Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 141144
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
644 AM CDT MON APR 14 2014

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 345 AM CDT MON APR 14 2014

MAIN FORECAST CONCERN IS WITH THE PRECIPITATION CHANCES TODAY AND
THEN TUESDAY NIGHT INTO WEDNESDAY.

SURFACE ANALYSIS SHOWS AN AREA OF LOW PRESSURE OVER NORTHERN
ILLINOIS. LOCAL AND REGIONAL RADARS SHOWING THE DEFORMATION BAND
OF PRECIPITATION ON THE NORTHWEST SIDE OF THE LOW EXTENDS FROM
SOUTHERN IOWA ACROSS THE AREA INTO EASTERN LAKE SUPERIOR. COLDER
AIR HAS FILTERED IN AND CHANGED MOST OF THE PRECIPITATION OVER TO
SOME LIGHT SNOW. THE PRECIPITATION IS MOVING TO THE NORTHEAST AND
THE 14.05Z HRRR SEEMS TO HAVE A GOOD HANDLE ON THE CURRENT
SITUATION. IT INDICATES THAT BY 12Z THE BACK EDGE OF THE
PRECIPITATION COMING OUT OF SOUTHERN IOWA WILL HAVE SHIFTED INTO
SOUTHERN WISCONSIN WITH THE WESTERN EDGE INTO THE WESTERN AND
CENTRAL PARTS OF WISCONSIN. WILL ADJUST THE MORNING SNOW CHANCES
BASED ON RADAR TRENDS...BUT EXPECT THAT THE MAJORITY OF THE
ACTIVITY SHOULD BE EAST OF THE FORECAST AREA BY 12Z AND THEN WHAT
IT IS LEFT WILL QUICKLY DISSIPATE BY THE MID MORNING HOURS.

HIGH PRESSURE WILL THEN BUILD IN OVER THE UPPER MIDWEST AND LINGER
INTO TUESDAY BEFORE DEPARTING TO THE NORTHEAST. THE HIGH WILL HELP
TO KEEP TEMPERATURES BELOW NORMAL WITH HIGHS TODAY ONLY IN THE
30S FOR THE ENTIRE AREA AND THEN IN THE 30S AND 40S FOR TUESDAY.

THE NEXT CHANCE FOR SOME PRECIPITATION WILL START TO COME IN
TUESDAY NIGHT AND CONTINUE INTO WEDNESDAY. THIS WILL BE IN
RESPONSE TO A SHORT WAVE TROUGH THAT WILL CROSS THE NORTHERN
ROCKIES TUESDAY NIGHT AND MOVE OUT OVER THE UPPER MIDWEST
WEDNESDAY. THE BEST PV ADVECTION IN THE 500-300 MB LAYER IS
EXPECTED TO REMAIN NORTHWEST OF THE AREA THROUGH WEDNESDAY...BUT
THE WAVE SHOULD STILL BE ABLE TO PRODUCE AT LEAST SOME WEAK PV
ADVECTION OVER THE NORTHWEST SECTIONS OF THE FORECAST AREA. LOW
PRESSURE AT THE SURFACE IS EXPECTED TO MOVE EAST ACROSS SOUTH
DAKOTA DURING THE DAY WEDNESDAY WITH A WARM FRONT EXTENDING EAST
INTO WISCONSIN. WEAK FRONTOGENESIS IN THE 1000-700 MB LAYER IS
EXPECTED TO DEVELOP ALONG AND NORTH OF THE WARM FRONT ACROSS
MINNESOTA AND WISCONSIN. THE WARM AIR ADVECTION AHEAD OF THE SHORT
WAVE TROUGH AND SURFACE LOW IS EXPECTED TO PRODUCE 5 TO 8 UBAR/S
OF UP GLIDE ON THE 290K ISENTROPIC SURFACE. WITH THE FORCING FROM
THE SHORT WAVE TROUGH AND THE LOW LEVEL FRONTOGENESIS AND
ISENTROPIC UP GLIDE...EXPECT TO SEE PRECIPITATION BEGIN TO DEVELOP
ALONG AND NORTH OF THE WARM FRONT LATE TUESDAY NIGHT AND CONTINUE
INTO WEDNESDAY. WILL START OUT WITH SOME SMALL CHANCES ALONG AND
NORTH OF INTERSTATE 94 LATE TUESDAY NIGHT AND THEN SPREAD THE
CHANCES SOUTH TO ABOUT THE IOWA/MINNESOTA BORDER WEDNESDAY WHILE
INCREASING TO 50 PERCENT ACROSS THE FAR NORTH. BUFKIT SOUNDINGS
INDICATE THAT ICE WILL BE PRESENT IN THE CLOUDS AND THERE SHOULD
NOT BE A WARM LAYER TO DEAL WITH...SO THE PRECIPITATION TYPE
SHOULD BE CONTROLLED BY THE BOUNDARY LAYER TEMPERATURES. WILL
START WITH ALL SNOW TUESDAY NIGHT GOING TO RAIN WEDNESDAY AS
READINGS WARM INTO THE 40S AND 50S.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 345 AM CDT MON APR 14 2014

SLOW AND COMPLICATED UPPER AIR PATTERN WILL KEEP THE PRECIPITATION
CHANCES IN THE FORECAST THROUGH THE WEEKEND. ONCE THE FIRST SHORT
WAVE TROUGH MOVES PAST THE REGION WEDNESDAY NIGHT...ALL THE MODELS
SHOW A CUT OFF LOW FORMING OVER SOUTHERN SASKATCHEWAN FROM A
STRONG NORTHERN STREAM SHORT WAVE TROUGH COMING DOWN FROM THE
NORTHERN CANADA. THIS IS EXPECTED TO KEEP THE MEAN LONG WAVE
TROUGH ALONG AND EAST OF THE ROCKIES WITH SEVERAL SHORT WAVE
TROUGHS COMING THROUGH THIS LONG WAVE TROUGH. THE CLOSED LOW
SHOULD THEN OPEN UP AND START TO MOVE EAST WITH THE LONG WAVE
TROUGH PASSING OVER FOR THE WEEKEND. WITHIN THIS EXTENDED PERIOD
OF PRECIPITATION CHANCES...THE BEST CHANCES LOOK TO OCCUR THURSDAY
NIGHT INTO FRIDAY WHEN A STRONG SHORT WAVE TROUGH IS SHOWN BY THE
MODELS TO MOVE ACROSS THE REGION. TEMPERATURES STILL LOOK TO BE
COOL ENOUGH FOR SNOW OR A RAIN/SNOW MIX AT NIGHT GOING TO RAIN
DURING THE DAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 644 AM CDT MON APR 14 2014

NOW THAT THE SNOW HAS EXITED EAST OF THE AREA...MAIN CONCERN TURNS
TO WINDS AND CLOUD COVER. LOOKING FOR MVFR CLOUDS TO SCATTER KRST
BY 13Z AND KLSE BY 15Z...LEAVING A VFR CIG OF MID-
CLOUD/ALTOCUMULUS. STEEPENING LAPSE RATES THIS AFTERNOON EXPECTED
TO PRODUCE CUMULUS WITH VFR BASES IN THE 4-5KFT RANGE. LOOK FOR
THIS TO SCATTER OUT AFTER SUNSET WITH LOSS OF SURFACE HEATING.
OTHERWISE...A TIGHT PRESSURE GRADIENT WILL EXIST ACROSS THE AREA
TODAY BETWEEN LOW PRESSURE OVER THE GREAT LAKES AND HIGH PRESSURE
BUILDING IN FROM THE NORTHERN PLAINS. AS A RESULT...PLAN ON
NORTH/NORTHWEST WINDS IN THE 15-25KT RANGE SUSTAINED WITH GUSTS
AROUND 30KT. THIS WINDS WILL SUBSIDE RAPIDLY THIS EVENING AFTER
SUNSET WITH LOSS OF DEEPER MIXING AND AS HIGH PRESSURE BUILDING
OVERHEAD.

&&

.HYDROLOGY...
ISSUED AT 345 AM CDT MON APR 14 2014

PARTS OF SOUTHWEST WISCONSIN RECEIVED BETWEEN 2 AND 4 INCHES OF
RAIN OVER THE WEEKEND. THIS HAS RESULTED IN SATURATED SOILS AND
RUNOFF INTO AREAS STREAMS. THIS HAS RESULTED IN MAINLY IN BANK
RISES BUT THE LATEST FORECASTS INDICATE SOME MINOR FLOODING IS
POSSIBLE ALONG THE KICKAPOO IN THE VICINITY OF READSTOWN. SOME
FLOODING LATER THIS WEEK IS POSSIBLE ALONG THE MISSISSIPPI RIVER
AS RUNOFF FROM THE SNOWMELT UPSTREAM AND THE RECENT RAINS MOVES
DOWNSTREAM.

&&

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

$$

SHORT TERM...04
LONG TERM...04
AVIATION...DAS
HYDROLOGY...04



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