be exiting the ern portions of the County Warning Area early this
afternoon. Expect areas of fzdz to develop as the snow comes to an end
this afternoon. Exactly how expansive this area of fzdz will be is
difficult to determine, but expect most of the region to see a light
glaze of ice.

To add to the complexity of this forecast, temps are expected to
warm to just above the freezing mark across portions of central MO
this afternoon as the clipper moves thru the region. These warm
temps will be short lived as temps are expected to drop quickly with
nightfall.

Tilly

Long term: (tonight through saturday)
issued at 417 am CST sun Feb 14 2016

A longwave trough will continue to prevail over eastern North America
until the middle of this week. This will continue the train of
disturbances, about one every 24 hours or so.

First off is tonight, with the setup for drizzle almost identical
from this afternoon lingering into the evening, with a fairly thick
deck of low stratus and weak low level convergence. Surface temps
again look to be sufficiently cold for the drizzle to be freezing
drizzle. This should exit by midnight

The next disturbance is currently just coming ashore over British
Columbia province and should be sampled fairly well with the next
set of raob launches in a few hours. A good model consensus has
developed with this system, with the GFS the first to latch on to
this possibility a day or two ago, and the rest have since fallen in
line...tracking it thru northern Arkansas and the mid-south during the
daytime Monday, placing the lift associated with it thru the entire
forecast area at some point during that day. Now the lift will not
be as strong as what we should see with the system today, but it
should still be sufficient enough to now justify adding mentionable
pops into the forecast. Pcpn-types will increasingly favor liquid
over frozen types heading thru the day on Monday, but if this system
arrives early in the morning like it currently is expected, it
should still be cold enough to begin as snow. Some very light
additional snow accums will be possible for areas in northeast and
central MO.

Temps on Monday will be tough with the track of this next clipper-
like system to effectively separate areas that warm very well (into
the lower 50s) to the right of the track of its surface reflection,
from areas that will warm very poorly to its left and likely never
get out of the 30s. Have a large temp gradient across the forecast
area as a result, but with decent bust potential in place as well.

Another disturbance is still progged for late Monday night into
Tuesday as well, but the details associated with this continue to
shift with timing and track, and thus remains low confidence. The
latest model consensus now tracks this more northeastward thru
southern Iowa and central Illinois and will leave much of the forecast area
in its warm sector (with temps rising well into the 40s or lower
50s) and likely dry. The system itself is still over the Pacific
Ocean and will not get sampled well until tomorrow. Where this
system does track, it should still be sufficiently cold for mostly
snow given the more favorable diurnal timing, and should lead to
additional small snow accums for where it does track.

The models are trying to develop another (and final) weak clipper
system on Wednesday daytime, but details and confidence on this are
even more sketchy and have maintained a dry forecast for most areas
with this package.

Otherwise, look for a mainly dry forecast from Wednesday on, with
above average temps into next weekend, with what could be a very
warm day on Friday.

Tes
&&

Aviation: (for the 18z tafs through 18z Monday afternoon)
issued at 1235 PM CST sun Feb 14 2016

Will see MVFR cigs lift to VFR at kcou by 01z Monday, while rest
of taf sites to remain MVFR through the evening hours. Some patchy
freezing drizzle still possible for stl Metro area, so kept
mention in through 00z Monday, then cigs to slowly lift there. As
for KUIN, cigs to remain IFR/MVFR for rest of forecast period.
Southeast to south winds to diminish by this evening, then become
light and variable. Because of the snowfall and winds becoming
light, could see some fog develop, so added mention to tafs.

Specifics for kstl:
MVFR cigs and some patchy freezing drizzle still possible for stl
Metro area, so kept mention in through 00z Monday, then cigs to
slowly lift there. Southeast winds to diminish by 00z Monday,
then become light and variable. Because of the snowfall and winds
becoming light, could see some fog develop, so added mention to
taf.

Byrd
&&

Lsx watches/warnings/advisories:
MO...Winter Weather Advisory until 6 PM CST this evening for Crawford
MO-Franklin MO-Iron MO-Jefferson MO-Lewis MO-Lincoln MO-
Madison MO-Marion MO-Pike MO-Ralls MO-Reynolds MO-St.
Charles MO-St. Francois MO-St. Louis city MO-St. Louis MO-
Ste. Genevieve MO-Warren MO-Washington MO.

Illinois...Winter Weather Advisory until 6 PM CST this evening for Adams Illinois-
Bond Illinois-Brown Illinois-Calhoun Illinois-Clinton Illinois-Fayette Illinois-Greene Illinois-
Jersey Illinois-Macoupin Illinois-Madison Illinois-Marion Illinois-Monroe Illinois-
Montgomery Illinois-Pike Illinois-Randolph IL-St. Clair Illinois-Washington
Illinois.

&&

$$
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