Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 242015
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
315 PM CDT TUE MAR 24 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 314 PM CDT TUE MAR 24 2015

WATER VAPOR SATELLITE THIS AFTERNOON SHOWS TWO SHORT WAVE TROUGHS
OVER THE REGION. THE SOUTHERN WAVE WAS OVER SOUTHERN NEBRASKA AND
NORTHERN KANSAS WITH THE NORTHERN WAVE OVER NORTH DAKOTA. THERE
HAS NOT BEEN MUCH CHANGE WITH THE HANDLING OF THESE WAVES IN THE
24.12Z MODELS. THE SOUTHERN WAVE IS STILL EXPECTED TO LIFT
NORTHEAST ACROSS THE REGION TONIGHT AS A POSITIVE TILT OPEN WAVE
TROUGH. THIS WILL ALLOW FOR A QUICK NORTHEAST MOVEMENT OF THE WAVE
BUT WITH A STRONG ROUND OF FORCING AS IT COMES ACROSS. THE WAVE IS
EXPECTED TO PRODUCE MODERATE TO STRONG PV ADVECTION IN THE 500-300
MB LAYER FROM ABOUT 00Z THROUGH 09Z OR SO ALONG WITH MODERATE QG
CONVERGENCE IN THE 850-300 MB LAYER. THIS IS ALSO ABOUT THE SAME
TIMING WHEN THE LEFT EXIT REGION OF THE UPPER LEVEL JET WILL BE
OVER THE AREA TO ENHANCE THE FORCING FROM THE SHORT WAVE TROUGH.
IN THE LOW LEVELS...THE MODELS HAVE CONVERGED ON A TRACK FOR THE
SURFACE LOW TAKING IT FROM THE KANSAS CITY AREA NORTHEAST TOWARD
CHICAGO TONIGHT. WITH THIS TRACK...SOME WARM AIR ALOFT WILL STILL
GET BROUGHT NORTH INTO THE AREA...BUT MUCH LESS THAN WITH PREVIOUS
MODEL RUNS. THE GENERAL CONSENSUS NOW IS THAT THE WARM LAYER MOST
LIKELY WILL NOT BE ENOUGH THIS EVENING TO ALLOW FOR COMPLETE
MELTING BUT ENOUGH THAT THERE COULD BE SOME PARTIAL MELTING FOR
THE POSSIBILITY OF SLEET. BASED ON THIS...EXPECT THE PRECIPITATION
TYPES THIS EVENING TO BE RAIN AND SLEET OR A RAIN/SNOW/SLEET MIX
GOING OVER TO MAINLY ALL SNOW. DURING THE OVERNIGHT HOURS...THERE
IS STILL THE POTENTIAL FOR THE ICE TO BE LOST IN THE CLOUDS
LEADING TO THE POSSIBILITY OF FREEZING DRIZZLE. THE CONFIDENCE IN
THIS OCCURRING REMAINS LOW AS THE FORCING WILL BE DROPPING OFF
RAPIDLY WITH THE BUFKIT SOUNDINGS SHOWING THE LOST OF ICE TO BE
ABOUT THE SAME TIME AS WHEN SUBSIDENCE SETS IN. WILL CONTINUE TO
CARRY THE CHANCE OF SOME FREEZING DRIZZLE ON THE BACK EDGE OF THE
PRECIPITATION WITH JUST A GLAZING OF ICE ACCUMULATION IF IT DOES
OCCUR. GENERALLY EXPECTING SNOW ACCUMULATIONS TO BE IN THE 2 TO 3
INCH RANGE FOR LOCATIONS NORTH OF A LINE FROM KOLZ TO THE
WISCONSIN RIVER.

THE NORTHERN SHORT WAVE TROUGH WILL MOVE ACROSS THE NORTHERN
SECTIONS OF THE UPPER MIDWEST WEDNESDAY WITH A SECONDARY WAVE
COMING ACROSS THE CENTRAL MISSISSIPPI RIVER VALLEY. THE BEST
FORCING FROM THE NORTHERN WAVE IS EXPECTED TO STAY PRIMARILY NORTH
OF THE AREA...BUT COULD STILL BE CLOSE ENOUGH TO KEEP A LITTLE BIT
OF LIGHT PRECIPITATION GOING ACROSS THE NORTHERN SECTIONS OF THE
FORECAST AREA THROUGH THE DAY WEDNESDAY. AS THE SECONDARY SHORT
WAVE TROUGH ROTATES ACROSS THE REGION...IT SHOULD PRODUCE SOME
WEAK PV ADVECTION ACROSS THE AREA WEDNESDAY AFTERNOON. THIS IS
ALSO WHEN THE AREA WILL COME UNDER THE RIGHT ENTRANCE REGION OF
THE UPPER LEVEL JET AND HAVE ADDED IN A SMALL CHANCE FOR SOME
LIGHT RAIN ACROSS THE SOUTHERN SECTIONS WITH THIS FEATURE.

.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 314 PM CDT TUE MAR 24 2015

THE MODELS REMAIN CONSISTENT IN SHOWING NORTHWEST FLOW DEVELOPING
OVER THE UPPER MIDWEST IN THE WAKE OF THE SYSTEM THAT MOVES
THROUGH TONIGHT/WEDNESDAY. A PACIFIC SHORT WAVE TROUGH IS EXPECTED
TO TOP THIS RIDGE AND DROP ACROSS THE GREAT LAKES REGION SATURDAY
NIGHT AND SUNDAY. FOR NOW...THE MODELS HAVE SHIFTED TO THE
SOUTHWEST SOME WITH THE TRACK OF THIS WAVE BRINGING SOME BETTER
FORCING TO THE AREA AS THE ASSOCIATED COLD FRONT MOVES THROUGH AT
THE SURFACE. BASED ON THIS...THE PRECIPITATION CHANCES HAVE BEEN
INCREASED INTO THE 30 TO 40 PERCENT RANGE FOR A LIGHT RAIN/SNOW
MIXTURE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1230 PM CDT TUE MAR 24 2015

TAF SITES SHOULD REMAIN IN VFR UNTIL THE RAIN AND SNOW BEGINS
LATER THIS EVENING BRINGING IFR CONDITIONS FOR MUCH OF THE LATE
EVENING INTO THE OVERNIGHT HOURS. MOST OF THE PRECIPITATION SHOULD
FALL AS SNOW...HOWEVER THERE COULD BE A MIX OF RAIN AND SNOW
DURING THE ONSET AT BOTH LOCATIONS. CONFIDENCE NOT HIGH ENOUGH AT
THIS TIME TO INCLUDE AT KRST BUT WAS INCLUDED AT KLSE. WINDS WILL
MAINLY BE OUT OF THE SOUTHEAST THOUGH THE OVERNIGHT HOURS WITH A
WIND SHIFT MID MORNING AT BOTH SITES. LOOK FOR KRST TO GUST
WEDNESDAY MORNING INTO THE AFTERNOON AS A COLD FRONT SWINGS
THROUGH.


&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 7 AM CDT
     WEDNESDAY FOR WIZ032>034-041-042-053.

     WINTER WEATHER ADVISORY FROM 1 AM TO 10 AM CDT WEDNESDAY FOR
     WIZ017-029-043-044.

MN...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM CDT
     WEDNESDAY FOR MNZ086-087-094-095.

     WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 7 AM CDT
     WEDNESDAY FOR MNZ079-088-096.

IA...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM CDT
     WEDNESDAY FOR IAZ008>010-018-019.

     WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 7 AM CDT
     WEDNESDAY FOR IAZ011.

&&

$$

SHORT TERM...04
LONG TERM...04
AVIATION...CC


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