000
FXUS63 KARX 071156
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
556 AM CST FRI MAR 7 2014

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 310 AM CST FRI MAR 7 2014

THE MAIN CONCERN IS WITH THE PRECIPITATION CHANCES FOR TODAY AND
TONIGHT.

WATER VAPOR SATELLITE THIS MORNING SHOWS A WEAK SHORT WAVE TROUGH
COMING ACROSS THE DAKOTAS. THE 07.00Z MODELS ARE IN GOOD AGREEMENT
THAT THIS WAVE WILL CONTINUE MOVING EAST AND ACROSS THE AREA
TODAY. HOWEVER...THE NAM AND ECMWF DO NOT SHOW THIS WAVE
AMPLIFYING AS IT COMES ACROSS WHILE THE GFS WANTS TO DEEPEN THE
WAVE CONSIDERABLY. AT THIS POINT...THE GFS ALMOST LOOKS LIKE IT
SUFFERS SOME CONVECTIVE FEEDBACK WITH THIS WAVE GIVEN HOW FAST IT
DEEPENS THE WAVE AND IT LOOKS TO BE THE OUTLIER. AS THE WAVE COMES
ACROSS IT IS NOT EXPECTED TO PRODUCE MUCH FORCING WITH LITTLE OR
NO PV ADVECTION IN THE 500-300 MB LAYER AND ONLY SOME WEAK QG
CONVERGENCE. THE COLD FRONT THAT WILL MOVE THROUGH WITH THE WAVE
LOOKS LIKE IT SHOULD HAVE WEAK FRONTOGENESIS IN THE 1000-500 MB
LAYER AND BY THE TIME THE FRONT ARRIVES...THE ISENTROPIC UP GLIDE
WILL HAVE ALREADY MOVED OFF TO THE EAST OF THE REGION. SO IF THIS
WEAK FORCING IS ENOUGH TO PRODUCE SOME LIGHT PRECIPITATION...THE
QUESTION THEN BECOMES WHAT TYPE. A WARM LAYER ALOFT WILL BE ENOUGH
TO PRODUCE PARTIAL TO COMPLETE MELTING WHICH WOULD LEAD TO SLEET
OR DRIZZLE/FREEZING DRIZZLE. IT LOOKS LIKE TEMPERATURES SHOULD
WARM ENOUGH TO CHANGE ANY FREEZING DRIZZLE OVER TO DRIZZLE BEFORE
THE NOON HOUR BEFORE THE CHANCES REDEVELOP LATE IN THE AFTERNOON
AS COOLING BEGINS TO SET IN. WITH DOUBTS ON WHETHER THE
PRECIPITATION WILL EVEN OCCUR...WILL NOT SHOW ANYTHING MORE THAN
ABOUT A 30 PERCENT CHANCE AND IF FREEZING DRIZZLE DOES OCCUR...THE
AMOUNTS WOULD BE SO LIGHT THAT IS SHOULD NOT CAUSE TOO MANY
PROBLEMS...SO NO HEADLINES PLANNED AT THIS POINT.

ANOTHER SHORT WAVE TROUGH IS EXPECTED TO COME OUT OF THE CENTRAL
ROCKIES AND MOVE ACROSS THE MIDDLE MISSISSIPPI RIVER VALLEY
TONIGHT. IT APPEARS THAT THE MODELS HAVE SETTLED IN ON A TRACK
WITH THIS WAVE AND THE BULK OF THE PRECIPITATION WITH IT STAYING
SOUTH OF THE FORECAST AREA. THE SOUTHERN SECTIONS COULD GET
BRUSHED BY THE NORTHERN FRINGES OF THIS PRECIPITATION TONIGHT AND
WHILE MAINTAINING SOME CHANCES...DID LOWER THE OVERALL
PRECIPITATION CHANCES. ONCE THIS SYSTEM MOVES PAST...HIGH PRESSURE
AT THE SURFACE WILL DRIFT ACROSS THE REGION THROUGH SUNDAY.
WARMER AIR WILL START TO COME IN ON THE BACK SIDE OF THE FOR
SUNDAY WITH HIGHS EXPECTED TO REACH INTO THE 30S WITH SOME 40S
POSSIBLE.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 310 AM CST FRI MAR 7 2014

TEMPERATURES WILL CONTINUE TO WARM INTO MONDAY WITH MOST LOCATIONS
EXPECTED TO TOP OUT ABOVE 40. THE NEXT CHANCE FOR SOME
PRECIPITATION WILL OCCUR FROM MONDAY NIGHT THROUGH TUESDAY NIGHT.
MODELS SOMEWHAT AT ODDS DURING THIS TIME PERIOD WHETHER A PACIFIC
SYSTEM WILL PHASE WITH NORTHERN STREAM ENERGY AND COME ACROSS AS
ONE LONG WAVE TROUGH OR WHETHER THE PACIFIC SYSTEM WILL GET CUT
OFF FROM THE FLOW AND LINGER OVER THE DESERT SOUTHWEST THROUGH THE
END OF THE WEEK. EITHER WAY...ALL THE MODELS PUSH A COLD FRONT
THROUGH WITH THE NORTHERN STREAM SYSTEM WITH THE POSSIBILITY OF
SOME PRECIPITATION ALONG IT. THE DIFFERENCES WITH THE HANDLING OF
THE PACIFIC SYSTEM LOOK TO HAVE A GREATER IMPACT ON THE SOUTHERN
AND EASTERN PARTS OF THE COUNTRY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 556 AM CST FRI MAR 7 2014

LOW LEVEL WIND SHEAR WILL CONTINUE THROUGH 07.14Z AND THEN THE
WINDS BETWEEN 1500 AND 2K FEET WILL WEAKEN. A COLD FRONT WILL
MOVE THROUGH THE TAF SITES BETWEEN 07.17Z AND 07.19Z. AS THIS
OCCURS...WINDS WILL TRUN TO THE NORTHWEST AND REMAIN IN THE 10 TO
15 KNOT RANGE. IN ADDITION...AS THIS FRONT APPROACHES CEILINGS
WILL FALL TO AROUND 2500 FEET BETWEEN 07.16Z AND 07.18Z...AND THEN
DROP INTO THE 1-2K FOOT RANGE BEHIND THE FRONT FROM THIS AFTERNOON
THROUGH TONIGHT.

&&

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

$$

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