Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 231604
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1100 AM CDT SAT MAY 23 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 254 AM CDT SAT MAY 23 2015

IN HURRY UP AND WAIT MODE AS UPPER LOW EVER SO SLOWLY LIFTS OUT OF
SOUTHWEST U.S. THROUGH HOLIDAY WEEKEND. TIMING OF RAIN THREATS MAIN
CHALLENGE BUT ALSO WATCHING FOR ANY SEVERE WEATHER RISKS.

ANOTHER QUIET DAY ON TAP AS MAINLY MID LEVEL WARM AIR ADVECTION AND
FRONTOGENESIS WILL SPREAD MORE AND MORE CLOUD COVER IN FROM THE
SOUTHWEST. CONTINUE TO DELAY ONSET OF ANY RAIN THREAT BUT AS
SOUTHWEST FLOW AHEAD OF UPPER LOW CONTINUES TO ADVECT MOISTURE AND
WARMER AIR NORTHWARD...EXPECT THIS FORCING TO SATURATE DRY AIRMASS
WITH RAIN THREAT MOVING IN TONIGHT FROM SOUTHWEST TO NORTHEAST.
AREAS NORTH AND EAST OF LA CROSSE COULD REMAIN DRY WELL INTO SUNDAY
MORNING BASED ON LATEST MODEL TRENDS.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 254 AM CDT SAT MAY 23 2015

BY SUNDAY...UPPER LOW SHOULD BE WORKING THROUGH THE ROCKIES AND MORE
AND MORE SHORT WAVES EJECTING NORTHEAST. INCREASE IN MOISTURE
TRANSPORT BACKS IDEA OF INCREASING RAIN THREAT THROUGH THE DAY AND
INTO SUNDAY NIGHT. INSTABILITY REMAINS LOW BUT SOME SUGGESTIONS IN
MODELS OF AT LEAST SOME MIXED LAYER CAPE /500 J/KG ?/ BY LATE SUNDAY
AS DEW POINTS CONTINUE TO INCREASE. UP TO THAT POINT THUNDER RISK
LIMITED.

AS UPPER LOW BECOMES MORE OF AN OPEN WAVE BY MEMORIAL DAY...
INTERESTING TREND IN 23.00Z MODEL RUNS BRINGING SURFACE LOW FURTHER
NORTH AS BROAD SOUTHWEST FLOW CONTINUES TO ADVECT IN MOISTURE. NOT
SURE IDEA OF A DRY SLOT DEVELOPING WILL MATERIALIZED...BUT PER
COORDINATION WITH SURROUNDING OFFICES...HAVE MADE ADJUSTMENTS IN
FORECAST FOR THAT POSSIBILITY LOWERING RAIN THREATS IN SOUTHERN
AREAS ON MONDAY...ALONG WITH WARMER TEMPERATURES.

AFOREMENTIONED SETUP WILL ALSO INCREASE RISK OF SEVERE THUNDERSTORMS
ON MEMORIAL DAY AFTERNOON AND EVENING WITH LOWER TO MID 60S SURFACE
DEW POINTS POSSIBLE AND MODEST CAPE ADVECTING AHEAD OF FRONT TO THE
WEST. DECENT SHEAR SHOULD BE REALIZED WITH HODOGRAPHS SUPPORTING
IDEA OF A FEW SUPERCELLS IF WE CAN DEVELOP ENOUGH INSTABILITY. STILL
UNCERTAINTIES OF HOW EARLIER CONVECTION COULD MUDDLE SETUP BUT
WOULD NOT BE SURPRISED IF MARGINAL DAY 3 OUTLOOK IS BUMPED UP TO
SLIGHT RISK.

FRONT GRADUALLY PASSES THROUGH AREA ON TUESDAY WITH RAIN THREATS
DROPPING OFF FROM WEST TO EAST. BUT NO BIG AIRMASS CHANGE EXPECTED
AS NEXT UPSTREAM UPPER TROUGH DROPS OUT OF NORTHWEST U.S. INTO
THE ROCKIES. WHILE COULD SEE SOME DRY TIME MID WEEK...SERIES OF
SHORT WAVE TROUGHS IN BROAD SOUTHWEST FLOW WILL CONTINUE TO KEEP A
RAIN RISK UP UNTIL NEXT WEEKEND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1100 AM CDT SAT MAY 23 2015

CIGS...
HIGH/MID LEVEL CLOUDS WILL CONTINUE TO SPREAD NORTHEAST
ACROSS THE AREA...AND SHOULD KEEP A BKN VFR CIG AT KRST/KLSE THROUGH
TONIGHT. LOOK FOR LOWERING SUN MORNING AS LOW LEVEL SATURATION
INCREASES AHEAD OF AN UPPER LEVEL SHORTWAVE TROUGH. EXPECTING A DROP
INTO MVFR AT KRST BEFORE 18Z. ONCE IN...MOSTLY MVFR CIGS SHOULD HANG
AROUND FOR KRST/KLSE INTO MONDAY.

VSBY/WX...
FRONTOGENETIC FORCING/WARM AIR ADVECTION WILL WORK ON THE
INCREASING SATURATION TO BRING A ROUND OF -SHRA TO THE AREA SUN
MORNING. LIMITED IF ANY INSTABILITY WILL KEEP THE TS THREAT IN
CHECK. EXPECT ROUNDS OF SHRA/TS THEN FOR THE REST OF SUNDAY INTO
MONDAY NIGHT.

WINDS...
SOUTH TO SOUTHEAST WINDS WILL PERSIST THROUGH SUNDAY...WITH
SOME INCREASE IN SPEEDS SUNDAY MORNING.

&&

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

$$

SHORT TERM...SHEA
LONG TERM...SHEA
AVIATION...RIECK


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