455
FXUS63 KDLH 070823
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
323 AM CDT SUN SEP 7 2025
KEY MESSAGES
- FROST FOR INTERIOR PORTIONS OF NORTHEAST MINNESOTA AND NORTHWEST
WISCONSIN THROUGH EARLY THIS MORNING. FREEZING TEMPERATURES
ARE LIKELY FOR MANY PLACES IN KOOCHICHING AND NORTH/CENTRAL
ST. LOUIS COUNTIES. FROST AND FREEZE HEADLINES ARE IN EFFECT.
- PATCHY FROST POSSIBLE AGAIN TONIGHT IN PORTIONS OF THE
BORDERLANDS, ARROWHEAD, AND NORTH-CENTRAL WISCONSIN.
- TEMPERATURES REBOUND TO AROUND SEASONAL NORMALS FOR THIS WEEK.
- SHOWERS AND THUNDERSTORMS RETURN MONDAY AFTERNOON INTO
TUESDAY. THERE IS A SMALL CHANCE (~20%) FOR A FEW OF THE
STORMS TO BECOME STRONG MONDAY AFTERNOON AND EVENING.
DISCUSSION
ISSUED AT 322 AM CDT SUN SEP 7 2025
TODAY - TONIGHT:
PROMINENT SURFACE HIGH PRESSURE SETTLING INTO THE DAKOTAS AND
MINNESOTA HAS LED TO CLEARING SKIES AND CALM TO LIGHT WINDS OVER
MOST OF THE NORTHLAND. ONE EXCEPTION WILL BE SOME CLOUD COVER
THAT SHOULD CONTINUE TO LINGER IN LAKE AND COOK COUNTIES
THROUGH THE OVERNIGHT HOURS DUE TO SUBTLE SHORTWAVE ENERGY ON
THE BACKSIDE OF AN EXITING MID/UPPER-LEVEL SHORTWAVE TO OUR
EAST. AREAS OUTSIDE OF THIS CLOUD COVER REGION HAVE ALREADY SEEN
TEMPERATURES DROP INTO THE MID 30S TO LOW 40S, WITH FORECAST
LOWS FORECAST TO BOTTOM OUT IN THE LOW TO MID 30S FOR MOST OF
THE NORTHLAND INLAND FROM LAKE SUPERIOR BY AROUND SUNRISE. GIVEN
THIS, WE DECIDED TO EXPAND THE FROST ADVISORY TO NOW INCLUDE
EVERYWHERE BESIDES SOUTHERN LAKE AND COOK COUNTIES ALONG THE
NORTH SHORE. THE FREEZE WARNING ALSO REMAINS IN EFFECT FOR
KOOCHICHING COUNTY AS WELL AS NORTHERN AND CENTRAL ST. LOUIS
COUNTY WHERE ENSEMBLE PROBABILITIES OF <32F ARE HIGHEST
(50-70%). THERE REMAINS A SIGNAL OF 40-70% FOR <32F IN PORTIONS
OF INLAND NORTHWEST WISCONSIN, AS WELL, BUT THE COVERAGE APPEARS
TO NOT BE AS WIDESPREAD. FOR THIS REASON, WE HELD OFF ON
EXPANDING FREEZE WARNINGS INTO PARTS OF INLAND NORTHWEST
WISCONSIN.
IN ADDITION TO THE FROST/FREEZE, THE RADIATIONAL COOLING THROUGH
EARLY THIS MORNING IS/WILL ALSO PRODUCE AREAS OF FOG--SOME
LOCALLY DENSE--IN NORTHEAST MINNESOTA AND NORTHWEST WISCONSIN.
THIS FOG SHOULD DISSIPATE TOWARDS 8-10 AM CDT THIS MORNING WITH
DAYLIGHT RETURNING.
THE CENTER OF THE SURFACE HIGH PRESSURE WILL PASS THROUGH TO OUR
SOUTHWEST AS TODAY PROGRESSES, BACKING SURFACE WINDS TO
SOUTHWESTERLY LATER TODAY AND SOUTHERLY THIS EVENING AND
TONIGHT. WINDS WILL REMAIN LIGHT, BUT WE WILL SEE HIGH
TEMPERATURES WARM A FEW DEGREES MORE THAN YESTERDAY INTO THE
UPPER 50S TO MID 60S ALONG WITH DIURNAL CUMULUS CLOUDS WITH
DAYTIME HEATING. A FEW HIGH CLOUDS RETURN TONIGHT, BUT ONE MORE
NIGHT OF BELOW-AVERAGE TEMPERATURES IS IN STORE RANGING FROM THE
MID TO UPPER 30S IN THE BORDERLANDS, ARROWHEAD, AND NORTH-
CENTRAL WISCONSIN WHERE ANOTHER ROUND OF PATCHY FROST IS
POSSIBLE TO LOW TO MID 40S ELSEWHERE.
MONDAY - TUESDAY:
WARM AIR ADVECTION AND MOISTURE ADVECTION RAMPS UP ON MONDAY IN
TANDEM WITH AN INCREASING 850 MB LOW-LEVEL JET INTO THE
NORTHLAND. THIS WILL PUSH HIGH TEMPERATURES INTO THE LOW 60S TO
LOW 70S, NEAR NORMAL FOR THIS TIME OF YEAR. DEWPOINTS SHOULD
ALSO CLIMB INTO THE MID 50S TO LOW 60S DURING THE AFTERNOON AND
EVENING. FAIRLY MODEST INSTABILITY SHOULD DEVELOP AS A RESULT OF
THE WARMER AND MORE MOIST AIRMASS, WITH MLCAPE VALUES OF
500-1500 J/KG PUSHING INTO CENTRAL AND NORTH-CENTRAL MINNESOTA
DURING THE AFTERNOON AND EVENING. THE STRONGEST PORTION OF THE
LOW-LEVEL JET SHOULD BE DISPLACED FARTHER EAST INTO NORTHWEST
WISCONSIN, SO EFFECTIVE SHEAR SHOULD ONLY BE AROUND 25-30 KT IN
THE AFOREMENTIONED HIGHEST INSTABILITY REGION. THESE PARAMETERS
COMBINED WITH FORCING FOR ASCENT FROM THE WARM AIR ADVECTION
AND A PASSING SHORTWAVE TROUGH WOULD BE SUFFICIENT ENOUGH TO
KICK OFF SCATTERED SHOWERS AND STORMS, PRIMARILY OF A PULSE-TYPE
STORM OR SMALL CLUSTERS OF STORMS VARIETIES MONDAY AFTERNOON AND
EVENING. THERE IS SOME UNCERTAINTY AS TO WHETHER THESE STORMS
CAN BREAK THROUGH A CAPPING INVERSION AND BECOME SURFACE-BASED,
OTHERWISE MODEL SOUNDINGS FAVOR STORM MODE BEING PRIMARILY
ELEVATED. WHILE THE THUNDERSTORMS SHOULD BE MOSTLY GENERAL
THUNDERSTORMS, THERE IS A NON-ZERO CHANCE (~20%) FOR A COUPLE STRONG
STORMS MONDAY AFTERNOON AND EVENING WITH HAIL UP TO DIME TO
QUARTER SIZE AND WIND GUSTS OF 40-60 MPH, WITH THE WIND GUST
THREAT MAINLY IF STORMS CAN BECOME SURFACE-BASED.
THE STRONG THUNDERSTORM THREAT SHOULD WANE BEYOND MONDAY
EVENING, THOUGH SCATTERED SHOWERS AND STORMS SHOULD PERSIST
MONDAY NIGHT INTO DAYTIME TUESDAY MAINLY ALONG AND EAST OF THE
I-35 CORRIDOR AND ARROWHEAD INTO NORTHWEST WISCONSIN. PWAT
VALUES DON'T APPEAR TO BE OVERLY HIGH, BUT WILL BE ON THE ORDER
OF 1-1.5" WITH SATURATED WARM CLOUD DEPTHS (WARMER THAN 0 DEG C)
AROUND 10000 FT DEEP. THIS SHOULD FAVOR SOME MORE EFFICIENT
RAINFALL RATES, WITH LOCALIZED RAINFALL AMOUNTS FROM MONDAY
AFTERNOON THROUGH TUESDAY OF >1" POSSIBLE (20-30% CHANCE), BUT
FLOODING IS NOT EXPECTED. PRECIPITATION SHOULD BE ENDING FROM
WEST TO EAST BY LATE TUESDAY, WITH HIGH TEMPERATURES TOPPING
OUT IN THE MID 60S TO MID 70S, WARMEST IN NORTH-CENTRAL AND
NORTHEAST MINNESOTA WHERE CLOUD COVER WILL BE CLEARING SOONER.
WEDNESDAY - NEXT WEEKEND:
SOME COLD ADVECTION AND CYCLONIC FLOW ON THE BACKSIDE OF THE
TROUGH ON WEDNESDAY MAY KEEP SOME ISOLATED SHOWERS GOING INTO
WEDNESDAY, BUT THE POTENTIAL IN THIS OCCURRING IS LOW GIVEN
FORECAST MODEL SOUNDINGS SHOW FAIRLY PROMINENT DRY AIR ABOVE A
SURFACE MIXED LAYER. THEREFORE, WE HAVE KEPT THE FORECAST DRY
FOR WEDNESDAY FOR NOW. TEMPERATURES ALSO REMAIN NEAR NORMAL FOR
THURSDAY INTO NEXT WEEKEND AS SOME GENERAL MID AND UPPER-LEVEL
RIDGING HANGS OUT OVER THE CENTRAL CONUS, THOUGH SOUTHERLY FLOW
AND WARM AIR-ADVECTION TO END THE WEEK COULD KEEP SCATTERED RAIN
SHOWERS AND PERHAPS A FEW THUNDERSTORM CHANCES GOING FOR FRIDAY
INTO THE WEEKEND FOR THE NORTHLAND.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1241 AM CDT SUN SEP 7 2025
ASIDE FROM SOME FOG POTENTIAL DURING THE CURRENT OVERNIGHT INTO
EARLY THIS MORNING, VFR CONDITIONS SHOULD PREVAIL THROUGH THE
TAF PERIOD. ALREADY SEEING FOG DEVELOP AT SOME TERMINALS IN THE
NORTHLAND, WITH THE FOG SIGNAL FOR TONIGHT HAVING INCREASED.
EXPECT SOME MVFR FOG AT KDLH, IFR FOG AT HIB, AND IFR TO LIFR
FOG AT HYR LATER DURING THE CURRENT OVERNIGHT INTO EARLY THIS
MORNING. COULD SEE SOME SCT TO BKN LOWER CIGS WITH THIS FOG, AS
WELL, WITH THE BEST POTENTIAL AT KHYR. FOG SHOULD DISSIPATE
TOWARDS 13-15Z THIS MORNING, HANGING AROUND LONGEST AT KHYR.
OTHERWISE, CALM TO LIGHT WINDS TURN LIGHT FROM THE NORTHWEST
TODAY ALONG WITH SOME DIURNAL CUMULUS ROUGHLY FROM 07.15Z TO
08.00Z.
MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/
ISSUED AT 322 AM CDT SUN SEP 7 2025
NORTHWEST WINDS EARLY THIS MORNING BACK TO SOUTHWESTERLY FOR
LATE THIS MORNING THROUGH MONDAY MORNING AND THEN TO SOUTHERLY
FOR MONDAY AFTERNOON AND EVENING BEFORE TURNING BACK TO
SOUTHWESTERLY FOR MONDAY NIGHT INTO TUESDAY. SUSTAINED WINDS OF
5-15 KT PERSIST THROUGH MONDAY, WITH GUSTS FREQUENTLY IN THE
10-20 KT RANGE. THERE IS A 30-40% CHANCE THAT GUSTS COULD REACH
TO 20-25 KT WITH WAVES OF 2-4 FT BOTH THIS AFTERNOON AND MIDDAY
MONDAY AND MONDAY AFTERNOON THAT COULD RESULT IN HAZARDOUS
CONDITIONS FOR SMALLER VESSELS. WINDS AND GUSTS WEAKEN ON
TUESDAY WITH GUSTS OF LESS THAN 15 KT. A FEW THUNDERSTORMS WILL
BE POSSIBLE IN AN AREA OF SHOWERS MONDAY AFTERNOON INTO MONDAY
NIGHT. A FEW WIND GUSTS UP TO 40 KT MAY OCCUR WITHIN THE
STRONGEST STORMS MONDAY AFTERNOON AND EVENING.
FOR THE OPEN WATER DISCUSSION, REFER TO THE NWS MARQUETTE AREA
FORECAST DISCUSSION AT WEATHER.GOV/MQT.
DLH WATCHES/WARNINGS/ADVISORIES
MN...FREEZE WARNING UNTIL 8 AM CDT THIS MORNING FOR MNZ010-011-019.
FROST ADVISORY UNTIL 8 AM CDT THIS MORNING FOR MNZ012-018-025-
026-033>038.
WI...FROST ADVISORY UNTIL 8 AM CDT THIS MORNING FOR WIZ001>004-
006>009.
MARINE...NONE.
DISCUSSION...ROTHSTEIN
AVIATION...ROTHSTEIN
MARINE...ROTHSTEIN
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