Area Forecast Discussion
Issued by NWS La Crosse, WI

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690
FXUS63 KARX 011724
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1224 PM CDT SUN MAY 1 2016

.UPDATE...
ISSUED AT 1020 AM CDT SUN MAY 1 2016

WILL SEE A BREAK IN SHOWERS THIS MORNING...BUT THEN MID-LEVEL WAVE
MOVES IN FROM WESTERN IA/EASTERN NE THIS AFTERNOON. THIS WILL
SPREAD SHOWER CHANCES BACK IN ACROSS NORTHEAST IA/SOUTHEAST MN
INTO SOUTHERN WI...HIGHEST CHANCES SOUTH OF A LINE FROM CHARLES
CITY IA TO THE WISCONSIN RIVER. IN ADDITION...ADDED A SLIGHT
CHANCE OF SHOWERS ACROSS PORTIONS OF NORTHERN WI...MAINLY ACROSS
TAYLOR COUNTY WHERE SOME SURFACE HEATING AND LINGERING LOWER
LEVEL FRONTOGENESIS WILL EXIST. OTHERWISE...SOME BREAKS IN THE
CLOUDS WILL PROVIDE A GLIMMER OF SUNSHINE FROM TIME TO TIME WITH
HIGH EXPECTED TO TOP OFF IN THE 50S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 328 AM CDT SUN MAY 1 2016

CHALLENGES TODAY/TONIGHT INCLUDE TIMING AND COVERAGE OF LINGERING
SHOWERS AND ASSOCIATED TEMPERATURE TRENDS. 01.00Z GFS/NAM/ECMWF
ARE A BIT TOO ROBUST WITH QPF FOR THE REST OF TODAY...SO WILL
FOLLOW LATEST RAP/HRRR THROUGH 00Z TONIGHT FOR PRECIP...FOLLOWED
BY A MODEL BLEND.

01.08Z ANALYSIS SHOWS AN ELONGATED SURFACE TROUGH FROM CENTRAL
MISSOURI TO CENTRAL INDIANA WITH A TIGHT PRESSURE GRADIENT AND
DRIER NORTHEASTERLY FLOW ACROSS THE FORECAST AREA. LINGERING
SHOWER ACTIVITY EARLY THIS MORNING ALONG DEFORMATION AXIS FROM
AUSTIN MN TO NECEDAH WI WILL DISSIPATE OVER THE NEXT SEVERAL HOURS
AS FRONTOGENESIS WEAKENS AND SHIFTS SOUTH. WILL MAINTAIN SLIGHT
CHANCE POPS FOR MUCH OF THE AREA THIS MORNING. AS SURFACE LOW
LIFTS NORTHEASTWARD THIS AFTERNOON...A TRAILING INVERTED TROUGH
COMBINED WITH SOME 700 HPA FRONTOGENESIS WILL BRING A BETTER
CHANCE FOR ONE LAST ROUND OF SHOWERS ACROSS THE SOUTHERN TIER
COUNTIES. OTHERWISE...POPS DECREASE FROM NORTH TO SOUTH THIS
AFTERNOON AS THE OVERALL SYSTEM MOVES INTO THE SOUTHERN GREAT
LAKES. EXPECT MOSTLY CLOUDY SKIES REGION WIDE TODAY...WITH
TEMPERATURES FROM NEAR 50 ACROSS THE SOUTH TO THE UPPER 50S NORTH
OF I-90.

DRY CONDITIONS WILL RETURN BY MID-TO LATE EVENING WITH CLEARING
FROM NORTHWEST TO SOUTHEAST OVERNIGHT. LOWS WILL DROP INTO THE
UPPER 30S TO LOWER 40S.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 328 AM CDT SUN MAY 1 2016

CANADIAN SHORT-WAVE DROPS SOUTH ACROSS THE UPPER MIDWEST ON
MONDAY...BUT BEST UPPER LEVEL FORCING IS FARTHER WEST ACROSS THE
DAKOTAS. DEEP LAYER SHEAR IS ACTUALLY VERY WEAK WITH SURFACE HIGH
PRESSURE BUILDING ACROSS THE FORECAST AREA. LIKELY TO BE SOME
AFTERNOON THERMAL CU THAT COULD RESULT IN SOME ISOLATED
SHOWERS...BUT WILL KEEP FORECAST DRY AT THIS TIME. OTHERWISE...
EXPECT TEMPERATURES TO RISE INTO THE LOWER TO MID 60S WITH LIGHT
NORTHERLY WINDS.

TUESDAY APPEARS TO BE THE WARMEST DAY OF THE UPCOMING WORK WEEK
AS 925 HPA TEMPERATURES SOAR TO BETWEEN +13 AND +16 CELSIUS BY 00Z
WEDNESDAY. WHEN COMBINED WITH A WELL MIXED BOUNDARY LAYER TO AT
LEAST 800 HPA...EXPECT AFTERNOON HIGHS AROUND 70 DEGREES. WESTERLY
WINDS WILL ALSO BE BREEZY TO LOCALLY WINDY DEPENDING ON WHICH
MODEL SOLUTION VERIFIES. TOP OF THE AFTERNOON BOUNDARY LAYER ON
THE GFS SHOWS 30 KTS...WHEREAS THE NAM IS CLOSER TO 40 KTS. AS A
RESULT...INCREASED WINDS A BIT WITH GUSTS TO AT LEAST 30 MPH...
POSSIBLY UP TO 40 MPH. A COLD FRONT WILL DROP SOUTH ACROSS THE
AREA LATE TUESDAY AFTERNOON/EVENING...BRINGING A CHANCE FOR
SHOWERS/ISOLATED THUNDER GIVEN ELEVATED CAPE FROM 100 TO 300
J/KG.

WEDNESDAY THROUGH FRIDAY...AN OMEGA BLOCKING PATTERN SETS-UP
ACROSS THE CONUS...PROGRESSING SLOWLY EASTWARD EACH DAY. THE
HIGHLY AMPLIFIED 500 HPA RIDGE MOVES OUT OF THE ROCKIES ON
THURSDAY AND INTO THE GREAT PLAINS BY FRIDAY. AT THE SURFACE...
BROAD HIGH PRESSURE WILL CONTROL THE REGIONAL WEATHER PATTERN. A
LOT OF WORDS TO SAY DRY CONDITIONS WILL PREVAIL WITH PARTLY TO
MOSTLY SUNNY SKIES. A GRADUAL WARMING TREND WILL OCCUR WITH HIGHS
RIGHT AROUND NORMAL FOR EARLY MAY. MEDIUM RANGE MODELS DIVERGE FOR
SATURDAY WITH THE ECMWF SHOWING A SHORT-WAVE TOPPING THE RIDGE AND
PROVIDING A CHANCE FOR PRECIP WHEREAS THE GFS IS DRY. GIVEN MODEL
UNCERTAINTY...WILL FAVOR DRY GFS SOLUTION AT THIS TIME GIVEN
OVERALL SYNOPTIC SET-UP. TEMPERATURES WILL BE DEPENDENT ON CLOUDS/
RAIN...BUT HAVE THE POTENTIAL TO TOP 70 DEGREES TO START NEXT
WEEKEND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1223 PM CDT SUN MAY 1 2016

LOW PRESSURE WILL TRACK ACROSS IA/NORTHERN IL THIS
AFTERNOON/TONIGHT. AS SUCH...APPEARS SHRA ASSOCIATED WITH THIS
LOW WILL REMAIN SOUTH OF THE KRST/KLSE TAF SITES WITH JUST
LINGERING VFR CUMULUS/STRATOCUMULUS TO CONTEND WITH. LOOK FOR
THESE CLOUDS TO DIMINISH THIS EVENING WITH LOSS OF SURFACE
HEATING. WILL PROBABLY SEE CUMULUS DEVELOPMENT AGAIN ON
MONDAY...BUT REMAINING VFR. NORTH/NORTHEAST WINDS OF 10-20KT WILL
SUBSIDE THIS EVENING...THEN REMAINING BELOW 10KT THROUGH 18Z
MONDAY.

&&

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

$$

UPDATE...DAS
SHORT TERM...ROGERS
LONG TERM...ROGERS
AVIATION...DAS



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