959  
FXUS63 KARX 241029  
AFDARX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LA CROSSE WI  
530 AM CDT THU MAY 24 2018  
   
SHORT TERM
 
(TODAY THROUGH FRIDAY NIGHT)  
ISSUED AT 255 AM CDT THU MAY 24 2018  
 
MID/UPPER RIDGING WAS POSITIONED OVER THE UPPER MS VALLEY EARLY THIS  
MORNING. SCATTERED SHOWERS AND STORMS WERE PERCOLATING ACROSS  
CENTRAL/NORTHERN MN INTO NORTHWEST WI ON THE NOSE OF THE STRONGER  
850 MB MOISTURE TRANSPORT. A FEW OF THESE COULD SNEAK INTO CLARK  
OR TAYLOR COUNTIES THIS MORNING, BUT BETTER CHANCES WILL BE TO THE  
NORTH.  
 
THROUGH THE REST OF THE DAY INTO TONIGHT, A SHORTWAVE TROUGH OVER  
EASTERN MONTANA WILL LIFT INTO MANITOBA, WITH THE AXIS OF  
STRONGER LOW LEVEL MOISTURE TRANSPORT AND WEAK MID-LEVEL HEIGHT  
FALLS SPREADING EAST ACROSS THE REGION. WITH LIMITED UPPER SUPPORT  
TODAY, EXPECT MOST AREAS TO REMAIN DRY. AS 925 MB TEMPS CONTINUE  
TO INCH UPWARDS, HIGH TEMPS SHOULD PEAK IN THE MID TO UPPER 80S IN  
MOST AREAS ALONG WITH INCREASINGLY BREEZY SOUTHERLY WINDS,  
ESPECIALLY WEST OF THE MS RIVER.  
 
WITH THE APPROACH OF THE UPPER TROUGHING, EXPECT SHOWER/STORM  
CHANCES TO INCREASE FROM THE WEST TONIGHT. CONFIDENCE IN  
COVERAGE/TIMING ISN'T VERY HIGH WITH HIGH RES MODELS SHOWING A  
RANGE OF POSSIBLE SOLUTIONS. HOWEVER, IT IS POSSIBLE THAT  
CONVECTION DEVELOPING WEST OF THE AREA COULD MOVE INTO THE AREA  
DURING THE EVENING, WITH AT LEAST SOME POTENTIAL FOR ADDITIONAL  
SCATTERED SHOWER/STORM DEVELOPMENT AS MOISTURE TRANSPORT/LOW-LEVEL  
JET AXIS AIMS INTO THE AREA THROUGH THE NIGHT.  
 
THE CONVECTIVE SCENARIO FOR FRIDAY REMAINS SIMILARLY MUDDLED GIVEN  
WEAK UPPER LEVEL FORCING AND ILL-DEFINED SURFACE BOUNDARIES.  
MODERATE INSTABILITY SHOULD BUILD, WITH POTENTIAL FOR AT LEAST  
ISOLATED TO SCATTERED SHOWERS/STORMS DURING THE AFTERNOON/EVENING.  
WEAK DEEP LAYER SHEAR SHOULD INHIBIT STORM ORGANIZATION, BUT A  
FEW STRONGER STORMS COULD DEVELOP WITH LOCALLY HEAVY RAIN POSSIBLE  
GIVEN THE MOIST ENVIRONMENT AND RELATIVELY SLOW STORM MOTIONS.  
   
LONG TERM
 
(SATURDAY THROUGH WEDNESDAY)  
ISSUED AT 255 AM CDT THU MAY 24 2018  
 
THIS WEEKEND INTO EARLY NEXT WEEK THE MAIN BELT OF WESTERLIES  
REMAINS UP ACROSS CANADA WHILE AN UPPER LOW ROTATES SLOWLY EASTWARD  
ACROSS THE WESTERN US, PROMOTING RIDGING DOWNSTREAM INTO THE  
MIDWEST. A SHORTWAVE TROUGH DROPPING INTO THE NORTHERN GREAT LAKES  
COULD HELP SPARK A FEW SHOWERS/STORMS ON SATURDAY, ESPECIALLY ACROSS  
NORTHERN WI. OVERALL, HOWEVER, PREDOMINANTLY DRY WEATHER IS EXPECTED  
THROUGH THE HOLIDAY WEEKEND. HAVE MAINTAINED SOME LOW RAIN CHANCES  
AT TIMES WITH THE GFS MORE AGGRESSIVE IN BRINGING SEVERAL WEAK UPPER  
WAVES THROUGH THE UPPER RIDGE. HOWEVER, GFS BOUNDARY LAYER MOISTURE  
APPEARS WAY TOO HIGH, LIKELY CONTRIBUTING TO ITS PROPENSITY TO  
DEVELOP MORE CONVECTION. BY THE MIDDLE OF THE WEEK SHOWER/STORM  
CHANCES MAY INCREASE AS THE UPPER FLOW BECOMES SOUTHWESTERLY WITH AN  
UPPER TROUGH EJECTING TOWARDS THE REGION.  
 
VERY WARM/HOT TEMPS ARE EXPECTED THROUGH THE WEEKEND WITH  
IMPRESSIVE 850 MB TEMP ANOMALIES FOCUSED FROM THE NORTHERN PLAINS  
INTO THE UPPER MS VALLEY. SOME 90 DEGREE READINGS LOOK LIKELY  
SAT/SUN AND POSSIBLY INTO MONDAY. TEMPS SHOULD COOL A BIT FOR MID-  
WEEK, BUT REMAIN ABOVE AVERAGE.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)  
ISSUED AT 530 AM CDT THU MAY 24 2018  
 
CIGS: PERIODS OF SCT-BKN HIGH CIRRUS ALONG WITH SOME VFR DIURNAL CU  
EXPECTED TODAY...WITH SOME INCREASE IN MID/HIGH CLOUDS LATER TONIGHT  
AHEAD OF AN APPROACHING FRONT/CONVECTION.  
 
WX/VSBY: APPROACHING FRONT AND A COUPLE UPPER LEVEL SHORTWAVES WILL  
BRING INCREASING CHANCES FOR SHRA/TS ON FRIDAY. TIMING AND HOW  
WIDESPREAD STILL REMAINS UNCERTAIN WITH THE OVERALL PATTERN NOT  
POINTING TO STRONG FORCING. WON'T ADD TO FORECAST YET, BUT EXPECT  
INCLUSION FOR FRI INTO FRI NIGHT.  
 
WIND: STAYING SOUTH TODAY WITH SOME AFTERNOON GUSTINESS. GRADIENT  
STAYING TIGHT AHEAD OF APPROACHING SO DON'T EXPECT A LOT OF DROP OFF  
IN SPEEDS IN THE NIGHT. COME FRIDAY, ANY SHOWER/STORM THREAT WOULD  
INCLUDE SOME ENHANCED GUSTS THANKS TO A RELATIVELY DRY SUB CLOUD  
LAYER.  
 

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

 
 

 
 
SHORT TERM...JM  
LONG TERM...JM  
AVIATION...RIECK  
 
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