521  
FXUS63 KMKX 210830  
AFDMKX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI  
230 AM CST WED FEB 21 2018  
   
DISCUSSION
 
 
TODAY AND TONIGHT...FORECAST CONFIDENCE IS MEDIUM...  
 
MAIN ISSUE IS WITH RIVER FLOODING. THE FASTER RESPONSE RIVERS ARE  
FALLING, BUT THE SLOWER RESPONSE ONES STILL RISING. SEVERAL  
RIVERS IN MODERATE FLOOD.  
 
OTHER ISSUE IS REMAINING STANDING ROADS IN LOW AREAS, ALONG WITH  
FREEZING OF THE WATER WITH THE COLDER TEMPERATURES.  
 
SOUTHERN WISCONSIN WILL REMAIN IN THE RIGHT ENTRANCE REGION OF A  
STRONG 190 KNOT 250 MB JET. THIS RESULTS IN CONTINUED UPPER  
DIVERGENCE. AS A RESULT EXPECT HIGH CLOUDS TO BE SLOW TO DECREASE  
AFTER THE STRATOCUMULUS CLOUDS MOVE OFF WITH DRIER LOW LEVEL AIR.  
 
700 MB UPWARD MOTION INCREASES TONIGHT, AND THE MID LEVELS  
SATURATE AGAIN. LOW LEVELS REMAIN DRY, BUT SOME VERY LIGHT SNOW  
MAY REACH THE GROUND OVER SOUTH CENTRAL WISCONSIN TOWARD SUNRISE  
THURSDAY.  
 
THURSDAY - CONFIDENCE...MEDIUM  
INITIALLY DOMINANT LOW LEVEL ANTICYCLONIC FLOW GIVES WAY TO MORE  
OF A WARM AIR ADVECTION PATTERN. PROGS SUGGEST SOME LIGHT SNOW  
POTENTIAL ACROSS MAINLY THE WESTERN CWA. BUFKIT SOUNDINGS SHOW A  
MUCH SLOWER EROSION OF THE DRY AIR IN THE EAST WITH BETTER  
TOP/DOWN SATURATION PROGRESSION IN THE WEST. SO WILL HAVE SOME  
WHAT HIGHER POPS THERE.  
 
THURSDAY NIGHT AND FRIDAY - CONFIDENCE...MEDIUM  
PRECIP TYPE GETS TRICKY THURSDAY NIGHT AS WARM LAYER EVOLVES WITH  
SHALLOW COLD AIR LINGERING. SO HAVE A POTPOURRI OF WEATHER TYPES  
THIS PERIOD. LESS OF A WARM MAY SEE SOME CONCERNS AS IT RELATES  
TO ICE ACCUMULATION SO MAY EVENTUALLY NEED A HEADLINE OVERNIGHT  
AND POSSIBLY INTO EARLY FRIDAY MORNING. THE LOWER LEVEL THERMAL  
FIELD MODIFIES DURING FRIDAY MORNING SO ANY LINGERING MIXED PRECIP  
WOULD BECOME LIGHT RAIN. OVERALL THIS IS NOT A STRONG SYSTEM WITH  
A TON OF MOISTURE WITH IT, BUT ENOUGH FORCING AND LIFT COMBINED  
WITH A POTENTIALLY BORDERLINE THERMAL PROFILE TO MAKE FOR SOME  
SLICK ROADS.  
 
FRIDAY NIGHT THROUGH SATURDAY NIGHT - CONFIDENCE...LOW TO MEDIUM  
SURFACE RIDGING IS EXPECTED TO LINGER BUT THERE IS DISAGREEMENT  
BETWEEN THE GEM AND GFS. THE ECMWF IS OLD DATA BUT SIDED WITH THE  
LONGER LASTING INFLUENCE OF THE RIDGING DEEP INTO FRIDAY NIGHT AND  
EVEN INTO SATURDAY MORNING. MEANWHILE THE GFS IS QUICKER TO  
SPREAD PRECIP INTO THE AREA LATE FRIDAY NIGHT AND SATURDAY  
MORNING. INITIALLY THE THERMAL PROFILE SUPPORTS A PERIOD OF LIGHT  
SNOW THEN A MIX AND EVENTUALLY RAIN. THE GFS IS THE WARMEST  
SOLUTION ON THIS SYSTEM WHILE THE OLDER ECMWF IS A COMPROMISE  
WITH THE MORE SOUTHEAST AND COLDER TRACK OF THE GEM. SO PRETTY  
GOOD CONFIDENCE OF HIGHER POPS WITH STILL SOME UNCERTAINTY OUT  
THERE ON PRECIP TYPE. HOWEVER CONSENSUS OF THE OLDER ECMWF AND  
CURRENT GFS WOULD SUGGEST MORE RAIN WITH SOME SNOW ON THE BACK  
SIDE. HOWEVER BEST SHOT AT ANY APPRECIABLE SNOW WOULD BE WELL  
NORTH.  
 
SUNDAY THROUGH TUESDAY - CONFIDENCE...LOW TO MEDIUM  
OVERALL THIS LOOKS LIKE A QUIET PERIOD. THE GFS IS A BIT MORE  
ROBUST ON THE COLD ADVECTION SUNDAY INTO SUNDAY NIGHT. ANOTHER  
TROUGH/FRONT APPROACHES TUESDAY WITH SOME RAIN OR A MIX ARRIVING  
LATER IN THE DAY OR INTO TUESDAY NIGHT.  
 

 
   
AVIATION(09Z TAFS)
 
MVFR CONDITIONS SHOULD IMPROVE TO VFR DURING  
THE MORNING HOURS. HIGH CLOUDS SHOULD REMAIN. MID CLOUDS INCREASE  
AGAIN LATE TONIGHT WITH A SMALL CHANCE OF LIGHT SNOW TOWARD SUNRISE  
THURSDAY, MAINLY WEST OF MADISON.  
 

 
   
MARINE
 
NORTHWEST TO NORTH WINDS WILL APPROACH SMALL CRAFT ADVISORY  
LEVELS THIS MORNING. HIGH PRESSURE WILL THEN BUILD IN THIS  
AFTERNOON AND EVENING WITH LIGHT NORTHEAST WINDS.  
 

 
   
MKX WATCHES/WARNINGS/ADVISORIES
 
 
WI...NONE.  
LM...NONE.  

 
 

 
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ  
THURSDAY THROUGH TUESDAY...COLLAR  
 
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