114  
FXUS63 KMKX 210454  
AFDMKX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI  
1154 PM CDT FRI SEP 20 2019  
   
UPDATE
 
 
FOG AS BECOME A LITTLE MORE WIDESPREAD, ESPECIALLY NEAR LAKE  
MICHIGAN, AND UPDATED THE FORECAST TO ACCOUNT. OTHERWISE, NO  
CHANGES THROUGH THE REST OF THE OVERNIGHT.  
 

 
   
AVIATION(06Z TAFS)
 
 
SOME PATCHY FOG WILL BE POSSIBLE OVERNIGHT, BUT VISIBILITY  
RESTRICTIONS SHOULD BE LIMITED. SOUTH WINDS WILL BEGIN TO INCREASE  
TOWARD DAYBREAK, WHICH WILL HELP DISSIPATE ANY FOG.  
 
SHOWERS AND THUNDERSTORMS ARE THEN EXPECTED TO PUSH INTO THE AREA  
FROM WEST TO EAST SHORTLY AFTER DAYBREAK, WITH MVFR VISIBILITY  
AND MVFR TO IFR CEILINGS. THIS ACTIVITY WILL PERSIST IN AT LEAST A  
SCATTERED FASHION THROUGH MUCH OF THE DAY. SOUTH TO SOUTHWEST  
WINDS WILL ALSO BE ON THE INCREASE, WITH GUSTS INTO THE 20-25 KNOT  
RANGE AT TIMES.  
 
THERE MAY BE A BREAK IN ACTIVITY SATURDAY AFTERNOON AND EARLY  
EVENING, WITH MORE WIDESPREAD SHOWERS AND THUNDERSTORMS DEVELOPING  
SATURDAY EVENING INTO SATURDAY NIGHT.  
 

 
   
PREV DISCUSSION
 
(ISSUED 930 PM CDT FRI SEP 20 2019)  
 
UPDATE...  
 
HAVE SEEN A LITTLE LIGHT FOG DEVELOP THIS EVENING, INCLUDING SOME  
COMING IN OFF OF LAKE MICHIGAN. CURRENTLY DON'T EXPECT THIS TO  
BECOME DENSE OR TERRIBLY WIDESPREAD, BUT DRIVERS SHOULD BE ALERT  
FOR LOCALIZED AREAS OF REDUCED VISIBILITY.  
 
MARINE...  
 
FOR THE REST OF THIS EVENING, SOME PATCHY FOG HAS DEVELOPED ACROSS  
THE NEARSHORE WATERS, AS WELL AS PARTS OF THE NORTHERN HALF OF THE  
OPEN WATERS. CURRENTLY DON'T EXPECT THIS TO BECOME TOO WIDESPREAD,  
BUT WILL CONTINUE TO MONITOR.  
 
OTHERWISE, SOUTH TO SOUTHWEST WINDS WILL RAMP UP SATURDAY MORNING,  
CONTINUING THROUGH THE FIRST HALF OF THE DAY ON SUNDAY. A SMALL  
CRAFT ADVISORY IS IN EFFECT STARTING MID MORNING ON SATURDAY FOR  
THE NEARSHORE. FOR THE OPEN WATERS, GUSTS TO 30 KNOTS WILL BE  
COMMON, AND A FEW MARGINAL GALES ARE POSSIBLE ACROSS THE NORTHERN  
REACHES OF THE LAKE, ESPECIALLY GOING INTO TOMORROW EVENING.  
 
A COLD FRONT WILL MOVE THROUGH THE LAKE ON SUNDAY, SHIFTING WINDS  
TO THE WEST AND NORTHWEST. HIGH PRESSURE WILL THEN BUILD INTO THE  
AREA FOR MONDAY.  
 
PREV DISCUSSION... (ISSUED 651 PM CDT FRI SEP 20 2019)  
 
UPDATE...  
 
DESPITE A RELATIVELY UNSTABLE AIRMASS, LITTLE IN THE WAY OF  
CONVECTION WAS ABLE TO DEVELOP THIS EVENING, DUE TO AN ABSENCE OF  
ANY ORGANIZED SOURCE OF LIFT. A FEW STORMS TRIED TO DEVELOP ACROSS  
EXTREME SOUTHERN ROCK COUNTY, BUT HAVE SINCE FIZZLED. WITH THE  
IMPENDING LOSS OF SUNLIGHT, THINGS SHOULD REMAIN DRY THROUGH THE  
REST OF THE EVENING HOURS.  
 
SOUTHERLY WINDS WILL BEGIN TO INCREASE OVERNIGHT AS LOW PRESSURE  
LIFTS FROM EASTERN COLORADO INTO SOUTH DAKOTA. BEFORE THE WINDS  
PICK UP, SOME FOG IS POSSIBLE LATER THIS EVENING, THOUGH IT SHOULD  
NOT BE TERRIBLY WIDESPREAD. ANY FOG THAT DOES FORM SHOULD  
DISSIPATE BEFORE DAWN AS WINDS INCREASE AND MID AND HIGH LEVEL  
CLOUDS STREAM INTO THE AREA.  
 
DIDN'T MAKE ANY SIGNIFICANT CHANGES TO THE TIMING OF  
SHOWERS/THUNDERSTORMS FOR TOMORROW. CONVECTION SHOULD BEGIN TO  
OVERSPREAD THE AREA FROM THE WEST AND SOUTHWEST AROUND SUNRISE,  
WITH A GRADUAL EASTWARD EXPANSION THROUGH THE MORNING. WILL  
PROBABLY SEE MULTIPLE WAVES OF SHOWERS AND THUNDERSTORMS THROUGH  
THE DAY TOMORROW, SO DESPITE HIGH POPS, SOME BREAKS ARE LIKELY. A  
MORE CONTINUOUS PERIOD OF CONVECTION IS MORE LIKELY TOMORROW NIGHT  
AS THE FRONT BEGINS TO APPROACH.  
 
AVIATION(00Z TAFS)...  
 
VFR IS EXPECTED THROUGH THE NIGHT, WITH JUST SOME MID AND HIGH  
LEVEL CLOUDS STREAMING IN TOWARD MORNING. SOME FOG IS NOT  
ENTIRELY OUT OF THE QUESTION, BUT IS NOT CURRENTLY EXPECTED TO BE  
WIDESPREAD ENOUGH TO HAVE A SIGNIFICANT IMPACT AT THE TERMINALS.  
 
SHOWERS AND THUNDERSTORMS ARE THEN EXPECTED TO PUSH INTO THE AREA  
FROM WEST TO EAST TOMORROW MORNING, WITH MVFR VISIBILITY AND MVFR  
TO IFR CEILINGS. THIS ACTIVITY WILL PERSIST IN AT LEAST A  
SCATTERED FASHION THROUGH MUCH OF THE DAY. SOUTH TO SOUTHWEST  
WINDS WILL ALSO BE ON THE INCREASE, WITH GUSTS INTO THE 20-25 KNOT  
RANGE AT TIMES.  
 
PREV DISCUSSION... (ISSUED 356 PM CDT FRI SEP 20 2019)  
 
SHORT TERM...  
 
TONIGHT AND SATURDAY - CONFIDENCE...MEDIUM  
 
LINGERING ANTICYCLONIC FLOW IN THE LOW LEVELS AND ALOFT BREAKS  
DOWN THIS PERIOD AS LOW PRESSURE APPROACHES FROM THE PLAINS. A  
SOUTHERLY FLOW WILL BE ON THE INCREASE AND WILL BECOME QUITE  
GUSTY ON SATURDAY. MOISTURE TRANSPORT WILL BE ENHANCED WITH THE  
NORTHWARD PULL OF TROPICAL MOISTURE FROM THE SOUTHERN PLAINS. WITH  
EXTENSIVE CLOUD COVER CAPE SHOULD BE SOMEWHAT LIMITED. BUT HAVE  
INCREASED POPS AS THE DAY WEARS ON SATURDAY TO ACCOUNT FOR BETTER  
MID LEVEL FORCING AS WELL AS THE LOWER LEVEL MOISTURE ADVECTION.  
 
LONG TERM...  
 
SATURDAY NIGHT THROUGH SUNDAY... FORECAST CONFIDENCE IS MEDIUM.  
 
THE UPPER JET WILL SIT OVER THE UPPER MIDWEST THROUGH THE WEEKEND,  
ALONG WITH THE LEADING EDGE OF AN UPPER TROUGH. A SURFACE TROUGH  
WILL BE THE FOCUS FOR REPEATED ROUNDS OF THUNDERSTORMS WITH THE  
FOCUS OVER SOUTHERN WISCONSIN TO NORTHEAST WISCONSIN AND LAKE  
MICHIGAN. THE TROUGH WILL FINALLY SLIDE SOUTHEAST BY SUNDAY NIGHT.  
 
MONDAY... FORECAST CONFIDENCE IS MEDIUM.  
 
THE CLOSED UPPER LOW WILL SIDE THROUGH THE GREAT LAKES REGION ON  
MONDAY. CYCLONIC FLOW WILL KEEP US IN THE CLOUDS AT LEAST MONDAY  
MORNING AND WE COULD SEE SOME LIGHT SHOWERS AS WELL.  
 
TUESDAY THROUGH FRIDAY... FORECAST CONFIDENCE IS MEDIUM.  
 
OUR NEXT CHANCE FOR SHOWERS AND THUNDERSTORMS WILL BE WITH THE  
NEXT UPPER TROUGH SWINGING THROUGH AND AN ASSOCIATED COLD FRONT.  
WARM AIR ADVECTION WILL ARRIVE DURING THE DAY WEDNESDAY AND THE  
FRONT WILL SLIDE THROUGH WEDNESDAY AFTERNOON OR EVENING. THE ECMWF  
IS SHOWING A STRONGER UPPER TROUGH THAN THE GFS AT THIS TIME.  
 
YET ANOTHER ROUND OF SHOWERS AND STORMS WILL ARRIVE FRIDAY. THIS  
SURFACE LOW SHOULD FOCUS MORE TOWARD LAKE SUPERIOR AT THIS TIME.  
 

 
   
MKX WATCHES/WARNINGS/ADVISORIES
 
 
WI...NONE.  
LM...DENSE FOG ADVISORY UNTIL 7 AM CDT SATURDAY FOR LMZ261-362-364-  
366-563-565-567-643>645-669-671-673-868-870.  
 
SMALL CRAFT ADVISORY FROM 10 AM SATURDAY TO 1 PM CDT SUNDAY FOR  
LMZ643>646.  
 

 
 

 
 
UPDATE...BOXELL  
TONIGHT/SATURDAY AND AVIATION/MARINE...BOXELL  
SATURDAY NIGHT THROUGH FRIDAY...99  
 
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