Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 230940
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
340 AM CST SUN NOV 23 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 340 AM CST SUN NOV 23 2014

CHALLENGES INCLUDE RAIN CHANCES AND AMOUNTS TODAY...THE CHANGE OVER
TO SNOW TONIGHT AND THEN SNOW PLACEMENT/AMOUNTS AND BLOWING SNOW
POTENTIAL LATE TONIGHT THROUGH MONDAY. FORECAST CONFIDENCE IS BELOW
AVERAGE WITH MODELS HAVING PROBLEMS RESOLVING HOW THE NORTHERN AND
SOUTHERN STREAM WAVES WILL CONVERGE AND INTERACT TONIGHT THROUGH
MONDAY ACROSS THE UPPER MIDWEST.

23.09Z WATER VAPOR LOOP SHOWS A CLOSED LOW ACROSS SOUTHERN
SASKATCHEWAN AND A SECONDARY OPEN WAVE DRAPED ACROSS THE SOUTHERN
PLAINS. AT THE SURFACE...THE PRIMARY LOW CENTER IS ACROSS SOUTHEAST
SASKATCHEWAN WITH A STATIONARY FRONT EXTENDING TO THE SOUTHEAST
ACROSS EASTERN ND. THE COLD FRONT DROPS SOUTH ACROSS EASTERN SD INTO
CENTRAL NE AND THE WARM FRONT EXTENDS TO THE EAST ACROSS CENTRAL MN
INTO WEST CENTRAL WI. EXPECT PERIODS OF LIGHT TO MODERATE RAIN TO
RAPIDLY DEVELOP LATER THIS MORNING IN THE WARM SECTOR OF THIS SYSTEM
WITHIN REGION OF BROAD ISENTROPIC LIFT AND STRONG MOISTURE ADVECTION
AHEAD OF THE APPROACHING COLD FRONT. EXPECT ACCUMULATING RAINFALL
ACROSS THE ENTIRE FORECAST AREA TODAY...BUT HIGHEST AMOUNTS WILL
FALL ACROSS NORTHEAST IA INTO SOUTHWEST WI WHERE OVER 0.75 INCHES
ARE POSSIBLE. AMOUNTS WILL DROP OFF TO AROUND A TENTH FARTHER NORTH
AND WEST. TEMPERATURES WILL BE VERY WARM TODAY WITH AFTERNOON HIGHS
IN THE UPPER 40S TO LOWER 50S. WHAT REMAINING SNOWPACK IS LEFT WILL
MELT AND CAUSE ADDITIONAL AREAS OF FOG...ESPECIALLY ACROSS NORTH
CENTRAL WI. A STRONG COLD FRONT SWEEPS ACROSS THE UPPER MISSISSIPPI
RIVER VALLEY TONIGHT. PRECIP WILL QUICKLY CHANGE FROM RAIN TO SNOW
FROM WEST TO EAST BETWEEN 24.06Z AND 24.12Z WITH TEMPERATURES
DROPPING BELOW FREEZING.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 340 AM CST SUN NOV 23 2014

23.00Z MODELS DIVERGE INTO TWO DISTINCT CAMPS CONCERNING PLACEMENT
AND AMOUNTS OF HIGHEST SNOWFALL ON MONDAY. THIS IS MOST APPARENT
LOOKING AT 500 HPA HEIGHTS. AS THE SOUTHERN STREAM WAVE LIFTS
NORTHEASTWARD AND BEGINS TO INTERACT WITH THE CLOSED LOW ACROSS
THE SOUTHERN CANADIAN PRAIRIES...THE GFS/ECMWF DEVELOP A SECONDARY
LOW ACROSS EASTERN LAKE SUPERIOR BY 24.12Z AND THEN QUICKLY LIFT
IT INTO EASTERN ONTARIO BY 25.00Z. THE NAM/GEM ON THE OTHER HAND
DEVELOP THE SECONDARY LOW BY 24.18Z ACROSS CENTRAL WI AND ARE MUCH
SLOWER LIFTING IT INTO CANADA. AS A RESULT...THE GFS/ECMWF
DEFORMATION SNOW BAND SETS UP ACROSS EASTERN IA/NORTHERN
IL/SOUTHERN WI WITH MINIMAL ACCUMULATIONS ACROSS THE FORECAST
AREA. THE NAM/GEM DEFORMATION SNOW BAND IS FARTHER NORTH AND
WEST...DROPPING AS MUCH AS 4 TO 6 INCHES OR MORE ACROSS A LARGE
SWATH OF THE FORECAST AREA. THESE DIFFERENCES ARE FURTHER
ILLUSTRATED LOOKING AT THE 23.21Z SREF PLUME FOR LA CROSSE WITH
ITS MEMBERS GENERATING ANYWHERE FROM 0 TO 17 INCHES OF SNOW
THROUGH TUESDAY MORNING.

CONFIDENCE CERTAINLY NOT HIGH ENOUGH TO HOIST A WINTER STORM WATCH
AND WILL INSTEAD FOLLOW A MIDDLE-OF-THE-ROAD APPROACH WITH MOST
AREAS SEEING SOME SNOW ACCUMULATION THROUGH MONDAY NIGHT. THINK
HIGHEST AMOUNTS BETWEEN 3 TO 5 INCHES WILL FALL EAST OF THE
MISSISSIPPI RIVER CLOSEST TO THE DEEPEST MOISTURE AND STRONGEST LIFT
NEAREST THE TRACK OF THE MID-LEVEL CIRCULATION. ELSEWHERE...1 TO 3
INCHES ARE POSSIBLE. WILL HIGHLIGHT SNOW POTENTIAL AND UNCERTAINTY
IN A SPS...BUT WILL NEED TO WATCH THIS SYSTEM CAREFULLY AS ANY
SHIFT TOWARDS ONE OF THE TWO MODEL SCENARIOS COULD DRASTICALLY
ALTER SNOWFALL FORECAST. OF GREATER CERTAINTY MONDAY ARE STRONG
NORTHWEST WINDS WITH GUSTS AS HIGH AS 35 MPH ACROSS PORTIONS OF
SOUTHEAST MN AND NORTHEAST IA. BLOWING SNOW A POSSIBILITY REGION-
WIDE...BUT WILL BE DEPENDENT ON AREAS THAT RECEIVE THE MOST
ACCUMULATION.

TUESDAY INTO THE UPCOMING THANKSGIVING HOLIDAY WEEKEND WILL BE
MARKEDLY COLDER WITH DAILY HIGHS GENERALLY IN THE UPPER TEENS AND
20S. THE EXCEPTION BEING WEDNESDAY WHEN HIGHS WILL BE IN THE LOWER
30S AS THE THERMAL PROFILE BRIEFLY WARMS AHEAD OF AN APPROACHING
SHORT-WAVE ALOFT. WITH THIS WAVE...HOWEVER...COMES THE NEXT CHANCE
FOR ACCUMULATING SNOWFALL TUESDAY NIGHT THROUGH WEDNESDAY. AT THIS
TIME...A FEW INCHES OF SNOW ARE POSSIBLE...BUT PERSONS WITH
HOLIDAY TRAVEL PLANS SHOULD PAY CLOSE ATTENTION TO THE LATEST
FORECASTS AS ROAD CONDITIONS COULD BE IMPACTED. THANKSGIVING DAY
WILL BE COLD BUT DRY WITH HIGHS FROM THE MID TEENS INTO THE LOWER
20S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY TONIGHT)
ISSUED AT 1111 PM CST SAT NOV 22 2014

VSBYS HAVE BEEN VERY CHALLENGING TONIGHT...AND WILL LIKELY STAY THIS
WAY THROUGH SUNDAY. VARIABILITY AND MULTIPLE WEATHER ELEMENTS ARE
KEEPING FORECAST CONFIDENCE SHAKY IN HOW LOW VSBYS WILL GO...AND HOW
LONG THEY WILL STAY THERE. DON/T THINK THEY WILL IMPROVE OUT OF
MVFR...AND LIKELY STAY IFR FOR A BULK OF THE NEXT 24
HOURS...ESPECIALLY AT KRST. LIFR ALSO A GOOD BET THROUGH THE
OVERNIGHT HOURS.

AS FOR DRIZZLE. STILL SIGNALS IN THE MODELS FOR LIFT THROUGH THE
STRATUS LAYER...WHICH SHOULD LEAD TO AREAS OF -DZ. THIS SHOULD HANG
AROUND THROUGH SUNDAY MORNING...WITH AN AREA OF RAIN THEN ADVANCING
NORTHEAST OUT OF IA AS AN AREA OF LOW PRESSURE TAKES AIM ON THE
REGION. LOOKING FOR A WIND SHIFT TO THE NORTHEAST AS THE LOW MOVES
IN/SLIDES EAST...AND A SIGNIFICANT INCREASE IN WIND SPEED FOR SUNDAY
EVENING.

FOR CIGS...GOING TO KEEP THEM UNDER 1KFT FOR NOW. BUFKIT SOUNDINGS
VIA ALL MODELS DON/T BUDGE ON THE LOW LEVEL SATURATION.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY UNTIL 8 AM CST THIS MORNING FOR WIZ017-029.

MN...NONE.
IA...NONE.
&&

$$

SHORT TERM...ROGERS
LONG TERM...ROGERS
AVIATION.....RIECK


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