Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 020525
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1125 PM CST SUN MAR 1 2015

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 324 PM CST SUN MAR 1 2015

CHALLENGES SURROUND WINTER STORM MONDAY NIGHT INTO TUESDAY. EXACT
TRACK AND TIMING OF SURFACE LOW STILL A BIT UNCERTAIN...IMPACTING
SNOW AMOUNTS AND WIND STRENGTH/BLOWING SNOW POTENTIAL. WILL LEAN
ON AN EQUAL BLEND OF THE 01.12Z GFS/ECMWF GUIDANCE...WITH BOTH
MODELS TRENDING SLIGHTLY TO THE NORTH AND SLOWING THE EASTWARD
PROGRESS OF THE SURFACE LOW.

FOR TONIGHT...BROAD SURFACE HIGH WILL DRIFT ACROSS THE UPPER MS
RIVER VALLEY RESULTING IN LIGHT WESTERLY WINDS AND CLEARING SKIES.
TEMPERATURES WILL DROP INTO THE SINGLE DIGITS ABOVE ZERO. PLEASANT
CONDITIONS TO CONTINUE THROUGH MONDAY AS SURFACE HIGH MOVES INTO
THE OHIO RIVER VALLEY. THIS ALLOWS MID-HIGH LEVEL CLOUDS TO
INCREASE FROM SOUTHWEST TO NORTHEAST ALONG WITH INCREASING
SOUTHERLY WINDS. AFTERNOON HIGHS WILL RISE INTO THE MID-UPPER 20S.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 324 PM CST SUN MAR 1 2015

MONDAY NIGHT THROUGH TUESDAY...A SHORT-WAVE EJECTS FROM THE
CENTRAL CA COAST INTO THE UPPER MIDWEST AND PHASES WITH A CLOSED
LOW ACROSS THE SOUTHERN CANADIAN PRAIRIES. THE FIRST WAVE OF WARM
AIR ADVECTION-INDUCED LIGHT SNOW LIFTS NORTHWARD ACROSS SOUTHEAST
MN AND WESTERN WI MONDAY EVENING. MEANWHILE...MUCH STRONGER WARM
AIR ADVECTION AND ISENTROPIC LIFT ON THE 280K SURFACE INCREASES
ACROSS IA AND LIFTS INTO THE SOUTHERN FORECAST AREA BY 03.12Z.
ADDITIONAL SNOW DEVELOPS TUESDAY MORNING ALONG STRONG 850 TO 700
HPA FRONTOGENESIS ASSOCIATED WITH THE CANADIAN WAVE/COLD FRONT
ACROSS SOUTHEAST SD INTO CENTRAL MN. BY 03.18Z...WARM AIR
ADVECTION SNOW FROM THE SOUTH AND COLD FRONTAL SNOW FROM THE
NORTH COLLIDE ACROSS MUCH OF SOUTHERN MN/NORTHERN IA AND ALL OF
WI. AS A RESULT...THERE COULD BE PERIODS OF MODERATE TO EVEN HEAVY
SNOW TUESDAY MORNING...IMPACTING THE MORNING COMMUTE.

SURFACE LOW AT 03.18Z SOMEWHERE NEAR THE TRI-STATE BORDER AREA
WILL QUICKLY LIFT TO THE NORTH AND EAST TUESDAY AFTERNOON WITH ALL
SNOW EXITING THE IMMEDIATE REGION NO LATER THAN 04.00Z. WHEN ALL
IS SAID AND DONE...LOOK FOR 2 TO 5 INCHES OF SNOW ACROSS THE
ENTIRE UPPER MS RIVER VALLEY WITH THE HIGHER AMOUNTS (4 TO 5
INCHES) ACROSS CENTRAL WI. OVERALL...A SOLID WINTER WEATHER
ADVISORY EVENT. FOR NOW KEPT ALL PRECIPITATION AS SNOW...BUT IF
NORTHWARD SHIFTS IN THE LOW TRACK CONTINUE...MAY NEED TO INTRODUCE
A WINTRY MIX ACROSS THE SOUTHERNMOST FORECAST AREA GIVEN
INCREASING MAXIMUM TEMPERATURES ALOFT.

ONCE THE SNOW ENDS...ATTENTION QUICKLY TURNS TO STRONG WINDS IN
THE WAKE OF THE COLD FRONT. GFS/ECMWF BOTH SHOW A NARROW CORRIDOR
OF 40 KT WINDS AT 0.5 KM DEVELOPING ALONG A LINE FROM WILMAR MN TO
MARSHALLTOWN IA BY 04.00Z. SOME OF THESE STRONGER WINDS DO PUSH
INTO THE WESTERN FORECAST AREA...ESPECIALLY WEST OF THE HWY 63
CORRIDOR. WITH TEMPERATURES TUESDAY GENERALLY IN THE 20S TO THE
LOWER 30S...SNOW RATIOS FROM SNOW THAT FALLS EARLIER IN THE DAY
EXPECTED TO BE 8-12:1. IN ADDITION...SLIGHTLY SLOWER MODEL
SOLUTIONS DELAY STRONGEST WINDS UNTIL LATE TUESDAY AFTERNOON/
EVENING. WITH WETTER SNOW AND IDEAL LOW-LEVEL LAPSE RATES IN
QUESTION DUE TO TIMING...CAN WINDS INCREASE TO A LEVEL THAT
GENERATE BLIZZARD CONDITIONS? THAT IS THE QUESTION. AFTER
COLLABORATING WITH NEIGHBORING OFFICES...WILL HOLD OFF ON A
BLIZZARD WATCH FOR NOW...BUT DEFINITELY SOMETHING TO WATCH
CLOSELY. STILL EXPECT PERIODIC NORTHWEST WIND GUSTS FROM 35 TO 40
MPH WHICH WILL CAUSE AREAS OF REDUCED VISIBILITY IN BLOWING/
DRIFTING SNOW LATE TUESDAY ACROSS NORTHEAST IA/SOUTHEAST MN WEST
OF THE MS RIVER. THIS WILL IMPACT THE EVENING COMMUTE. WILL
HIGHLIGHT POTENTIAL IN THE HWO/WEATHER STORY.

THE REST OF THE WEEK WILL BE DRY...BUT COLD WEDNESDAY/THURSDAY IN
THE WAKE OF TUESDAY/S COLD FRONT WITH HIGHS IN THE SINGLE DIGITS
TO MID TEENS ABOVE ZERO. EXPECT A WARMING TREND FRIDAY INTO THE
NEXT WEEKEND AS NORTHWEST FLOW ALOFT FLATTENS A BIT...ALLOWING
WARMER AIR UNDERNEATH WESTERN CONUS RIDGE TO SPILL INTO THE UPPER
MIDWEST. HIGHS FOR THE END OF THE WEEK LIKELY TO REACH INTO THE
LOWER TO MID 30S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1125 PM CST SUN MAR 1 2015

VFR CONDITIONS PREVAIL LATE THIS EVENING AS SHORT WAVE PASSES ACROSS
WESTERN GREAT LAKES. BULK OF EARLIER CLOUDS HAD DISSIPATED FROM
DIURNAL NATURE BUT WAVE STILL HAS SOME HIGHER BASED STRATUS MOVING
THROUGH AREA NORTH OF INTERSTATE 90...WHICH COULD BRIEFLY HIT KLSE.
OTHERWISE EXPECT MOSTLY CLEAR CONDITIONS THRU DAYBREAK MONDAY.

ALREADY SEEING SOME HIGH CLOUDS STREAM IN FROM ROCKIES FROM
SOUTHWEST LOW...AND WITH SHORT WAVE EJECTING OUT OF THIS FLOW NEXT
24 HOURS...EXPECT THIS CLOUD COVER TO GRADUALLY INCREASE FROM WEST
TO EAST MONDAY. WILL ALSO SEE A RESPONSE WITH SOUTHERLY FLOW
REDEVELOP. WILL STAY VFR THROUGH 03.06Z BUT AS WARM AIR ADVECTION
LEADS TO BROAD LIFT ACROSS AREA...PRECIPITATION WILL BREAK OUT
RAPIDLY AFTER THIS TAF SET...AND COULD IMPACT A FAIRLY WIDE AREA
GOING INTO TUESDAY MORNING.

&&

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

$$

SHORT TERM...ROGERS
LONG TERM...ROGERS
AVIATION...SHEA


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