474  
FXUS63 KMKX 071719  
AFDMKX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI  
1219 PM CDT TUE JUL 7 2020  
   
UPDATE
 
 
LOTS OF CUMULUS DEVELOPMENT ACROSS SOUTHERN WISCONSIN WITH A FEW  
SHOWERS. NO MAJOR SOURCES OF FORCING APPARENT BUT WITH THE LAKE  
BREEZE AND POTENTIALLY SOME FORCING PUSHING IN FROM THE WEST WE  
MAY START TO SEE MORE DEVELOPMENT OVER THE NEXT FEW HOURS.  
 

 
   
AVIATION(18Z TAFS)
 
 
SCATTERED 5 KFT CUMULUS ACROSS SOUTHERN WISCONSIN. WHILE GENERALLY  
VFR CONDITIONS ARE EXPECTED THROUGHOUT THE DAY THUNDERSTORM/SHOWER  
DEVELOPMENT IS POSSIBLE ACROSS THE REGION SO OVER THE NEXT FEW  
HOURS THROUGH THE AFTERNOON EXPECT POTENTIAL FOR SOME SHOWERS AND  
THUNDERSTORMS. SOME OF THESE THUNDERSTORMS COULD BECOME STRONG,  
PRIMARILY FURTHER WEST BUT WILL BE ISOLATED TO SCATTERED. MFVR  
VSBYS ARE POSSIBLE WITH ANY STORMS PRODUCING HEAVY RAINS AND SOME  
STORMS MAY BE CAPABLE OF SMALL HAIL AND GUSTY WINDS. OTHERWISE  
EXPECT MOSTLY WEST WINDS WITH THE LAKE BREEZE TO THE EAST  
POTENTIALLY SWITCHING WINDS TO THE SOUTH/SOUTHEAST LATER THIS  
AFTERNOON.  
 

 
   
PREV DISCUSSION
 
(ISSUED 920 AM CDT TUE JUL 7 2020)  
 
UPDATE...  
NO MAJOR CHANGES TO THE FORECAST WITH ISOLATED TO SCATTERED  
THUNDERSTORMS EXPECTED ACROSS SOUTHERN WISCONSIN WITH THE BEST  
CHANCES ALONG THE LAKE WHERE THE LAKE BREEZE SHOULD PROVIDE ENOUGH  
LIFT FOR A FEW STORMS.  
 
MARINE...  
LIGHT SOUTH TO WEST WINDS EXPECTED TODAY WITH SCATTERED STORMS  
POSSIBLE DURING THE AFTERNOON, PRIMARILY ALONG THE EDGES OF THE  
LAKE. QUIET CONDITIONS THEN MOVE IN FOR WEDNESDAY WITH HIGH  
PRESSURE OVER LAKE MICHIGAN AND PRIMARILY LIGHT SOUTHERLY WINDS  
EXPECTED. WINDS WILL BE A BIT MORE BREEZY FROM THE SOUTH OVER THE  
LAKE INTO THURSDAY.  
 
PREV DISCUSSION... (ISSUED 630 AM CDT TUE JUL 7 2020)  
 
UPDATE...  
 
FORECAST DETAILS REMAIN ON TRACK FROM THE PREVIOUS DISCUSSION.  
 
AVIATION(12Z TAFS)...  
 
GENERALLY VFR CIGS AND VIS ARE EXPECTED TODAY. SCATTERED  
THUNDERSTORM ACTIVITY IS EXPECTED STARTING IN THE AFTERNOON.  
LAKESHORE AND NEAR-LAKESHORE TERMINALS WILL LIKELY SEE THIS  
ACTIVITY STARTING FIRST IN THE EARLY AFTERNOON AS THE LAKE BREEZE  
MOVES INLAND. THEN, FURTHER INLAND TERMINALS WILL SEE INCREASING  
COVERAGE OF SCATTERED STORMS DURING THE MID AFTERNOON. FELT  
COVERAGE TODAY, ALTHOUGH SCATTERED, WARRANTED PERIODS OF VCTS FOR  
ALL TERMINALS. WHERE THESE STORMS OCCUR, BRIEF DROPS TO LOWER  
FLIGHT CATEGORIES CAN BE EXPECTED. THESE STORMS WILL DISSIPATE  
LATE IN THE AFTERNOON TO EARLY EVENING.  
 
PREV DISCUSSION... (ISSUED 357 AM CDT TUE JUL 7 2020)  
 
SHORT TERM...  
 
FORECAST TODAY THROUGH TOMORROW...FORECAST CONFIDENCE IS  
MODERATE...  
 
AFTER A DRY PERIOD IN THE MORNING, SCATTERED SHOWER AND  
THUNDERSTORM ACTIVITY WILL RAMP UP DURING THE AFTERNOON HOURS  
AGAIN TODAY. STORMS WILL LIKELY BEGIN FIRST ALONG THE LAKE BREEZE  
AS IT BEGINS TO MOVE INLAND DURING THE LATE MORNING AND EARLY  
AFTERNOON, THEN INLAND COVERAGE WILL INCREASE AS A WEAK 500MB  
SHORTWAVE APPROACHES FROM THE WEST DURING THE REMAINDER OF THE  
AFTERNOON. DAYTIME HEATING WILL SUPPORT MUCAPE VALUES RANGING FROM  
1500 TO 2500 J/KG PER NAM AND RAP SOUNDINGS BUT EFFECTIVE SHEAR  
WILL STAY LESS THAN 20KTS. ANY STORMS THAT DO FORM WILL BE PULSE-  
LIKE TO MULTICELLULAR IN NATURE. CAN'T RULE OUT A FEW WIND GUSTS  
TO 40 TO 50 MPH AND SOME SMALL HAIL WITH SOME OF THE STRONGER  
STORMS TODAY. STORMS WILL THEN BEGIN TO SUBSIDE AS THE SUN SETS  
THIS EVENING.  
 
TUESDAY NIGHT INTO WEDNESDAY APPEARS DRY AND SUNNY AS A SURFACE  
HIGH PRESSURE BUILDS BACK INTO THE AREA AND WARM 700MB TEMPS ARE  
ADVECTED OVER THE GREAT LAKE REGION DURING THE DAYTIME,  
EFFECTIVELY CAPPING WOULD BE CONVECTION.  
 
BOTH TUESDAY AND WEDNESDAY WILL BE HOT AND HUMID WITH HIGHS IN THE  
LOW 90S. HEAT INDICES BOTH DAYS WILL EASILY APPROACH THE UPPER  
90S.  
 
LONG TERM...  
 
WEDNESDAY NIGHT THROUGH MONDAY...FORECAST CONFIDENCE IS MEDIUM:  
 
THE HIGHEST PRECIP CHANCES THROUGH THE EXTENDED PERIOD REMAIN ON  
THURSDAY, WHEN A STRONGER SHORTWAVE COMES THROUGH SOUTHERN  
WISCONSIN. LEFT A CHANCE FOR STORMS FOR FRIDAY, AS THE MOIST AND  
UNSTABLE AIRMASS LINGERS AHEAD OF ANOTHER WAVE AND A COLD FRONT  
VIA THE NAM AND ECMWF. THE GFS BRINGS THE FRONT AND DRIER AIRMASS  
INTO THE STATE A BIT QUICKER.  
 
LOWER MOISTURE IS EXPECTED FOR THE WEEKEND BEHIND THE  
FRONT/TROUGH. LEFT A CHANCE FOR SHOWERS AND STORMS FOR THIS  
PERIOD THOUGH, AS A WAVE OR TWO MAY DROP THROUGH THE NORTHWEST  
FLOW. DECENT AGREEMENT THEN AMONG MODELS FOR DRIER WEATHER TO  
START THE WORK WEEK UNDER HIGH PRESSURE.  
 
THE HOT AND HUMID CONDITIONS WILL LINGER THURSDAY AND POSSIBLY  
INTO AT LEAST THE FIRST PART OF FRIDAY. TEMPERATURES WILL BE A  
LITTLE COOLER FOR THE WEEKEND INTO EARLY NEXT WEEK, THOUGH STILL  
LIKELY A COUPLE/FEW DEGREES ABOVE NORMAL.  
 
AVIATION(09Z TAF UPDATE)...  
 
WIDESPREAD FOG DOES NOT APPEAR LIKELY EARLY THIS MORNING, BUT THE  
OCCASIONAL ROAMING BANK CAN'T BE RULED OUT, ESPECIALLY IN LOW  
LYING AREAS. OTHERWISE VFR CONDITIONS WILL CONTINUE THROUGHOUT THE  
REST OF THE MORNING. THUNDERSTORM TIMING WILL LIKELY BE NUDGED A  
BIT LATER WITH THE UPCOMING 12Z ISSUANCE, BUT NO SWEEPING CHANGES  
TO PREVIOUS TAFS ARE ANTICIPATED.  
 
MARINE...  
 
SOUTHERLY WINDS WILL BECOME MORE WESTERLY AS THE DAY PROGRESSES ON  
TUESDAY. WINDS WILL STAY FAIRLY LIGHT AND WAVES WILL BE CONFINED  
TO A FOOT OR LESS. SOME SCATTERED THUNDERSTORM ACTIVITY IS  
POSSIBLE DURING THE AFTERNOON HOURS TODAY AS WELL.  
 

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

 
 

 
 
UPDATE...ARK  
TODAY/TONIGHT AND AVIATION/MARINE...ARK  
WEDNESDAY THROUGH MONDAY...DDV  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab WI Page Main Text Page