496  
FXUS63 KMKX 291509  
AFDMKX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI  
1009 AM CDT WED MAR 29 2017  
   
MARINE
 
DENSE FOG ADVISORY WAS ALLOWED TO EXPIRE AT 9 AM. MAIN  
FOCUS SHIFTS NOW TO INCREASING ONSHORE AND LONG DURATION WIND  
REGIME TONIGHT WHICH GETS UNDERWAY TONIGHT. THIS WILL BUILD HIGH  
WAVES NEAR THE SHORE AND REMAIN IN PLACE THROUGH LATE FRIDAY  
NIGHT.  
 
PC  
 

 
   
PREV DISCUSSION
 
(ISSUED 625 AM CDT WED MAR 29 2017)  
 
UPDATE...  
 
WAS TEMPTED TO CANCEL THE DENSE FOG ADVISORY FOR A COUPLE  
NORTHEAST COUNTIES GIVEN OBSERVATIONS AND WEBCAMS, BUT LATEST  
SATELLITE IS SHOWING SOME FOG OR LOW CLOUD DEVELOPMENT IN THAT  
AREA. THUS FIGURED IT WAS WORTH KEEPING THOSE COUNTIES IN FOR A  
COUPLE MORE HOURS UNTIL THE EXPIRATION.  
 
OTHERWISE, SHOULD SEE THE FOG HANG ON IN THE SOUTH HALF OF THE  
FORECAST AREA THIS MORNING...WINDING DOWN AROUND MID-MORNING. FOG  
MAY KEEP GOING INTO LATE MORNING TOWARD LAKE MICHIGAN.  
 
AVIATION(12Z TAFS)...  
 
WILL SEE FOG HANG ON INTO MID-MORNING, POSSIBLY INTO LATE MORNING  
TOWARD LAKE MICHIGAN. DAYTIME MIXING SHOULD IMPROVE CONDITIONS FOR  
THE AFTERNOON.  
 
ATTENTION THEN TURNS TO PRECIP AHEAD OF APPROACHING LOW PRESSURE.  
RAIN WILL MOVE INTO THE WEST BY LATE AFTERNOON, SPREADING EAST  
ACROSS THE FORECAST AREA DURING THE EVENING HOURS. THE RAIN WILL  
PERSIST THROUGH THURSDAY.  
 
STILL LOOKS LIKE THERE COULD BE A MIX WITH OR CHANGEOVER TO SNOW  
IN THE NORTH TONIGHT INTO THURSDAY MORNING, MAINLY NORTH OF A  
LINE FROM WISCONSIN DELLS TO PORT WASHINGTON. IT WILL BE A  
STRUGGLE TO GET MUCH ACCUMULATION DUE TO BORDERLINE TEMPERATURES,  
THOUGH AN INCH OR SO IS POSSIBLE. SNOW WILL TRANSITION TO RAIN  
EVERYWHERE BY LATE THURSDAY MORNING.  
 
LOWER CLOUDS AND VISIBILITIES WILL RETURN TONIGHT INTO THURSDAY  
WITH THE ARRIVAL OF THE PRECIPITATION.  
 
PREV DISCUSSION... (ISSUED 326 AM CDT WED MAR 29 2017)  
 
SHORT TERM...  
 
TODAY AND TONIGHT...FORECAST CONFIDENCE IS MEDIUM TO HIGH:  
 
EXTENDED THE DENSE FOG ADVISORY FARTHER WEST PER LATEST SATELLITE  
AND OBS. MAY NEED TO EVENTUALLY INCLUDE THE LAST ROW OF WESTERN  
COUNTIES IF THIS AREA OF FOG KEEPS GOING. STILL LOOKS LIKE DAYTIME  
MIXING SHOULD BRING AN END TO THE DENSE FOG BY MID-MORNING, SO NO  
CHANGE TO THE EXPIRATION TIME OF THE ADVISORY.  
 
HIGH CLOUDS WILL CONTINUE TO PUSH IN FROM THE WEST THIS  
MORNING...WITH CLOUD BASES GRADUALLY LOWERING INTO THE AFTERNOON AS  
DEEPER MOISTURE ARRIVES AHEAD OF APPROACHING LOW PRESSURE. TRICKY  
TEMPS TODAY GIVEN THE CURRENT FOG/STRATUS IN THE AREA AND  
APPROACHING CLOUDS. STUCK CLOSE TO A BLEND OF MODEL TEMPS DUE TO THE  
UNCERTAINTY.  
 
RAIN IS EXPECTED TO ARRIVE IN THE WEST BY LATE THIS AFTERNOON,  
SPREADING EAST ACROSS THE FORECAST AREA THIS EVENING AND CONTINUING  
OVERNIGHT. THE RAIN IS STILL EXPECTED TO MIX WITH OR CHANGEOVER TO  
SNOW IN THE NORTH. MODELS HAVE BEEN TRENDING NORTH WITH THIS SYSTEM  
THE LAST 24-36 HOURS THOUGH, WHICH HAS RESULTED IN SOMEWHAT LIGHTER  
AMOUNTS THIS FORECAST. TEMPERATURES WILL BE BORDERLINE THROUGH THIS  
EVENT, SO ACCUMULATIONS WILL STRUGGLE WHERE IT DOES SNOW.  
 
LONG TERM...  
 
THURSDAY AND FRIDAY... FORECAST CONFIDENCE IS MEDIUM.  
 
THE WEAKENING UPPER LOW AND SURFACE LOW WILL TRACK ACROSS ILLINOIS  
THROUGH TONIGHT. ROUNDS OF LIGHT RAIN ARE EXPECTED ACROSS SOUTHERN  
WI THU AND THU NIGHT AS WAVES OF VORTICITY AND FRONTOGENESIS  
SPREAD THROUGH THE AREA. BRISK EAST WINDS AND PRECIP WILL KEEP  
TEMPERATURES RAW, WITH HIGHS THU IN THE UPPER 30S AND LOWS THU  
NIGHT IN THE LOWER TO MID 30S.  
 
THERE IS A CHANCE FOR SOME SNOW TO BE MIXED INTO THE RAIN EARLY THU  
MORNING, BUT TEMPS WILL WARM ABOVE FREEZING RATHER QUICKLY AS THE  
LOW GETS CLOSER.  
 
DRIZZLE OR LIGHT RAIN IS EXPECTED TO LINGER ALL THE WAY THROUGH  
FRIDAY.  
 
SATURDAY... FORECAST CONFIDENCE IS HIGH.  
 
DRIER AIR WITH HIGH PRESSURE BUILDING INTO THE REGION ON SATURDAY  
WILL HELP TO SCOUR OUT THE CLOUDS A LITTLE. HIGHS SHOULD RETURN TO  
THE 50S INLAND FROM THE LAKE.  
 
SUNDAY THROUGH TUESDAY... FORECAST CONFIDENCE IS MEDIUM.  
 
ANOTHER UPPER LOW WILL TRACK FROM THE SOUTHERN PLAINS THROUGH THE  
MID MISSISSIPPI RIVER VALLEY OVER THE WEEKEND. THE RAIN WITH THIS  
SYSTEM IS EXPECTED TO REMAIN PRIMARILY SOUTH OF THE WI/IL BORDER,  
BUT MAY CLIP SOUTHERN WI MON INTO TUESDAY. PRECIP TYPE SHOULD BE ALL  
RAIN.  
 
AVIATION(06Z TAFS)...  
 
FOG AND LOW CLOUDS WILL CONTINUE TO DRIFT WESTWARD ACROSS SOUTHERN  
WISCONSIN EARLY THIS MORNING. IMPROVING CONDITIONS ARE EXPECTED BY  
MID MORNING ON WEDNESDAY WITH VFR CIGS/VSBYS RETURNING FOR A TIME.  
 
LOWER MVFR CIGS WILL STREAM BACK IN BY EVENING AHEAD OF ADVANCING  
LOW PRESSURE. PRECIPITATION WILL OVERSPREAD THE AREA DURING THE  
EVENING. IT SHOULD REMAIN RAIN ALONG THE WI/IL STATE LINE, BUT  
BECOME MIXED WITH OR CHANGE OVER TO SNOW FOR A TIME NORTH OF  
MILWAUKEE AND MADISON.  
 
MARINE...  
 
DENSE FOG IS LIKELY TO CONTINUE INTO MID-MORNING, SO WILL LEAVE THE  
ADVISORY AS IS FOR NOW.  
 
GUSTY WINDS AND HIGHER WAVES ARE LIKELY FROM THIS EVENING INTO  
FRIDAY NIGHT AS LOW PRESSURE MOVES THROUGH THE REGION. HAVE DECIDED  
TO ISSUE A SMALL CRAFT ADVISORY FOR THIS PERIOD.  
 

 
   
MKX WATCHES/WARNINGS/ADVISORIES
 
 
WI...NONE.  
LM...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 4 AM CDT  
SATURDAY FOR LMZ645-646.  
 
SMALL CRAFT ADVISORY FROM 2 AM THURSDAY TO 4 AM CDT SATURDAY FOR  
LMZ643-644.  
 

 
 

 
TODAY/TONIGHT AND AVIATION/MARINE...DDV  
THURSDAY THROUGH TUESDAY...CRONCE  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab WI Page Main Text Page