Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 302343
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
643 PM CDT MON MAR 30 2015

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 316 PM CDT MON MAR 30 2015

THE MAIN FOCUS INTO TOMORROW IS ON THE BAND OF RAIN MOVING
THROUGH THE REGION RIGHT NOW INTO TONIGHT.

CURRENTLY...A MID LEVEL SHORT WAVE TROUGH IS NOTED ON WATER VAPOR
IR/RAP ANALYSIS OVER EASTERN MINNESOTA. THIS TROUGH WILL CONTINUE ITS
PROPAGATION THROUGH THE NORTHWEST FLOW ALOFT INTO THE GREAT LAKES
REGION OVERNIGHT. AT THE SURFACE...A LOW PRESSURE SYSTEM IS
CENTERED NEAR FARGO NORTH DAKOTA WITH A WARM FRONT EXTENDING
SOUTHEAST THROUGH NORTHEAST IOWA. A BAND OF LIGHT TO MODERATE RAIN
HAS DEVELOPED TO THE NORTHEAST OF THIS FRONT WHERE THE NOSE OF
THE LOW LEVEL WARM AIR ADVECTION IS PUSHING UP INTO. ALL OF THE
MESO-GUIDANCE SUGGESTS THAT THIS BAND WILL CONTINUE TO PUSH
EASTWARD INTO TONIGHT AS THE MAIN SHORTWAVE TROUGH AND SURFACE LOW
TRACKS THAT WAY AS WELL. THE SURFACE WARM FRONT HAS NOT BEEN
ADVANCING MUCH TO THE EAST...SO THE WARM AIR SHOULD MAINLY STAY
WHERE IT IS NOW WITH THE LOW TRACKING ALONG IT.

THIS NORTHWEST TO SOUTHEAST TEMPERATURE GRADIENT LOOKS LIKE IT
WILL REMAIN IN PLACE FOR TOMORROW AS THE FLOW ALOFT STAYS OUT OF
THE NORTHWEST. A SECONDARY LOW CURRENTLY OVER SOUTHERN MANITOBA
LOOKS LIKE IT WILL TRACK TO THE NORTHEAST OF THE REGION TOMORROW
AND SHOULD NOT CAUSE ANY PRECIPITATION LOCALLY.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 316 PM CDT MON MAR 30 2015

THE FOCUS THEN GOES TO WEDNESDAY WITH HOW WARM IT WILL GET...WHEN
THE RAIN WILL MOVE THROUGH...AND WHETHER THERE WILL BE ANY THUNDER
THAT OCCURS.

THE TREND FOR THIS SYSTEM CONTINUES TO BE TO SLOW DOWN THE ARRIVAL
OF THE RAIN ON WEDNESDAY AFTERNOON AND THEN SPEED UP ITS
DEPARTURE EARLY ON THURSDAY. CLOUD COVER LOOKS LIKE IT SHOULD HOLD
OFF UNTIL LATE IN THE AFTERNOON/EARLY EVENING...SO THE STRONG LOW
LEVEL FLOW SHOULD BE ABLE TO PUSH MUCH OF THE REGION INTO THE MID
TO UPPER 60S WITH SOME 70S POSSIBLE AS WELL. WITH THE DRY AIR IN
PLACE AHEAD OF THE SYSTEM...SOME GUSTY CONDITIONS SHOULD DEVELOP
WITH THE PRESSURE GRADIENT TIGHTENING UP.

AS FOR THE RAIN/THUNDER CHANCES WITH THIS SYSTEM...THE GULF OF
MEXICO LOOKS LIKE IT WILL OPEN UP WITH SOME STRONG MOISTURE FLOW
PUSHING UP TOWARD THE SURFACE FRONT. THE 30.12Z NAM/GFS/ECMWF ARE
ALL IN GOOD AGREEMENT WITH BUILDING ABOUT 500-1000 J/KG OF 0-3KM
MUCAPE IN A NARROW RIBBON UP TOWARD THE FRONT IN SOUTH
CENTRAL/NORTH CENTRAL IOWA BY 00Z THURSDAY AND THEN SWINGING IT
THROUGH THE REGION AS THE FRONT PASSES WEDNESDAY NIGHT/THURSDAY
MORNING. FORECAST SOUNDINGS SHOW A TROPICAL/MOIST PROFILE WITH
SKINNY CAPE AND UNIDIRECTIONAL WIND SHEAR THROUGH THE COLUMN WHICH
ALSO IS PARALLEL TO THE BOUNDARY. THERE IS SOME DECENT LOW LEVEL
SPEED SHEAR WITH WINDS GOING FROM AROUND 10KTS OUT OF THE
SOUTHWEST AT THE SURFACE TO 40KTS AROUND 1KM. FOR THE MOST
PART...THIS JUST LOOKS LIKE A HEAVY RAIN PRODUCER AS THE FRONT
COMES THROUGH WITH PWS AROUND 1.25 INCHES WITH LITTLE IN THE WAY
OF SEVERE WEATHER LOCALLY DUE TO THE LOW INSTABILITY AND LACK OF
DEEP SHEAR.

BEYOND THIS...PRECIPITATION CHANCES LOOK MARGINAL GIVEN THAT THE
FLOW ALOFT STAYS NORTHWESTERLY TO ZONAL. THE 30.12Z GFS IS A BIT
MORE PROGRESSIVE WITH HAVING SOME SYSTEMS MOVE DOWN INTO THE
REGION THROUGH THIS FLOW WHILE THE ECMWF IS MORE SET ON BUILDING A
RIDGE.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 643 PM CDT MON MAR 30 2015

EXPECT MOSTLY CLEAR/SUNNY CONDITIONS AT KRST/KLSE THROUGH 01.00Z.
VFR CLOUD DECK/LIGHT RAIN ACROSS NORTHEAST MN INTO NORTH-CENTRAL
WI WILL SLIDE EAST THIS EVENING KEEPING THE TAF SITES DRY. BIGGER
CHALLENGE WILL BE WIND DIRECTION...ALBEIT SPEEDS WILL BE
RELATIVELY LIGHT. SURFACE LOW CURRENTLY ACROSS SOUTH-CENTRAL MN
WILL MOVE INTO NORTHERN IL/IN TONIGHT...RESULTING IN SOUTHEAST
WINDS EVENTUALLY TURNING TO THE NORTHWEST. THIS CHANGE WILL OCCUR
MORE QUICKLY AT KRST THAN KLSE.

&&

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

$$

SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...ROGERS


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