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000
FXUS63 KARX 101809
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
109 PM CDT MON MAR 10 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 345 AM CDT MON MAR 10 2014

AT 3 AM...A WEAK COLD FRONT EXTENDED FROM INTERNATIONAL FALLS TO
SIOUX FALLS SOUTH DAKOTA. THE 10.00Z MODELS ARE IN GENERAL
AGREEMENT THAT THIS FRONT WILL MOVE SOUTHEAST THROUGH THE FORECAST
AREA THIS MORNING. 925 MB TEMPERATURES DROP FROM 6 TO 14C AT
10.12Z TO 4 TO 9C BY 11.00Z. THE LARGEST DECREASE IN TEMPERATURES
WILL BE IN THE AREAS SOUTH OF THE INTERSTATE 90 CORRIDOR. DUE TO
THIS DROP AND THE SNOW PACK ACROSS THE AREA...A BIT CONCERNED THAT
THE MAXIMUM TEMPERATURES FOR TODAY MAY BE A BIT ON THE HIGH SIDE.
THE TWO PLUSES FOR GOING WITH TEMPERATURES IN THE MID AND UPPER
40S IS THAT WE ARE ALREADY IN THE 30S AND WE WILL SEE MORE
SUNSHINE THAN SUNDAY. OVERALL...THE ECMWF SEEMS TO HAVE THE BEST
HANDLE WITH COOLER AIR OVER THE DEEP SNOW PACK ACROSS SOUTHEAST
MINNESOTA AND NORTHEAST IOWA...SO WENT WITH A BLEND OF THAT GRID
AND THE CURRENT FORECAST GRID TO LOWER THE TEMPERATURES JUST A
BIT.

FOR TONIGHT...THE MODELS CONTINUE TO SHOW THAT A STRONG 900 TO
700 MB FRONTOGENETIC BAND WILL DEVELOP ALONG AND SOUTH THE
INTERSTATE 90 CORRIDOR. IN ADDITION SOUTHEAST MINNESOTA AND
NORTHEAST IOWA WILL BE IN THE RIGHT ENTRANCE REGION OF A 90 KNOT
250 MB JET. THE COMBINATION OF THESE TWO WILL DEVELOP DEEP OMEGA
ACROSS THE REGION. THIS LIFT WILL HELP TO SLOWLY SATURATE THE VERY
DRY AIR THAT WAS BROUGHT IN ISENTROPICALLY OFF OF THE HIGH PLAINS
ON MONDAY. THE TEMPERATURES ALOFT WILL BE WARM ENOUGH FOR THE
PRECIPITATION TO START OFF AS RAIN AND THEN IT WILL CHANGE TO SOME
SLEET AS EVAPORATIVE COOLING OCCURS. THIS SLEET WILL THEN
TRANSITION TO SNOW AS THE SOUNDING BECOME SATURATED LATE TONIGHT.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 345 AM CDT MON MAR 10 2014

ON TUESDAY...THE STRONG 900 TO 700 MB CONTINUES TO MOVE SOUTHEAST
ACROSS NORTHEAST IOWA AND SOUTHWEST WISCONSIN. AS THIS OCCURS...
THE PRECIPITATION WILL END ALONG THE INTERSTATE 90 CORRIDOR BY MID
TO LATE MORNING. WITH THE STRONG EVAPORATIVE COOLING ALOFT...THE
DEPTH OF WARM AIR ALOFT WILL DRAMATICALLY DECREASE...AND THE
PRECIPITATION WILL TRANSITION OVER TO SNOW ACROSS NORTHEAST IOWA
AND SOUTHEAST MINNESOTA. MEANWHILE WITH A BIT WARMER BOUNDARY
LAYER ACROSS SOUTHWEST WISCONSIN...THERE WILL LIKELY BE A MIX OF
RAIN AND SNOW INTO THE AFTERNOON. THE MIX OF RAIN...SLEET...AND
SNOW AND THE SHORT DURATION OF PRECIPITATION WILL GREATLY LIMIT
THE SNOW POTENTIAL. 1 TO 2 INCHES LOOKS POSSIBLE ACROSS SOUTHEAST
MINNESOTA AND NORTHEAST IOWA...AND UP TO A HALF INCH ALONG AND
SOUTH OF INTERSTATE 90 IN WESTERN WISCONSIN.

ON TUESDAY NIGHT...THE MODELS TRY TO HOLD ON SOME PRECIPITATION
ACROSS NORTHEAST IOWA AND SOUTHWEST WISCONSIN. THIS IS DUE TO A
WAVE IN THE SOUTHERN STREAM. THIS WAVE LOOKS TO BE RATHER
PROGRESSIVE SO LIMITED THE SNOW TO THE EVENING.

ON WEDNESDAY...THE MODELS ARE IN AGREEMENT THAT A NORTHERN STREAM
SHORT WAVE WILL MOVE THROUGH THE REGION. THE NAM HAS SOME VERY
WEAK CAPE /LESS THAN 100 J/KG/ AND 950-900 MB LAPSE RATES AROUND
8C/KM IN THE WAKE OF THIS SYSTEM. THIS WAS ENOUGH THAT IT ACTUALLY
GENERATED SOME SNOW SHOWERS ACROSS THE AREA. MEANWHILE THE OTHER
MODELS ARE TOO DRY TO GENERATE ANY PRECIPITATION. SINCE THIS IS A
NEW PHENOMENON IN THE NAM...KEPT THE FORECAST DRY.

ON LATE WEDNESDAY NIGHT AND THURSDAY...THE MODELS SHOW STRONG WARM
AIR ADVECTION WILL DEVELOP ACROSS THE AREA AHEAD OF YET ANOTHER
SHORT WAVE TROUGH. BUFKIT SOUNDINGS SATURATE THE AIR MASS BELOW
900 MB. HOWEVER THIS MOISTURE IS BELOW THE OMEGA...SO KEPT THE
FORECAST DRY ACROSS MUCH OF THE FORECAST AREA.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 109 PM CDT MON MAR 10 2014

VFR CONDITIONS TO PREVAIL INTO THIS EVENING. HOWEVER...LOW
PRESSURE MOVING INTO THE PLAINS WILL PUSH MVFR CLOUDS AND A
RAIN/SNOW MIX INTO THE KRST AROUND 10Z AND KLSE AROUND 11Z. LOOK
FOR THIS PRECIPITATION TO BECOME ALL SNOW IN THE 13-14Z TIME FRAME
WITH CONDITIONS RAPIDLY DETERIORATING INTO IFR/OCNL LIFR CATEGORY
AND LASTING THROUGH 18Z. RIGHT NOW...IT APPEARS 1-3 INCHES OF
SNOWFALL LOOKS LIKELY FOR THE KLSE/KRST TAF SITES.

&&

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

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...DAS