Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 051146
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
546 AM CST FRI FEB 5 2016

.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 249 AM CST FRI FEB 5 2016

WATER VAPOR SATELLITE SHOWS AN ELONGATED TROUGH EXTENDING FROM
NORTH DAKOTA INTO NEW MEXICO. SEVERAL SHORT WAVE TROUGHS ARE
EMBEDDED WITHIN THIS LONG WAVE TROUGH. THE 05.00Z MODELS ARE ALL
FAIRLY CONSISTENT IN SHOWING THE NORTHERN MOST WAVE OVER THE
DAKOTAS DIVING SOUTHEAST AND MISSING MUCH OF THE LOCAL AREA AS IT
MOVES ACROSS IOWA AND MISSOURI. AN UPPER LEVEL LOW WILL MOVE
ACROSS NORTHERN ONTARIO AND HUDSON BAY WITH A SHORT WAVE TROUGH ON
THE SOUTH SIDE OF THIS MOVING ACROSS SOUTHERN ONTARIO. THIS LEAVES
THE LOCAL REGION IN BETWEEN SYSTEMS WITH NOT A LOT OF FORCING. THE
WAVE GOING ACROSS IOWA LOOKS TO BE CLOSE ENOUGH TO PRODUCE SOME
WEAK PV ADVECTION IN THE 500-300 MB LAYER THIS EVENING BUT ANY QG
CONVERGENCE LOOKS TO BE WEAK AND CONFINED TO THE 1000-700 MB
LAYER. THERE IS NO FRONTOGENESIS WITH THIS SYSTEM AND ONLY BETWEEN
1 AND 2 UBAR/S OF UP GLIDE ON THE 280K ISENTROPIC SYSTEM. THERE IS
GENERAL AGREEMENT BETWEEN THE MODELS THAT THE BEST CHANCE FOR ANY
SNOW WITH THIS SYSTEM SHOULD BE ACROSS THE NORTHERN SECTIONS OF
THE FORECAST AREA WHERE THE ISENTROPIC UP GLIDE LOOKS TO BE A BIT
BETTER. BUFKIT SOUNDINGS FOR KMDZ DO NOT LOOK VERY IMPRESSIVE WITH
THIS SYSTEM. THE OMEGA THROUGH THE COLUMN IS WEAK AND ONLY REACHES
THE DENDRITIC GROWTH ZONE FOR A COUPLE OF HOURS. WILL MAINTAIN THE
LIGHT SNOW CHANCES WITH THIS SYSTEM...UP TO 60 PERCENT ACROSS THE
NORTH...BUT THIS COULD END UP BEING JUST SOME FLURRIES OR A VERY
SHORT PERIOD OF LIGHT SNOW.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 249 AM CST FRI FEB 5 2016

THE NORTHWEST FLOW ALOFT WILL CONTINUE INTO THE START OF NEXT WEEK
WITH ANOTHER SYSTEM COMING THROUGH FOR SUNDAY THROUGH MONDAY. THIS
SYSTEM LOOKS TO COME ACROSS THE NORTHERN ROCKIES SATURDAY AND THEN
START TO INTENSIFY WITH AN UPPER LEVEL LOW FORMING SATURDAY NIGHT.
THIS UPPER LEVEL IS SHOWN TO TAKE A SOUTHEAST TRACK BUT
DIFFERENCES BETWEEN THE MODELS ON HOW SOON THIS OCCURS. THE 05.00Z
GFS IS THE QUICKEST TO TURN IT SOUTHEAST AND BRINGS THE UPPER
LEVEL LOW OVER THE AREA WHILE THE 05.00Z ECMWF AND GEM ARE SLOWER
WITH THE UPPER LEVEL LOW PASSING NORTH OF THE AREA BUT DO SHOW A
SHORT WAVE TROUGH ROTATING AROUND THE LOW COMING ACROSS THE AREA.
THE MORE SOUTHERN SOLUTION OF THE GFS ALLOWS THE SURFACE LOW TO
TRACK RIGHT ACROSS THE AREA AND BRINGS IN SOME LIGHT PRECIPITATION
AS EARLY AS SUNDAY AFTERNOON WHILE THE MORE NORTHERN ECMWF AND GEM
KEEP THE SURFACE LOW TO THE NORTH AS WELL AND DO NOT SHOW ANY
PRECIPITATION COMING IN UNTIL SUNDAY NIGHT. FOR NOW...WILL HONOR
THE FASTER GFS SOLUTION WITH A 30 TO 40 PERCENT CHANCE OF SNOW
SUNDAY AFTERNOON AND THEN TAKE THIS UP TO 50 PERCENT FOR MOST OF
THE AREA SUNDAY NIGHT. SOME LIGHT SNOW COULD LINGER INTO MONDAY ON
THE BACK SIDE OF THIS SYSTEM. TEMPERATURES WILL COOL DOWN BEHIND
THIS SYSTEM WITH HIGHS IN THE TEENS AND 20S FOR THE REST OF THE
PERIOD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 546 AM CST FRI FEB 5 2016

FROM THE OFFICE...IT APPEARS THAT THE DENSE FOG IS LOCALIZED AT
KLSE. AS THE SOUTHERLY WINDS INCREASE THIS MORNING...ANTICIPATE
THAT THE DENSE FOG AT KLSE WILL DISSIPATE BY 05.14Z.

FOR TODAY...THE MID AND HIGH CLOUDS WILL GRADUALLY THICKEN AS A
SHORT WAVE TROUGH APPROACHES THE AREA FROM THE NORTHERN PLAINS.

SNOW WILL MOVE INTO KRST BETWEEN 06.02Z AND 06.03Z AT KRST AND
THEN END AROUND 06.07Z. FOR KLSE...IT WILL BE AN HOUR LATER. ONCE
THE SNOW MOVES INTO THE AREA...VISIBILITIES WILL DROP TO LESS THAN
A MILE....AND THEN IMPROVE TO AROUND 4 SM WITH BR AS IT MOVES OUT
OF THE AREA. SNOW AMOUNTS WILL BE AROUND A HALF INCH.

&&

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

$$

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


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