Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 251132
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
632 AM CDT SAT APR 25 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 255 AM CDT SAT APR 25 2015

FORECAST FOCUS IN THE SHORT TERM IS THE RAIN THREAT TODAY. CLOSED
CIRCULATION SPINNING THROUGH KS EARLY THIS MORNING...HEADING EAST
AND WEAKENING THROUGH THE DAY TODAY. DEFORMATION AND FRONTOGENETIC
FOCUS ON THE NORTHERN EDGE OF THIS SYSTEM WILL SPREAD RAIN AND
EMBEDDED THUNDERSTORMS ACROSS IA AND NORTHERN IL. MAIN DILEMMA IS
HOW FAR NORTH RAIN WILL GET. VARIOUS MODEL SOLUTIONS OVER THE PAST
SEVERAL DAYS HAD BEEN SUGGESTING RAIN WOULD SPREAD NORTH AS FAR
AS THE I-90 CORRIDOR. BUT THE LAST FEW RUNS HAVE NOW SHIFTED THAT
FOCUS FURTHER SOUTH. LOOKING AT THE FORCING AND THE INFLUX OF MORE
DRY LOW LEVEL AIR ON EAST/NORTHEAST WINDS SUPPORT A TIGHTER
RAIN/NO-RAIN GRADIENT AND THE SOUTHWARD SHIFT. THIS TREND IS
ALREADY BORNE OUT LOOKING AT OVERNIGHT RADAR LOOPS SHOWING THE
DIMINISHING TREND. SO MOVED THE FORECAST IN THIS DIRECTION FOR
TODAY. RAIN THREAT WILL END BY SUNSET AS HIGH PRESSURE OVER MB/ONT
BUILDS SOUTHWARD INTO THE REGION. AIRMASS DRIES AND BOUNDARY LAYER
TEMPERATURES TUMBLE. A CHILLY NIGHT IS ON TAP...ESPECIALLY OVER
OUR TYPICAL COOL AREAS OF CENTRAL WI.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 255 AM CDT SAT APR 25 2015

LOOKING INTO THE LONGER TERM...UPPER FLOW PATTERN REMAINS BLOCKED
THANKS TO THE EAST COAST CLOSED LOW WHICH PERSISTS INTO AT LEAST
TUESDAY. THIS KEEPS SURFACE HIGH PRESSURE AND DRY EASTERLY FLOW
POURING INTO THE AREA. A WEAK SHORT WAVE TROUGH DROPS INTO THE
BACK SIDE OF THE UPPER LOW LATE ON TUESDAY. THIS COULD BRING A FEW
LIGHT SHOWERS TO PARTS OF THE AREA...BUT WITH A VERY DRY
ATMOSPHERE THE CHANCES WILL BE QUITE LOW. THE PATTERN TRANSITIONS
TO MORE OF AN OMEGA LOOK BY LATE IN THE WEEK...PUTTING THE AREA
MORE IN THE UPPER RIDGE. THUS...A WARMING TREND IS ON TAP WITH
TEMPERATURES BACK ABOVE NORMAL. THE NEXT SIGNIFICANT CHANCE FOR
ANY RAINFALL LOOKS TO BE NEXT WEEKEND AS THE PERSISTENT SOUTHERLY
FLOW FINALLY GETS ENOUGH MOISTURE INTO THE REGION.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 632 AM CDT SAT APR 25 2015

MAIN AVIATION CONCERNS ARE THE POSSIBILITY OF MVFR CONDITIONS AT
BOTH THE RST/LSE TAF SITES TODAY. LATEST 11Z SURFACE ANALYSIS
SHOWS LOW PRESSURE OVER EASTERN KANSAS WITH LATEST FOG SATELLITE
PRODUCT INDICATING STRATUS DECK CLOUDS COVERING MUCH OF THE
NORTHERN PLAINS AND GREAT LAKES REGION. LATEST METARS REPORTING
CEILING HEIGHTS GENERALLY IN THE VFR RANGE WITH A FEW
METARS REPORTING MVFR CONDITIONS. THE LATEST 25.06Z GFS/NAM
SUGGEST THE CEILING HEIGHTS TO REMAIN IN THE VFR RANGE. EXPECT
VFR CONDITIONS TO PREVAIL AT TAF BOTH RST/LSE SITES TODAY. HIGH
PRESSURE BUILDS INTO NORTHERN WISCONSIN AND NORTHERN MINNESOTA
AFTER 00Z SUNDAY. DRIER AIRMASS ADVECTS INTO THE REGION AND ALLOWS
SKIES TO CLEAR BY 03Z SUNDAY AT BOTH RST/LSE TAF SITES. WINDS WILL
SHIFT TO THE NORTHEAST AND BECOME LESS THAN 10 KNOTS BY 03Z
SUNDAY.

&&

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

$$

SHORT TERM...MW
LONG TERM...MW
AVIATION...DTJ



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