FXUS63 KARX 262027
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
230 PM CST SAT DEC 26 2009

.SHORT TERM...TODAY THROUGH TUESDAY NIGHT

FORECAST CONCERNS CENTER ON THE AMOUNT OF CLOUD COVER FOR THE NEXT 
COUPLE DAYS. 

THE STORM SYSTEM RESPONSIBLE FOR THE WINTRY MIX ACROSS THE LOCAL 
AREA...AND THE AMPLE SNOWS FARTHER WEST...CONTINUED TO WEAKEN 
TODAY...WITH THE UPPER LEVEL LOW CURRENTLY OVER WI...PER LATEST 
WATER VAPOR SATELLITE IMAGERY. THE LOW WILL CONTINUE TO SPIN IN 
PLACE INTO SUNDAY MORNING...BUT START TO PUSH OFF BY THE AFTERNOON 
AS A 120 KT 300 MB JET GIVES IT A SHOVE EAST. THERE WAS STILL SOME 
SNOW BANDS ROTATING AROUND THE LOW...ACROSS THE NORTHERN 
PLAINS/WESTERN MN AND SOUTHEAST WI/NORTHERN ILL...BUT ONLY SOME 
FLURRIES LOCALLY. 

BITS OF SHORTWAVE ENERGY WILL CONTINUE TO ROTATE AROUND THE LOW 
TONIGHT INTO SUN MORNING...BUT MOST OF THE SNOW SHOWERS ASSOCIATED 
WITH THIS UPPER LEVEL FORCING SHOULD STAY WEST/SOUTH OF THE FORECAST 
AREA. STILL...WITH CYCLONIC FLOW AND COLD AIR A LOFT...A FEW SNOW 
SHOWERS/FLURRIES CAN BE EXPECTED TONIGHT INTO THE BETTER PART OF 
SUNDAY. DON/T EXPECT MUCH...IF ANY ACCUMULATION FROM THIS ACTIVITY. 

MORE OF A CHALLENGE WILL BE THE CLOUD COVER. CURRENT VSBY SATELLITE 
IMAGERY SHOWS A RELATIVELY CLEAR AREA UNDER THE HEART OF THE UPPER 
LEVEL LOW...ACROSS PARTS OF WESTERN/NORTHERN WI. HOWEVER...WEST OF 
THE LOW A BLANKET OF CLOUDS EXTENDED INTO THE DAKOTAS. RH FIELDS ARE 
DOING A DECENT JOB WITH THIS SCENARIO. THE UPPER LEVEL LOW WILL 
WOBBLE OVER THE FORECAST AREA TONIGHT...AND THESE SAME RH FIELDS 
POINT TO A MORE PARTLY CLOUDY RATHER THAN MOSTLY CLOUDY SKY. THERE 
IS SOME LOW LEVEL MOISTURE THAT COULD MANIFEST INTO CLOUDS...AS 
SHOWN VIA THE BUFKIT SOUNDINGS...BUT BELIEVE THIS IS BEING OVERCOME 
BY SUBSIDENCE...ALSO SHOWN IN THESE SAME SOUNDINGS. WHILE THE BUFKIT 
SOUNDINGS CONTINUE TO INDICATE THIS SUBSIDENCE TONIGHT...WEST TO 
EAST RUNNING TIME/HEIGHT X-SECTIONS VIA THE 26.12Z GFS AND NAM ARE 
NOT AS STRONG. IN FACT...SOME INDICATIONS OF A LITTLE LIFT. FOR 
NOW...WILL LEAN TOWARD A BIT LESS CLOUDS FOR THE FORECAST AREA 
TONIGHT...BUT WHERE THERE ARE CLOUDS...SOME FLURRIES OR SNOW SHOWERS 
WILL BE POSSIBLE. TEMPERATURES WILL POSE SOME DIFFICULTIES TONIGHT 
TOO...AS WHERE ITS MORE CLEAR...LOWS COULD DROP INTO THE SINGLE 
DIGITS. WHERE THE CLOUDS ARE MORE ABUNDANT...READINGS WILL BE IN THE 
TEENS. 

ON SUNDAY...THERE WILL BE THE CLOUDS ON THE WESTERN FRINGES OF THE 
NOW EXITING STORM SYSTEM...AND AGAIN...ISOLATED SNOW SHOWERS OR 
FLURRIES. OVERNIGHT SUNDAY INTO MONDAY AN UPPER LEVEL SHORTWAVE 
TROUGH WILL DROP INTO THE LEE OF THE UPPER LEVEL TROUGH...NOW 
SCOOTING OVER THE EASTERN GREAT LAKES. WHILE THE HEART OF THE UPPER 
LEVEL FORCING WILL BE WELL EAST...LOW LEVEL COLD AIR ADVECTION AND A 
SFC TROUGH COULD SERVE TO SPARK MORE SCATTERED SNOW 
SHOWERS/FLURRIES. NOT EXCITED OVER THESE CHANCES AS THE SATURATION 
LOOKS RATHER MEAGER. WILL LIKELY CONTINUE SOME FLURRY MENTION FOR 
THIS TIME PERIOD EAST OF THE MISSISSIPPI RIVER. 

FORECAST CONFIDENCE IS NOT HIGH IN TERMS OF THE CLOUD COVER FOR 
TONIGHT INTO SUNDAY...AND UPDATES MAY BE NEEDED. 

.LONG TERM...WEDNESDAY THROUGH SATURDAY

THE OVERALL PATTERN BETWEEN THE ECMWF AND GFS IS THE SAME...WEAK 
RIDGING GIVING WAY TO AN UPPER LEVEL TROUGH ACROSS THE GREAT LAKES 
FOR FRI INTO THE NEW YEAR/S WEEKEND. VARIOUS PERTURBATIONS SPIN 
THROUGH THE TROUGH...AND COULD LEAD TO PERIODIC LIGHT SNOW/FLURRY 
CHANCES. ANY ACCUMULATIONS LOOK MINOR AT THE MOMENT. ANOTHER SLUG OF 
COLD AIR WILL ACCOMPANY THE TROUGH THOUGH...GETTING THE NEW YEAR OFF 
TO A CHILLY START.  

&&

.AVIATION...

PRIMARY CONCERN IS CLOUD COVER FOR THE NEXT 24 HOURS. AREA REMAINS 
UNDER THE CORE OF THE UPPER LOW THIS AFTERNOON...WITH SUBSIDENCE AND 
DRY OCCLUSION RESULTING IN CLEAR OR NEARLY CLEAR SKIES OVER MUCH OF 
THE LOCAL TRI-STATE AREA.  MODELS INDICATE HIGHER HUMIDITY IN THE 
BOUNDARY LAYER. DO THINK THAT THIS IS ACCURATE...AS WE ARE SEEING A 
GOOD DEAL OF SNOW CRYSTAL/ICE CRYSTAL PRODUCTION WITH NEARLY CLEAR 
SKIES. VERY THIN STRATUS ALSO SEEN...WHICH IS PRODUCING S- AS WELL.  
SO THE QUESTION IS...WILL THIS MOISTURE EVENTUALLY MANIFEST AS CLOUD 
TONIGHT?  FOR THE 18Z TAF ISSUANCE...OPTED TO GO WITH MORE CLOUD AND 
THE RESULTING CHANCE FOR SNOW...BUT THIS WILL HAVE TO BE MONITORED. 
APPEARS VFR CONDITIONS FOR KLSE/KRST FOR THE MOST PART...BUT COULD 
BE MVFR AT TIMES...ESPECIALLY AT KLSE. 
 
AIRMASS IS QUITE COLD OVER THE REGION WITH THE COLDEST POOL OF AIR 
OVER THE AREA TODAY AND TONIGHT. AS LONG AS THAT PREVAILS...THERE 
WILL BE A THREAT FOR SOME CLOUD COVER AND SNOW PRODUCTION. 

STACKED SYSTEM TO EVENTUALLY SHIFT EAST...ALLOWING THE WRAP AROUND 
CLOUDINESS TO INVADE...BUT THAT IS LOOKING TO BE INTO SUNDAY 
AFTERNOON. 

&&

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

$$

SHORT/LONG TERM... RIECK
AVIATION.......... MW