Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 220440
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1140 PM CDT THU MAY 21 2015

.SHORT TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 230 PM CDT THU MAY 21 2015

SFC HIGH AND UPPER LEVEL RIDGE LOOK TO BE THE MAIN WEATHER
INFLUENCES THROUGH SATURDAY...KEEPING THE TREND OF DRY CONDITIONS IN
PLACE. SOME HINTS IN THE GFS/NAM THAT A RIPPLE IN THE UPPER LEVEL
FLOW COULD WORK INTO THE RIDGE SATURDAY AFTERNOON...COUPLED WITH LOW
LEVEL WARM AIR ADVECTION AND PERHAPS A LITTLE INSTABILITY ADDED TO
THE MIX. SATURATION PER RH FIELDS AND BUFKIT SOUNDINGS LOOK MOSTLY
MID/UPPER LEVEL...BUT RH/LIFT COULD BE ENOUGH TO PRODUCE A FEW
SHOWERS. THE NAM PRODUCES SOME SPOTTY SHOWERS ACROSS THE FORECAST
AREA...THE GFS/GEM KEEPS MOST OF THE QPF TO THE WEST...WHILE THE EC
STAYS DRY. WILL KEEP THE SMALL CHANCE POPS FOR SAT AFTERNOON -
MOSTLY WEST. BUT CONSIDERING THE RELATIVELY WEAK SIGNALS AND SOME
MODEL DIFFERENCES...MAY NEED TO DRY THIS PERIOD OUT.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 230 PM CDT THU MAY 21 2015

UPPER LEVEL TROUGH STARTS TO PUSH INTO THE RIDGE SAT EVENING...WITH
BITS OF ENERGY KICKING OUT OF THE TROUGH AND THROUGH THE RIDGE INTO
MONDAY. INFLUX OF MOIST AIR AHEAD OF THE APPROACHING TROUGH...WITH A
STEADY STREAM OF 850 MB MOISTURE TRANSPORT SUN AFTERNOON INTO MONDAY
NIGHT. PWS ON SUNDAY CLIMB ABOVE 1.5 INCHES. INSTABILITY IS MEAGER
ON SUNDAY...BUT THE GFS INCREASES SBCAPES ABOVE 1000 J/KG MONDAY
AFTERNOON. SOME SHEAR TO PLAY WITH IN THIS TIME PERIOD TOO.
SHOWERS/STORMS LOOK LIKELY FOR THE SUNDAY-MONDAY TIME FRAME. SEVERE
THREAT LOOKS LOW AT THIS TIME...WITH MONDAY SHOWING THE BEST COMBO
OF INSTABILITY/SHEAR...BUT TOO MUCH UNCERTAINTY TO LABEL IT AS
FAVORABLE AT THIS TIME.

THE TROUGH WEAKENS AS IT LIFTS NORTHEAST INTO THE AREA TUE...WITH THE
SYSTEM/S COLD FRONT SLATED TO EVENTUALLY LAY OUT SOUTHWEST-NORTHEAST
SOUTH OF THE FORECAST AREA. OTHER BITS OF UPPER LEVEL ENERGY COULD
WORK ON THE BOUNDARY TO SPARK MORE SHOWERS/STORMS TUE-WED...BUT
MODELS HAVING VARYING OPINIONS ON WHERE THE FRONT WILL LAYUP AND
WHERE THE RIPPLES IN THE UPPER LEVEL FLOW WILL MOVE. WILL STICK WITH
CONSENSUS SOLUTION FOR RAIN CHANCES AS A RESULT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1140 PM CDT THU MAY 21 2015

HIGH PRESSURE WILL CONTINUE TO BUILD SOUTH INTO THE GREAT LAKES
REGION TONIGHT. THIS HIGH WILL THEN SINK SLOWLY SOUTH INTO THE
OHIO RIVER VALLEY THROUGH FRIDAY EVENING. WITH THE HIGH BEING
THE DOMINANT WEATHER FEATURE...EXPECT VFR CONDITIONS WITH LITTLE
OR NO CLOUDS THROUGH THE PERIOD. THE WINDS WILL BE LIGHT OUT OF
THE NORTH TONIGHT GOING AROUND TO THE SOUTHEAST FRIDAY.

&&

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

$$

SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION...04


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