733
FXUS63 KDLH 101139
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
639 AM CDT WED SEP 10 2025
KEY MESSAGES
- WIDESPREAD DENSE FOG THIS MORNING. A DENSE FOG ADVISORY IS IN
EFFECT.
- ADDITIONAL AREAS OF DENSE FOG EXPECTED TONIGHT INTO EARLY
THURSDAY. ANOTHER DENSE FOG ADVISORY WILL LIKELY BE NEEDED FOR
PORTIONS OF THE NORTHLAND.
- ASIDE FROM VERY LIMITED COVERAGE OF LIGHT RAIN SHOWERS IN
NORTH-CENTRAL WISCONSIN TODAY, HIGH PRESSURE WILL KEEP THE
NORTHLAND DRY THROUGH THURSDAY.
- A WARM FRONT WILL BRING CHANCES (30-50%) FOR SCATTERED SHOWERS
AND THUNDERSTORMS TO PORTIONS OF THE NORTHLAND LATE THURSDAY
NIGHT AND FRIDAY.
- ON AND OFF CHANCES FOR SHOWERS AND THUNDERSTORMS RETURN LATE
SUNDAY INTO NEXT WEEK.
DISCUSSION
ISSUED AT 233 AM CDT WED SEP 10 2025
TODAY - THURSDAY:
WIDESPREAD DENSE FOG HAS DEVELOPED DURING THE CURRENT OVERNIGHT
HOURS ACROSS MUCH OF THE NORTHLAND ASIDE FROM NEAR INTERNATIONAL
FALLS AND IN PORTIONS OF NORTHWEST WISCONSIN. EXPECT THIS FOG TO
CONTINUE TO EXPAND INTO MUCH OF NORTHWEST WISCONSIN TOWARDS
EARLY MORNING AS RAIN SHOWERS AND CLOUDS DEPART INTO NORTH-
CENTRAL WISCONSIN. WHILE FOG COULD BRIEFLY BECOME DENSE IN
KOOCHICHING COUNTY, CONFIDENCE WAS NOT HIGH ENOUGH IN WIDESPREAD
DENSE FOG DEVELOPING THERE TO DO ANY EXPANSION TO THE DENSE FOG
ADVISORY, BUT WILL CONTINUE TO MONITOR TRENDS IN CONDITIONS IN
CASE THIS CHANGES. FOG/LOW STRATUS WILL BE SLOW TO BURN OFF THIS
MORNING, SO DENSE FOG COULD LINGER INTO THE MID TO POSSIBLY LATE
MORNING HOURS (GENERALLY IMPROVING TOWARDS AND AFTER 10 AM CDT).
DESPITE SURFACE HIGH PRESSURE MOVING ACROSS NORTHERN ONTARIO AND
FUELING RAIN-FREE CONDITIONS FOR MOST OF THE NORTHLAND TODAY,
SOME LINGERING MID-LEVEL VORTICITY/WEAK SURFACE TROUGH IN
NORTH-CENTRAL WISCONSIN COULD KEEP SOME SPORADIC LIGHT
SHOWERS/SPRINKLES LINGERING THERE INTO EARLY THIS AFTERNOON.
LITTLE TO NO ADDITIONAL RAIN ACCUMULATIONS ARE EXPECTED.
GENERALLY SEASONAL TEMPERATURES ARE EXPECTED TODAY, WITH HIGHS
RANGING FROM THE MID 60S NEAR LAKE SUPERIOR TO LOW TO MID 70S
INLAND.
HIGH RESOLUTION MODELS AND ENSEMBLES (HREF/REFS) SHOW A GOOD
SIGNAL (50% TO LOCALLY 80% CHANCE) FOR DENSE FOG DEVELOPMENT
AGAIN TONIGHT INTO THURSDAY MORNING FOR MUCH OF THE NORTHLAND
ASIDE FROM NEAR THE INTERNATIONAL BORDER AND IN COUNTIES OF
INLAND NORTHWEST WISCONSIN. ANOTHER ROUND OF DENSE FOG
ADVISORIES WILL LIKELY BE NEEDED. HIGH TEMPERATURES ON THURSDAY
WILL ALSO BE IN THE MID 60S TO MID 70S.
THURSDAY NIGHT - FRIDAY:
WHILE A MID/UPPER-LEVEL RIDGE WILL BE OVERHEAD FOR TONIGHT INTO
FRIDAY, SOME WEAK SHORTWAVE ENERGY/VORTICITY ROUNDING THE TOP
OF THE RIDGE AND SOUTHERLY RETURN FLOW OF MOISTURE/WARM AIR
ADVECTION COMBINING WITH A WARM FRONTAL ZONE WILL BRING A 30-50%
CHANCE FOR SCATTERED SHOWERS AND THUNDERSTORMS TO PORTIONS OF
THE NORTHLAND LATE THURSDAY NIGHT AND FRIDAY. THE HIGHEST
PRECIPITATION POTENTIAL WILL BE ACROSS NORTH-CENTRAL AND
NORTHEAST MINNESOTA. ANY SHOWERS AND STORMS THAT DEVELOP SHOULD
REMAIN ELEVATED DUE TO A LOW-LEVEL (750-850 MB) CAPPING
INVERSION. WHILE PROGGED BULK SHEAR WILL BE RATHER FAVORABLE
(0-10 KM BULK SHEAR OF 45-55 KT), INSTABILITY WILL BE MODEST
(200-600 J/KG MUCAPE), SO SEVERE WEATHER IS NOT ANTICIPATED.
WHILE PWATS WILL ALSO BE ABOVE AVERAGE AT 1-1.5", THE SCATTERED
NATURE OF SHOWERS AND STORMS SHOULD MITIGATE RAINFALL
ACCUMULATIONS. FRIDAY WILL ALSO BE SLIGHTLY ABOVE AVERAGE UNDER
THE RIDGE, WITH HIGH TEMPERATURES IN THE UPPER 60S TO AROUND
80F, WARMEST AWAY FROM LAKE SUPERIOR.
THIS WEEKEND:
WHILE SOUTHERLY RETURN FLOW WILL KEEP ABOVE AVERAGE MOISTURE
(PWATS OF 1-1.5"; SURFACE DEWPOINTS IN THE UPPER 50S TO 60S)
CONTINUING INTO THE WEEKEND, A PSEUDO-OMEGA BLOCKING PATTERN
ALOFT SETTING UP OVER THE UPPER MIDWEST FOR SATURDAY INTO EARLY
SUNDAY SHOULD PREVENT PRECIPITATION CHANCES IN THE NORTHLAND
UNTIL AT LEAST LATE SUNDAY. ABOVE AVERAGE TEMPERATURES PERSIST
THIS WEEKEND WITH THE RIDGE, WITH HIGHS AROUND 70F NEAR LAKE
SUPERIOR TO 70S/LOW 80S AWAY FROM THE LAKE.
NEXT WEEK:
ENSEMBLE GUIDANCE/CLUSTERS HAVE GENERAL AGREEMENT IN THE OMEGA
BLOCKING PATTERN/RIDGE AXIS SHIFTING EAST OF THE NORTHLAND FOR
LATE SUNDAY INTO NEXT WEEK AS THE UPPER-LEVEL PATTERN GRADUALLY
BECOMES MORE ZONAL. THIS WILL ALLOW A SERIES OF SHORTWAVE
TROUGHS TO TREK ACROSS THE UPPER MIDWEST VICINITY THROUGH MUCH
OF NEXT WEEK, WITH PERIODIC CHANCES FOR SHOWERS AND
THUNDERSTORMS AS SOUTHERLY LOW-LEVEL WINDS KEEP ABOVE AVERAGE
MOISTURE AND TEMPERATURES PUMPING INTO THE AREA. WHILE
CONFIDENCE IS MEDIUM TO HIGH IN A MORE ACTIVE PRECIPITATION
PATTERN FOR NEXT WEEK, DIFFERENCES IN TIMING AND PLACEMENT OF
THE SYNOPTIC/MESOSCALE FORCING MECHANISMS BETWEEN ENSEMBLE
MEMBERS KEEP CONFIDENCE LOWER IN WHERE AND WHEN SHOWERS AND
STORMS WILL EXACTLY DEVELOP AND MOVE THROUGH NEXT WEEK.
AVIATION /12Z TAFS THROUGH 12Z THURSDAY/
ISSUED AT 640 AM CDT WED SEP 10 2025
WIDESPREAD LIFR TO VLIFR CONDITIONS IN DENSE FOG FOR MOST
TERMINALS EARLY THIS MORNING (ASIDE FROM INL) WILL BE SLOW TO
IMPROVE THIS MORNING, WITH FOG BURNING OFF TOWARDS THE 15-17Z
TIMEFRAME. CEILINGS SCATTER OUT TO VFR TOWARDS LATE
MORNING/AFTERNOON, BUT HANG ON LONGEST IN NORTHWEST
WISCONSIN/HYR. A GOOD SIGNAL FOR MORE WIDESPREAD FOG AND DENSE
FOG WITH IFR TO VLIFR CONDITIONS RETURNS LATE THIS EVENING INTO
EARLY THURSDAY MORNING TO MOST OF NORTHEAST MINNESOTA AND
NORTHWEST WISCONSIN ONCE AGAIN, THOUGH INL LOOKS TO STAY NORTH
OF THE LOWEST VISIBILITIES WITH THIS UPDATE.
MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/
ISSUED AT 233 AM CDT WED SEP 10 2025
MAIN MARINE HAZARD OVER THE NEXT 48 HOURS IS PERIODS OF DENSE
FOG ACROSS MUCH OF WESTERN LAKE SUPERIOR. A MARINE DENSE FOG
ADVISORY IS CURRENTLY IN EFFECT UNTIL 10 AM, BUT THERE IS A
POSSIBILITY THAT DENSE FOG (VISIBILITY LESS THAN 1 NM) PERSISTS
FOR PORTIONS OF THE SOUTH SHORE THROUGH MUCH OF TODAY. MORE
WIDESPREAD DENSE FOG IS EXPECTED TO DEVELOP AGAIN TONIGHT INTO
THURSDAY MORNING, SO AN ADDITIONAL DENSE FOG ADVISORY LOOKS
LIKELY.
OUTSIDE OF FOG, EXPECT PERSISTENT NORTHEAST WINDS TODAY THROUGH
AT LEAST FRIDAY AT 5-15 KT, STRONGEST FOR THE SOUTH SHORE AND
SOUTHWESTERN ARM OF LAKE SUPERIOR WHERE WINDS WILL GET FUNNELED.
THE NEXT CHANCE FOR SCATTERED THUNDERSTORMS (30-50% CHANCE)
RETURNS TO WESTERN LAKE SUPERIOR ON FRIDAY.
FOR THE OPEN WATER DISCUSSION, REFER TO THE NWS MARQUETTE AREA
FORECAST DISCUSSION AT WEATHER.GOV/MQT.
DLH WATCHES/WARNINGS/ADVISORIES
MN...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR MNZ011-012-
018>021-025-026-033>038.
WI...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR WIZ001>003-
006>008.
MARINE...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR LSZ121-
140>148-150.
DISCUSSION...ROTHSTEIN
AVIATION...ROTHSTEIN
MARINE...ROTHSTEIN
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