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Area forecast discussion 
National Weather Service La Crosse WI
500 PM CST Wednesday Mar 4 2015

Short term...(tonight through Thursday night)
issued at 200 PM CST Wednesday Mar 4 2015

Main forecast concern in the short term will be very cold
temperatures and wind chills later tonight into Thursday morning.

High pressure building into the region tonight with coldest core of
modified Arctic air moving overhead//925mb temperatures of -20 to -22c//.
Northwest winds east of the ridge axis should decouple pretty good
later this evening/overnight with clear skies and slackening
pressure gradient. This in turn should allow temperatures to dip
down into the single digits/teens below zero. Northwest winds less
than 10 miles per hour will produce wind chills in the teens/lower 20s below
zero as a result. Since this will be borderline for a Wind Chill
Advisory...and based on collaboration with neighboring
offices...will issue a Special Weather Statement and continue to
mention in the hazardous weather outlook product. Will leave up to
the evening shift to continue assessing temperature/wind trend and
possible need for a wind chill headline.

With the ridge overhead on Thursday...not much in the way of
moderating temperatures in store as highs struggle into the upper
single digits/middle teens above zero.

Expecting increasing middle-cloud Thursday night in response to an
approaching warm front from the northern plains. Otherwise...look
for temperatures to bottom out by late evening in the single digits
above and below zero...then slowly increasing overnight in warm air
advection/increasing cloud cover kicks in.

Long term...(friday through wednesday)
issued at 200 PM CST Wednesday Mar 4 2015

For Friday into Saturday...mid-level/500mb heights slowly on the
rise with the main low pressure track staying well north of the
border in Canada. This will draw milder air into the region. May
have some middle clouds to contend with along with a shot at some very
light snow Friday night into Saturday morning but nonetheless...highs
on Friday expected to top off in the 30s...and possibly reaching
near the 40 degree mark at a few locations on Saturday.

Moderating heights being shown by both the GFS/European model (ecmwf) into next week
as West Coast ridge ridge finally breaks down and builds eastward
into central Continental U.S.. European model (ecmwf) a bit more robust with ridge strength and
therefore much warmer than the GFS. Blend yields highs Sunday in the
middle 30s/lower 40s...in the 40s Monday...middle 40s/lower 50s on
Tuesday and Wednesday.

&&

Aviation...(for the 00z tafs through 00z Thursday evening)
issued at 500 PM CST Wednesday Mar 4 2015

Expect the thin layer/diurnal cumulus cloud streets to quickly dissipate
with Sundown...with perhaps a few more diurnally driven cumulus for late
morning/afternoon on Thursday. Conditions less favorable with high
pressure over Iowa. Don/T anticipate any ceilings.

Expecting a turn from northwest to southwest in wind direction from
this evening into Thursday evening...thanks to a surface high meandering
southeast across Iowa. Winds should lighten at klse with
decoupling...perhaps vrb03kt. Pressure gradient remains relatively
slack through Thursday...tightening up Thursday night as the high continues to
move southeast.

&&

Arx watches/warnings/advisories...
WI...none.
Minnesota...none.
Iowa...none.
&&

$$

Short term...das
long term...das
aviation...rieck

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