137
FXUS63 KGRB 150131
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
ISSUED BY NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
831 PM CDT WED MAY 14 2025
KEY MESSAGES
- MARINE DENSE FOG ADVISORY FOR THE NEARSHORE AREAS OF LAKE
MICHIGAN THROUGH THURSDAY.
- A DENSE FOG ADVISORY HAS BEEN ISSUED FOR THE EASTERN LAKE
SHORE COUNTIES THIS EVENING INTO THURSDAY MORNING. FOG MAY
CONTINUE TO ADVECT WEST TOWARD CENTRAL WISCONSIN AFTER DARK.
- SCATTERED SHOWERS AND THUNDERSTORMS ARE OCCURRING IN CENTRAL
AND NORTH CENTRAL WI THIS AFTERNOON. ISOLATED STORMS ARE POSSIBLE
ALONG THE LAKE BREEZE AS WELL.
- A BROKEN LINE OF STRONG THUNDERSTORMS WILL CROSS NORTHERN WI
BETWEEN 4 AND 9 PM THURSDAY. 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.
DISCUSSION
UPDATE...ISSUED AT 835 PM CDT WED MAY 14 2025
LIGHT WINDS ALONG THE LAKE SHORE AND SMALL DEWPOINT DEPRESSIONS
HAVE ALLOWED FOG TO MOVE INLAND OFF LAKE MICHIGAN. AS THE SUN
CONTINUES TO SET THIS EVENING, FOG IS EXPECTED TO EXPAND
WESTWARD. LOW STRATUS WILL ALSO BE MOVING IN AND DEVELOPING
ACROSS EAST CENTRAL AND NORTHEASTERN WISCONSIN. UNCERTAINTY
REMAINS ON HOW FAR INLAND THE FOG WILL ADVECT AND DEVELOP. WITH
A SET UP SIMILAR TO THE PREVIOUS NIGHT THERE IS SOME BETTER
CONFIDENCE (MODERATE TO HIGH ROUGHLY 60 TO 80%) THAT THE FOG AND
LOW STRATUS WILL NOT MOVE ANY FURTHER WEST THAN IT DID
YESTERDAY. A DENSE FOG ADVISORY HAS BEEN ISSUED FOR THE EASTERN
LAKE SHORE COUNTIES THROUGH MID THURSDAY MORNING. WILL CONTINUE
TO MONITOR TEMPERATURES, DEWPOINTS AND WINDS THROUGH THIS
EVENING FOR ANY EXPANSIONS WESTWARD.
ISSUED AT 327 PM CDT WED MAY 14 2025
TONIGHT THROUGH THURSDAY MORNING...
SCATTERED SHOWERS AND THUNDERSTORMS DEVELOPED OVER CENTRAL AND NORTH
CENTRAL WI THIS AFTERNOON, WHICH IS IN AN AREA WITH SOME WEAK MID
LEVEL VORTICITY ADVECTION. MAIN THREAT IS LIGHTNING, BUT THERE IS A
SMALL CHANCE FOR SMALL HAIL. THERE ARE A FEW SHOWERS POPPING UP
ALONG THE LAKE BREEZE FROM GREEN BAY TO SOUTHERN CALUMET COUNTY.
THERE IS WEAK INSTABILITY SO THE SHOWERS CAN DEVELOP ALONG WEAK
FORCING, BUT NO SHEAR, SO THE UPDRAFTS CANNOT BE SUSTAINED.
WE WILL CONTINUE TO HAVE LOW LEVEL MOISTURE FLOWING OVER THE
RELATIVELY COOL LAKE MICHIGAN AND THEREFORE A CONTINUED FOG THREAT
FOR THE OVERNIGHT HOURS. THE SETUP IS SIMILAR TO LAST NIGHT WHERE
THE MARINE FOG WILL SPILL INLAND DURING THE LATE EVENING HOURS. IT
SHOULD NOT GET QUITE AS FAR INLAND AS LAST NIGHT, BUT I WOULD
SUSPECT THAT WE WILL HAVE TO ISSUE DENSE FOG ADVISORY ONCE AGAIN FOR
AT LEAST THE LAKESHORE TO THE FOX VALLEY AREA.
FOG AND LOW CLOUDS WILL DISSIPATE QUICKLY DURING THE MID MORNING AS
WINDS START TO INCREASE OUT OF THE SOUTHEAST. THIS IS IN RESPONSE TO
LOW PRESSURE APPROACHING FROM THE NORTHERN PLAINS. SYNOPTIC FORCING
WILL REMAIN WEAK DURING THE MORNING HOURS, AND THERE WILL BE A LOT
OF MID LEVEL DRY AIR IN PLACE. SUNSHINE WILL HELP TEMPS QUICKLY WARM
TO AROUND 80 IN CENTRAL WI, BUT THE ONSHORE BREEZE WILL KEEP
LAKESHORE TEMPS IN THE 60S. SOUTHEAST WINDS WILL BE IN THE 20 TO 30
MPH RANGE FOR INLAND AREAS.
THURSDAY AFTERNOON AND NIGHT
A MID LEVEL TROUGH SWINGING ACROSS MT AND WY WILL CLOSE OFF OVER THE
NORTHERN PLAINS EARLY THURSDAY MORNING. THE ASSOCIATED SURFACE LOW
CENTERED OVER EASTERN SOUTH DAKOTA WILL QUICKLY OCCLUDE, AND THE
FRONTAL BOUNDARY EXTENDING FROM THE LOW (ACROSS SOUTHERN MN AND INTO
WEST CENTRAL WI) WILL SET UP BY MIDDAY THU AND WAIT FOR FURTHER
FORCING. THAT FORCING WILL ARRIVE WITHIN A FEW HOURS WHEN THE NEXT
FRONT ROUNDS THE BASE OF THAT LOW AND PUSHES INTO SOUTHWEST WI. THIS
IS THE WHERE THE INITIAL STORMS (FOR WI) ARE EXPECTED TO DEVELOP.
MOST MESO MODELS AGREE ON THERE BEING A LINE OF STORMS EXTENDING
FROM CENTRAL MN TO THE TWIN CITIES AT 2 PM AND THEN THAT LINE
QUICKLY EXPANDS EAST-SOUTHEAST AS THE FRONT LIFTS INTO CENTRAL WI
BETWEEN 2 AND 4 PM. BY 5 PM, THERE SHOULD BE A LINE OF STORMS
(POSSIBLY A SECOND LINE BEHIND IT) THAT GOES FROM NORTHWEST WI TO
WISCONSIN RAPIDS, AND POTENTIALLY DOWN THROUGH MADISON AND
JANESVILLE. STORMS SHOULD BE FAIRLY CLOSE TOGETHER ALONG THAT FRONT
(IN A LINE) IN THE NORTHWEST AND CENTRAL PORTIONS OF WI, BUT MUCH
FARTHER APART (DISCRETE) IN SOUTHERN PORTIONS.
A LINE OF STRONG STORMS WILL QUICKLY TRACK ACROSS NORTHERN WI
BETWEEN 4 PM AND 8 PM, ALTHOUGH THEY MAY BE JUST EXITING DOOR
COUNTY AT 9 PM. AS STORMS ROLL INTO CENTRAL WI BETWEEN 4 AND 5 PM,
ALL SEVERE HAZARDS WILL BE POSSIBLE. THE SYNOPTIC FORCING WITH
STRONG VORTICITY ADVECTION AND LOW LEVEL FRONT WILL BE PLENTY TO GET
STORMS TO DEVELOP AND PUNCH THROUGH THAT EML CAP. WITH DEWPOINTS IN
THE LOWER 60S, CAPE AROUND 2000 J/KG, AND DEEP LAYER SHEAR AT AN
IMPRESSIVE 40 KT (THANKS TO SOUTHEAST WINDS AND THE SURFACE AND
SOUTHWEST WINDS PUSHING IN JUST ABOVE), THE ENVIRONMENT IS CONDUCIVE
FOR SUPERCELLS. LARGE HAIL, DAMAGING WINDS, AND TORNADOES WILL ALL
BE POSSIBLE AS THESE STORMS MOVE INTO OUR AREA. AS THE LINE SPEEDS
EASTWARD, IT WILL START TO ENCOUNTER THE STOUT MARINE LAYER (FOX
VALLEY UP TO IRON MOUNTAIN) AND STORMS WILL START TO BECOME ELEVATED.
THERE WILL STILL BE A LARGE HAIL THREAT, BUT THE THREATS FOR
DAMAGING WINDS AND TORNADOES WILL START TO DIMINISH.
QUIET WEATHER WITH FAIRLY MILD TEMPERATURES IN THE 50S AND LIGHTER
SOUTH-SOUTHWEST WINDS WILL OCCUR FOR THE OVERNIGHT HOURS.
FRIDAY THROUGH SATURDAY...
THE CLOSED UPPER LOW AND ASSOCIATED WEAKENING SURFACE LOW WILL TRACK
FROM CENTRAL MN TO THE MN ARROWHEAD DURING THE DAY FRIDAY, AND
STRAIGHT ACROSS UPPER MICHIGAN FRIDAY NIGHT THROUGH SATURDAY
MORNING. A PIECE OF ENERGY (500MB VORTICITY) IS EXPECTED TO RIPPLE
UP ACROSS THE EAST HALF OF WI ON FRIDAY OUT AHEAD OF THAT UPPER LOW.
IN ADDITION, THE LOW LEVEL JET WILL ALSO BE STREAMING ACROSS THE
REGION AND THERE WILL BE SOME UPPER DIVERGENCE PRESENT FROM THE
LEFT EXIT REGION OF A STRONG UPPER JET.
THE MAIN CONCERN WITH THIS WILL BE THE VERY STRONG WINDS AVAILABLE
TO MIX DOWN TO THE SURFACE DURING THE DAY FRIDAY. GUSTS IN THE 35 TO
45 MPH RANGE ARE LOOKING LIKELY FOR THE EARLY AFTERNOON HOURS IN THE
FOX VALLEY, AND THIS WOULD MEET WIND ADVISORY CRITERIA. IN ADDITION,
A FEW THUNDERSTORMS ARE POSSIBLE FRIDAY AFTERNOON, MAINLY SOUTH OF
APPLETON TO SHEBOYGAN. CONTINUED GUSTY WINDS AND A FEW SHOWERS ARE
POSSIBLE OVER THE REST OF THE AREA FRIDAY EVENING.
WE WILL REMAIN IN CYCLONIC FLOW SATURDAY, SO DIURNAL SHOWERS ARE
POSSIBLE ACROSS ALL OF NORTHERN WI. GUSTY NORTHWEST WINDS UP TO 30
MPH WILL ALSO BE POSSIBLE.
SUNDAY THROUGH TUESDAY...
HIGH PRESSURE WILL CROSS ONTARIO SUNDAY AND NORTHERLY WINDS WILL
USHER COLDER TEMPS INTO THE REGION. SUNDAY NIGHT LOOKS THE COLDEST
WITH NORTH/CENTRAL AREAS DROPPING INTO THE LOWER 30S, THUS A FROST
POTENTIAL. QUIET WEATHER WILL CONTINUE MONDAY. OUR NEXT CHANCE FOR
SHOWERS AND SOME THUNDERSTORMS WILL ARRIVE MONDAY NIGHT AS AN UPPER
TROUGH APPROACHES FROM THE PLAINS AND WE GET INTO THE WARM AIR
ADVECTION AREA TO GIVE US SOME ELEVATED CONVECTION.
CRONCE
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 645 PM CDT WED MAY 14 2025
SCATTERED SHOWERS AND THUNDERSTORMS CONTINUE ACROSS NORTH
CENTRAL AND CENTRAL WISCONSIN THROUGH THIS EVENING. SHOWERS AND
STORMS WILL QUICKLY DIMINISH AFTER SUNSET. SIMILAR TO YESTERDAY
LOW LEVEL CLOUDS AND FOG ARE EXPECTED TONIGHT. LAKE SHORE ARES
ARE LIKELY TO SEE THE LOW LEVEL CLOUDS/FOG FIRST AS BOTH MOVE
INLAND OFF LAKE MICHIGAN. FOG AND LOW CLOUDS ARE EXPECTED ONCE
WINDS DECREASE AND THE SUN HAS SET BY MID TO LATE THIS EVENING
INTO EARLY TOMORROW MORNING FOR THE LAKE SHORE AND FOX VALLEY
AREAS.
VISIBILITY OF A HALF MILE OR LESS AND IFR CEILINGS AROUND 200 TO 500
FT ARE EXPECTED AGAIN. SOME AREAS COULD SEE CEILINGS DROP SLIGHTLY
LOWER, ESPECIALLY WHERE FOG IS DENSE. UNCERTAINTY REMAIN IN HOW
FAR WESTWARD FOG AND LOW STRATUS WILL PROGRESS. IF WINDS REMAIN
LIGHT AND SKIES CLEAR, THEN IT IS POSSIBLE FOG WILL EXPAND JUST
AS FAR AS IT DID LAST NIGHT. FOG AND STRATUS WILL QUICKLY
DIMINISH BY MID THURSDAY MORNING.
A LINE OF STORMS IS EXPECTED TO MOVE THROUGH CENTRAL AND NORTHERN
WISCONSIN BETWEEN 4 AND 10PM THURSDAY AFTERNOON/EVENING. ALL HAZARDS
WILL BE POSSIBLE FOR NORTHERN AND CENTRAL WISCONSIN. LARGE HAIL
LOOKS TO BE THE MAIN CONCERNS FOR LAKE SHORE AREAS.
LIGHT SOUTHEAST TO EAST WINDS ARE EXPECTED THIS EVENING THROUGH
TONIGHT. THURSDAY AFTER SUNRISE WINDS WILL INCREASE AGAIN BECOMING A
BIT BREEZY BY THE EARLY AFTERNOON. SOUTHEAST WINDS WILL QUICKLY
SWITCH TO SOUTHWESTERLY BEHIND THE FRONT. SOUTH TO SOUTHWEST WINDS
ARE EXPECTED THURSDAY NIGHT INTO FRIDAY.
PATTERSON
MARINE
ISSUED AT 327 PM CDT WED MAY 14 2025
GIVEN THAT THE ENVIRONMENT WILL CONTINUE TO REMAIN FAVORABLE
(MOIST AIR OVER THE COOL OPEN WATERS) FOR DENSE FOG UNTIL THIS
PATTERN BREAKS, THE MARINE DENSE FOG ADVISORY IS IN EFFECT UNTIL
7PM THURSDAY. WE MAY BE ABLE TO EXPIRE THAT A LITTLE EARLIER ON
THURSDAY AS SOUTHEAST WINDS KICK IN, SO THERE IS UNCERTAINTY IN
THE END TIME. THIS INCLUDES THE BAY AREA, ALTHOUGH WE MAY SEE
LESS FOGGY CONDITIONS DURING THE DAYLIGHT HOURS THERE.
CRONCE
GRB WATCHES/WARNINGS/ADVISORIES
WI...DENSE FOG ADVISORY UNTIL 10 AM CDT THURSDAY FOR WIZ022-039-040-
050.
MARINE...DENSE FOG ADVISORY UNTIL 7 PM CDT THURSDAY FOR LMZ521-522-
541>543.
DISCUSSION...
AVIATION...
MARINE...
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