Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 052358
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
558 PM CST FRI 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 CWA 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 WAA 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 TROF 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 CAA
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, NW 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 00z TAFs through 00z Saturday Evening)
Issued at 546 PM CST Fri Feb 5 2016

Expect dry and VFR conditions through the TAF period. High
pressure will move away from the area early tomorrow causing winds
to pick up from the southwest during the day.

Specifics for KSTL: Expect dry and VFR conditions through the TAF
period.

Britt

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX


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