Area Forecast Discussion
Issued by NWS La Crosse, WI

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448
FXUS63 KARX 300405
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1105 PM CDT FRI APR 29 2016

.SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT)
ISSUED AT 224 PM CDT FRI APR 29 2016

CUMULUS/STRATO-CUMULUS CLOUDS HOLDING STUBBORNLY ACROSS THE AREA
THIS AFTERNOON AS MOISTURE IS TRAPPED UNDER HIGH PRESSURE SUBSIDENCE
INVERSION. BUFKIT SOUNDINGS AND NSSL WRF SYNTHETIC FORECASTED
IMAGERY SHOWING EVENTUAL SCATTERING OF THESE CLOUDS 5-6PM TIME
FRAME...SO STILL MIGHT HAVE A COUPLE HOURS OF AMPLE SUN BEFORE THE
SUN SETS. OTHERWISE...TEMPERATURES WERE A BIT COOL WITH READINGS IN
THE UPPER 40S TO THE MIDDLE 50S.

SURFACE RIDGE OF HIGH PRESSURE SLIPS SLOWLY EAST TONIGHT AS LOW
PRESSURE LIFTS NORTHEAST OUT OF THE SOUTHERN PLAINS INTO NORTHWEST
MO BY MORNING. MOISTURE CONVEYOR BELT/BAND OF SHOWERS WRAPPING AHEAD
OF THE LOW LOOKS TO STAY MAINLY SOUTH OF THE AREA..WITH PERHAPS A
FEW BRUSHING PARTS OF NORTHEAST IA INTO FAR SOUTHWEST WI BY DAYBREAK.
WAS A LITTLE CONCERNED FOR SOME PATCHY FROST POTENTIAL NORTHEAST OF
THE I-94 CORRIDOR...BUT SLOWLY TIGHTENING PRESSURE GRADIENT
OVERNIGHT SHOULD HELP KEEP THE LOWER BOUNDARY LAYER STIRRED WITH
NORTHEAST WINDS IN THE 5-10 MPH RANGE TO DETER FROST DEVELOPMENT.
LOOK FOR OVERNIGHT LOWS TONIGHT IN THE MIDDLE 30S ACROSS CENTRAL
WI...TO THE LOWER 40S MAINLY ALONG AND WEST OF THE MISSISSIPPI RIVER.

RAIN SHOWERS LOOK TO SLOWLY EDGE NORTHWARD INTO THE AREA THROUGH
SATURDAY AS AREA OF SURFACE LOW PRESSURE SLIPS EAST THROUGH
ILLINOIS. DRY NORTHEAST FLOW OUT OF HIGH PRESSURE OVER CANADA SHOULD
PRODUCE A SHARP NORTHERN EDGE TO THESE RAIN SHOWERS. CURRENT
THINKING IS THAT THESE SHOWERS SHOULD BE CONFINED MAINLY ALONG/SOUTH
OF I-90.
TEMPERATURES ACROSS THE SOUTH/SOUTH OF I-90 WILL BE HELD DOWN BY
DENSER CLOUD COVER AND RAIN SHOWERS...TOPPING OFF IN THE LOWER 50S.
MEANWHILE...FARTHER NORTH IN PARTIAL SUNSHINE/NORTH OF I-90...LOOK
FOR HIGHS IN THE 55-60 DEGREE RANGE.

SHOWERS SLOWLY DIMINISH SATURDAY NIGHT AS HIGH PRESSURE BUILDS SOUTH
OUT OF CANADA WITH LOW TEMPERATURES FALLING INTO THE UPPER 30S TO
THE LOWER 40S.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 224 PM CDT FRI APR 29 2016

MID-LEVEL TROUGH OF LOW PRESSURE LINGERS ACROSS SOUTHERN
WI/NORTHEAST IA SUNDAY...BUT BETTER FORCING APPEARS TO BE PUSHED
SOUTH AND EAST OF THE AREA FOR ANY SHOWER THREAT. A FEW POP-UP
SHOWERS MAY BEE SEEN UNDER THIS COLDER/CYCLONIC FLOW ALOFT THROUGH
THE MORNING HOURS SOUTH OF I-90. BY SUNDAY AFTERNOON...DRIER
SUBSIDENT AIR TAKES OVER CLEARING OUT THE SHOWER CHANCES.
OTHERWISE...LOOK FOR HIGHS IN THE 60-65 DEGREE RANGE.

PLAN ON DRY WEATHER FOR SUNDAY NIGHT THROUGH MONDAY NIGHT AS HIGH
PRESSURE DOMINATES THE UPPER MISSISSIPPI RIVER VALLEY REGION. HIGHS
ON MONDAY LOOK TO TOP OFF IN THE LOWER/MIDDLE 60S.

A MID-LEVEL TROUGH/SURFACE COLD FRONT PUSH THROUGH THE REGION
TUESDAY NIGHT/WEDNESDAY FOR A CHANCE OF SHOWERS. PRE-COLD FRONT
TUESDAY LOOKS TO PUSH HIGHS WELL INTO THE 60S TO NEAR 70. A BIT
CHILLIER WEDNESDAY BEHIND THE FRONT WITH HIGHS TOPPING OFF IN THE
UPPER 50S TO THE MIDDLE 60S.

FORECAST CONFIDENCE FALLS OFF THURSDAY AND FRIDAY AS THE LATEST
GFS/ECMWF STILL AT ODDS ON WHETHER WE WILL SEE AN AMPLIFYING RIDGE
OF HIGH PRESSURE PER THE ECMWF OR RATHER DEEP TROUGHING PER THE GFS.
AS SUCH...WILL KEEP CONSENSUS/BLEND TREND GOING FOR NOW WHICH YIELDS
A SMALL CHANCE OF SHOWERS THURSDAY NIGHT WITH HIGHS IN THE 60S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1105 PM CDT FRI APR 29 2016

STRATO-CU HAVE DECREASED THRU THE EVENING...WITH FEW/SCT EXPECT AT
THE TAF SITES INTO THE OVERNIGHT HOURS. HOWEVER...SOME RENEWED LOWER
LEVEL MOISTURE/2500-3500 FT CLOUDS AROUND THE SOUTHERN END OF LK MI
WERE ADVECTING TOWARD THE AREA ON SOUTHEAST 925-850MB FLOW. THIS
WOULD ARRIVE AFTER 12Z...AND CONTINUED WITH A SCT025-030 MENTION AT
BOTH KLSE/KRST THRU MUCH OF SAT MORNING. MODEL SOUNDINGS/X-SECTIONS
SHOW THIS TO RISE TO 4K-5K FT BY MID-DAY WITH DIURNAL WARMING/MIXING
AND THE CONTINUED DRY EAST-NORTHEAST SFC-925MB FLOW. NOW APPEARS THE
NORTHERN EDGE OF THE PRECIP WITH THE SYSTEM MOVING ACROSS THE
CENTRAL PLAINS IS GOING TO SPREAD INTO THE I-90 CORRIDOR DURING THE
LATE AFTERNOON/EARLY EVENING HOURS OF SAT. WITH THE TAF SITES ON THE
NORTH EDGE OF THIS PRECIP AND BRISK/GUSTY/DRY EAST/NORTHEAST LOWER
LEVEL FLOW CONTINUING...CIGS/VSBYS EXPECTED TO REMAIN VFR AS THE
BAND OF -SHRA MOVES THROUGH THE AREA. A SHIFT NORTHWARD OF THE
PRECIP BY AS LITTLE AS 25-50 MILES COULD BRING MVFR VSBYS IN SHRA
INTO THE TAF SITES DURING THE 21Z-02Z PERIOD. MAIN FORCING/LIFT OVER
THE AREA WEAKENS RATHER QUICKLY DURING THE MID/LATE EVENING HOURS
WITH ONLY A VCSH MENTION AFTER 01-02Z. GRADIENT RELAXES FOR LIGHTER
NORTHEAST WINDS BY MID EVENING AS WELL.

&&

.HYDROLOGY...
ISSUED AT 224 PM CDT FRI APR 29 2016

RECENT RAINFALLS THIS PAST WEEK WILL PRODUCE MINOR RISES ON THE
MISSISSIPPI RIVER. THOSE WITH INTERESTS OR PLANS ALONG THE RIVER
SHOULD MAY WANT TO KEEP AN EYE ON WATER LEVELS AND INCREASED FLOW
RATES.

&&

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

$$

SHORT TERM...DAS
LONG TERM....DAS
AVIATION.....RRS
HYDROLOGY....DAS



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