304
FXUS63 KGRB 212330
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
630 PM CDT SAT MAR 21 2026
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
KEY MESSAGES
- SNOWMELT WILL CAUSE INCREASED FLOWS AND RISING LEVELS ON RIVERS
AND STREAMS. SEVERAL RIVERS MAY REACH BANKFULL OR EVEN MINOR
FLOOD STAGE WITHIN THE NEXT COUPLE DAYS.
- RAIN, MIXED WITH SLEET AT TIMES, IS EXPECTED LATE TONIGHT INTO
SUNDAY MORNING. LOCALLY SLIPPERY ROAD CONDITIONS ARE POSSIBLE,
ESPECIALLY IN NORTHERN WI.
- TEMPERATURES WILL COOL TO NEAR NORMAL TONIGHT INTO SUNDAY, THEN
RISE TO ABOVE NORMAL AGAIN DURING THE MIDDLE OF THE WORK WEEK.
- A WINTRY MIX OF PRECIPITATION IS POSSIBLE DURING THE MIDDLE OF
NEXT WEEK, WITH BEST CHANCES OCCURRING REGIONWIDE WEDNESDAY
NIGHT INTO THURSDAY.
DISCUSSION
ISSUED AT 232 PM CDT SAT MAR 21 2026
AFTER A SLOW START DUE TO EXTENSIVE CLOUD COVER, TEMPERATURES
CLIMBED INTO THE MIDDLE 50S TO LOWER 60S ACROSS THE SOUTHWEST
PART OF THE FORECAST AREA EARLY THIS AFTERNOON. FARTHER NORTHEAST,
LINGERING CLOUDS AND SOUTHEAST WINDS OFF THE COLD WATERS OF LAKE
MICHIGAN WERE HOLDING TEMPERATURES IN THE UPPER 30S AND 40S.
DAYTIME MIXING WAS PRODUCING BREEZY CONDITIONS, WITH SOUTH WINDS
GUSTING TO 20 TO 30 MPH.
A CLIPPER LOW PRESSURE SYSTEM WILL MOVE THROUGH THE REGION THIS
EVENING, CAUSING A COLD FRONT TO SWEEP THROUGH THE FORECAST AREA.
MODELS SHOW STRONG MID-LEVEL FGEN FORCING WITH THIS SYSTEM, WHICH
SHOULD BRING A BAND OF POST-FRONTAL PRECIPITATION THROUGH THE
AREA LATE TONIGHT INTO EARLY SUNDAY. PRECIPITATION TYPE IS A BIT
TRICKY, WITH A FAIRLY STRONG, BUT ERODING WARM LAYER ALOFT THAT
GETS UNDERCUT BY POST-FRONTAL CAA, AND BOUNDARY LAYER
TEMPERATURES THAT ARE INITIALLY SUPPORTIVE OF RAIN, BUT COOL
SUBSTANTIALLY OVERNIGHT/EARLY SUNDAY. FEEL THAT THE MOST LIKELY
P-TYPES WILL BE RAIN AND SLEET, BUT CAN'T RULE OUT SPOTTY LIGHT
FREEZING RAIN AND SNOW. REGARDLESS, DON'T ENVISION ANY SIGNIFICANT
SNOW OR ICE ACCUMULATIONS, WITH LOCALLY SLIPPERY ROAD CONDITIONS
EXPECTED AS TEMPERATURES DROP BELOW FREEZING IN NORTHERN WI. THE
PRECIPITATION IS EXPECTED TO TAPER OFF IN OUR SOUTHEAST COUNTIES
BY MID TO LATE MORNING, WITH OVERCAST CONDITIONS BECOMING SCT-BKN
IN THE AFTERNOON. HIGH TEMPERATURES DROP BACK TO NORMAL OR A
LITTLE BELOW, WITH HIGHS ONLY IN THE 30S TO MIDDLE 40S.
HIGH PRESSURE WILL THEN PROVIDE MAINLY DRY WEATHER AND SEASONABLE
TEMPERATURES SUNDAY NIGHT AND MONDAY. SMALL PRECIPITATION CHANCES
OCCUR ACROSS MAINLY NORTHERN WI FROM LATE MONDAY NIGHT THROUGH
WEDNESDAY, WITH PERHAPS MORE WIDESPREAD PRECIPITATION OCCURRING
AS ANOTHER CLIPPER SYSTEM AND COLD FRONT MOVE THROUGH WEDNESDAY
NIGHT INTO THURSDAY. A WINTRY MIX OF RAIN/SNOW IS EXPECTED
THROUGH THIS PERIOD. MILD TEMPERATURES ARE EXPECTED MID-WEEK, WITH
HIGHS REACHING INTO THE 40S AND LOWER 50S FROM TUESDAY THROUGH
THURSDAY. HIGH PRESSURE BRINGS MAINLY DRY CONDITIONS AND
SEASONABLE TEMPERATURES FRIDAY AND SATURDAY.
AVIATION
FOR 00Z TAF ISSUANCE
ISSUED AT 511 PM CDT SAT MAR 21 2026
VFR CONDITIONS PREVAILED ACROSS THE AREA EARLY THIS EVENING. A
COLD FRONT THEN DROPS SOUTH OVERNIGHT, BRINGING WITH IT MVFR/IFR
STRATUS AND A MIX OF SLEET AND RAIN. RAIN/SLEET SHOULD MAKE IT RHI
BY AROUND 05 OR 06Z, SPREADING SOUTH TO THE CENTRAL AND EAST-
CENTRAL WI SITES BY 08 TO 10Z. PRECIP THEN EXITS BY MID-MORNING
SUNDAY, GIVING WAY TO VFR CIGS AT MOST TERMINALS BY LATE SUNDAY
AFTERNOON. HOWEVER, MVFR STRATUS WILL LINGER IN/AROUND RHI
THROUGH THE END OF THE TAF PERIOD.
NORTHERLY WINDS RAMP UP BEHIND THE FRONT SUNDAY AFTERNOON, GUSTING
BETWEEN 15 AND 20 KNOTS AT MOST SITES, HIGHEST ACROSS EAST-
CENTRAL WI. WINDS THEN SUBSIDE WITH THE LOSS OF DAYTIME MIXING
SUNDAY EVENING. LLWS CONCERNS WILL ARISE AT TIMES EARLY IN THE TAF
PERIOD AS AN 850 MB JET EXITS TO THE EAST.
HYDROLOGY
ISSUED AT 232 PM CDT SAT MAR 21 2026
AS TEMPERATURES WARM ACROSS THE REGION, THE SNOWMELT WILL RESULT
IN INCREASING FLOWS AND RISING RIVER LEVELS. MODELED SNOWPACK
TEMPERATURE FROM THE NOHRSC SITE POINTS TO WIDESPREAD RIPENING OF
THE SNOWPACK, AND HIGHER SUSCEPTIBILITY OF MELTING. HOWEVER, THE
LACK OF A PROLONGED SIGNIFICANT WARMUP (AND NIGHTTIME
TEMPERATURES DROPPING BELOW FREEZING MOST NIGHTS) POINTS TO A
MORE GRADUAL RISE IN AREA RIVERS AS OPPOSED TO WIDESPREAD RAPID
RISE FLOODING. SOME RIVERS WILL LIKELY REACH BANKFULL OR EVEN
MINOR FLOOD STAGE WITHIN THE NEXT COUPLE DAYS.
THE FLOODING SITUATION WILL BE MONITORED CLOSELY GIVEN HOW MUCH
WATER IS LOCKED UP IN THE CURRENT SNOWPACK ACROSS THE REGION.
FORTUNATELY, NO SIGNIFICANT PRECIPITATION EVENTS ARE EXPECTED OVER
THE NEXT WEEK, SO NEARLY ALL OF THE RUNOFF WILL BE ATTRIBUTED TO
MELTING SNOW.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION.....KIECKBUSCH
AVIATION.......GOODIN
HYDROLOGY......KIECKBUSCH
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