782  
FXUS63 KMKX 222001  
AFDMKX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI  
301 PM CDT TUE JUN 22 2021  
   
SHORT TERM
 
 
(ISSUED 300 PM CDT TUE JUN 22 2021)  
 
TONIGHT THROUGH WEDNESDAY NIGHT:  
 
A SURFACE RIDGE EXTENDING NORTHWARD INTO OUR AREA WILL BEGIN TO  
BREAK DOWN AS HIGH PRESSURE CENTERED OVER THE MIDDLE MISSISSIPPI  
VALLEY REGION SHIFTS EASTWARD THIS EVENING. AS THIS HIGH PRESSURE  
SHIFTS EAST, WINDS WILL COME AROUND TO SOUTHERLY AND WAA WILL  
INCREASE AS A WARM FRONT DRAPED FROM WEST TO EAST OVER IOWA  
APPROACHES THE WI/IL BORDER. CONVECTION IS EXPECTED TO FORM ALONG  
THIS FRONT LATE IN THE AFTERNOON OVER IOWA. WHILE THE SURFACE FRONT  
MAY WASH OUT SOME TIME DURING THE EVENING HOURS, CONVECTION IS  
EXPECTED TO RIDE THE 925 TO 850MB WAA AND ENHANCED CONVERGENCE AT  
THE TIP OF THE LLJ OVERNIGHT INTO OUR AREA, BRINGING SOME CHANCES  
FOR RAIN DURING THE EARLY MORNING HOURS FOR ALL OF SOUTHERN  
WISCONSIN, WITH BETTER CHANCES TOWARD THE WI/IL BORDER. THE WAA  
LOOKS LIKE IT WILL GROW SOMEWHAT WEAK AS IT NOSES INTO SOUTHERN WI  
AND MODEL MUCAPE IS ALMOST NON-EXISTENT OVER SOUTHERN WISCONSIN, SO  
CHANCES FOR SEVERE THUNDERSTORMS ARE NIL AND EVEN CHANCES FOR THE  
OCCASIONAL RUMBLE OF THUNDER LOOK LOW.  
 
SHOWERS WILL CONTINUE THROUGH THE MORNING HOURS ON WEDNESDAY AS A  
SECONDARY 850MB SPEED MAX NOSES INTO SOUTHERN WISCONSIN JUST AFTER  
DAWN. MODELS DEPICT SHOWER ACTIVITY CEASING DURING THE EARLY  
AFTERNOON AS THE NOSE OF THE SPEED MAX SHIFTS EASTWARD OVER LOWER  
MICHIGAN. SUBSIDENCE FROM A BUILDING RIDGE ALOFT SHOULD THEN ALLOW  
CLOUDS TO CLEAR BRIEFLY LATE IN THE AFTERNOON THROUGH THE EARLY  
EVENING BEFORE CLOUDS INCREASE AHEAD OF AN APPROACHING FRONTAL  
BOUNDARY.  
 
OVERALL, TEMPERATURES SHOULD BEGIN TO MODERATE DURING THE SHORT-TERM  
PERIOD OWING TO THE INCOMING WAA. LOWS WILL BE IN THE MID-50S  
TONIGHT AND THE MID-60S TOMORROW NIGHT. DAYTIME HIGHS ON WEDNESDAY  
WILL BE IN THE UPPER 70S, BUT LIKELY HELD BACK FROM BEING WARMER BY  
THE SHOWER ACTIVITY AND LINGERING CLOUD COVER.  
 
CMILLER  
 

 
   
LONG TERM
 
 
(ISSUED 300 PM CDT TUE JUN 22 2021)  
 
THURSDAY THROUGH TUESDAY:  
 
THE AM LONG-TERM DISCUSSION MENTIONED MODEL DISAGREEMENT AND THAT  
PROBLEM LARGELY STILL PERSISTS IN THE EXTENDED PERIOD AFTER SOME NEW  
MORNING MODEL RUNS. A RAINY, ACTIVE PERIOD THURSDAY THROUGH  
SATURDAY, LOOKS TO REMAIN ON TRACK, HOWEVER.  
 
SYNOPTICALLY, LOW PRESSURE OVER THE HUDSON BAY REGION IN CANADA WILL  
DRAG A COLD FRONT OVER THE NORTHERN PLAINS ON WEDNESDAY. THURSDAY  
MORNING, THIS FRONT LOOKS TO STALL OR AT LEAST SLOW DOWN AS IT  
ENCOUNTERS THE INFLUENCE OF BROAD HIGH PRESSURE OVER THE EASTERN  
SEABOARD. AS A RESULT, THE FRONT WILL BE PARKED OVER PARTS OF NW  
WI AND CENTRAL MN. AS THIS FRONT SLOWLY SLIDES SE THURSDAY THROUGH  
FRIDAY, MULTIPLE ROUNDS OF STORMS WILL FORM ALONG THIS FRONT AND  
THEN COME OFF OF IT, DRIVEN BY THE UPPER LEVEL FLOW. THE UPSIDE  
FOR THIS EVENT IS THAT WIDESPREAD RAIN APPEARS LIKELY AND AT LEAST  
AN INCH SEEMS ASSURED FOR MUCH OF THE AREA THROUGH SATURDAY  
AFTERNOON WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE. THE DOWNSIDE  
IS THAT THE EVOLUTION OF THE SEVERE THREAT IN ASSOCIATION WITH  
THIS COLD FRONT IS UP IN THE AIR THIS EARLY IN THE WEEK, AND WILL  
BE CONTINGENT UPON HOW MUCH SUN WE RECEIVE ON THURSDAY AND FRIDAY  
AND TIMING OF ANY OF THE MYRIAD OF CONVECTIVE COMPLEXES MODELS  
DEPICT. TRENDS WILL BE MONITORED.  
 
BEYOND, MODELS CONTINUE TO SHOW AN MORE ACTIVE PATTERN GOING  
FORWARD INTO NEXT WEEK.  
 
CMILLER  
 

 
   
AVIATION
 
 
(ISSUED 300 PM CDT TUE JUN 22 2021)  
 
CU AND AREAS OF MID-LEVEL STRATOCU WILL LINGER UNTIL THE LATE  
AFTERNOON AND EARLY EVENING WHEN WE LOSE OUR DAYTIME HEATING.  
WE'LL CLEAR OUR FOR A FEW HOURS AND WINDS WILL SLACKEN SOME, THEN  
CLOUDS WILL INCREASE AGAIN AS AN AREA OF WARM AIR ADVECTION  
APPROACHES FROM THE SOUTHWEST. WINDS WILL TURN SOUTHERLY DURING  
THIS TIME AS WELL AND BECOME MODESTLY GUSTY AGAIN. SOME SCATTERED  
SHOWER ACTIVITY IS ANTICIPATED WITH THIS WAA, AND WILL MAINLY  
OCCUR DURING THE EARLY MORNING HOURS AND THROUGH THE POST-DAWN  
HOURS FOR MUCH OF SOUTHERN WISCONSIN. MOST AREAS SHOULD EXPERIENCE  
VFR CONDITIONS FOR THE REST OF THIS AFTERNOON AND INTO TOMORROW,  
BUT A FEW INLAND LOCATIONS COULD SEE SOME MVFR CEILINGS EARLY  
WEDNESDAY MORNING, OWING TO SOME OF THE BETTER MOISTURE BROUGHT IN  
ON THE WAA. VISIBILITY DROPS WILL ALSO BE POSSIBLE WITH ANY  
SHOWER.  
 
CMILLER  
 

 
   
MARINE
 
 
(ISSUED 300 PM CDT TUE JUN 22 2021)  
 
HIGH PRESSURE OF 30.1 INCHES WILL SLIDE EASTWARD THROUGH THE  
OVERNIGHT HOURS AND SETTLE INTO MIDDLE APPALACHIA BY WEDNESDAY  
MORNING. AS THIS HAPPENS, WESTERLY WINDS WILL BECOME SOUTHERLY  
TONIGHT. THEY'LL REMAIN MODESTLY GUSTY, HOWEVER AS THERE WILL BE A  
LOW-LEVEL WIND SPEED MAX ABOVE A SHALLOW INVERSION. GOING INTO THE  
DAYTIME HOURS TOMORROW, LOW PRESSURE OF 29.3 INCHES WILL APPROACH  
THE HUDSON BAY REGION IN CANADA. THIS WILL STEEPEN THE PRESSURE  
GRADIENT BETWEEN THE LOW PRESSURE NORTH AND THE HIGH PRESSURE TO  
THE SOUTHEAST. AS A RESULT WINDS WILL STRENGTHEN THROUGH THE DAY  
ON WEDNESDAY AND INTO THE OVERNIGHT HOURS ON THURSDAY. WINDS TO  
GALE FORCE LOOK POSSIBLE FOR THE NORTHERN END OF THE LAKE FOR A  
BRIEF PERIOD EARLY THURSDAY MORNING.  
 
SHOWERS AND A RUMBLE OF THUNDER OR TWO WILL BE POSSIBLE OVER  
NORTHERN END OF THE LAKE LATE THIS AFTERNOON, AND THEN OVER THE  
SOUTHERN HALF OF THE LAKE TONIGHT INTO WEDNESDAY MORNING. BETTER  
CHANCES FOR WIDESPREAD, STRONGER STORMS LOOK POSSIBLE ON THURSDAY.  
 
LOCALLY, WINDS MAY BLOW TO SMALL CRAFT ADVISORY CRITERIA WEDNESDAY  
AFTERNOON AND INTO THURSDAY MORNING OWING TO THE AFOREMENTIONED  
SHARP PRESSURE GRADIENT.  
 
CMILLER  
 

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

 
 

 
 
VISIT US AT WEATHER.GOV/MILWAUKEE  
 
FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:  
WWW.FACEBOOK.COM/NWSMILWAUKEE  
WWW.TWITTER.COM/NWSMILWAUKEE  
WWW.YOUTUBE.COM/NWSMILWAUKEE  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab WI Page Main Text Page