000 
FXUS63 KARX 040659
AFDLSE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
200 AM CDT SAT MAY 4 2002

FORECAST FOCUS IS ON RAIN CHANCE AND TEMPERATURES TODAY...AND
SUNDAY...AND MONDAY...AND TUESDAY...

LATEST SURFACE ANALYSIS SHOWS HIGH PRESSURE CENTERED OVER DETROIT.
A LOW PRESSURE AREA WAS OVER NORTHWEST ONTARIO...WITH A COLD FRONT
TRAILING THROUGH NORTHWEST MN INTO EASTERN SD AND CENTRAL NEB.
SKIES WERE CLEAR OVER THE IMMEDIATE AREA...BUT THERE WAS A GOOD DEAL
OF CLOUDINESS ALONG AND BEHIND THE APPROACHING FRONT.  RADAR AND
LIGHTNING DATA SHOWS A NARROW BAND SHOWERS AND THUNDERSTORMS ALONG
THE FRONT...WITH ANOTHER SMALL BAND 100 MILES OR SO BEHIND.

MODELS SIMILAR IN THE EARLY PERIODS...WITH SOME DIFFERENCES SHOWING
UP FROM SUNDAY ON INTO NEXT WEEK.  OVERALL...ETA SEEMS TO CAPTURE
FEATURES THE BEST...AND IS PREFERRED.

FRONT AND ASSOCIATED CLOUDS AND CHANCY CONVECTION WILL CROSS THE
FORECAST AREA TODAY.  TIMING IS CONSIDERABLY SLOWER THAN WHAT WAS
DEPICTED AT THIS TIME LAST NIGHT.  EXPECTING FRONT TO ENTER NORTHWEST
PORTION OF FORECAST AREA NEAR 18Z...AND SHOULD EXIT THE EAST AROUND
SUNSET.  THERE ARE SOME DYNAMICS AND LIFT PRESENT TO FUEL CONVECTION
IN THE FORM OF Q-G AND THE RIGHT ENTRANCE REGION OF A JET STREAK
ACROSS SOUTHERN CANADA. BUT VERY LIMITED MOISTURE IS KEEPING COVERAGE
SPARSE.  NOT MUCH IN THE WAY OF QPF PAINTED BY MODELS...WITH AVN
WETTEST AND MOST WIDESPREAD PER USUAL. CURRENT FORECAST HAS 30/40
POPS AND THIS STILL APPEARS REASONABLE.  WITH SLOWER PROGRESSION OF
FRONT...LIMITED CLOUDS AHEAD OF IT...AND WITH THERMAL RIDGE TO BE
OVER AREA NEAR MID-DAY...HAVE NUDGED TEMPERATURES BACK UP TO JUST A
LITTLE ABOVE GUIDANCE NUMBERS.

AFTER FRONTAL PASSAGE...SKIES SHOULD CLEAR OUT...AND HIGH PRESSURE
WILL QUICKLY BUILD IN.  LIGHT WINDS...DRY AIRMASS AND COLD ADVECTION
SHOULD RESULT IN COOL NIGHT. GUIDANCE REASONABLE.

BUT HIGH DOESNT STICK AROUND LONG...AND SOUTHERLY FLOW AND WARM
ADVECTION KICK IN AGAIN SUNDAY MORNING.  ADVECTION OF WARM AND
MOIST AIR SUGGEST THE POSSIBILITY FOR CONVECTION FIRING DURING THE
AFTERNOON.  AS THE LOW LEVEL JET CRANKS UP SUNDAY NIGHT...MORE
WIDESPREAD RAINS ARE LIKELY.  WHILE MODELS DIFFER ON THE EXACT
LOCATIONS FOR THE HEAVIEST RAIN AREAS...THE IDEA FOR WIDESPREAD RAIN
IS THE SAME. WILL LEAVE THE LOW CHANCE WEST FOR SUNDAY AFTERNOON...
BUT WILL RAISE POPS INTO THE LIKELY CATEGORY FOR SUNDAY NIGHT.

PARADE OF SYSTEMS WILL TRAVERSE THE REGION UNDER BASICALLY ZONAL
FLOW.  THIS WILL KEEP CHANCES FOR PRECIPITATION AROUND.  LEFT
EXTENDED PERIODS ALONE FOR NOW.

.LSE...NONE.

MW