097  
FXUS63 KGRB 270343  
AFDGRB  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREEN BAY WI  
1043 PM CDT THU APR 26 2018  
 
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE  
   
SHORT TERM
 
TONIGHT AND FRIDAY  
ISSUED AT 306 PM CDT THU APR 26 2018  
 
WEAK COLD FRONT MOVING ACROSS NORTHWEST WISCONSIN  
THIS AFTERNOON WILL MOVE ACROSS THE REMAINDER OF THE FORECAST  
AREA DURING THE EARLY EVENING HOURS. IT COULD PRODUCE SCATTERED  
SHOWERS, ESPECIALLY AS IT GETS CLOSER TO THE LAKE AND BAY WHERE  
LOW LEVEL MOISTURE IS A LITTLE BETTER. SKIES SHOULD CLEAR FOR A  
LITTLE WHILE BEHIND THE FRONT LATER TONIGHT, WHICH WILL MAKE  
TEMPERATURE FORECASTING DIFFICULT. PLACES THAT STILL HAVE SNOW  
COVER IN THE NORTH COULD GET DOWN INTO THE LOWER TO MIDDLE 20S.  
 
A CLIPPER SYSTEM WILL RAPIDLY MOVE ACROSS THE AREA FRIDAY, AND  
BRING SOME PRECIPITATION. 850/925/SFC TEMPERATURES WOULD SUGGEST  
THAT SOME SNOW IS LIKELY IN THE FAR NORTH EARLY FRIDAY BEFORE IT  
WARMS UP. THINK AN INCH OR LESS IS THE MOST LIKELY AMOUNT, BUT  
LOCALLY HIGHER AMOUNTS ARE NOT OUT OF THE QUESTION. CLOUDY SKIES  
AND RAIN WILL HOLD DOWN TEMPERATURES FRIDAY INTO THE 40S IN MOST  
PLACES. RAINFALL AMOUNTS SHOULD BE LOW ENOUGH NOT TO AGGRAVATE  
MINOR FLOODING IN SOME RIVERS AND STREAMS.  
   
LONG TERM
 
FRIDAY NIGHT THROUGH THURSDAY  
ISSUED AT 306 PM CDT THU APR 26 2018  
 
A RATHER AMPLIFIED FLOW IS EXPECTED ACROSS THE CONUS WELL INTO  
NEXT WEEK. INITIALLY, WE ARE LOOKING AT CLOSED UPPER LOWS OVER THE  
PACIFIC NORTHWEST AND NEW ENGLAND WITH AN UPPER RIDGE OVER THE  
CENTRAL CONUS THIS WEEKEND. MODELS AGREE THAT BY EARLY NEXT WEEK  
THE FLOW TRANSLATES TO AN UPPER TROUGH WESTERN CONUS/UPPER RIDGE  
EASTERN CONUS WITH A SOUTHWEST FLOW OVER THE CENTRAL CONUS  
BRINGING A TASTE SUMMER TO NORTHEAST WI. THE IMPENDING SOUTHWEST  
FLOW WILL ALSO PULL GULF MOISTURE NORTH, BRINGING SEVERAL ROUNDS  
OF SHOWERS/STORMS TO WI WHICH MIGHT AGGRAVATE THE HIGH RIVER  
LEVELS.  
 
CHANCE OF RAIN OR RAIN/SNOW SHOWERS WILL CONTINUE INTO FRIDAY  
EVENING ACROSS EAST-CENTRAL WI AS THE SHORTWAVE TROUGH EXITS THE  
REGION. WINDS ARE EXPECTED TO PICK UP A BIT BEHIND THE SYSTEM  
(ESPECIALLY ACROSS EASTERN WI) AS THE PRESSURE GRADIENT TIGHTENS  
UP BETWEEN THE LOW PRESSURE OVER THE EASTERN GREAT LAKES AND HIGH  
PRESSURE LOCATED OVER WESTERN ONTARIO. OTHERWISE, THE REST OF THE  
NIGHT WILL SEE CLOUDS ON THE DECREASE WITH MIN TEMPERATURES IN THE  
LOWER TO MIDDLE 20S NORTH-CENTRAL WI, TO THE LOWER 30S ACROSS  
EAST-CENTRAL WI. THIS AREA OF HIGH PRESSURE IS FORECAST TO BUILD  
INTO THE WESTERN GREAT LAKES REGION ON SATURDAY, PROVIDING FOR  
SUNNY, BUT COOL CONDITIONS BY LATE APRIL STANDARDS. WINDS MAY  
STILL BE LITTLE ON THE BREEZY SIDE INTO SATURDAY MORNING BEFORE  
SLOWLY DIMINISHING LATER SATURDAY AFTERNOON. LOOK FOR MAX  
TEMPERATURES TO RANGE FROM THE MIDDLE TO UPPER 40S NORTH-CENTRAL/  
NEAR LAKE MI, TO THE LOWER TO MIDDLE 50S ELSEWHERE.  
 
THIS BROAD AREA OF HIGH PRESSURE IS EXPECTED TO STRETCH FROM JUST  
SOUTH OF HUDSON BAY, THROUGH THE WESTERN GREAT LAKES, ALL THE WAY  
TO THE GULF ON SATURDAY NIGHT. CLEAR SKIES AND LIGHT WINDS WILL  
BRING ANOTHER COLD NIGHT TO NORTHEAST WI WITH MIN TEMPERATURES IN  
THE LOWER TO MIDDLE 20S NORTH, UPPER 20S TO AROUND 30 DEGREES  
SOUTH. THE SURFACE HIGH FINALLY SHIFTS TO THE EAST, ALLOWING WINDS  
TO GRADUALLY BECOME SOUTH-SOUTHWEST. THESE WINDS WILL START TO  
PULL WARMER AIR INTO THE REGION WITH MAX TEMPERATURES 5 TO 15  
DEGREES WARMER THAN SATURDAY. THIS WOULD BRING READINGS INTO THE  
LOWER 50S NEAR LAKE MI, MAINLY UPPER 50S TO LOWER 60S FARTHER  
INLAND.  
 
A SURGE OF WAA INTO WI IS EXPECTED FOR SUNDAY NIGHT AND AFTER A  
CLEAR EVENING, MID/HIGH CLOUDS SHOULD BEGIN TO OVERSPREAD THE  
REGION DURING THE OVERNIGHT HOURS. MODELS PRETTY MUCH BRING A  
CHANCE OF RAIN SHOWERS ACROSS NORTHEAST WI ONCE THE ATMOSPHERE  
SATURATES ON MONDAY. THE BETTER INSTABILITY REMAINS TO OUR SOUTH  
AND WEST, HOWEVER MID-LEVEL LAPSE RATES DO STEEPEN IN THE  
AFTERNOON, SO A RUMBLE OR TWO OF THUNDER CANNOT BE RULED OUT OVER  
CENTRAL WI. MAX TEMPERATURES FOR MONDAY TO RANGE FROM THE LOWER  
60S NEAR LAKE MI, UPPER 60S TO LOWER 70S INLAND. PRECIPITATION  
CHANCES APPEAR TO BRIEFLY TREND DOWN MONDAY NIGHT AS THE  
ISENTROPIC LIFT WEAKENS AND AN APPROACHING COLD FRONT REACHES THE  
UPPER MS VALLEY BY 12Z TUESDAY. PRECIPITATION CHANCES SHOULD BE  
ON THE INCREASE ONCE AGAIN BY TUESDAY AFTERNOON AS THE COLD FRONT  
PUSHES TOWARD THE MN/WI BORDER. LOW-LEVEL MOISTURE WILL CONTINUE  
TO SLOWLY INCREASE THROUGH THE DAY WITH DEW POINTS APPROACHING 50  
DEGREES OVER CENTRAL/EAST-CENTRAL WI. INSTABILITY WILL ALSO BE  
INCREASING WITH MODELS SHOWING STEEP MID-LEVEL LAPSE RATES AND  
CAPES UP TO 500 J/KG. IN ADDITION, MODELS INDICATE SEVERAL  
INDIVIDUAL SHORTWAVES LIFTING NORTHEAST WITHIN THE SOUTHWEST MEAN  
FLOW ALOFT. THEREFORE, HAVE KEPT A CHANCE OF SHOWERS/THUNDERSTORMS  
IN THE FORECAST FOR TUESDAY WITH MAX TEMPERATURES IN THE MIDDLE  
60S NEAR LAKE MI, LOWER TO MIDDLE 70S ELSEWHERE.  
 
AS THE COLD FRONT SWEEPS INTO WI TUESDAY NIGHT, ANTICIPATE A  
CONTINUED NEED FOR A CHANCE OF SHOWERS/THUNDERSTORMS IN THE  
FORECAST. WE WILL NEED TO WATCH QPF AMOUNTS CLOSELY WITH RIVER  
LEVELS STILL ELEVATED BY THE SNOWMELT/EARLIER RAINS. IT APPEARS  
THAT THIS SYSTEM EXITS THE AREA BY THE START OF WEDNESDAY, THUS A  
COOLER/DRIER DAY IS FORECAST FOR NORTHEAST WI. MAX TEMPERATURES  
WILL BE SLIGHTLY ABOVE NORMAL WITH LOWER TO MIDDLE 60S NORTH-  
CENTRAL/LAKESHORE, UPPER 60S TO AROUND 70 DEGREES ELSEWHERE.  
 
THE BIG QUESTION FOR WEDNESDAY NIGHT/THURSDAY WILL BE WHERE THE  
COLD FRONT TO BE SITUATED AS A SURFACE WAVE IS PROGGED TO RIDE THE  
FRONTAL BOUNDARY. IF THE COLD FRONT CAN BE PUSHED FAR ENOUGH  
SOUTH, NORTHEAST WI WOULD NOT BE IMPACTED. IF THE FRONT IS STILL  
CLOSE ENOUGH, NORTHEAST WI COULD SEE ANOTHER ROUND OF SHOWERS WITH  
LOCALLY HEAVY RAIN. NOT GOOD FOR THE RIVERS! FOR NOW, HAVE SPLIT  
THE DIFFERENCE AND KEEP POPS AT A CHANCE. MAX TEMPERATURES TO BE  
PRIMARILY IN THE UPPER 50S TO LOWER 60S.  

 
   
AVIATION
 
FOR 06Z TAF ISSUANCE  
ISSUED AT 1042 PM CDT THU APR 26 2018  
 
A COLD FRONT WILL CONTINUE BRINGING CLOUDS AND SOME SHOWERS RIGHT  
AROUND TAF ISSUANCE TIME. HOWEVER CLEARING SKIES ARE EXPECTED  
BEHIND THE FRONT AFTER IT CLEARS. A PERIOD OF MVFR CIGS IS  
POSSIBLE IN THE FAR NORTH BEHIND THE FRONT LATER TONIGHT. A  
CLIPPER SYSTEM WILL BRING CLOUDS AND SOME LIGHT PRECIPITATION  
FRIDAY. THE PRECIPITATION COULD BEGIN AS SNOW NORTH OF RHINELANDER  
WITH RAIN ELSEWHERE. FLIGHT CONDITIONS WILL GENERALLY BE MVFR,  
WITH LOCAL IFR POSSIBLE. THE PRECIPITATION WILL END FRIDAY  
EVENING, POSSIBLY AS RAIN MIXED WITH SNOW.  

 
   
FIRE WEATHER
 
 
ISSUED AT 306 PM CDT THU APR 26 2018  
 
VERY LOW RELATIVE HUMIDITY VALUES BELOW 30 PERCENT ARE EXPECTED  
DURING THE AFTERNOON AND EARLY EVENING HOURS SATURDAY AND SUNDAY  
NORTH AND WEST OF THE FOX VALLEY. HIGH TEMPERATURES SATURDAY WILL  
BE IN THE MIDDLE 40S TO LOWER 50S, AND IN THE UPPER 50S TO MIDDLE  
60S ON SUNDAY. NORTH WINDS AT 10 TO 20 MPH ON SATURDAY ARE  
EXPECTED TO SWITCH TO THE SOUTHWEST AT AROUND 10 MPH ON SUNDAY.  

 
   
GRB WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
SHORT TERM.....RDM  
LONG TERM......AK  
AVIATION.......KURIMSKI  
FIRE WEATHER...AK  
 
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