478  
FXUS63 KMKX 190019 AAA  
AFDMKX  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI  
619 PM CST FRI JAN 18 2019  
   
UPDATE
 
 
MODERATE TO HEAVY SNOW BAND ASSOCIATED WITH 850 MB TO 700 MB  
FRONTOGENESIS RESPONSE CONTINUES TO DEVELOP AND SPREAD ACROSS  
SOUTHERN PORTIONS OF THE AREA EARLY THIS EVENING. THIS IS EXPECTED  
TO SLOWLY SLIDE EAST SOUTHEAST ACROSS THE SOUTHERN COUNTIES THIS  
EVENING, BEFORE GRADUALLY MOVING OUT OF THE AREA FROM WEST TO EAST  
LATER TONIGHT INTO EARLY SATURDAY MORNING. SNOWFALL RATES OF UP  
TO 1 INCH PER HOUR ARE EXPECTED IN THIS BAND. LIGHTER SNOW RATES  
WILL OCCUR TO THE NORTH OF THIS AREA TONIGHT INTO EARLY SATURDAY  
MORNING.  
 
LAKE ENHANCEMENT WILL ALSO OCCUR FOR AREAS NEAR LAKE MICHIGAN  
TONIGHT INTO SATURDAY MORNING, WITH A SINGLE LAKE EFFECT SNOW BAND  
DEVELOPING LATER TONIGHT AND LINGERING INTO SATURDAY NIGHT. 1/2  
INCH PER HOUR OR GREATER SNOWFALL RATES COULD OCCUR WITH THE LAKE  
ENHANCEMENT AND LAKE EFFECT BAND NEAR THE LAKE. HIGHEST  
ACCUMULATIONS WILL CONTINUE TO BE AREAS SOUTH OF MILWAUKEE.  
 
WILL MONITOR THE PROGRESS OF THE HIGHER SNOWFALL RATES IN THE  
FRONTOGENETIC BAND AND LAKE ENHANCEMENT/LAKE EFFECT BAND TONIGHT,  
AND SEE IF ANY UPWARD ADJUSTMENTS IN SNOWFALL ARE NECESSARY. MODEL  
CERTAINTY GRAPHICS ARE SHOWING FAIRLY HIGH CONFIDENCE IN THE GOING  
SNOWFALL FORECAST FOR THIS EVENT, SO MAY ONLY NEED SMALL  
ADJUSTMENTS. HEADLINES APPEAR TO BE ON TRACK AS WELL.  
 

 
   
AVIATION(00Z TAFS)
 
 
EXPECT SNOW WITH VISIBILITY VALUES OF 1/2 TO 1 MILE IN THE HEAVIER  
SNOW BAND ACROSS SOUTHERN PORTIONS OF THE AREA TONIGHT, INCLUDING  
THE TERMINALS. CEILINGS WILL BE AROUND 1000 FEET, AND MAY DIP  
BELOW THAT AT TIMES. NORTHEAST WINDS WILL GRADUALLY BECOME GUSTY  
TONIGHT AS WELL, LEADING TO SOME BLOWING SNOW.  
 
SNOWFALL RATES OF 1/2 TO 1 INCH PER HOUR ARE EXPECTED WITHIN THE  
HEAVIER SNOW BAND ACROSS SOUTHERN PORTIONS OF THE AREA TONIGHT,  
INCLUDING THE TERMINALS. SNOWFALL RATES WILL BE LOWER TO THE  
NORTH. FAIRLY CONFIDENT WITH THE GOING SNOWFALL FORECAST, WITH  
SOME MINOR UPWARD ADJUSTMENTS IN AMOUNTS POSSIBLE WHERE THE  
HEAVIER SNOW BANDS OCCUR.  
 
THE GUSTY NORTHEAST WINDS WILL GRADUALLY BECOME NORTH LATER  
SATURDAY INTO SATURDAY NIGHT. SOME BLOWING SNOW WILL REMAIN DURING  
THIS TIME OVER AREAS NEAR LAKE MICHIGAN. LAKE EFFECT SNOW SHOWERS  
SHOULD CONTINUE SATURDAY INTO SATURDAY NIGHT ACROSS AREAS NEAR THE  
LAKE, INCLUDING THE MILWAUKEE AND KENOSHA TERMINALS.  
 
VISIBILITY AND CEILING VALUES SHOULD GRADUALLY IMPROVE SATURDAY  
INTO SATURDAY NIGHT, THOUGH MAY DROP QUICKLY WITHIN ANY HEAVIER  
SNOW SHOWERS NEAR THE LAKE. SNOWFALL RATES HERE MAY REACH 1/4 TO  
1/2 INCH PER HOUR, DEPENDING ON WHERE THE BAND SETS UP AND HOW  
LONG IT LASTS.  
 
CONDITIONS INLAND ON SATURDAY INTO SATURDAY NIGHT WILL GRADUALLY  
IMPROVE AS THE SNOW ENDS, THOUGH GUSTY NORTHWEST TO NORTH WINDS  
WILL LINGER.  
 

 
   
PREV DISCUSSION
 
(ISSUED 325 PM CST FRI JAN 18 2019)  
 
SHORT TERM...  
 
TONIGHT AND SATURDAY...FORECAST CONFIDENCE IS MEDIUM TO HIGH.  
 
WILL BE ADDING MARQUETTE, GREEN LAKE AND FOND DU LAC COUNTIES TO  
WINTER WEATHER ADVISORY SHORTLY. STILL EXPECTING 2 TO 4 INCHES IN  
THESE COUNTIES, BUT WITH ADDITIONAL THREAT OF BLOWING SNOW, AND  
POTENTIAL FOR FRONTOGENETICAL BAND AFFECTING THEM THIS EVENING,  
THOUGHT IT WAS WORTHY TO ADD THESE AREAS TO HEADLINE. OTHERWISE,  
LOW LEVEL FRONTOGENETICAL BAND SPREADING INTO WESTERN CWA ATTM.  
COMBINATION OF THIS FRONTOGENESIS AND SYNOPTIC SCALE LIFT FROM  
RIGHT ENTRANCE REGION OF UPPER JET WILL BRING WIDESPREAD  
ACCUMULATING SNOW TO THE AREA THROUGH TONIGHT. SNOW BEGINNING TO  
DEVELOP TO THE SOUTH OF THE FRONTOGENETICAL BAND ACROSS PARTS OF  
NORTHERN AND EASTERN IA. ENHANCED LIFT WILL BE IN THE DENDRITIC  
GROWTH ZONE FOR A TIME TONIGHT, SO FAVORABLE SITUATION FOR RAPID  
SNOW BUILDUP. NO CHANGES TO PREVIOUS HEADLINE CHANGES AT THIS  
POINT WITH SNOWFALL FROM 2 TO 4 INCHES IN THE NORTH TO THE 6 TO 9  
INCH RANGE IN THE SOUTHEAST. LAKE ENHANCEMENT WILL AID SNOWFALL IN  
THE EAST OVERNIGHT. SYNOPTIC SCALE LIFT AND WEAKENING MID-LEVEL  
DEFORMATION LOSES ITS GRIP ON THE EASTERN AREAS SATURDAY MORNING,  
BUT A PERSISTENT NORTHEAST WIND AND DELTA-T AROUND 15C WILL RESULT  
IN SNOW SHOWERS LINGERING IN THE EASTERN AREAS THROUGH THE  
AFTERNOON WITH ADDITIONAL ACCUMULATIONS. WIND GUSTS TO 25 MPH WILL  
ALSO CREATE PATCHY BLOWING SNOW, ESPECIALLY CLOSER TO LAKE  
MICHIGAN DUE TO LESS FRICTIONAL AFFECTS.  
 
LONG TERM...  
 
SATURDAY NIGHT THROUGH MONDAY...FORECAST CONFIDENCE IS MEDIUM TO  
HIGH:  
 
LAKE EFFECT SNOWFALL WILL LINGER SATURDAY NIGHT, WITH ADDITIONAL  
ACCUMULATIONS OF 1 TO 2 INCHES MAINLY FROM THE MILWAUKEE AREA  
SOUTHWARD. SLIGHT VARIATIONS TO THE WIND DIRECTION WILL IMPACT  
WHERE EXACTLY THIS SNOW FALLS AND LAKE EFFECT ALWAYS HAS THE  
POTENTIAL TO HAVE LOCALLY HIGHER AMOUNTS.  
 
LAKE EFFECT SHOWERS SHOULD BE OFF SHORE FOR SUNDAY, WITH SOME  
SUNSHINE RETURNING TO THE AREA UNDER HIGH PRESSURE. WINDS WILL  
THEN BECOME NORTHEAST TO EAST AND THEN EVENTUALLY SOUTHEAST SUNDAY  
NIGHT INTO MONDAY, ALLOWING SOME LAKE EFFECT TO PUSH BACK INLAND.  
ANY ACCUMULATIONS SHOULD BE ON THE LOW END SINCE THE WIND  
DIRECTION WILL BE CHANGING THROUGH MOST OF THE EVENT, NOT ALLOWING  
THE SHOWERS TO FOCUS ON ONE PARTICULAR AREA.  
 
BELOW NORMAL TEMPERATURES WILL PREVAIL FOR SUNDAY AND MONDAY, WITH  
TEMPERATURES STRUGGLING TO 15 SUNDAY AND 20 AT BEST ON MONDAY.  
 
MONDAY NIGHT THROUGH TUESDAY NIGHT...FORECAST CONFIDENCE IS MEDIUM  
TO HIGH:  
 
MODELS ARE IN PRETTY GOOD AGREEMENT THAT LOW PRESSURE WILL MOVE BY  
TO THE SOUTH EARLY NEXT WEEK AND BRING MORE ACCUMULATING SNOWFALL  
TO SOUTHERN WISCONSIN. WARM ADVECTION AHEAD OF THE SYSTEM SHOULD  
RESULT IN LIGHT ACCUMULATIONS BRUSHING THE NORTHERN FORECAST AREA.  
THE MEAT OF THE SYSTEM IS THEN EXPECTED TO COME THROUGH DURING THE  
DAY TUESDAY. THOUGH THERE IS HIGH CONFIDENCE IN WIDESPREAD  
PRECIPITATION, THERE ARE VARIATIONS AMONG FORECAST MODELS WITH THE  
LOW TRACK AND TIMING. THE NORTHERN SOLUTIONS COULD RESULT IN SOME  
RAIN MIXING IN FOR A PERIOD IN THE SOUTHEAST. NOT HIGH CONFIDENCE  
IN WHERE THE HIGHEST SNOW TOTALS WOULD BE EITHER. OVERALL THOUGH,  
CONFIDENCE IS INCREASING THAT SEVERAL INCHES OF SNOWFALL COULD  
IMPACT THE AREA DURING THIS TIME PERIOD.  
 
WEDNESDAY THROUGH FRIDAY...FORECAST CONFIDENCE IS MEDIUM:  
 
NEAR TO BELOW NORMAL TEMPERATURES ARE EXPECTED FOR THE SECOND HALF  
OF NEXT WEEK, WITH A SHORTWAVE OR TWO BRINGING SNOW CHANCES AT  
TIMES. THERE IS NO MAJOR SYSTEM ON THE HORIZON DURING THIS PERIOD.  
THOUGH MODELS ARE ALL SHOWING OCCASIONAL SNOW CHANCES, THERE ISN'T  
GREAT AGREEMENT WITH TIMING/PLACEMENT/STRENGTH OF THESE SYSTEMS.  
 
AVIATION(21Z TAFS)...  
 
SNOW SPREADING INTO SOUTH CENTRAL WISCONSIN WILL RAPIDLY SPREAD  
EAST ACROSS SOUTHEAST AND EAST CENTRAL WISCONSIN LATE THIS  
AFTERNOON AND EARLY EVENING. VISIBILITIES QUICKLY DROP TO LESS  
THAN 2 MILES. SNOW WILL AFFECT MUCH OF THE AREA THIS EVENING,  
TAPERING OFF FROM WEST TO EAST LATER TONIGHT INTO SATURDAY MORNING  
MOST AREAS. PERIODS OF SNOW SHOWERS WILL AFFECT EASTERN AREAS IN  
THE AFTERNOON/EVENING.  
 
MARINE...  
 
NEARSHORE WATERS...WINDS WILL VEER TO THE NORTHEAST AND INCREASE  
THIS EVENING WITH GUSTS UP TO 30 KNOTS TONIGHT INTO SATURDAY. THE  
WINDS WILL BACK TO THE NNE LATER SATURDAY AND PERSIST INTO  
SATURDAY NIGHT. THESE ONSHORE WINDS WILL CAUSE HIGH WAVES TO BUILD  
AND PERSIST. THE SMALL CRAFT ADVISORY REMAINS IN EFFECT INTO  
SUNDAY.  
 
OPEN WATERS...STRENGTHENING LOW PRESSURE PASSING TO THE SOUTH OF  
LAKE MICHIGAN LATER TONIGHT AND SATURDAY WILL RESULT IN A TIGHT  
PRESSURE GRADIENT ACROSS SOUTHERN LAKE MICHIGAN, AND GUSTY  
NORTHEAST WINDS. AT THIS POINT, FREQUENT WIND GUSTS ARE EXPECTED  
TO REMAIN BELOW 35 KNOTS ON SATURDAY AND SATURDAY NIGHT, SO WILL  
HOLD OFF ON A GALE WARNING FOR NOW. COLD TEMPERATURES AND WIND  
GUSTS OF 20 TO 25 KNOTS ARE EXPECTED TO CAUSE AREAS OF HEAVY  
FREEZING SPRAY ACROSS THE NORTHERN PART OF THE LAKE ON SATURDAY  
INTO SUNDAY. HENCE A HEAVY FREEZING SPRAY WARNING IS BEING ISSUED  
AT THIS TIME. THE FREEZING SPRAY WILL BE NOT AS WIDESPREAD OR  
INTENSE ACROSS THE SOUTHERN PART OF THE LAKE.  
 

 
   
MKX WATCHES/WARNINGS/ADVISORIES
 
 
WI...WINTER STORM WARNING UNTIL 6 AM CST SATURDAY FOR WIZ062-063-  
067>069.  
 
WINTER STORM WARNING UNTIL MIDNIGHT CST SATURDAY NIGHT FOR  
WIZ066-071-072.  
 
WINTER STORM WARNING UNTIL NOON CST SATURDAY FOR WIZ064-065-070.  
 
WINTER WEATHER ADVISORY UNTIL NOON CST SATURDAY FOR WIZ051-052-  
058>060.  
 
WINTER WEATHER ADVISORY UNTIL 6 AM CST SATURDAY FOR WIZ046-047-  
056-057.  
 
LM...HEAVY FREEZING SPRAY WARNING FROM 6 AM SATURDAY TO NOON CST  
SUNDAY FOR LMZ261-362-364-366-563-565-567-868.  
 
SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 3 PM CST SUNDAY  
FOR LMZ645-646.  
 
SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 10 AM CST SUNDAY  
FOR LMZ643-644.  
 

 
 

 
 
UPDATE...WOOD  
TONIGHT/SATURDAY AND AVIATION/MARINE...MBK  
SATURDAY NIGHT THROUGH FRIDAY...DDV  
 
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