513  
FXUS63 KGRB 190024  
AFDGRB  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREEN BAY WI  
624 PM CST FRI JAN 18 2019  
 
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE  
   
SHORT TERM
 
TONIGHT AND SATURDAY  
ISSUED AT 252 PM CST FRI JAN 18 2019  
 
MAIN CONCERN IN THE SHORT-TERM WILL BE THE CHANCES OF LIGHT SNOW  
THIS EVENING INTO SATURDAY MORNING, ACROSS MAINLY THE SOUTHERN TIER  
OR TWO TIERS OF COUNTIES. THIS WOULD BE FROM KEWAUNEE COUNTY WEST TO  
AROUND SOUTHERN MARATHON COUNTY AND POINTS SOUTH. OTHERWISE, THE  
HEAVIER SNOW POTENTIAL WILL LIKELY REMAIN CLOSE TO THE LAKE MICHIGAN  
SHORELINE AND MOST NOTABLE FOR MANITOWOC COUNTY AND POSSIBLY  
SOUTHERN KEWAUNEE COUNTY, WHERE LAKE EFFECT/ENHANCEMENT WILL DEVELOP  
AND LINGER INTO SATURDAY AFTERNOON. IN FACT, HAVE ISSUED A WINTER  
WEATHER ADVISORY FOR MANITOWOC COUNTY FROM THIS EVENING THROUGH  
EARLY SATURDAY AFTERNOON.  
 
WIDESPREAD CLOUD COVER WAS OBSERVED ON VISIBLE SATELLITE IMAGERY  
THIS AFTERNOON ACROSS MUCH OF THE MIDWEST. ADDITIONALLY, WATER VAPOR  
IMAGERY SHOWS TWO KEY FEATURES. ONE IS THE STRONGER UPPER-LEVEL WAVE  
ACROSS THE CENTRAL PLAINS WITH A SECONDARY/WEAK SHORTWAVE SLIDING  
ACROSS SOUTHERN MN. RADAR TRENDS CONTINUE TO SHOW A FAIRLY WIDE  
SWATH OF LIGHT TO MODERATE SNOW STRETCHING ACROSS EASTERN SD INTO  
THE SOUTH HALF OF MN AND SLOWLY WORKING INTO WEST-CENTRAL AND  
SOUTHWEST WI THIS AFTERNOON. THE HEAVIER SNOW BAND HAS BEEN NOTED  
OVER NORTHERN IA INTO FAR SOUTHERN MN, WHERE VISIBILITIES HAVE  
GENERALLY BEEN LESS THAN A MILE. FARTHER NORTH, VISIBILITIES HAVE  
GENERALLY BEEN IN THE 2 TO 5 MILE RANGE.  
 
TONIGHT: THE AFOREMENTIONED STRONG UPPER LOW OVER THE CENTRAL PLAIN,  
ALONG WITH THE ASSOCIATED SURFACE LOW, WILL SHIFT EASTWARD INTO THE  
MID-MISSISSIPPI VALLEY BY SATURDAY MORNING. AT THE SAME TIME, THE  
NORTHERN PIECE OF ENERGY IS EXPECTED TO SLIDE EASTWARD AND CROSS THE  
CWA. AS THESE FEATURES SLIDE THROUGH AND SOUTH OF THE AREA, THE  
AFOREMENTIONED LIGHT SNOW IS EXPECTED TO SHIFT EASTWARD THIS  
EVENING. THE BEST CHANCE OF SEEING ACCUMULATING SNOW WILL LIKELY BE  
ALONG THE SOUTHERN COUPLE TIERS OF COUNTIES, GENERALLY SOUTH OF A  
LINE FROM SOUTHERN MARATHON COUNTY TO ROUGHLY SOUTHERN BROWN COUNTY.  
THOSE LOCATIONS COULD SEE AN INCH OR TWO BY MIDNIGHT OR SHORTLY  
THEREAFTER. THE SHARP CUTOFF TO ACCUMULATING SNOW STILL SEEMS TO BE  
AN ISSUE, AS THE NORTH HALF OF THE AREA SEES DRY NORTHEAST FLOW  
FILTERING INTO THOSE LOCATIONS. THERE WILL LIKELY BE SOME FLURRIES  
OR LIGHT SNOW, BUT ACCUMULATIONS FARTHER NORTH ARE EXPECTED TO  
REMAIN LIGHT. AS THE SYSTEMS SHIFT FARTHER EAST OVERNIGHT, WINDS  
WILL SHIFT TO THE NORTH/NORTHEAST ALLOWING LAKE EFFECT/ENHANCED SNOW  
TO DEVELOP ALONG LAKE MICHIGAN. 850MB TEMPERATURES WILL BE COLD  
ENOUGH AS THEY DROP DOWN TO AROUND THE -16C TO -18C RANGE. LAKE  
TEMPS ARE ANALYZED AROUND 5C, WHICH GIVES DELTA T VALUES IN THE 21C  
TO 23C RANGE. INVERSION HEIGHTS (LAKE INDUCED) ARE EXPECTED TO PUSH  
UP AROUND 5KFT, WITH A FAIRLY DEEP LAYER IN THE DGZ. THIS SHOULD  
ALLOW FOR AT LEAST MODERATE LAKE EFFECT SNOW OVERNIGHT. CURRENT  
THINKING IS THAT SOUTHERN MANITOWOC COUNTY WOULD HAVE THE BEST  
CHANCE OF SEEING SNOWFALL RANGING FROM 1 TO 4 INCHES BY 12Z  
SATURDAY. THIS WILL BE LARGELY DUE TO THE MORE FAVORABLE WIND  
DIRECTION/FETCH ALONG WITH ENHANCED LOW-LEVEL CONVERGENCE.  
 
SATURDAY: NORTHEASTERLY FLOW WILL CONTINUE THROUGH MUCH OF THE DAY  
AS THE AFOREMENTIONED SYSTEMS CONTINUE TO SLIDE OFF TO THE EAST.  
THIS FLOW WILL KEEP LAKE EFFECT SNOW IN THE FORECAST THROUGHOUT THE  
DAY ALONG WITH INCREASED CLOUD COVER. AGAIN, THIS WILL LIKELY REMAIN  
ALONG OR CLOSE TO THE LAKE MICHIGAN SHORELINE IN MANITOWOC COUNTY  
AND POSSIBLY PORTIONS OF KEWAUNEE COUNTY, WHERE AN ADDITIONAL INCH  
OR SO OF SNOW MAY FALL. THIS WOULD BRING SNOWFALL TOTALS UP TO THE  
2 TO 5 INCH RANGE FOR MANITOWOC COUNTY. OTHERWISE, THE REST OF  
THE AREA WILL LIKELY SEE IMPROVING CONDITIONS ALONG WITH SOME  
AFTERNOON SUNSHINE. TEMPERATURES WILL REMAIN CHILLY, WITH NORTH-  
CENTRAL LOCATIONS LIKELY REMAINING IN THE UPPER SINGLE DIGITS,  
WHILE THE REST OF THE AREA REMAINS IN THE TEENS ABOVE ZERO.  
   
LONG TERM
 
SATURDAY NIGHT THROUGH FRIDAY  
ISSUED AT 252 PM CST FRI JAN 18 2019  
 
UPPER TROUGH AT 500MB WILL APPROACH THE WESTERN UNITED STATES ON  
SUNDAY, THEN TRACK ACROSS THE CENTRAL UNITED STATES TUESDAY INTO  
WEDNESDAY. WESTERN RIDGE WILL THEN BUILD LATER NEXT WEEK INTO THE  
WEEKEND OF THE JAN 26-27, WITH CORRESPONDING DOWNSTREAM TROUGH  
ACROSS THE EASTERN HALF OF THE UNITED STATES WILL LEAD TO BELOW  
NORMAL TEMPERATURES FOR MUCH OF THE PERIOD.  
 
FOR SATURDAY NIGHT, CONTINUED A SMALL CHANCE OF SNOW SHOWERS  
ACROSS PORTIONS OF FAR EASTERN KEWAUNEE AND MANITOWOC AS LOW  
LEVEL WINDS ARE STILL FLOWING OFF THE LAKE. HIGH PRESSURE BUILDS  
INTO THE REGION LATE SATURDAY NIGHT AND ACROSS THE REGION ON  
SUNDAY. THINGS GET MORE INTERESTING SUNDAY NIGHT AND MONDAY WITH  
RETURN SOUTH/SOUTHEAST FLOW OFF THE LAKE. LAKE TO 850MB  
TEMPERATURE DIFFERENCES OF 15C TO 20C NOTED SUNDAY NIGHT INTO  
MONDAY MORNING SHOULD BRING LAKE EFFECT SNOW SHOWERS OFF LAKE  
MICHIGAN. WITH INCREASING SOUTHERLY FLOW MONDAY, THERE COULD BE  
SOME DECENT LAKE EFFECT SNOW SHOWERS MOVING NORTHWARD INTO  
NORTHERN DOOR COUNTY. WILL NEED TO WATCH THIS SCENARIO OVER THE  
NEXT DAY OR TWO. WOULD NOT BE SURPRISE ME IF NORTHERN DOOR COUNTY  
RECEIVES AT LEAST SEVERAL INCHES OF SNOW.  
 
SYSTEM WILL APPROACH FROM THE WEST MONDAY AFTERNOON. SNOW IS  
EXPECTED TO BREAK OUT ACROSS THE REGION MONDAY NIGHT WITH SNOW  
CONTINUING INTO TUESDAY AFTERNOON/EVENING. SEVERAL INCHES OF SNOW  
ARE POSSIBLE WITH THIS SYSTEM, CREATING HAZARDOUS CONDITIONS FOR  
MOTORISTS. THE SNOW SHOULD END SOMETIME TUESDAY NIGHT. DRY  
CONDITIONS ARE EXPECTED ON WEDNESDAY, EXCEPT ACROSS THE FAR NORTH  
WHERE THERE IS A CHANCE OF LAKE EFFECT SNOW SHOWERS. LOW  
CONFIDENCE IN THE CHANCES OF SNOW SHOWERS ON THURSDAY AND FRIDAY.  
BELOW NORMAL TEMPERATURES THROUGH THE PERIOD, EXCEPT TUESDAY WHERE  
TEMPERATURES WILL BE CLOSE TO NORMAL AND WILL THE WARMEST DAY  
DURING THE PERIOD.  

 
   
AVIATION
 
FOR 00Z TAF ISSUANCE  
ISSUED AT 624 PM CST FRI JAN 18 2019  
 
A WINTER STORM MOVING ACROSS THE OHIO VALLEY WILL  
PRODUCE CLOUDS ACROSS THE AREA TONIGHT AND SATURDAY, WITH SOME  
LIGHT SNOW OR FLURRIES SOUTH OF A GREEN BAY TO WAUSAU LINE, AND  
LAKE EFFECT SNOW NEAR LAKE MICHIGAN. MVFR OR IFR CONDITIONS ARE  
POSSIBLE LATER TONIGHT AND PART OF SATURDAY AT MTW BUT IT SHOULD  
REMAIN VFR ELSEWHERE.  

 
   
GRB WATCHES/WARNINGS/ADVISORIES
 
 
WINTER WEATHER ADVISORY UNTIL NOON CST SATURDAY FOR WIZ050.  

 
 

 
 
SHORT TERM.....COOLEY  
LONG TERM......ECKBERG  
AVIATION.......RDM  
 
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