Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 230754
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
254 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
UNCERTAINITIES 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 UPSTREM 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 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1148 PM CDT FRI MAY 22 2015

THE AREA IS STILL DOMINATED BY THE AREA OF HIGH PRESSURE CENTERED
OVER THE OHIO RIVER VALLEY AND THE RIDGE AXIS EXTENDING NORTHWEST
FROM THE HIGH ACROSS THE UPPER MIDWEST. MID AND HIGH LEVEL
MOISTURE IS BEGINNING TO RETURN AHEAD OF THE DEVELOPING SYSTEM
OVER THE CENTRAL ROCKIES...BUT THIS IS JUST RESULTING IN VERY
HIGH VFR CEILINGS ACROSS THE REGION. THE RIDGE AXIS WILL DRIFT
NORTH THROUGH SATURDAY EVENING ALLOWING A LITTLE BIT MORE MOISTURE
TO RETURN TO THE AREA. THIS SHOULD ONLY RESULT IN SOME LOWERING
VFR CEILINGS AND DO NOT REALLY SEE THE FORCING AND POTENTIAL FOR
ANY RAIN UNTIL SOMETIME SUNDAY.

&&

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

$$

SHORT TERM...SHEA
LONG TERM...SHEA
AVIATION...04


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