Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 281158
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
558 AM CST SAT FEB 28 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 305 AM CST SAT FEB 28 2015

THE MAIN FOCUS TODAY INTO TONIGHT IS ON THE DECREASING CHANCES FOR
AN ACCUMULATING SNOW TONIGHT.

CURRENTLY...A BROAD SURFACE RIDGE OF HIGH PRESSURE IS IN PLACE
ACROSS THE EASTERN HALF OF THE CONUS. THE UPPER MISSISSIPPI RIVER
VALLEY REGION IS STARTING TO GET INTO THE WESTERN PERIPHERY OF
THIS RIDGE WITH WINDS COMING AROUND TO THE SOUTH. SOME LOWER WIND
CHILLS IN THE 20 TO 30 BELOW ZERO RANGE REMAIN IN PORTIONS OF
NORTHEAST IOWA AND SOUTHEAST MINNESOTA...SO WILL ALLOW THE
ADVISORY TO CONTINUE.

AS THE RIDGE CONTINUES TO DRIFT TO THE EAST TODAY...THE NEXT
SYSTEM WILL MOVE INTO THE REGION WITH INCREASING CLOUD COVER
COMING IN AHEAD OF A 700MB TROUGH THIS AFTERNOON. THE TREND IN THE
28.00Z MODELS CONTINUES TO BE WITH KEEPING THE MAIN BAROCLINIC
ZONE OFF TO THE SOUTH OF THE REGION WHICH SHOULD KEEP ANY SNOW
SOUTH AS WELL. 28.00Z NAM/GFS FORECAST SOUNDINGS SUGGEST THAT
THERE COULD BE SOME SATURATION THAT OCCURS WITH WEAK LIFT AHEAD OF
A SURFACE COLD FRONT TONIGHT. HAVE DROPPED MUCH OF THE SNOW
ACCUMULATIONS AND JUST PUT IN FLURRIES STARTING TONIGHT.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 305 AM CST SAT FEB 28 2015

FLURRIES SHOULD CONTINUE INTO SUNDAY AS CYCLONIC FLOW REMAINS IN
PLACE FROM THE SURFACE ALOFT TO 250MB. THESE FLURRIES SHOULD DROP
OFF SUNDAY NIGHT AS A RIDGE OF HIGH PRESSURE MOVES IN FROM THE
WEST.

THE MAIN FEATURE OF NOTE THROUGH THE FORECAST PERIOD IS ON THE
POTENTIAL FOR A WINTER STORM ON TUESDAY. CONFIDENCE CONTINUES TO
GROW AS ANOTHER ROUND OF MODEL RUNS SHOW A DEEPENING SURFACE
LOW/MID LEVEL TROUGH COMING THROUGH FROM LATE MONDAY NIGHT THROUGH
EARLY WEDNESDAY MORNING. THIS IDEA IS FAIRLY CONSISTENT AMONGST
THE GFS/ECMWF/GEM THOUGH THERE ARE SOME DIFFERENCES IN SOME OF THE
DETAILS SUCH AS QPF/WARM LAYER/ARRIVAL OF SNOW. THE 28.00Z GFS IS
THE HIGHEST WITH QPF THROUGH THE EVENT WITH IT DROPPING ABOUT 0.60
TO 0.90 INCHES OF LIQUID ACROSS THE REGION WHILE THE GEM/ECMWF IS
MORE TAME AT ABOUT 0.40 INCHES. THE GFS IS ALSO THE FASTEST WITH
SATURATING OUT THE COLUMN AND THE DEVELOPMENT OF SNOW MONDAY
EVENING AS OPPOSED TO THE GEM/ECMWF WHICH HOLD OFF UNTIL AFTER
MIDNIGHT. THE GFS ALSO IS FURTHER NORTH WITH THE WARM LAYER MAKING
IT INTO SOUTHERN WISCONSIN...WHICH WOULD CAUSE A CHANGE OVER TO A
WINTRY MIX/RAIN WHILE THE GEM/ECMWF APPEAR TO KEEP IT COLD ENOUGH
TO KEEP THE PRECIPITATION TYPE AS SNOW THROUGHOUT IN FAR
SOUTHWEST WISCONSIN/NORTHEAST IOWA. THE TRACK/TIMING OF THE
SURFACE LOWS BETWEEN THESE MODELS ARE FAIRLY SIMILAR WITH A
NORTHWEST KANSAS TO NORTHWEST MISSOURI TO CENTRAL LAKE MICHIGAN
PATH. WHILE SNOW TOTALS WILL HAVE AN IMPACT ON THE AREA...THE
STRONG WINDS WILL ALSO BE AN ISSUE AS A TIGHT PRESSURE GRADIENT
DEVELOPS ALONG THE BACK SIDE OF THE SYSTEM WHICH COULD CAUSE SOME
BLOWING SNOW. DETAILS WILL BE HASHED OUT OVER THE NEXT FEW DAYS
BUT...AS HAS BEEN SEEN WITH RECENT SNOW EVENTS...THE PATH CAN
CHANGE QUITE A BIT LEADING UP TO THE EVENT.

BEHIND THIS SYSTEM...ANOTHER ROUND OF COLD AIR WILL BE DROPPING
DOWN INTO THE REGION FOR WEDNESDAY/THURSDAY FOLLOWED BY WHAT
ACTUALLY LOOKS TO AT LEAST BE A BRIEF WARMING TREND GOING INTO
FRIDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 558 AM CST SAT FEB 28 2015

VFR CONDITIONS ARE EXPECTED THROUGH EARLY THIS AFTERNOON THEN PLAN
ON A GRADUAL INCREASE IN CLOUD COVER AS A TROUGH APPROACHES FROM
THE NORTHERN PLAINS. CONDITIONS WILL LOWER TO MVFR THIS EVENING
AS THE TROUGH MOVES IN AND BRINGS A STRATUS DECK ACROSS THE TAF
SITES. PLAN ON CEILINGS LOWERING INTO THE 1500 TO 2500 FT RANGE.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...WIND CHILL ADVISORY UNTIL 9 AM CST THIS MORNING FOR MNZ086-087-
     094-095.

IA...WIND CHILL ADVISORY UNTIL 9 AM CST THIS MORNING FOR IAZ008>010-
     018-019-029-030.

&&

$$

SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...WETENKAMP


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