897  
FXUS63 KGRB 050236  
AFDGRB  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREEN BAY WI  
936 PM CDT SAT APR 4 2020  
 
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE  
   
SHORT TERM
 
TONIGHT AND SUNDAY  
ISSUED AT 237 PM CDT SAT APR 4 2020  
 
THE SHORT TERM WILL BE A FAIRLY QUIET PERIOD WEATHER WISE AS HIGH  
PRESSURE PERSISTS. THE MAIN FOCUS WILL BE LOW TEMPERATURES  
TONIGHT.  
 
TONIGHT, IDEAL COOLING CONDITIONS ARE EXPECTED ACROSS THE REGION,  
ESPECIALLY ACROSS NORTHERN WISCONSIN. DRY AIR, CALM WINDS, AND  
CLEAR SKIES WILL BRING TEMPERATURES DOWN QUICKLY, ESPECIALLY IN  
OUR TYPICAL COLD SPOTS ACROSS THE FAR NORTH WHERE WE ALSO HAVE A  
LINGERING SNOWPACK. LOW TEMPERATURES IN THE NORTH WILL BE IN THE  
TEENS, POSSIBLY EVEN DROPPING BRIEFLY INTO THE SINGLE DIGITS  
BEFORE SUNRISE. TEMPERATURES ELSEWHERE WILL REMAIN IN THE 20S.  
 
SUNDAY WILL BE BRIGHT AND SUNNY, WITH TEMPERATURES RECOVERING  
QUICKLY FROM THE OVERNIGHT HOURS, ESPECIALLY NEAR THE FOX VALLEY  
WHICH WILL HAVE A WARMER START. KEPT TEMPERATURES TOWARDS THE  
HIGHER END OF GUIDANCE, WITH HIGHS IN THE LOWER TO MIDDLE 50S.  
   
LONG TERM
 
SUNDAY NIGHT THROUGH SATURDAY  
ISSUED AT 237 PM CDT SAT APR 4 2020  
 
PRIMARY FOCUS IS ON THE TUESDAY/TUESDAY EVENING TIME FRAME, WHEN  
THERE IS POTENTIAL FOR WIDESPREAD SHOWERS AND THUNDERSTORMS, AND  
POSSIBLY SOME SEVERE WEATHER IN THE SOUTHERN PART OF THE CWA.  
 
EXPECT GENERALLY DRY CONDITIONS ON SUNDAY NIGHT, AS HIGH PRESSURE  
CONTINUES TO SHIFT EAST THROUGH THE GREAT LAKES REGION.  
 
DEVELOPING RETURN FLOW AND H8 WAA WILL BRING A CHANCE OF SHOWERS  
TO THE REGION MONDAY INTO MONDAY NIGHT. THE GFS IS MOST AGGRESSIVE  
WITH THIS, AND HAS TWO SEPARATE BANDS OF RAIN, ONE OVER THE FAR  
NORTH AND ANOTHER OVER CENTRAL AND EAST CENTRAL WI. KEPT POPS IN  
THE CHANCE CATEGORY FOR NOW. WEAK ELEVATED INSTABILITY WILL WORK  
IT'S WAY INTO THE SOUTHWEST PART OF THE FORECAST AREA, LEADING TO  
THE POTENTIAL FOR ISOLATED THUNDERSTORMS.  
 
MODELS SHOW A CLIPPER-LIKE SYSTEM IN ZONAL FLOW MOVING THROUGH WI  
ON TUESDAY AND TUESDAY EVENING. IT IS POSSIBLE THE LOW MAY TRACK  
FAR ENOUGH NORTH TO ALLOW THE WARM FRONT TO LIFT INTO CENTRAL AND  
EAST CENTRAL WI. THIS SYSTEM WILL BE AIDED BY UPPER DIVERGENCE  
FROM COUPLED UPPER JETS AND A SHORT-WAVE TROF (LATE AFTERNOON AND  
EVENING). DEEP LAYER SHEAR IS QUITE STRONG (45-55 KTS) AND 0-3 KM  
SRH IS 200-400. MUCAPE IS FORECAST TO REACH 1000-1500 J/KG IN  
CENTRAL AND EAST CENTRAL WI, AND 700-500 MB LAPSE RATES ARE  
EXPECTED TO BE 7.5-8 C/KM. INGREDIENTS ARE IN PLACE FOR A POSSIBLE  
SEVERE EVENT, BUT CONFIDENCE IS STILL LOW GIVEN THE POTENTIAL FOR  
THE FRONT TO STAY FARTHER SOUTH THAN ANTICIPATED, AND EXPECTED  
CLOUD COVER/LACK OF INSOLATION. TOOK A QUICK LOOK AT CIPS ANALOGS,  
AND THEY VALIDATED THE POTENTIAL FOR AT LEAST A MARGINAL SEVERE  
EVENT IN CENTRAL AND EAST CENTRAL WI. WILL BEEF UP THE WORDING IN  
THE HAZARDOUS WEATHER OUTLOOK. HIGHS WILL BE MUCH ABOVE NORMAL,  
RANGING FROM THE UPPER 40S TO MIDDLE 50S NORTHEAST, TO THE MIDDLE  
TO UPPER 60S SOUTHWEST.  
 
A COLD FRONT WILL MOVE THROUGH THE REGION ON WEDNESDAY AND  
WEDNESDAY EVENING, BRINGING ANOTHER CHANCE OF SHOWERS, FOLLOWED BY  
GUSTY WINDS AND COOLER TEMPERATURES INTO THURSDAY.  
 
COOL BUT GENERALLY DRY WEATHER IS ANTICIPATED LATE IN THE WEEK,  
WITH WEAK RIDGING AT THE SURFACE AND ALOFT ARRIVING BY SATURDAY.  

 
   
AVIATION
 
FOR 06Z TAF ISSUANCE  
ISSUED AT 936 PM CDT SAT APR 4 2020  
 
DRY HIGH PRESSURE BUILDING ACROSS THE AREA WILL ALLOW FOR GOOD  
FLYING CONDITIONS THROUGH MOST OF THIS TAF PERIOD. THE EXCEPTION  
WILL BE THE EASTERN TAF SITES, WHERE SOME LOW CLOUDS HAVE FORMED  
WITH LIGHT FLOW OFF LAKE MICHIGAN. CEILINGS HAVE GENERALLY DROPPED  
TO AROUND 800FT WITH THE ONSHORE/UPSLOPE FLOW AND WILL LIKELY  
LINGER THROUGH THE NIGHT AS THEY EXPAND WESTWARD. THE LOW CLOUDS  
AT MTW WILL EXPAND TO GRB AND ATW BETWEEN 03Z AND 04Z. LIGHT AND  
VARIABLE WINDS ARE EXPECTED.  
 

 
   
GRB WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
SHORT TERM.....UHLMANN  
LONG TERM......KIECKBUSCH  
AVIATION.......COOLEY  
 
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