Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 071141
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
541 AM CST SUN FEB 7 2016

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 346 AM CST SUN FEB 7 2016

WATER VAPOR SATELLITE THIS MORNING SHOWS AN UPPER LEVEL LOW
FORMING IN THE VICINITY OF LAKE WINNIPEG. ONE SHORT WAVE TROUGH
WAS OVER NORTHERN MINNESOTA WITH ANOTHER DROPPING OUT OF SOUTHERN
MANITOBA INTO NORTH DAKOTA. THE UPPER LEVEL LOW IS EXPECTED TO
MOVE SOUTHEAST TOWARD LAKE SUPERIOR TODAY AS THE WAVE COMING OUT
OF MANITOBA DROPS QUICKLY SOUTHEAST INTO IOWA AND MISSOURI. AS
THIS WAVE THEN SWINGS EAST TONIGHT...THE UPPER LEVEL LOW IS
EXPECTED TO REFORM EAST OF LAKE MICHIGAN WITH THE REMAINS OF THE
MINNESOTA SHORT WAVE TROUGH THEN ROTATING AROUND THE BACK SIDE OF
THE UPPER LEVEL LOW AND ACROSS THE LOCAL AREA. AT THE SURFACE...AN
AREA OF LOW PRESSURE OVER SOUTHERN SASKATCHEWAN MOVES STEADILY
SOUTHEAST ALONG THE WARM FRONT AND REACHES LOWER MICHIGAN MONDAY.
THE COLD FRONT WITH THIS SYSTEM WILL SWING ACROSS THE LOCAL AREA
THIS EVENING AND USHER IN A SIGNIFICANT CHANGE.

THE 07.00Z MODELS ARE ALL IN GOOD AGREEMENT THAT WITH THE
MINNESOTA SHORT WAVE TROUGH STAYING TO THE NORTH OF THE AREA...THE
PRECIPITATION THIS MORNING WILL BE TIED TO THE WARM FRONT. SOME OF
THIS LIGHT PRECIPITATION COULD IMPACT NORTH CENTRAL WISCONSIN THIS
MORNING AND WILL SHOW JUST A SMALL CHANCE ACROSS THE NORTHERN
SECTIONS THROUGH THE MORNING. OTHERWISE...THE PRECIPITATION WILL
BE TIED TO BEING JUST AHEAD OF AND THE BEHIND THE COLD FRONT. AS
THE COLD FRONT COMES THROUGH THE MANITOBA SHORT WAVE TROUGH SHOULD
BE SLIDING ACROSS WITH A SHOT OF STRONG PV ADVECTION IN THE
500-300 MB LAYER. THE BEST QG CONVERGENCE WITH THIS WAVE LOOKS TO
REMAIN TO THE SOUTHEAST OF THE AREA...MORE INTO THE OHIO RIVER
VALLEY. A BAND OF WEAK FRONTOGENESIS IN THE 1000-700 MB LAYER WILL
COME THROUGH WITH THE COLD FRONT. ONCE THE COLD FRONT MOVES
THROUGH...THERE WILL BE SOME PERSISTENT VERTICAL MOTION AS THE
SHORT WAVE TROUGH FROM LAKE SUPERIOR APPROACHES AND MOVES THROUGH.
ONCE THE AREA OF COLD AIR ADVECTION RIGHT BEHIND THE FRONT MOVES
PAST...THE MODELS ARE INDICATING IT WILL BE REPLACED BY SOME WEAK
WARM AIR ADVECTION THAT HELPS TO PRODUCE AROUND 1 UBAR/S OF UP
GLIDE ON THE 280K SURFACE THROUGH THE REST OF THE NIGHT. THE LIFT
FROM THE SECONDARY SHORT WAVE TROUGH AND ISENTROPIC UP GLIDE
COMBINED WITH THE STRONG LOW LEVEL CYCLONIC FLOW...SHOULD BE
ENOUGH TO KEEP SOME LIGHT SNOW FALLING THROUGH THE NIGHT AND FOR
MUCH OF MONDAY AS WELL. ACCUMULATIONS THROUGH THIS PERIOD ARE NOT
EXPECTED TO BE A WHOLE LOT...MAYBE AROUND AN INCH IN THE SOUTHERN
SECTIONS TO ABOUT 2 INCHES FOR NORTH CENTRAL WISCONSIN. BASED ON
THESE SIGNALS...SLOWED DOWN THE ARRIVAL OF THE PRECIPITATION THIS
AFTERNOON TO BE CLOSER IN TIMING TO THE COLD FRONT SO THAT BY LATE
AFTERNOON...THE FAR SOUTHEAST SECTIONS SHOULD STILL BE DRY WITH
ABOUT A 60 PERCENT CHANCE OF LIGHT SNOW ACROSS THE NORTHWEST
SECTIONS. THESE CHANCES THEN INCREASE INTO THE 90 PERCENT RANGE
FOR THE ENTIRE AREA TONIGHT. STILL EXPECTING SOME LIGHT SNOW FOR
MOST OF THE AREA INTO MONDAY SO INCREASED THESE CHANCES INTO THE
70 TO 80 PERCENT RANGE MONDAY MORNING AND 60 TO 70 PERCENT FOR
MONDAY AFTERNOON BEFORE THEY REALLY START TO DROP OFF MONDAY NIGHT
INTO TUESDAY AS THE FORCING MOVES AWAY FROM THE AREA AND THE
CYCLONIC FLOW RELAXES.

AS FOR THE WINDS AND THE POTENTIAL BLIZZARD CONDITIONS...THE
07.00Z MODELS REALLY HAVE NOT CHANGED MUCH FROM THIS TIME LAST
NIGHT. THE AXIS OF STRONGEST WINDS AT 850 MB...WHICH IS AROUND 50
KNOTS...REMAINS PRIMARILY TO THE WEST OF THE AREA. THE STRONGEST
COLD AIR ADVECTION WILL OCCUR THIS EVENING AND IS THEN REPLACED BY
WARM AIR ADVECTION FOR LATE TONIGHT THROUGH MUCH OF MONDAY. THE
MOST FAVORABLE LAPSE RATES IN THE 1000-850 MB LAYER WILL ALSO BE
THIS EVENING AND THEN THESE START TO LOWER AND FALL BELOW 8 C/KM
EXCEPT FOR THE FAR SOUTHWEST SECTION BY 12Z MONDAY. THE 07.00Z NAM
BUFKIT SOUNDING FOR KRST SHOWS THE BEST LOW LEVEL LAPSE RATES JUST
BEHIND THE COLD FRONT TONIGHT WITH A 3 HOUR PERIOD WHERE THESE ARE
IN THE 9-10 C/KM RANGE BUT THEN ARE GENERALLY 8.5 C/KM OR LESS FOR
THE REST OF THE NIGHT. THERE CONTINUES TO BE A LACK OF A STRONG
SUBSIDENCE SIGNAL IN THE SOUNDINGS SO HAVE SERIOUS CONCERNS THAT
THE 40 KNOT WINDS SHOWN AT THE TOP OF THE MIXED LAYER WILL HAVE A
TOUGH TIME CONSISTENTLY GETTING DOWN TO THE SURFACE. THE LACK OF
SUBSIDENCE MAKES SENSE GIVEN THE APPROACH OF THE SECONDARY SHORT
WAVE TROUGH AND THE WARM AIR ADVECTION/ISENTROPIC UP GLIDE THAT
DEVELOPS OVERNIGHT. FARTHER TO THE SOUTHWEST AT KMCW...THE SIGNALS
ARE BETTER FOR THE WINDS TO GET MIXED DOWN. THERE IS A GENERAL
SUBSIDENT SIGNAL BEHIND THE FRONT...BUT IT IS NOT ALL THAT STRONG
AND LOOKS TO BE AROUND 2 UBAR/S OR SO. THERE IS NO DOUBT THAT IT
IS GOING TO BE WINDY/GUSTY BEHIND THE FRONT AND THAT THERE WILL BE
SOME BLOWING AND DRIFTING SNOW...BUT THE QUESTION STILL REMAINS
HOW MUCH WILL ACTUALLY OCCUR. THERE WILL BE SOME FRESH SNOW TO
MOVE AROUND THAT SHOULD BE PRETTY LIGHT AND FLUFFY THAT WILL
PRODUCE SOME VISIBILITY RESTRICTIONS WHEN IT GETS LOFTED. THE
CONDITION OF THE EXISTING SNOW PACK IS STILL A CONCERN. THE
EVENING SHIFT TOOK THE INITIATIVE TO MAKE SOME PHONE CALLS TO THE
WESTERN SECTIONS WITH THE DODGE COUNTY EM REPORTING THAT THE SNOW
PACK DOES HAVE A CRUST TO IT...BUT THAT THE VERY TOP PART IS STILL
AVAILABLE TO MOVE AS THERE WAS SOME DRIFTING SATURDAY WITH WINDS
OF 20 KNOTS OR LESS. THIS REPORT INDICATES THERE WILL BE SOME
ADDITIONAL SNOW AVAILABLE TO BE MOVED...BUT THE CRUSTING IS A
CONCERN AND IF THE WINDS WILL BE ABLE TO BREAK THROUGH THIS OR
NOT.

THE OUTPUT FROM THE EXPERIMENTAL BLOWING SNOW GRIDS STILL
INDICATES THAT WITHOUT ANY FALLING SNOW...THE PROBABILITIES FOR A
TRUE BLIZZARD ARE VERY LOW. WHERE THESE PROBABILITIES DO INCREASE
SOME IS STILL OVER THE VERY FAR SOUTHWEST SECTIONS OF THE FORECAST
AREA. WHEN THE CHANCES FOR FALLING SNOW IS THROWN INTO THE
EQUATION...THE PROBABILITIES FOR A BLIZZARD DO INCREASE ACROSS THE
WESTERN SECTIONS INTO THE RANGE WHERE OCCASIONAL BLIZZARD
CONDITIONS MIGHT OCCUR IN THE RURAL AREAS. PUTTING THIS ALL
TOGETHER...THE CONFIDENCE IN A TRUE BLIZZARD OCCURRING STILL
REMAINS RATHER LOW. FEEL GOOD THAT THERE WILL BE SHORT PERIODS
WHEN BLIZZARD LIKE CONDITIONS WILL OCCUR WITH LOW VISIBILITIES AND
SOME IMPACTS TO THE DRIVING CONDITIONS. WHETHER THESE WILL PERSIST
LONG ENOUGH TO HAVE SIGNIFICANT IMPACTS REMAINS TO BE SEEN. WITH
THE PREVIOUSLY ISSUED BLIZZARD WATCH AND NO SUBSTANTIAL CHANGE IN
THE MODEL DATA...FEEL THERE REALLY IS NO OTHER OPTION BUT TO GO
WITH A BLIZZARD WARNING WITH A WINTER WEATHER ADVISORY EAST TO THE
MISSISSIPPI RIVER TO COVER THE AREAS WHERE THE BLOWING SNOW IS
MOST LIKELY TO OCCUR. HAVE COLLABORATED THE STARTING AND ENDING
TIMES WITH NEIGHBORING OFFICES AS MUCH AS POSSIBLE AND WILL START
BOTH THE BLIZZARD WARNING AND WINTER WEATHER ADVISORY AT 7 PM THIS
EVENING. THE WINDS WILL BE DECREASING FROM NORTH TO SOUTH DURING
THE DAY MONDAY SO WILL END THE HEADLINES ACROSS SOUTHEAST
MINNESOTA AT NOON WHILE CONTINUING THEM UNTIL 6 PM FOR NORTHEAST
IOWA...BUT THIS COULD END UP BEING A LITTLE LONGER THAN NEEDED.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 346 AM CST SUN FEB 7 2016

THIS PERIOD NOW LOOKS TO BE DRY BUT ON THE COLD SIDE. THE UPPER
LEVEL RIDGE LOOKS TO AMPLIFY OVER THE ROCKIES PUSHING WELL
NORTHWARD INTO CANADA. AN UPPER LEVEL LOW LOOKS TO BE NEARLY
STATIONARY ON THE SOUTHEAST SIDE OF HUDSON BAY AND WITH THIS
PATTERN...ANY SHORT WAVE TROUGHS TOPPING THE RIDGE SHOULD REMAIN
NORTH OF THE UPPER MIDWEST AS THEY DROP INTO THE MEAN TROUGH WITH
THE UPPER LEVEL LOW. HIGH TEMPERATURES LOOK TO BE STUCK IN THE
TEENS FOR MUCH OF THE PERIOD WITH OVERNIGHT LOWS IN THE SINGLE
DIGITS ABOVE AND BELOW ZERO COMMON.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 541 AM CST SUN FEB 7 2016

VFR CEILINGS AND VISIBILITIES WILL CONTINUE THROUGH MID AFTERNOON
AND THEN THE CEILINGS WILL BECOME IFR/MVFR BEHIND A STRONG COLD
FRONT. VISIBILITIES WILL REDUCED AT TIMES TO 3 MILES OR LESS IN
SNOW SHOWERS AND BLOWING SNOW AT KRST STARTING AT 07.23Z...AND AT
KLSE AFTER 08.01Z. WEST WINDS WILL REMAIN IN THE 15 TO 25 KNOT
RANGE THROUGH THIS AFTERNOON...AND THEN BECOME NORTHWEST AND
INCREASE INTO THE 20 TO 30 KNOT RANGE WITH GUSTS UP TO 35 KNOTS
TONIGHT.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...BLIZZARD WARNING FROM 7 PM THIS EVENING TO NOON CST MONDAY FOR
     MNZ086-094.

     WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO NOON CST
     MONDAY FOR MNZ079-087-088-095-096.

IA...BLIZZARD WARNING FROM 7 PM THIS EVENING TO 6 PM CST MONDAY FOR
     IAZ008-009-018-019.

     WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 6 PM CST
     MONDAY FOR IAZ010-011-029-030.

&&

$$

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


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