189  
FXUS63 KGRB 240337  
AFDGRB  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREEN BAY WI  
1037 PM CDT SAT MAR 23 2019  
 
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE  
   
SHORT TERM
 
TONIGHT AND SUNDAY  
ISSUED AT 249 PM CDT SAT MAR 23 2019  
 
THE MAIN FORECAST FOCUS TO BE ON TEMPERATURES TONIGHT AND EXTENT  
OF PRECIPITATION ON SUNDAY AS TWO WEATHER SYSTEM MERGE OVER THE  
GREAT LAKES.  
 
THE 19Z MSAS SURFACE ANALYSIS SHOWED AN AREA OF HIGH PRESSURE OVER  
NORTHERN INDIANA WHICH ENGULFED THE ENTIRE GREAT LAKES REGION WITH  
CLEAR SKIES AND MODEST WEST-SOUTHWEST WINDS. A WEAK AREA OF LOW  
PRESSURE WAS SITUATED OVER THE CENTRAL PLAINS WITH MID/HIGH-LEVEL  
CLOUDS PULLING NORTH ACROSS THE MIDWEST. FARTHER NORTH, A COLD  
FRONT WAS SITUATED OVER CENTRAL ONTARIO/SOUTHERN MANITOBA. LITTLE  
IN THE WAY OF CLOUDS WERE EVIDENT IN THE VICINITY OF THE FRONT.  
 
GENERALLY QUIET WEATHER CONDITIONS ARE EXPECTED ACROSS THE REGION  
TONIGHT AS THESE TWO SYSTEMS BEAR DOWN ON THE GREAT LAKES. THE  
WEAK SURFACE LOW (AND ITS ASSOCIATED MID-LEVEL SHORTWAVE TROUGH)  
OVER THE CENTRAL PLAINS WILL BRING LIGHT RAIN TOWARD SOUTHWEST WI  
BY DAYBREAK. THE WEST-EAST ORIENTATED COLD FRONT IS FORECAST TO  
DROP SOUTH INTO NORTHERN WI BY DAYBREAK. MODELS SUGGEST THAT ANY  
PRECIPITATION WOULD BE POST-FRONTAL, THUS NO PRECIPITATION  
EXPECTED IN THE NORTH TONIGHT. DO ANTICIPATE AN INCREASE IN MID/  
HIGH CLOUDS OVERNIGHT, HOWEVER THE AIR MASS IS STILL VERY DRY OVER  
NORTHEAST WI, THUS TEMPERATURES SHOULD QUICKLY FALL THIS EVENING  
EVEN BEFORE THE CLOUDS ARRIVE. LOOK FOR MIN TEMPERATURES IN THE  
LOWER TO MIDDLE 20S NORTH, UPPER 20S TO LOWER 30S SOUTH.  
 
THE SOUTHERN SYSTEM IS PROGGED TO TRACK EAST ACROSS THE MIDWEST/  
MID-MS VALLEY PM SUNDAY WITH THE NORTHERN PERIPHERY OF LIGHT RAIN  
ONLY REACHING THE SOUTHERN THIRD OF WI. MEANWHILE, THE COLD FRONT  
WILL CONTINUE PUSHING SOUTH AND MOVE THROUGH CENTRAL/EAST-CENTRAL  
WI AROUND MID-MORNING. CANNOT RULE OUT A SMALL CHANCE OF  
PRECIPITATION ACROSS NORTHERN WI FROM MID-MORNING TO MID-  
AFTERNOON, BUT ANY PRECIPITATION WOULD BE VERY LIGHT SINCE ANY  
GULF MOISTURE WOULD BE INTERCEPTED BY THE SOUTHERN SYSTEM.  
PRECIPITATION TYPE TO BE THE BIGGEST FORECAST ISSUE AS STRONG CAA  
BEHIND THE COLD FRONT WOULD FAVOR SNOW RATHER THAN RAIN. PROBLEM  
IS THAT THERE IS A LACK OF ICE CRYSTALS ALOFT, WHICH WOULD FAVOR  
FREEZING DRIZZLE. HAVE GONE WITH A DRIZZLE/FREEZING DRIZZLE MIX  
FOR NOW DEPENDING ON TEMPERATURES. GUSTY NORTHEAST WINDS IN THE  
WAKE OF THE COLD FRONT WILL LIKELY LEAD TO A MINIMAL RISE IN  
TEMPERATURES, ESPECIALLY ACROSS THE NORTH. LOOK FOR READINGS TO  
ONLY REACH THE MIDDLE TO UPPER 30S FAR NORTH-CENTRAL WI, BUT LOWER  
50S OVER PARTS OF CENTRAL WI.  
   
LONG TERM
 
SUNDAY NIGHT THROUGH SATURDAY  
ISSUED AT 249 PM CDT SAT MAR 23 2019  
 
NORTHWEST UPPER FLOW SHOULD KEEP DRY WEATHER ACROSS THE REGION  
THROUGH AT LEAST WEDNESDAY. THIS WILL ALLOW FOR SLOW MELTING OF  
SNOW WITH MILD DAYS AND BELOW FREEZING NIGHTS.  
 
JET ENERGY OUT AHEAD OF WESTERN UNITED STATES UPPER TROUGH WILL  
BRING THE CHANCE OF SHOWERS WEDNESDAY NIGHT THROUGH THURSDAY.  
MODEL DIFFERENCES INCREASE AFTER THAT WITH DIFFERING IDEAS OF  
PHASING OF NORTHERN AND SOUTHERN STREAM SHORTWAVES. THIS RESULTS  
IN SIGNIFICANT DIFFERENCES IN THE TIMING AND AMOUNT OF PRECIPITATION,  
AS WELL AS PRECIPITATION TYPE.  
 
IT IS NOT OUT OF THE QUESTION THAT THERE WILL BE SIGNIFICANT SNOW  
SOMEWHERE IN THE FORECAST AREA BY THE END OF THE WEEK, AS WELL AS  
POSSIBLE FLOOD PROBLEMS WITH RIVERS ALREADY AT BANKFULL IN MANY AREAS.  

 
   
AVIATION
 
FOR 06Z TAF ISSUANCE  
ISSUED AT 1032 PM CDT SAT MAR 23 2019  
 
VFR CONDITIONS ARE EXPECTED OVERNIGHT, WITH JUST AN INCREASE IN  
HIGH CLOUDS OVERNIGHT. LOW PRESSURE OVER THE CENTRAL PLAINS WILL  
TRACK SOUTH OF THE REGION LATER TONIGHT INTO SUNDAY, WITH THE  
LEADING EDGE OF LIGHT RAIN ONLY REACHING SOUTHERN WI. A CANADIAN  
COLD FRONT WILL SWEEP SOUTH THROUGH THE REGION LATE TONIGHT AND  
SUNDAY MORNING, CAUSING A WIND SHIFT TO THE NORTHEAST, AND  
BRINGING BLUSTERY CONDITIONS TO THE FOX VALLEY AND LAKESHORE AREAS  
BY AFTERNOON. MVFR CEILINGS ARE EXPECTED TO DEVELOP A FEW HOURS  
AFTER THE FRONTAL PASSAGE. SPOTTY VERY LIGHT DRIZZLE OR FREEZING  
DRIZZLE IS POSSIBLE OVER NORTH CENTRAL AND FAR NORTHEAST WI FROM  
MID-MORNING THROUGH EARLY AFTERNOON, BUT THE CHANCE IS TOO LOW TO  
MENTION AT THE RHI TAF SITE AT THIS TIME. CLEARING WILL PROGRESS  
SOUTH ACROSS THE REGION DURING THE LATE AFTERNOON AND EVENING.  

 
   
HYDROLOGY
 
 
ISSUED AT 249 PM CDT SAT MAR 23 2019  
 
FAVORABLE CONDITIONS FOR A SLOW SNOWMELT ACROSS THE NORTH WILL  
CONTINUE INTO EARLY NEXT WEEK. A SYSTEM IS EXPECTED TO AFFECT THE  
AREA DURING THE LATTER PART OF NEXT WEEK, HOWEVER THE MEDIUM  
RANGE MODELS CONTINUE TO EXHIBIT CONSIDERABLE DAY TO DAY CHANGES  
IN THE FORECAST TRACK AND INTENSITY OF THE SYSTEM. THEREFORE,  
CONFIDENCE REMAINS LOW ON WHERE THE AXIS OF POTENTIALLY HEAVY RAIN  
OR SNOW WOULD FALL. PEOPLE LIVING NEAR RIVERS, STREAMS AND CREEKS  
SHOULD CONTINUE TO WATCH FOR UPDATES ON THIS SYSTEM IN THE COMING  
DAYS.  

 
   
GRB WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
SHORT TERM.....KALLAS  
LONG TERM......RDM  
AVIATION.......KIECKBUSCH  
HYDROLOGY......KALLAS  
 
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