Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 190822
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
322 AM CDT SAT APR 19 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 322 AM CDT SAT APR 19 2014

THE MAIN FOCUS THROUGH TONIGHT IS ON THE WARMER/WINDIER CONDITIONS
TODAY ALONG WITH WHEN RAIN SHOWERS MOVE IN OVERNIGHT.

A SURFACE RIDGE OF HIGH PRESSURE HAS SHIFTED EAST INTO THE GREAT
LAKES WHILE A DEEPENING SURFACE LOW TRACKS THROUGH THE DAKOTAS.
THE PRESSURE GRADIENT BETWEEN THESE TWO FEATURES HAS BEEN FAIRLY
TIGHT CAUSING GUSTY WINDS ACROSS THE EASTERN DAKOTAS/WESTERN
MINNESOTA OVERNIGHT. AS THE LOW LIFTS UP INTO ONTARIO AND PHASES
WITH ANOTHER LOW CURRENTLY IN SOUTHERN SASKATCHEWAN...THIS TIGHT
GRADIENT WILL MOVE INTO THE UPPER MISSISSIPPI RIVER VALLEY AND
HELP TO DEVELOP SOME GUSTY SOUTH WINDS TODAY. THIS WILL ALSO HELP
TO BRING SOME WARMER IN FROM THE SOUTH WITH 850MB TEMPERATURES
CLIMBING TO AROUND +8C AND 925MB TEMPERATURES AROUND +15C. THIS
SHOULD ALLOW HIGHS TODAY TO BE ABLE TO REACH THE MID TO UPPER
60S.

THE COLD FRONT ASSOCIATED WITH THIS LOW WILL DRIFT INTO THE REGION
LATER THIS EVENING WITH SOME WEAK LOW LEVEL MOISTURE TRANSPORT
HELPING TO PRODUCE SOME RAIN SHOWERS OUT AHEAD OF IT. THIS BAND
WILL GRADUALLY DIP SOUTHEAST ACROSS THE REGION OVERNIGHT WITH
RAINFALL AMOUNTS GENERALLY ON THE LIGHT SIDE. 0-3KM MUCAPE IS
NON-EXISTENT THROUGH THE AFTERNOON AND EVENING BUT THEN STARTS TO
INCREASE ACROSS NORTHEAST IOWA AND SOUTHEAST MINNESOTA AFTER
MIDNIGHT. WITH MUCAPE ONLY AT A FEW HUNDRED J/KG AND 0-6KM BULK
SHEAR STAYING WEAK AT 20-30KT...AM NOT EXPECTING ANYTHING IN THE
WAY OF ORGANIZED CONVECTION.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 322 AM CDT SAT APR 19 2014

THIS FRONT WILL REMAIN STALLED OUT ACROSS THE REGION THROUGH
MONDAY MORNING BEFORE THE NEXT SYSTEM EJECTS OUT OF SOUTHWEST
CANADA AND GIVES IT A BUMP TO THE EAST MONDAY. AS THIS OCCURS...A
WEAKER MID LEVEL TROUGH CURRENTLY IN THE FOUR CORNERS REGION WILL
LIFT UP INTO THE MID MISSISSIPPI RIVER VALLEY AND COULD PROVIDE
SOME BETTER LIFT...PARTICULARLY IN THE LOW TO MID LEVELS...TO
PRODUCE SOME MORE WIDESPREAD CONVECTION. STILL A LOT OF DIFFERING
OPINIONS ON THE STRENGTH OF THE LOW LEVEL MOISTURE TRANSPORT
BETWEEN THE 19.00Z GUIDANCE WITH THE GFS BEING A LOT HIGHER ON THE
QPF COMPARED TO THE NAM/GEM. THE TIMING IS A BIT OFF AS WELL WITH
THE NAM PUSHING THE RAIN OFF TO THE EAST FASTER THAN WHAT THE
GFS/ECMWF ARE SHOWING...SO UNCERTAINTY LINGERS WITH THIS PORTION
OF THE FORECAST. OVERALL...ABOUT A HALF INCH TO AN INCH OF TOTAL
QPF LOOKS ABOUT GOOD FOR THIS WHOLE EVENT.

A COLDER AIR MASS DROPS DOWN FROM CANADA BEHIND THIS SYSTEM WITH
TEMPERATURES STRUGGLING TO GET TO 60F TUE/WED. MAY ACTUALLY BE A
FEW DEGREES TOO WARM ON HIGHS FOR TUESDAY WHEN WE ARE IN THE MAIN
CORRIDOR OF COLD AIR ADVECTION WITH THE 19.00Z ECMWF SUGGESTING
HIGHS ONLY IN THE LOW TO MID 50S.

THE FOCUS THEN GOES TO THE DEEP TROUGH THAT DEVELOPS ACROSS THE
NORTHERN PLAINS WEDNESDAY AND TRACKS THROUGH THE REGION BY FRIDAY.
THERE APPEARS TO BE A NUMBER OF CHANCES FOR SEEING RAIN FROM THIS
SYSTEM...FIRST WITH THE WARM AIR ADVECTION BELT ON
WEDNESDAY...FOLLOWED BY THE COLD FRONT/PRE-FRONTAL TROUGH
THURSDAY...AND THEN THE INVERTED SURFACE/MID LEVEL TROUGH ON
FRIDAY. AGAIN...NOT MUCH INSTABILITY WITH THIS SYSTEM WITH ONLY A
FEW HUNDRED J/KG OF 0-3KM MUCAPE COMING IN ON THURSDAY AHEAD OF
THE COLD FRONT.

COLDER AIR LOOKS LIKE IT IS ON TAP TO DROP DOWN BEHIND THIS SYSTEM
FOR NEXT WEEKEND WITH 850MB DROPPING DOWN INTO THE -2C TO -4C
RANGE.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1138 PM CDT FRI APR 18 2014

WINDS WILL BE ON THE INCREASE TODAY AS THE PRESSURE GRADIENT
TIGHTENS OVER THE TAF SITES. INITIALLY THIS INCREASE IS EXPECTED
ABOVE THE GROUND EARLY THIS MORNING...WITH 40-50 KT SOUTHEAST TO
SOUTH WINDS FORECAST NEAR 1500 FT. WITH WINDS ONLY 8-15 KT AT THE
SURFACE...HAVE CONTINUED LOW LEVEL WIND SHEAR. LOOK FOR THE LOW
LEVEL WIND SHEAR TO END AROUND 12-13Z AS THE WINDS BEGIN TO MIX
DOWN THE SURFACE...RESULTING IN SOUTHEAST TO SOUTH GUSTS OF 24-28
KT FOR MUCH OF THE DAY. WINDS SHOULD DIMINISH QUICKLY IN THE
EVENING DUE TO LOSS OF DAYTIME HEATING AND THE PRESSURE GRADIENT
RELAXING WITH THE APPROACH OF A COLD FRONT. THERE IS THE POTENTIAL
FOR LOW LEVEL WIND SHEAR LATE IN THE EVENING AT LSE...BUT MARGINAL
ENOUGH TO NOT MENTION AT THIS TIME.

OUTSIDE OF THE WINDS...VFR CONDITIONS ARE ANTICIPATED AS DRY AIR
HOLDS FIRMLY IN PLACE. THERE COULD BE SOME SHOWERS THIS EVENING
ASSOCIATED WITH LOWERING CEILINGS AND THE APPROACHING COLD FRONT
FROM THE WEST. HAVE ONLY INCLUDED A VCSH AT RST AT THIS TIME SINCE
THE FRONT WILL BE SLOW MOVING.


&&

.FIRE WEATHER...
ISSUED AT 322 AM CDT SAT APR 19 2014

DRY CONDITIONS ARE EXPECTED TODAY...PARTICULARLY ACROSS WESTERN
WISCONSIN WHERE RH VALUES WILL DROP INTO THE 30 TO 40 PERCENT
RANGE. WITH GUSTY SOUTH WINDS OF 25 TO 35 MPH AT TIMES...SOME FIRE
WEATHER CONCERNS ARE THERE FOR TODAY WITH MOST OF THE AREA NOT
HAVING GREENED UP YET. HOWEVER...RECENT HEAVY RAINFALL FROM LAST
WEEKEND MAY BE ENOUGH TO SUPPRESS SOME OF THESE DRIER CONDITIONS
AND LIMIT THE FIRE CONCERNS.

&&

.HYDROLOGY...
ISSUED AT 322 AM CDT SAT APR 19 2014

RIVER LEVELS REMAIN ELEVATED ACROSS MUCH OF THE REGION WITH THE
MAIN FLOODING OCCURRING NEAR MCGREGOR ON THE MISSISSIPPI RIVER.
RAIN FALL IS LIKELY LATE SATURDAY INTO MONDAY WITH ROUGHLY A HALF
INCH TO AN INCH OF RAIN FALLING OVER THIS PERIOD. WHILE THIS RAIN
WILL NOT CAUSE ANY ADDITIONAL FLOODING...IT WILL KEEP THE RIVER
LEVELS ELEVATED THROUGH NEXT WEEK.

&&

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

$$

SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...AJ
FIRE WEATHER...HALBACH
HYDROLOGY...HALBACH



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