003  
FXUS63 KARX 291100  
AFDARX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LA CROSSE WI  
600 AM CDT WED MAR 29 2017  
   
SHORT TERM
 
(TODAY THROUGH THURSDAY NIGHT)  
ISSUED AT 332 AM CDT WED MAR 29 2017  
 
WATER VAPOR IMAGERY EARLY THIS MORNING SHOWS A PRONOUNCED UPPER LOW  
OVER NEW MEXICO WITH WITH A PLUME OF MID/UPPER MOISTURE EXTENDING  
TO THE NORTH AND EAST WITH INCREASING LARGE SCALE ASCENT AHEAD OF  
THE WAVE. THIS SYSTEM WILL BE OUR MAIN WEATHER MAKER OVER THE  
NEXT 36-48 HOURS AS IT GRADUALLY LIFTS NORTHEASTWARD. 00Z MPX/GRB  
SOUNDINGS INDICATED QUITE A BIT OF DRY AIR IN PLACE, BUT CONTINUED  
MID/UPPER FORCING WILL HELP TO SATURATE THE LOWER LEVELS THROUGH  
THE DAY. BY LATE MORNING SHOWERS SHOULD BE INCREASING ACROSS  
NORTHEAST IOWA, POSSIBLY ENCOUNTERING SOME RESISTANCE WITH  
STUBBORN LOW-LEVEL DRY AIR REMAINING. RAIN WILL CONTINUE TO  
INCREASE FROM THE SOUTHWEST THROUGH THE AFTERNOON, TIED TO  
STRONGER 850- 700 MB WARM ADVECTION. THIS WARM ADVECTION ALONG  
WITH MID-LEVEL FRONTOGENESIS WILL HELP FOCUS THE PRECIP THROUGH  
THE OVERNIGHT HOURS INTO THURSDAY MORNING. THE HEAVIEST PRECIP  
TOTALS ARE EXPECTED TO BE ACROSS FAR SOUTHWEST WI AND NORTHEAST IA  
WHERE AN INCH OR A BIT HIGHER OF RAIN IS POSSIBLE, WITH AMOUNTS  
TAPERING TO AROUND A TENTH OF AN INCH OVER NORTH CENTRAL WI. THE  
29.00Z ECMWF REMAINS MORE PROGRESSIVE WITH MOST OF THE PRECIPITATION  
EXITING TO THE EAST THURSDAY AFTERNOON. HOWEVER, THE NAM/GFS HOLD  
ONTO DEFORMATION ZONE PRECIP LONGER INTO THURSDAY/THURSDAY NIGHT  
WITH MORE OF A PRONOUNCED TROWAL FEATURE EVIDENT ON 700 MB THETA-E  
FIELDS. THE NAM WOULD EVEN LINGER SOME PRECIP INTO FRIDAY IN  
WESTERN WISCONSIN. THUS, WILL KEEP HIGH PRECIP CHANCES GOING  
THROUGH THURSDAY, ESPECIALLY OVER THE SOUTHEAST HALF OF THE AREA  
DECREASING TO A MAINLY DRY FORECAST ON FRIDAY.  
 
THERE ARE STILL A FEW POTENTIAL ISSUES WITH PRECIP TYPE LATE THIS  
EVENING THROUGH EARLY THURSDAY, ESPECIALLY ACROSS CENTRAL/NORTH-  
CENTRAL WI. SURFACE TEMPS SHOULD FALL INTO THE LOW TO MID 30S  
OVERNIGHT TONIGHT. NAM SOUNDINGS IN CENTRAL WI SUGGEST A PERIOD OF  
WET SNOW IS POSSIBLE ESPECIALLY NORTH AND EAST OF I-94 OVERNIGHT,  
HIGHLY DEPENDENT ON LOWER TROPOSPHERIC TEMPS AND POSSIBLY PRECIP  
RATE AS WELL. HOWEVER, NAM SOUNDINGS IN THIS AREA INDICATE SOME  
POTENTIAL FOR LOSS OF ICE OVERNIGHT, WHICH WOULD LEAD TO A LIQUID  
SCENARIO WITH SURFACE TEMPS CRITICAL. GFS SOUNDINGS, ON THE OTHER  
HAND, KEEP CLOUD ICE THROUGH THE NIGHT AND SHOW A RAIN/SNOW  
SCENARIO. WITH A RATHER DEEP NEARLY ISOTHERMAL LAYER NEAR 0C,  
DEFINITELY A TRICKY FORECAST. ALL IN ALL, IT IS POSSIBLE THERE  
COULD BE SOME MINOR SNOW ACCUMULATIONS TONIGHT MAINLY NORTH/EAST  
OF I-94, BUT WITH WARM GROUND TEMPS AND MARGINAL AIR TEMPS, IT  
WILL LIKELY TAKE HIGH SNOW RATES TO CREATE ANY TRAVEL ISSUES.  
   
LONG TERM
 
(FRIDAY THROUGH TUESDAY)  
ISSUED AT 332 AM CDT WED MAR 29 2017  
 
WEAK SURFACE HIGH PRESSURE SHOULD BRING A RETURN TO DRY WEATHER  
FRIDAY INTO SATURDAY, ALTHOUGH FRIDAY LOOKS TO BE ON THE CLOUDY  
SIDE. ANOTHER SOUTHERN STREAM UPPER LOW IS EXPECTED TO MOVE FROM  
THE SOUTHERN ROCKIES ON SATURDAY EASTWARD THROUGH EARLY NEXT WEEK.  
IT IS POSSIBLE SOME LIGHT PRECIPITATION COULD SPREAD NORTH INTO  
THE AREA SATURDAY NIGHT INTO SUNDAY AS A WEAK UPPER SHORTWAVE  
EJECTS AHEAD OF THE MAIN UPPER LOW, BUT AT THIS TIME THE HIGHER  
RAIN CHANCES WITH THIS SYSTEM LOOK TO BE TO THE SOUTH. THE  
GFS/ECMWF THEN SHOW A DIGGING NORTHERN STREAM WAVE EARLY NEXT WEEK  
INTO THE WESTERN CONUS, BUT THERE IS POOR MODEL AGREEMENT AND RUN  
TO RUN CONSISTENCY IN THIS PATTERN WITH THE TIMING AND  
AMPLIFICATION OF WAVES, SO THERE IS VERY LOW FORECAST CONFIDENCE  
FOR EARLY NEXT WEEK. AT THIS POINT, AVERAGE TO SLIGHTLY ABOVE  
AVERAGE TEMPS ARE FAVORED.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)  
ISSUED AT 600 AM CDT WED MAR 29 2017  
 
CIGS: INCREASING AND LOWERING FROM THE SOUTHWEST TODAY, AHEAD OF A  
LOW PRESSURE SYSTEM SLATED TO BRING RAIN (PERHAPS MIXED WITH SNOW)  
TO THE REGION THIS AFTERNOON THROUGH THU NIGHT. MODELS FAVORING A  
SWIFTING DROP IN CIGS THIS AFTERNOON, WHICH MATCHES FAIRLY WELL WITH  
CURRENT OBS/SATELLITE TRENDS TO THE SOUTHWEST. EXPECT MVFR/IFR BY  
00Z. LOW CIGS WILL HANG AROUND THROUGH THU NIGHT, AND MIGHT NOT  
CLEAR UNTIL FRIDAY NIGHT.  
 
WX/VSBY: LOW LEVEL WARM AIR ADVECTION AND A NORTH-SOUTH  
FRONTOGENETIC REGION WILL RESULT IN AREAS/BANDS OF MOSTLY RAIN  
ACROSS THE TAF SITES FROM LATE AFTERNOON THROUGH TONIGHT. MVFR/IFR  
VSBYS WILL ACCOMPANY THE PCPN, WHICH COULD MIX WITH A FEW FLAKES OF  
SNOW LATER TONIGHT (BUT NO SNOW ACCUMULATION EXPECTED).  
 
WINDS: WITH THE SFC LOW RESPONSIBLE FOR THE CLOUDS/RAIN KEEPING TO  
THE SOUTH, WINDS WILL HOLD FROM AN EASTERLY DIRECTION THROUGH THU,  
WITH A LITTLE TURN TO NORTH AS THE LOW PASSES. TIGHTENING PRESSURE  
GRADIENT WILL RESULT IN SOME INCREASE IN THE WINDS THROUGH THE DAY,  
STAYING UP TONIGHT. SOME GUSTINESS ALSO POSSIBLE.  
 

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

 
 

 
 
SHORT TERM...JM  
LONG TERM...JM  
AVIATION...RIECK  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab WI Page
The Nexlab IA Page
The Nexlab MN Page Main Text Page