383
FXUS63 KGRB 160031
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
ISSUED BY NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
731 PM CDT THU MAY 15 2025
KEY MESSAGES
- MARINE DENSE FOG ADVISORY FOR THE NEARSHORE AREAS OF LAKE
MICHIGAN THROUGH THE EARLY EVENING. A SMALL CRAFT ADVISORY
- A BROKEN LINE OF STRONG THUNDERSTORMS WILL CROSS NORTHERN WI
BETWEEN 4 AND 9 PM TODAY. SOME SEVERE STORMS ARE LIKELY WITH
THE PASSAGE OF A COLD FRONT. ALL HAZARDS POSSIBLE OVER CENTRAL
WI AND LARGE HAIL POSSIBLE OVER EASTERN WI.
- ANOTHER PERIOD OF SHOWERS AND WEAK STORMS EXPECTED FRIDAY WITH
SOME POTENTIAL FOR GUSTY WINDS WITH SOME OF THESE
SHOWERS/STORMS.
DISCUSSION
ISSUED AT 304 PM CDT THU MAY 15 2025
THE REST OF THIS AFTERNOON THROUGH FRIDAY NIGHT:
A BROKEN LINE OF CELLULAR STORMS HAS BROKEN OUT, CURRENTLY FROM
EAU CLAIRE DOWN TO MADISON WI. THIS IS LINE IS EXPECTED TO
DEVELOP FURTHER AND RAMP UP IN INTENSITY THIS EVENING. HAIL AND
GUSTY WINDS ARE EXPECTED, OWING TO SBCAPE AROUND 2500 J/KG AMID
EFFECTIVE SHEAR AROUND 40 KNOTS. A COUPLE TORNADOES ALSO LOOK
POSSIBLE, GIVEN EFFECTIVE SRH VALUES AROUND 200 M2/S2 OVER MUCH
OF NE WI, AND AN EFFECTIVE WARM FRONT PARKED FROM THE FOX
VALLEY UP THROUGH MARATHON AND LINCOLN COUNTY. THE PEAK TIMING
FOR STORMS LOOKS TO BE FROM 5PM THROUGH 8PM THIS EVENING AS THE
BROKEN LINE MOVES NORTHEAST. A TORNADO WATCH IS OUT FROM NOW
THROUGH 10PM OVER MUCH OF OUR CWA.
STORMS WILL QUICKLY MOVE THROUGH AND A DRY PUNCH ALOFT WILL
CLEAR OUT SKIES FAIRLY QUICKLY BEHIND THE STORMS. THERE WILL BE
A BIT OF A LULL OVERNIGHT, BUT TOMORROW, ENHANCED MIXING WILL
LEAD TO GUSTY SOUTHWEST WINDS WITH SOME SCATTERED GUSTS TO 40
MPH. A SECONDARY SHORTWAVE PIVOTING AROUND AN UPPER LEVEL LOW
AND LINGERING MOISTURE WILL SQUEEZE OUT SOME MORE SCATTERED
THUNDERSTORM ACTIVITY IN THE AFTERNOON. VERY DRY LOW LEVELS AND
THE HIGH BASED NATURE OF THE STORMS WILL CAUSE THE POTENTIAL FOR
GUSTY WINDS WITH ANY STORMS THAT GET ESTABLISHED ENOUGH IN THE
ENVIRONMENT.
SATURDAY THROUGH WEDNESDAY
THE UPPER LOW WILL LINGER INTO SATURDAY. COOLER CONDITIONS ARE
EXPECTED DUE TO CLOUDS AND THE COOLER AIR ALOFT AND HIGHS WILL
TOP OUT IN THE LOW TO MID 60. DIURNALLY DRIVEN SCATTERED
SHOWERS MAY OCCUR THROUGH THE DAY. THIS UPPER LOW SHOULD MOVE
EAST ON SUNDAY, RESTORING RELATIVE HIGH PRESSURE, BUT CLOUDS
WILL LIKELY LINGER ALONG WITH COOLER TEMPERATURES AS WINDS WILL
COME AROUND TO NORTHEASTERLY. BY LATE IN THE EXTENDED PERIOD, A
LARGE LOW PRESSURE SYSTEM IS EXPECTED TO APPROACH THE UPPER
MIDWEST MONDAY INTO TUESDAY, BRINGING A PROLONGED PERIOD OF
SHOWERY RAIN AND CLOUDS TO THE AREA. WINDS WILL REMAIN
NORTHEASTERLY OFF OF THE LAKE, KEEPING OUR CWA COOL WITH HIGHS
IN THE 50S.
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 724 PM CDT THU MAY 15 2025
SCATTERED STORMS ARE PRESENT MOST EVERYWHERE OVER NORTHEAST WI.
THESE STORMS WILL FEATURE GUSTY WINDS AND LARGE HAIL. AN
ISOLATED TORNADO ALSO CAN'T BE RULED OUT THROUGH THE REST OF THE
EVENING. THESE STORMS SHOULD CONTINUE TO LIFT NORTHEAST AND
EXIT NORTHEAST WI BY 03 TO 04Z. FOLLOWING STORMS, SKIES ARE
EXPECTED TO QUICKLY CLEAR AND REMAIN CLEAR OVERNIGHT AS A DRY
SLOT MOVES IN, WITH LIGHTER WINDS THAT WILL TURN FROM SOUTHEAST
TO SOUTHWEST OVERNIGHT.
VFR CEILINGS RETURN TOMORROW THROUGH THE MORNING INTO THE
AFTERNOON WITH SFC WIND GUSTS BECOMING STRONG OUT OF THE
SOUTHWEST TO 35 KNOTS IN SPOTS, ESPECIALLY THE FOX VALLEY.
THERE MAY BE ADDITIONAL SCATTERED THUNDERSTORM DEVELOPMENT IN
THE AFTERNOON WITH GUSTY WINDS BEING THE PRIMARY THREAT.
MARINE
ISSUED AT 304 PM CDT THU MAY 15 2025
MARINE DENSE FOG WILL CONTINUE INTO THIS EVENING UNTIL
THUNDERSTORMS AND A FRONT PASS DURING THE EARLY EVENING HOURS. A
SMALL CRAFT ADVISORY WILL ALSO CONTINUE INTO TONIGHT ON
SOUTHEAST WINDS. FOLLOWING THE PASSAGE OF THE FRONT, WINDS
SHOULD EASE FOR A TIME OVERNIGHT AND THEN COME AROUND TO
SOUTHWESTERLY BY TOMORROW AT DAWN. GUSTY SOUTHWESTERLY WINDS ARE
THEN EXPECTED TO PICK UP LEADING TO A POTENTIAL SECOND PERIOD OF
SMALL CRAFT ADVISORY CONDITIONS DURING TOMORROW AFTERNOON.
GRB WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM CDT FRIDAY FOR LMZ522.
SMALL CRAFT ADVISORY UNTIL 11 PM CDT THIS EVENING FOR LMZ542-
543.
DISCUSSION...
AVIATION...
MARINE...
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