Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 250456
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1156 PM CDT FRI APR 24 2015

.UPDATE...
ISSUED AT 945 PM CDT FRI APR 24 2015

WITH THE MESO MODELS AND 25.00Z NAM SHOWING A DRAMATIC SOUTHWARD
IN PRECIPITATION CHANCES FOR SATURDAY...STARTED A DOWNWARD TREND
IN THE PRECIPITATION CHANCES. THIS IS IN RESPONSE TO THE BEST
SYNOPTIC AND FRONTOGENETIC FORCING BEING LOCATED ACROSS SOUTHERN
IOWA AND NORTHERN MISSOURI. IF OTHER 25.00Z MODELS FOLLOW THE SAME
TREND...MIDNIGHT SHIFT MAY BE ABLE TO DO EVEN FURTHER CUTS TO
THEM.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 222 PM CDT FRI APR 24 2015

AS WAVE EJECTS OUT OF SOUTHWEST U.S. MAIN FOCUS IN SHORT TERM IS
RAIN THREAT...ESPECIALLY ON SATURDAY AS SYNOPTIC SURFACE LOW PASSES
BY TO THE SOUTH.

WEAKER INITIAL SHORT WAVE TROUGH SWINGING THROUGH AREA THIS
AFTERNOON HAS GENERATED BROAD RAIN SHIELD WITH SOME WARM AIR
ADVECTION. CONSIDERABLY DRIER AIR IN CENTRAL AND EASTERN WISCONSIN
WILL BATTLE THIS. AS FORCING SHIFTS EAST THIS EVENING...BULK OF RAIN
SHOULD END BY EARLY EVENING WITH ONLY PATCHY THREAT AFTER THAT. THIS
TREND IS SUPPORTED IN HIGH RESOLUTION MODELS AND HAVE ADJUSTED RAIN
CHANCES DOWNWARD TO ACCOUNT FOR THAT.

AS STRONGER MAIN WAVE EJECTS INTO CENTRAL U.S. TONIGHT...WITH
STRONGER...DEEPER Q-G FORCING...EXTENSIVE AREA OF RAIN AND
THUNDERSTORMS WILL FORM ACROSS PARTS OF THE CORNBELT AND MID
MISSISSIPPI RIVER VALLEY. BETTER AGREEMENT IN 24.12Z MODELS WITH HOW
FAR NORTH PRECIPITATION WILL GET WHILE SOME MODELS HAVE BEEN VERY
CONSISTENT KEEPING RAIN SOUTH OF INTERSTATE 90 CONSISTENTLY. THIS
WILL MEAN A TIGHT NORTH-SOUTH GRADIENT IN RAIN CHANCES MAINLY
SATURDAY MORNING BEFORE SYSTEM EXITS BY LATE AFTERNOON. AS SURFACE
LOW SHIFTS EAST...COULD ALSO SEE INCREASING EAST TO NORTHEAST WINDS
PICK UP DRIER AIR TO THE NORTHEAST WHICH WOULD ALSO BATTLE NORTHWARD
EXTENT OF PRECIPITATION.

HAVE TRIED TO TIGHTEN THIS RAIN THREAT GRADIENT UP WITH UP TO AN
INCH OF RAIN POSSIBLE CLOSER TO HIGHWAY 20 IN IOWA...TO NOTHING
NORTH OF INTERSTATE 90. NIL TO MINIMAL CAPE SUGGEST THUNDER THREAT
TOO LOW TO MENTION THIS FAR NORTH.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 222 PM CDT FRI APR 24 2015

SHORT TERM UPPER RIDGE WILL BUILD IN QUICKLY SATURDAY NIGHT AS RAIN
THREAT ENDS AND SKIES CLEAR OUT. THIS WILL LAST INTO EARLY NEXT WEEK
WITH QUIET WEATHER ON TAP AND WARMING TEMPERATURES...CLOSER TO
NORMALS FOR LATE APRIL.

UPPER FLOW ACROSS U.S. BECOMES FAR MORE MESSY NEXT WEEK WITH LARGE
LOW OFF OF NORTHEAST AND SPLIT FLOW DEVELOPS IN WEST. THIS COULD
LEAVE OUR REGION IN FAIRLY QUIET PATTERN BETWEEN ALL THIS. MEDIUM
RANGE GUIDANCE SUGGESTS WEAK WAVE COULD DRAG COLD FRONT INTO AREA
NEXT TUESDAY WITH MINOR RAIN THREAT BUT BESIDES THAT...MORE SIGNALS
FOR RIDGING AND NICE SPRING WEATHER.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1151 PM CDT FRI APR 24 2015

WITH THE FRONTOGENESIS CONTINUING TO WEAKEN...EXPECT THE LIGHT
RAIN AT KLSE TO DISSIPATE BY 25.08Z. THIS RAIN WILL NOT CAUSE ANY
VISIBILITY RESTRICTIONS. A DRY EASTERLY FLOW IN THE 10 TO 20 KNOT
RANGE WITH OCCASIONAL WIND GUSTS UP TO 25 KNOTS WILL BRING DRY AIR
INTO THE REGION. THIS WILL KEEP CEILINGS IN THE 3 TO 5K RANGE
THROUGH 25.23Z...AND THEN SKIES WILL CLEAR.

&&

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

$$

UPDATE...BOYNE
SHORT TERM...SHEA
LONG TERM...SHEA
AVIATION...BOYNE



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