Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 290812
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
312 AM CDT FRI APR 29 2016

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 312 AM CDT FRI APR 29 2016

FORECAST CHALLENGES INCLUDE CLOUD TRENDS/TEMPERATURES FOR TODAY
AND TONIGHT. WILL INITIALLY LEAN ON HIGH RESOLUTION MODEL
GUIDANCE...THEN TRANSITION INTO A BLEND OF THE 29.00Z GLOBAL
MODEL SUITE FOR TONIGHT GIVEN GOOD OVERALL AGREEMENT.

WEAKENING 500 HPA OCCLUDED LOW OVER SOUTH-CENTRAL WI EARLY THIS
MORNING WILL FINALLY MOVE INTO THE GREAT LAKES REGION LATER TODAY
GIVEN AN UPSTREAM KICKER CLOSED LOW MOVING INTO THE CENTRAL
ROCKIES. BETWEEN THESE TROUGHS IS A HIGHLY AMPLIFIED RIDGE
STRETCHING FROM THE OHIO RIVER VALLEY NORTHWARD INTO THE SOUTHERN
CANADIAN PRAIRIES. WHILE LINGERING SHOWERS MAINLY NORTH AND EAST
OF I-94 WILL DISSIPATE BY 12Z WITH DRY CONDITIONS THEREAFTER...
EXPECT CLOUD COVER TO HANG TOUGH THROUGH THE DAY. NEAR SURFACE
FLOW SHIFTS TO THE EAST LATER TODAY USHERING IN DRIER LOW-LEVEL
AIR...BUT SOUNDINGS SHOW A SHALLOW SATURATED LAYER AROUND 850 HPA
GETTING TRAPPED BENEATH SUBSIDENT INVERSION ASSOCIATED WITH
BUILDING HIGH PRESSURE FROM THE NORTH. WHILE SOME SUN IS POSSIBLE
THIS AFTERNOON...COOL CONVECTIVE TEMPERATURES SHOULD RESULT IN
THERMAL CUMULUS QUICKLY FILLING IN THESE HOLES. ALL SAID...EXPECT
MOSTLY CLOUDY SKIES WITH TEMPERATURES RISING INTO THE MID 50S.

FOR TONIGHT...EXPECT SOME CLEARING TO FINALLY MOVE INTO AREAS
MAINLY ALONG AND NORTHEAST OF THE I-94 CORRIDOR WITH AT LEAST
PARTLY CLOUDY SKIES ELSEWHERE. WHERE CLOUDS DISSIPATE...LOWS WILL
FALL INTO THE 30S. OTHERWISE...LOW 40S ARE EXPECTED.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 312 AM CDT FRI APR 29 2016

AFOREMENTIONED CLOSED LOW ACROSS THE CENTRAL ROCKIES BEGINS TO
UNDER CUT THE AMPLIFIED RIDGE...MOVING ALONG THE KS/NE BORDER
REGION ON SATURDAY. SURFACE WARM FRONT AND ALL ASSOCIATED
INSTABILITY REMAINS WELL SOUTH ACROSS MO...BUT NORTHEASTWARD
ADVANCING WING OF MID-LEVEL MOISTURE TRANSPORT/WARM AIR ADVECTION/
FRONTOGENESIS LIFTS INTO THE UPPER MIDWEST. AS WITH THE LAST
SYSTEM...PRECIP WILL BE FIGHTING AGAINST DRY LOW LEVEL AIR
ASSOCIATED WITH STRONG HUDSON BAY SURFACE HIGH NOSING SOUTH ACROSS
MN/WI. STILL SOME MODEL DIFFERENCES WITH NORTHERN EXTENT OF
ACCUMULATING RAIN WITH THE GFS/GEM KEEPING SHOWERS MAINLY SOUTH OF
I-90 WHEREAS THE NAM/ECMWF BRING THEM AS FAR NORTH AS THE I-94
CORRIDOR. GIVEN OVERALL SYNOPTIC SET-UP...PREFER THE DRIER
SOLUTIONS. WITH THIS IN MIND...TOTAL RAINFALL THROUGH SATURDAY
NIGHT WILL RANGE FROM NOTHING ACROSS NORTH-CENTRAL WI TO AROUND A
HALF AN INCH FOR PORTIONS OF NORTHEAST IA INTO SOUTHWEST WI.
TEMPERATURES WILL BE RAINFALL DEPENDENT WITH HIGHS RANGING FROM
THE LOW 50S ACROSS THE SOUTH TO AROUND 60 DEGREES NORTH OF I-90.
EASTERLY WINDS WILL BE STRONGER...GUSTING UP TO 25 MPH AT TIMES.

EXPECT MOSTLY DRY CONDITIONS SUNDAY THROUGH THURSDAY WITH DOMINANT
SURFACE HIGH PRESSURE IN CONTROL ACROSS THE UPPER MIDWEST. THE
ONLY REAL CHANCE FOR ADDITIONAL PRECIP IS LATE TUESDAY THROUGH
WEDNESDAY AS A TRAILING COLD FRONT DROPS SOUTH ACROSS THE REGION.
HOWEVER...WILL FOLLOW MODEL CONSENSUS FOR NOW KEEPING FORECAST
DRY. SOME DAY TO DAY VARIATION IN TEMPERATURES EXPECTED...BUT WITH
NO MAJOR CHANGES IN AIR MASS...EXPECT DAILY HIGHS GENERALLY
OSCILLATING IN THE 60S WITH LOWS MAINLY THE 40S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1144 PM CDT THU APR 28 2016

THE SLOW MOVING SFC LOW HAD MOVED SOUTHEAST OF THE AREA...WHILE THE
MID LEVEL CIRCULATION WAS OVER SOUTHWEST WI. WITH THIS CIRCULATION
STILL IN THE AREA...AREAS OF -RA/-DZ AND MVFR/IFR CIGS/VSBYS
REMAINED OVER SOUTHEAST MN/WESTERN WI. THE MID LEVEL LOW IS EXPECTED
TO MOVE EAST MORE QUICKLY THRU THE REST OF TONIGHT INTO EARLY FRI
MORNING. THE LOWER CLOUDS AND AREAS OF PRECIP WILL DIMINISH THRU THE
OVERNIGHT HOURS. MORE NORTHERLY SFC-850MB FLOW ON THE BACK SIDE OF
THE DEPARTING LOW WILL PULL DRIER AIR SOUTHWARD INTO THE TAF SITES
LATER TONIGHT AND FOR FRI. VSBYS ARE EXPECTED TO BE VFR AFTER
09Z...WITH CIGS RISING TO VFR BY MID MORNING FRI. CLOUDS A LITTLE
TRICKY FOR FRI. ANY CIGS FRI SHOULD BE 3500-4500 FT BUT QUESTION IS
WILL THIS DECK BECOME SCT DURING THE AFTERNOON AS HIGH PRESSURE
TRIES TO NOSE SOUTH INTO MN/WI. MODEL SOUNDINGS SHOWING THE
LINGERING CLOUD LAYER MOISTURE TRAPPED UNDER AN INVERSION NEAR
850MB...WITH STEEP LAPSE RATES UNDER THE INVERSION. LEFT CLOUDS
DECKS THRU FRI AFTERNOON AS BKN...BECOMING SCT EARLY FRI EVENING
WITH LOSS OF HEATING/SUNSET.

&&

.HYDROLOGY...
ISSUED AT 312 AM CDT FRI APR 29 2016

WATER LEVELS ALONG THE MISSISSIPPI RIVER WILL BE RISING OVER THE
NEXT SEVERAL DAYS. AT THIS TIME...IT APPEARS THAT CRESTS WITHIN
1-5 FEET OF FLOOD STAGE ARE EXPECTED DURING THE FIRST WEEK OF
MAY. THOSE WITH INTERESTS OR CONCERNS ALONG THE RIVER SHOULD KEEP
AN EYE ON WATER LEVELS AND THE LATEST FORECAST INFORMATION.

&&

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

$$

SHORT TERM...ROGERS
LONG TERM...ROGERS
AVIATION.....RRS
HYDROLOGY...BOYNE



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