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Area forecast discussion 
National Weather Service St Louis MO
325 PM CST Friday Feb 5 2016

Short term: (through late tonight)
issued at 325 PM CST Fri Feb 5 2016

A pair of vort maxes will approach the region tonight, spreading
extensive mid/high cloudiness over the area. The northern vort Max
is the weaker of the pair and eventually phases with the southern
disturbance, although there is some model disagreement regarding how
quickly this occurs. Latest runs of the rap point to a quicker
phasing than shown by the local WRF or NAM, and the quicker timing
looks reasonable based on recent satellite imagery and pv analyses.
Quicker phasing means that the northern disturbance won't produce
much lift over the County Warning Area and therefore there is much less chance of
flurries or sprinkles given the already limited moisture. Overnight
lows should be a few degrees warmer than yesterday due to extensive
cloud cover and weak warm air advection at low levels behind a retreating surface
high pressure center.

Kanofsky

Long term: (saturday through next friday)
issued at 325 PM CST Fri Feb 5 2016

An upper level trough will swing thru our region dry on Saturday,
with forcing not strong enough and a column not moist enough, as the
main storm center passes well to our south, and should produce
nothing more than clouds that will decrease as the day wears on.
Otherwise, SW winds left in its wake will result in an above average
temp day, with maxes from the mid 40s to mid 50s favored, or at or
above the higher mav MOS.

A more direct hit from a decently strong upper level disturbance
will occur late Sunday and into Sunday night, but will still be
fighting a largely dry column. Have added low pops for most of our
region for light rain for Sunday afternoon, and areas south and east
of stl Metro heading into Sunday evening.

This initial disturbance Sunday will also correspond to the leading
edge of a brief shot of Arctic air that will begin later Sunday
night and continue into Monday night, resulting in scattered snow
showers over much of the region. Accums will be hard to nail down
this far out and due to the nature of the pcpn, but could see spotty
accums up to an inch from this event. Needless to say, the leading
edge of the Arctic airmass will also be accompanied by strong gusty
northwest winds, clouds, and stagnant daytime temps on Monday as cold air advection
remains strong thru the day.

Models are less clear, but it appears a second clipper-like system
may drop down for the Tuesday night or Wednesday timeframe, but the
signal is not enough, especially for this type of system, to place
mentionable pops in the forecast just yet.

Otherwise, northwest upper flow continues thru all of next week and will
leave the door open for additional cold air intrusions, one of which
is slated to drop down Thursday or Friday.

Overall a period of mainly below average temps separated briefly by
periods of above average temps, with little in the way of
precipitation.

Tes

&&

Aviation: (for the 18z tafs through 18z Saturday afternoon)
issued at 1108 am CST Fri Feb 5 2016

VFR through the period with increasing mid/high clouds. Initially
lgt/var winds will become southwesterly on Saturday morning due
to the approach and passage of a surface trough after 06/12z.

Kanofsky

&&

Lsx watches/warnings/advisories:
MO...none.
Illinois...none.
&&

$$

Weather forecast office lsx

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