Area Forecast Discussion
Issued by NWS La Crosse, WI

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277
FXUS63 KARX 101110
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
510 AM CST WED FEB 10 2016

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 353 AM CST WED FEB 10 2016

AT 3 AM...CLOUDS ON THE WESTERN PERIPHERY OF THE 999 MB SURFACE
LOW OVER EASTERN ONTARIO HAVE BEEN MOVING SOUTH ACROSS CENTRAL AND
NORTH-CENTRAL WISCONSIN EARLY THIS MORNING. THESE CLOUDS HAD A
HUGE IMPACT ON THE TEMPERATURES AT BLACK RIVER FALLS. AT
1035 PM...THEY WERE -11F UNDER MAINLY CLEAR SKIES. JUST A HALF
HOUR LATER...THEY BECAME CLOUDY AND TEMPERATURE ROSE 13 DEGREES TO
2F. SPARTA SAW A 12 DEGREE RISE IN TEMPERATURE FROM -7F AT 1135
PM TO 5F AT 1215 AM. ELSEWHERE NORTHWEST WINDS OF 5 TO 10 MPH HAVE
KEPT TEMPERATURES IN THE -1F TO 5F RANGE.

THE 02.10Z GFS 850 MB RELATIVE HUMIDITY PLOT HAS BEEN DOING A
GREAT JOB INDICATING WHERE THERE CLOUDS ARE CURRENTLY LOCATED IN
WISCONSIN. THEY SHOW THAT THE CLOUDS ACROSS CENTRAL AND NORTH-
CENTRAL WISCONSIN WILL MOVE EAST OUT OF CENTRAL WISCONSIN BY
10.12Z AND OUT OF NORTH-CENTRAL WISCONSIN BETWEEN 10.15Z AND
10.18Z. SKIES WILL THEN REMAIN MOSTLY TO PARTLY SUNNY FOR THE
REMAINDER OF TODAY.

FURTHER TO THE WEST AND SOUTHWEST TODAY...A SHORT WAVE TROUGH WILL
MOVE SOUTHEAST ALONG A TIGHT BAROCLINIC ZONE THROUGH WESTERN AND
SOUTHERN MINNESOTA AND WESTERN IOWA. THIS BAROCLINIC ZONE ENDED UP
BEING FURTHER SOUTH AND WEST OF THE AREA JUST LIKE THE NAM AND
ECMWF HAS BEEN FORECASTING THE LAST SEVERAL DAYS. OTHER THAN SOME
MID AND HIGH CLOUDS WEST OF THE MISSISSIPPI RIVER...THIS SYSTEM
WILL HAVE LITTLE ON THE FORECAST AREA.

UNDER MOSTLY CLEAR TO PARTLY CLOUDY SKIES AND LIGHT WINDS
TONIGHT...TEMPERATURES WILL FALL INTO THE SINGLE DIGITS BELOW
ZERO. THE WINDS WILL BE LIGHT ENOUGH TONIGHT THAT WIND CHILLS
WILL ONLY FALL INTO THE -10 TO -20 RANGE. WHILE A FEW PLACES MAY
REACH WIND CHILL ADVISORY CRITERIA TONIGHT...IT DOES NOT LOOK
WIDESPREAD ENOUGH TO WARRANT AND ADVISORY.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 353 AM CST WED FEB 10 2016

ON THURSDAY NIGHT...MOST OF THE DETERMINISTIC MODELS HAVE KEPT
THE BAROCLINIC ZONE WELL SOUTHWEST OF THE FORECAST AREA. AS A
RESULT...THE GFS...NAM...AND ECMWF NOW KEEP THE AREA DRY.
MEANWHILE...THE GEM HAS SOME LIGHT SNOW FALLING ACROSS PARTS OF
NORTHEAST IOWA. SINCE THIS WAS A RELATIVELY NEW DEVELOPMENT OPTED
TO LOWER SNOW CHANCES TO SLIGHT /15 TO 24 PERCENT/ AND MOVED THEM
FURTHER SOUTHWEST.

IN THE WAKE OF THE THURSDAY NIGHT SYSTEM...MUCH COLDER AIR SPILLS
SOUTH INTO THE REGION. 925 MB TEMPERATURES AT LA CROSSE FALL FROM
-12C AT 12Z FRIDAY TO -20C AT 18Z FRIDAY...AND TO -22C BY 00Z
SATURDAY. THIS COLD AIR THEN LINGERS ACROSS THE AREA THROUGH THE
NIGHT. LOW TEMPERATURES ON SATURDAY MORNING FALL INTO THE -5 TO
-15F RANGE. NORTH WINDS OF 5 TO 10F WILL LOWER THE WIND CHILLS
INTO THE -20 TO -30 RANGE ACROSS THE ENTIRE AREA. WITH WIND CHILLS
THIS COLD...IT STILL LOOKS LIKE A WIND CHILL ADVISORY WILL BE
NEEDED.

WHILE SATURDAY LOOKS TO BE THE COLDEST DAY OF THIS COLD SNAP...
THERE CONTINUES TO BE QUITE A FEW QUESTIONS ON HOW COLD IT WILL
ACTUALLY END UP BEING. THE GFS ONLY HAS HIGH TEMPERATURES IN THE
SINGLE DIGITS BELOW ZERO...BUT THIS MODEL HAS BEEN TRENDING TOO
COLD. THE BIAS CORRECTED FOR THIS DAY HAS BEEN RUNNING AROUND 10F
TOO COLD. MEANWHILE THE ECMWF HAS THE HIGH TEMPERATURES BETWEEN 5
AND 10F WITH A BIAS CORRECTION OF JUST 2F. IN ADDITION...WITH BOTH
THE GFS AND ECMWF SHOWING THAT THE 925 MB WILL WARM NEARLY 6C
DURING THE DAY...THE FORECAST WAS TRENDED TOWARD THE WARMER ECMWF
WHICH WAS JUST A COUPLE DEGREES WARMER THAN THE MODEL CONSENSUS.

FROM LATE SATURDAY NIGHT INTO SUNDAY NIGHT...THE MODELS CONTINUE
TO SHOW THAT STRONG WARM AIR ADVECTION WILL DEVELOP ACROSS THE
AREA AS THE ARCTIC HIGH MOVES EAST OF THE AREA. WHILE THERE HAS
BEEN CONSENSUS THAT THIS WILL OCCUR...THERE HAS BEEN LITTLE
CONSISTENCY ON HOW MUCH MOISTURE AND THE STRENGTH OF THE LOW
PRESSURE SYSTEM MOVING THROUGH THE REGION. WHILE THE 10.00Z
MODELS ARE SHOWING THAT THIS SYSTEM WILL LIKELY PRODUCE ANYWHERE
FROM 3 TO 6 INCHES. THE PREVIOUS RUN PRODUCED VERY LITTLE SNOW AT
ALL. LOOKING THE COBB DATA DPROG/DT...THIS TRENDED OF SNOW AND NO
SNOW HAS BEEN GOING BACK AND FORTH FOR THE PAST 5 RUNS OF THE GFS.

ANOTHER LOW PRESSURE SYSTEM LOOKS TO MOVE THROUGH THE AREA
SOMEWHERE BETWEEN TUESDAY AND WEDNESDAY. WHILE THE MODELS HAVE
BEEN CONSISTENTLY PRODUCING 3 TO 4 TENTHS OF AN INCH OF LIQUID...
THERE HAS BEEN DIFFERENCES ON HOW WARM THE TEMPERATURES ARE FROM
THE SURFACE TO 800 MB. THIS WILL HAVE AN IMPACT OF WHAT TYPE OF
PRECIPITATION MAY FALL. IN ADDITION...THE TIMING HAS BEEN
FLUCTUATING QUITE A BIT. EVEN IN THE LATEST MODEL RUN...THE GFS IS
ABOUT 12 HOUR FASTER THAN THE ECMWF. DUE TO THIS...JUST STAYED
WITH THE MODEL CONSENSUS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 510 AM CST WED FEB 10 2016

AN AREA OF LOW PRESSURE WILL MOVE RAPIDLY SOUTH FROM NORTH DAKOTA
INTO KANSAS AND OKLAHOMA TONIGHT. HIGH CLOUDS FROM THIS SYSTEM ARE
ALREADY SPREADING OVER THE AREA AND EXPECT THESE WILL GO BROKEN
FOR A HIGH VFR CEILING INTO THE EVENING HOURS. THE LIGHT SNOW WITH
THIS SYSTEM WILL STAY WELL TO THE SOUTHWEST OF THE AREA ACROSS
WESTERN SECTIONS OF MINNESOTA AND IOWA. THE CLOUDS WILL SCATTER
BACK OUT THIS EVENING FOR MOSTLY CLEAR CONDITIONS FOR THE
OVERNIGHT AS HIGH PRESSURE BUILDS IN FROM THE NORTH. THE WINDS
WILL BE NORTH TO NORTHWEST THROUGH THE PERIOD AT SPEEDS UNDER 10
KNOTS.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...04



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