512
FXUS63 KGRB 022321
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
621 PM CDT THU APR 2 2026
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
KEY MESSAGES
- RAIN AND FREEZING RAIN, MIXED WITH SLEET OVER NORTH-CENTRAL WI,
WILL CONTINUE THROUGH THIS EVENING, BEFORE DIMINISHING
OVERNIGHT. TREE DAMAGE AND POWER OUTAGES ARE THE MAIN IMPACTS
FROM THE FREEZING RAIN AND ICING THUS FAR, WITH SOME SLIPPERY
ROADS. THE EVENING COMMUTE ACROSS NORTHERN WI WILL BE IMPACTED.
ICE STORM WARNINGS AND WINTER STORM WARNINGS REMAIN IN EFFECT.
- THUNDERSTORMS ARE POSSIBLE LATE THIS AFTERNOON THROUGH THE
EVENING, ESPECIALLY OVER SOUTHERN PORTIONS OF WINNEBAGO, CALUMET,
AND MANITOWOC COUNTIES. TO THE NORTH OF THESE AREAS, THE RISK
FOR SEVERE STORMS HAS DIMINISHED.
- HEAVY RAINFALL, MIXED PRECIPITATION, AND THUNDERSTORMS ARE
POSSIBLE FRIDAY NIGHT INTO SATURDAY. WINTRY IMPACTS SHOULD BE FOCUSED
OVER NORTHERN WI. A WINTER STORM WATCH HAS BEEN ISSUED.
- FLOODING CONCERNS ARISE THIS WEEKEND INTO EARLY NEXT WEEK
FOLLOWING THE PASSAGE OF THE TWO MOISTURE RICH SYSTEMS.
DISCUSSION
ISSUED AT 226 PM CDT THU APR 2 2026
FREEZING RAIN, ICE THROUGH THIS EVENING...RAIN, MIXED WITH
FREEZING RAIN IS LIFTING INTO NORTHERN WI. EARLIER SLEET THAT
WAS OBSERVED FROM RHINELANDER NORTH HAS RECENTLY GIVEN WAY TO
FREEZING RAIN AS 800MB WARM LAYER SPREADS NORTH. NO CHANGE TO
WINTER HEADLINES IN THE NORTH (ICE STORM WARNING, WINTER STORM
WARNINGS) GIVEN THE INITIAL PUSH OF FREEZING RAIN INTO EARLY THIS
EVENING, FOLLOWED BY SECONDARY AREA OF MAINLY FREEZING RAIN THAT
OCCURS LATE EVENING INTO THE EARLY OVERNIGHT. ADDITIONAL ICE
ACCUMULATIONS UP TO 0.25 INCH ARE EXPECTED BEFORE THE FREEZING
RAIN, ICE END OVERNIGHT. IMPACTS SO FAR WITH THE ICE ACCUMULATION
(MANY REPORTS OF 0.25 TO 0.40 INCH OF ICE, WITH ISOLATED REPORTS
UP TO 0.50 INCH) HAVE BEEN TIED TO TREE DAMAGE, POWER OUTAGES
VERSUS ICY ROADS. CURRENTLY NEARLY 50K CUSTOMERS REMAIN WITHOUT
POWER FROM CENTRAL TO NORTHEAST WI.
SEVERE WEATHER POTENTIAL LATE THIS AFTERNOON AND EVENING...
SURFACE LOW OVER SOUTH-CENTRAL IA IS FORECAST TO LIFT INTO THE FOX
VALLEY TO THE LAKESHORE REGION LATE THIS EVENING. EXPECT A FEW
STORMS AS THIS MOVES THROUGH, BUT THE RISK OF SEVERE WEATHER WILL
BE PINNED OVER FAR SOUTHEAST FORECAST AREA (OSHKOSH TO MANITOWOC
AND POINTS SOUTH) ON GRADIENT OF SBCAPE WHICH STAYS MAINLY SOUTH
AND WHERE THERE IS BETTER POTENTIAL FOR MORE ORGANIZED LINE OF
STORMS MOVING THROUGH. EVEN THEN, FORECAST SOUNDINGS SHOW SHARP
INVERSION AROUND 0.5-1.0 KM (950-850MB) WITH MUCAPE UP TO 500J/KG
AND EFFECTIVE SHEAR LESS THAN 30 KTS. OVERLL, GIVEN THE LACK OF
SFC BASED INSTABILITY AND NOT AS FAVORABLE SETUP WITH ELEVATED
STORMS, SEEMS GREATEST RISK FOR SEVERE (DAMAGING WIND GUSTS) IN
OUR AREA WILL BE IF WELL ORGANIZED LINE OF STORMS CAN MOVE THROUGH
AND DRAW PORTION OF THE 50-55KT OF WINDS ALOFT DOWN TO THE SFC,
EVEN AS THE NEAR SFC INSTABILITY IS LACKING. TIMING LOOKS SIMILAR
TO WHAT WE HAVE BEEN INDICATING APPROXIMATELY 7P THROUGH MIDNIGHT.
A BREAK LATE TONIGHT THROUGH MOST OF FRIDAY, THEN ATTENTION TURNS
TO YET ANOTHER SIGNIFICANT SYSTEM LATE FRIDAY THROUGH SATURDAY.
SIMILAR TO THIS SYSTEM, MORE POTENTIALLY SIGNIFICANT FREEZING RAIN
AND ICING IS EXPECTED, THOUGH THE AREA MOST FAVORED IS DISPLACED
FARTHER NORTH, INTO NORTH-CENTRAL AND FAR NORTHEAST WI. SYSTEM IS
QUICKER MOVING, WITH BULK OF QPF/FREEZING RAIN OCCURRING FRIDAY
EVENING INTO MID MORNING SATURDAY. PROBABILITIES OF SEEING OVER
0.25 INCH ICE (NBM V5.0) HAVE INCREASED TO 35-55 PERCENT, HIGHEST
OVER VILAS AND NORTHERN FOREST INTO SOUTHWEST UPPER MICHIGAN.
FOOTPRINT THAT COULD SEE A COATING OF ICE TAKES UP MORE AREA,
REACHING INTO CENTRAL WI INTO FAR NORTHEAST WI. WINTER STORM WATCH
THAT WAS ISSUED ON MID SHIFT IS CENTERED WHERE PROBABILITIES FOR
0.25 INCH ARE HIGHEST AND WHERE WSSI-P SHOWS GOOD SIGNAL FOR AT
LEAST MODERATE IMPACTS (SMALLER AREA OF MAJOR IMPACTS), SO NO
CHANGES TO THAT HEADLINE. ALSO, GIVEN THE ONGOING FREEING RAIN,
ICING WITH THIS FIRST EVENT, WILL NOT DO ANY UPGRADING TO THAT
WATCH RIGHT NOW.
ANOTHER BREAK, BUT MORE OF A CLIPPER TYPE SYSTEM EXPECTED ON
MONDAY WITH SNOW OR A MIX OF RAIN/SNOW OCCURRING. AS OF RIGHT NOW,
ONLY LOOKING AT MINOR IMPACTS FOR THIS SYSTEM WITH MARGINAL SFC
TEMPS.
AVIATION
FOR 00Z TAF ISSUANCE
ISSUED AT 621 PM CDT THU APR 2 2026
A POTENT LOW PRESSURE SYSTEM WILL TRACK FROM SOUTHWEST TO EAST-
CENTRAL WISCONSIN THIS EVENING, MAINTAINING POOR FLYING CONDITIONS
THROUGH THE OVERNIGHT HOURS. WIDESPREAD IFR CEILINGS AND
MVFR VISIBILITIES WILL PREVAIL ACROSS ALL TERMINALS.
OVER EAST-CENTRAL WI (KGRB, KATW, KMTW), SCATTERED THUNDERSTORMS
ARE LIKELY BETWEEN 00Z AND 04Z AS THE SURFACE LOW PASSES. A FEW
STORMS MAY BE STRONG, CAPABLE OF PRODUCING BRIEF GUSTY WINDS AND
FURTHER VISIBILITY REDUCTIONS. FURTHER NORTH AND WEST (KAUW, KCWA,
KRHI), THE STEADY WINTRY MIX SHOULD TAPER OFF BY THE START OF THE
TAF PERIOD, BUT PATCHY LIGHT PRECIPITATION WILL REMAIN POSSIBLE
UNTIL THE EARLY OVERNIGHT.
LOW-LEVEL WIND SHEAR (LLWS) IS A SIGNIFICANT CONCERN THROUGH 06Z,
PARTICULARLY FOR THE EAST-CENTRAL WISCONSIN TERMINALS WHERE A
35-55 KT LOW- LEVEL JET EXISTS JUST ABOVE A SHARP SURFACE
INVERSION.
AS THE SYSTEM DEPARTS AFTER 06Z, SOME MINOR IMPROVEMENT TO LOW-
END MVFR CEILINGS IS POSSIBLE. HOWEVER, HIGH CONFIDENCE REMAINS
THAT MVFR STRATUS WILL LINGER THROUGH FRIDAY MORNING. PARTIAL
CLEARING TOWARD VFR IS NOT EXPECTED UNTIL FRIDAY AFTERNOON.
OUTLOOK...ANOTHER SIGNIFICANT SYSTEM ARRIVES LATE FRIDAY INTO
SATURDAY, BRINGING THE POTENTIAL FOR SIGNIFICANT ICING AND
FREEZING RAIN, ESPECIALLY FOR NORTH-CENTRAL AND FAR NORTHEAST WI.
HYDROLOGY
ISSUED AT 226 PM CDT THU APR 2 2026
THE COMBINATION OF TODAY'S AND FRIDAY NIGHT-SATURDAY'S MOISTURE
LADEN SYSTEMS WILL LEAD TO FLOODING CONCERNS. A FEW RIVER SITES
ARE ALREADY FORECAST TO REACH NEAR MINOR FLOOD STAGE THIS WEEKEND
INTO EARLY NEXT WEEK. ALSO, WITH THE GROUND NOW SATURATED, MINOR
FLOODING WILL BE POSSIBLE THROUGH THE WEEKEND IN LOW-LYING AND
POOR DRAINAGE AREAS.
GRB WATCHES/WARNINGS/ADVISORIES
WINTER STORM WARNING UNTIL 1 AM CDT FRIDAY FOR WIZ005-012-013.
WINTER STORM WATCH FROM FRIDAY EVENING THROUGH SATURDAY MORNING
FOR WIZ005-010>013-018-019.
ICE STORM WARNING UNTIL 1 AM CDT FRIDAY FOR WIZ010-011.
DISCUSSION.....JLA
AVIATION.......MPC
HYDROLOGY......JLA
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