793  
FXUS63 KMKX 211212 AAA  
AFDMKX  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI  
712 AM CDT THU JUN 21 2018  
   
UPDATE
 
 
RAIN SHOWERS CONTINUE TO SPREAD INTO SOUTHERN WI EARLY THIS  
MORNING. PRECIP RATES ARE STILL LIGHT, BUT EXPECT THAT TO INCREASE  
LATER THIS MORNING INTO THE AFTERNOON AS WE SHOULD PROBABLY GET A  
FEW THUNDERSTORMS. THERE IS A FLASH FLOOD WATCH FOR THE SOUTHERN  
TIER OF COUNTIES FOR TODAY AND TONIGHT. THERE WAS A SMALL DEBATE  
ABOUT THE HEADLINE TITLE OF FLASH FLOOD VS. AREAL FLOOD WATCH. IT  
WAS AGREED UPON BY THE QUAD CITIES AND CHICAGO OFFICES TO DO A  
FLASH FLOOD WATCH DUE TO THE GREATER CONCERN FOR CONVECTION IN  
THEIR AREAS.  
 

 
   
AVIATION(12Z TAFS)
 
 
CEILINGS ARE ONLY MVFR TO IFR IN FAR SOUTHWEST WI THIS MORNING AND  
VFR ELSEWHERE. THERE WILL BE A GENERAL NORTHWARD TREND OF THESE  
LOWER CEILINGS TODAY, BUT THEY ARE NOT EXPECTED TO MAKE IT INTO  
MSN, UES, AND MKE. AS RAIN TAPERS OFF OVERNIGHT AND THE LOW  
PRESSURE AREA GETS CLOSER, CEILINGS MAY DROP DOWN MORE.  
 
HEAVIER RAIN SHOWERS WITH POSSIBLE THUNDER WILL CAUSE TEMPORARY  
MVFR CEILINGS/VISIBILITIES TODAY. THERE IS NOT ENOUGH CONFIDENCE  
IN THE TIMING OF THESE HEAVIER BANDS TO PUT IN THE TAF YET.  
 

 
   
PREV DISCUSSION
 
(ISSUED 402 AM CDT THU JUN 21 2018)  
 
SHORT TERM...  
 
TODAY AND TONIGHT...FORECAST CONFIDENCE IS MEDIUM.  
 
A CLOSED UPPER LOW AND ASSOCIATED SURFACE LOW WILL TRACK ACROSS  
IOWA/NORTHERN MISSOURI TODAY AND ILLINOIS ON FRIDAY. THIS SLOW-  
MOVING SYSTEM WILL BRING AN EXTENDED PERIOD OF SHOWERS TO SOUTHERN  
WISCONSIN. THAT 850MB BAROCLINIC ZONE REMAINS DRAPED ACROSS  
SOUTHERN WI, ALONG WITH A PLUME OF VERY MOIST AIR WITH  
PRECIPITABLE WATER VALUES OF 1.5 TO 2 INCHES. THE STEADY EASTERLY  
850MB LOW LEVEL JET, WAVES OF VORTICITY ADVECTION, AND PERSISTENT  
UPPER DIVERGENCE ARE FAVORABLE FOR FAR SOUTHERN WI (AND NORTHERN  
IL) TO GET EFFICIENT RAINFALL OVER THE NEXT 24 HOURS. SOUTHERN WI  
HAS ALREADY HAD 4 TO 8 INCHES OF RAIN OVER THE PAST WEEK AND  
ANOTHER 1.5 TO 2 INCHES IS EXPECTED (WITH THE POSSIBILITY FOR  
MORE). THERE SHOULD BE A FEW THUNDERSTORMS, ESPECIALLY THIS  
AFTERNOON. THEREFORE, A FLASH FLOOD WATCH IS IN EFFECT THROUGH  
TONIGHT FOR OUR SOUTHERN TIER OF COUNTIES.  
 
TEMPERATURES WILL REMAIN COOL TODAY IN THE MID/UPPER 60S DUE TO  
STEADY EAST WINDS, CLOUDS, AND RAIN. THE NORTHERN COUNTIES TOWARD  
CENTRAL WI SHOULD BE ABLE TO WARM INTO THE LOWER 70S BY THE  
AFTERNOON WITH SOME FILTERED SUNSHINE.  
 
LONG TERM...  
 
FRIDAY THROUGH SUNDAY...FORECAST CONFIDENCE IS MEDIUM.  
 
THE CLOSED UPPER LOW RESPONSIBLE FOR THURSDAY'S PRECIP WILL PUSH OFF  
TO THE EAST ON FRIDAY, THOUGH CYCLONIC FLOW IN THE UPPER LEVELS WILL  
PERSIST THROUGH SUNDAY. UNSURPRISINGLY, THE LOW LEVEL CYCLONE  
WILL VERY SLOWLY PULL OFF TO THE NORTHEAST THROUGH THE WEEKEND,  
LEAVING COOL EAST TO NORTHERLY FLOW IN ITS WAKE. THE NORTHEAST  
WINDS WILL HELP TO SLOWLY DRY OUT THE LOW LEVELS, BUT THE SLOW NE  
PROPAGATION OF THE CYCLONE CENTER WILL KEEP ENOUGH MOISTURE AROUND  
TO KEEP MOST OF SOUTHERN WISCONSIN SOCKED IN BENEATH BROKEN  
CLOUDS THROUGH AT LEAST SATURDAY. SIMILARLY, WITH DIMINISHING  
MOISTURE AND FORCING AS THE LOW SLIDES AWAY, PRECIP CHANCES WILL  
FADE FRIDAY BEFORE FALLING TO NEAR 0 BY SATURDAY.  
 
WITH WINDS SWINGING AROUND FROM THE EAST TO THE NORTH AND MOSTLY  
CLOUDY SKIES THROUGH AT LEAST SATURDAY, TEMPERATURES WILL REMAIN  
RATHER COOL. UNSURPRISINGLY, THE RAW MODEL BLENDS ARE COMING IN A  
BIT COOLER THAN BC BLENDS AND MOS, BUT EVERYTHING IS 5-10 DEGREES  
BELOW NORMAL FOR FRIDAY AND SATURDAY.  
 
MONDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE IS MEDIUM.  
 
UPPER LEVEL RIDGING WILL FINALLY BUILD IN EARLY NEXT WEEK, ALLOWING  
FOR HIGH PRESSURE AND SOUTHERLY WINDS IN LOW LEVELS ON MONDAY,  
TRANSLATING INTO A RATHER NICE DAY.  
 
BY MIDWEEK, A DEEP, SLIGHTLY POSITIVELY-TILTED TROUGH WILL SWING  
THROUGH THE UPPER MIDWEST. MOST GUIDANCE SHOWS THE SURFACE CYCLONE  
ASSOCIATED WITH THIS TROUGH MOVING THROUGH WISCONSIN EARLY  
WEDNESDAY. THE SOUTHERLY FLOW AHEAD OF THIS LOW WILL RESULT IN  
RATHER ROBUST MOISTURE RETURN, WITH BOTH THE GFS AND GEM SHOWING  
PWS IN THE 1.75 TO 2 INCH RANGE BY TUESDAY EVENING.  
 
WITH THIS AMPLE MOISTURE, AND PLENTY OF LIFT PROVIDED BY THE DEEP  
UPPER TROUGH, WE SHOULD AT THE VERY LEAST SEE PLENTY OF SHOWERS  
AND THUNDERSTORMS. AS IT STANDS, THE TIMING OF THE SURFACE LOW  
WOULD REALLY LIMIT THE POTENTIAL FOR ANY STORMS TO BECOME STRONG  
OR SEVERE.  
 
AVIATION(09Z TAFS)...  
 
A MID-LEVEL DECK OF CLOUDS IS SLOWLY OVERSPREADING ALL OF  
SOUTHERN AND EAST CENTRAL WI FROM THE SOUTH. MEANWHILE, A  
SECONDARY DECK OF LOW CLOUDS WITH MVFR CEILINGS IS GRADUALLY  
SPREADING INTO SOUTH CENTRAL WI EARLY THIS MORNING. SHOWERS ARE  
BECOMING MORE WIDESPREAD AS DEEPER MOISTURE WORKS ITS WAY BACK  
INTO SOUTHERN WI.  
 
EXPECT STEADIER RAIN SHOWERS TO DEVELOP THIS MORNING ACROSS FAR  
SOUTHERN WISCONSIN. THESE SHOWERS WILL BE EFFICIENT RAIN  
PRODUCERS. ISOLATED THUNDER IS EXPECTED AS WELL. PERIODS OF RAIN  
WILL PERSIST THROUGH THE EVENING AND GRADUALLY DIMINISH FRIDAY  
MORNING. EXPECT MAINLY MVFR CEILINGS OF 1000 TO 2000 FEET IN THE  
RAIN TODAY. LOWER CEILINGS ARE POSSIBLE SOUTH OF THE MAIN RAIN  
BAND. CEILINGS SHOULD REMAIN VFR NORTH OF THE MAIN RAIN BAND.  
 
MARINE...  
 
EASTERLY WINDS WILL INCREASE THROUGHOUT THE DAY AND BECOME  
NORTHEASTERLY TONIGHT. THIS WILL HELP TO BUILD HIGH WAVES. A SMALL  
CRAFT ADVISORY GOES INTO EFFECT THIS EVENING. WINDS AND WAVES WILL  
DIMINISH FRIDAY NIGHT.  
 
BEACHES...  
 
PERSISTENT EAST TO NORTHEAST WINDS WILL BUILD HIGH WAVES TONIGHT  
THROUGH FRIDAY NIGHT. DANGEROUS CURRENTS ALONG THE SHORELINE ARE  
EXPECTED DURING THIS TIME, ESPECIALLY DURING THE DAYLIGHT HOURS ON  
FRIDAY. A BEACH HAZARDS STATEMENT WILL BE NEEDED.  
 

 
   
MKX WATCHES/WARNINGS/ADVISORIES
 
 
WI...FLASH FLOOD WATCH THROUGH FRIDAY MORNING FOR WIZ067>070-072.  
 
LM...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 4 AM CDT SATURDAY  
FOR LMZ644>646.  
 

 
 

 
 
UPDATE...CRONCE  
TODAY/TONIGHT AND AVIATION/MARINE...CRONCE  
FRIDAY THROUGH WEDNESDAY...BSH  
 
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