070
FXUS63 KGRB 201953
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
253 PM CDT SUN APR 20 2025
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
KEY MESSAGES
- WIDESPREAD RAIN EXPECTED TONIGHT, ALTHOUGH COULD TURN TO SNOW AND
SLEET ACROSS THE FAR NORTH FOR A FEW HOURS LATE TONIGHT INTO
MONDAY MORNING. HREF PROBABILITIES OF AN INCH OF RAIN IS 80-100%
NORTH AND WEST OF THE FOX VALLEY AND 50-70% FROM THE FOX VALLEY
EAST TO THE LAKESHORE.
- THE EXPECTED RAINFALL COULD LEAD TO SEVERAL RIVERS REACHING
BANKFULL, WITH A FEW OF THEM REACHING FLOOD STAGE.
- A MINOR SNOW ACCUMULATION IS EXPECTED ON GRASSY SURFACES AND
POSSIBLY SOME SLUSHY ROADS LATE TONIGHT INTO EARLY MONDAY
MORNING ACROSS FAR NORTH-CENTRAL WI. THE CHANCE OF 1" OF SNOW
RANGES FROM 20-60% ACROSS VILAS COUNTY, WITH THE HIGHEST
PROBABILITIES ACROSS THE NORTHWEST PORTION OF THE COUNTY.
- COOLER TEMPS ARRIVE TO START THE NEW WEEK, BUT A WARM UP IS ON
TAP BY WEDNESDAY, WITH PERIODIC RAIN (STORM?) CHANCES THROUGH
THE WEEK.
DISCUSSION
ISSUED AT 252 PM CDT SUN APR 20 2025
SHORT TERM...TONIGHT AND MONDAY
LIGHT RAIN CONTINUED TO SPREAD NORTHWARD INTO CENTRAL AND EAST-
CENTRAL WISCONSIN THIS AFTERNOON. TEMPERATURES WERE IN THE MIDDLE
40S TO LOWER 50S, WITH THE COOLEST READINGS NEAR THE BAY AND LAKE
MICHIGAN.
FOR THE REST OF THE AFTERNOON, WILL SPREAD INT NORTH-CENTRAL AND
FAR NORTHEAST WISCONSIN, WITH RAIN CONTINUING OVERNIGHT AS LOW
PRESSURE MOVES INTO WISCONSIN. ACROSS PORTIONS OF EAST-CENTRAL
WISCONSIN, THE FIRST WAVE OF RAIN WILL MOVE NORTH THIS AFTERNOON,
THEN THERE MAY BE A BREAK OR LULL IN THE RAIN EARLY THIS EVENING
BEFORE THE STEADIER RAIN ARRIVES LATER THIS EVENING. ATTENTION
TURNS TO LATE TONIGHT INTO EARLY MONDAY MORNING WHERE THE
PRECIPITATION MAY CHANGE OVER TO SLEET OR SNOW FOR A PERIOD OF
TIME, GENERALLY FROM 09Z TO 16Z ON MONDAY. OFFICIAL FORECAST HAS
UP TO AN INCH OF SNOW IN VILAS COUNTY. THE HREF PROBABILITIES
INDICATED A 20-60% CHANCE OF 1" OF SNOW, WITH THE HIGHEST
PROBABILITIES ACROSS NORTHWEST VILAS COUNTY.
RAIN AND SNOW WILL CONTINUE EARLY MONDAY MORNING, THEN PRECIPITATION
CHANCES WILL BE ON THE DECREASE THROUGH THE DAY AS LOW PRESSURE
MOVES AWAY FROM THE AREA. THE HREF PROBABILITIES INDICATED A
80-100% CHANCE OF 1" OF PRECIPITATION NORTH AND WEST OF THE FOX
VALLEY WITH A 50-70% CHANCE ACROSS THE FOX VALLEY EAST TO THE
LAKE. GUSTY NORTHWEST UP TO AROUND 35 MPH ARE POSSIBLE FROM LATE
MORNING THROUGH LATE AFTERNOON ON MONDAY. HIGHEST GUSTS ARE
EXPECTED ACROSS NORTHEAST WISCONSIN.
LONG TERM...MONDAY NIGHT THROUGH SUNDAY
PRECIPITATION WILL QUICKLY COME TO AN END MONDAY EVENING ACROSS
NORTH-CENTRAL WISCONSIN, AS A SHORTWAVE RIDGE PROVIDES DRY
CONDITIONS FOR THE REST OF MONDAY NIGHT. THE DRY WEATHER WILL BE
SHORT LIVED AS ANOTHER LOW PRESSURE SYSTEM BRINGS A PERIOD OF
SHOWERS AND A FEW THUNDERSTORMS TUESDAY AND TUESDAY NIGHT. THIS
SYSTEM WILL NOT BE AS DYNAMIC AS THE ONE EARLIER THIS WEEK, WITH
RAINFALL AMOUNTS EXPECTED TO BE MUCH LOWER. PROBABILITIES OF
REACHING OR EXCEEDING 0.25 INCHES TUESDAY AND TUESDAY NIGHT ARE
ONLY 15-25% ACROSS CENTRAL AND EAST-CENTRAL WISCONSIN.
AFTER ANOTHER BRIEF BREAK IN PRECIPITATION WEDNESDAY AND WEDNESDAY
NIGHT, ANOTHER LOW PRESSURE SYSTEM WILL AFFECT THE AREA TO END THE
WEEK. THERE ARE MODEL UNCERTAINTIES IN THE THURSDAY TO FRIDAY
TIMEFRAME REGARDING THE AMOUNT AND PLACEMENT OF THE HIGHEST
RAINFALL AMOUNTS. HOWEVER, THERE IS CONSENSUS THAT A LOW PRESSURE
SYSTEM WILL EMERGE FROM THE PLAINS AND TRACK THROUGH THE WESTERN
GREAT LAKES REGION THURSDAY NIGHT INTO FRIDAY. THE MAIN QUESTION
THAT CONTINUES TO PLAGUE THE FORECAST IS WHAT HAPPENS AFTER THAT.
THE GFS/ECMWF PLUNGE HIGH PRESSURE FROM SOUTHERN CANADA ACROSS THE
MIDWEST ON THE HEELS OF THE DEPARTING LOW, WITH DRY CONDITIONS
MOST OF FRIDAY AND INTO NEXT WEEKEND. THE CANADIAN STILL BRINGS A
SECOND LOW THROUGH THE CENTRAL GREAT LAKES REGION ON SATURDAY,
KEEPING WISCONSIN WET THROUGH SATURDAY AND DELAYING THE DRY
CONDITIONS UNTIL SUNDAY. BOTH OF THESE CONFLICTING SOLUTIONS HAVE
BEEN REMARKABLY CONSISTENT FROM RUN TO RUN, WHICH DOESN'T LEND
CONFIDENCE IN EITHER SOLUTION, WITH THE LREF 500MB CLUSTERS
SHOWING QUITE A BIT OF VARIABILITY IN THIS TIME FRAME. THE
WETTEST TIME FRAME STILL APPEARS TO BE THURSDAY NIGHT, WHICH
CONTINUES TO BE THE TARGET FOR THE HIGHEST CHANCE FOR RAIN (50-60%
CHANCE). HOWEVER, GIVEN THE MODEL DIFFERENCES BEYOND THURSDAY
NIGHT THERE ISN'T MUCH CLARITY IN HOW THIS LOW WILL CONTINUE TO
AFFECT THE REGION INTO NEXT WEEKEND.
AVIATION
FOR 18Z TAF ISSUANCE
ISSUED AT 1232 PM CDT SUN APR 20 2025
LIGHT SHOWERS WILL OVERSPREAD CENTRAL AND EAST CENTRAL WISCONSIN
BY MID TO LATE AFTERNOON, WITH STEADIER RAIN EXPECTED TONIGHT
INTO MONDAY MORNING. THE RAIN COULD BECOME MIXED WITH OR CHANGE TO
SLEET OR SNOW FOR A TIME ACROSS NORTH-CENTRAL WISCONSIN BETWEEN
10Z AND 15Z ON MONDAY. ANY SNOW ACCUMULATION WILL LIKELY BE ON
GRASSY SURFACES, HOWEVER IF IT SNOWS HARD ENOUGH SOME OF THE
RUNWAYS OVER THE FAR NORTH COULD BECOME SLUSH COVERED FOR A FEW
HOURS UNTIL THE HEAVIER PRECIPITATION MOVES AWAY AND TEMPERATURES
CLIMB WELL ABOVE FREEZING.
CIGS ARE EXPECTED TO DROP INTO THE MVFR AND THEN INTO THE IFR OR
LOWER CATEGORY TONIGHT AND LINGER THROUGH MONDAY MORNING. LOW
LEVEL WIND SHEAR IS EXPECTED TO DEVELOP THIS EVENING AND CONTINUE
OVERNIGHT. GUSTY EAST/SOUTHEAST WINDS EXPECTED THIS AFTERNOON AND
TONIGHT, WITH WINDS BECOMING NORTHWEST WITH GUSTS 25 TO 30 KTS
LATE MONDAY MORNING AND AFTERNOON.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION.....ECKBERG/KURIMSKI
AVIATION.......ECKBERG
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