199
FXUS63 KDLH 071850
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
150 PM CDT SUN SEP 7 2025
KEY MESSAGES
- 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 135 PM CDT SUN SEP 7 2025
HIGH PRESSURE WILL BRING TRANQUIL WEATHER TO THE REGION THIS
AFTERNOON AS RIDGING BUILDS TO OUR WEST AND A SURFACE HIGH MOVES
OVERHEAD. THIS WILL RESULT IN ANOTHER CHILLY NIGHT WITH BELOW-
AVERAGE TEMPERATURES AS A FEW HIGH CLOUDS BEGIN TO STREAM IN.
WHILE NOT AS WIDESPREAD OR INTENSE AS LAST NIGHT, ANOTHER ROUND
OF FROST WILL BE POSSIBLE, ESPECIALLY ACROSS THE BORDERLANDS,
ARROWHEAD, AND NORTH-CENTRAL WISCONSIN AND ABOUT 10 MILES AWAY
FROM LAKE SUPERIOR WHERE OVERNIGHT LOWS WILL DIP INTO THE MID
TO UPPER 30S. ELSEWHERE, LOWS WILL BOTTOM OUT IN THE LOW TO MID
40S. WAS A LITTLE AGGRESSIVE WITH THE FROST ADVISORY AS
RADIATIONAL COOLING PROFILES WILL BE FAVORABLE FOR QUICK
TEMPERATURE DROPS WELL BELOW WHAT MOST MODEL GUIDANCE SUGGESTS.
IF CLOUDS MOVE IN FASTER, THAT MAY BE A BAD CALL.
A NOTABLE PATTERN SHIFT BEGINS ON MONDAY AS A SOUTHERLY FLOW USHERS
IN A MUCH WARMER AND MORE HUMID AIR MASS, DRIVEN BY AN INCREASING
LOW-LEVEL JET. THIS WILL ALLOW HIGH TEMPERATURES TO REBOUND INTO
THE LOW 60S TO LOW 70S, WHICH IS NEAR NORMAL FOR EARLY SEPTEMBER,
WHILE DEWPOINTS CLIMB INTO MID 50S TO LOW 60S. THE INFLUX OF
WARMTH AND MOISTURE WILL LEAD TO MODEST INSTABILITY, WITH MLCAPE
VALUES OF 500-1500 J/KG DEVELOPING ACROSS CENTRAL AND NORTH-CENTRAL
MINNESOTA. WHILE DEEP-LAYER SHEAR WILL BE MODEST AT 25-30 KNOTS, THE
COMBINATION OF INSTABILITY AND LIFT FROM A PASSING SHORTWAVE TROUGH
WILL BE SUFFICIENT TO TRIGGER SCATTERED SHOWERS AND THUNDERSTORMS
MONDAY AFTERNOON AND EVENING. THERE IS SOME UNCERTAINTY REGARDING
A CAPPING INVERSION, WHICH COULD KEEP STORMS ELEVATED; HOWEVER,
IF THEY BECOME SURFACE-BASED, A COUPLE COULD BECOME STRONG. THE
PRIMARY THREATS WITH ANY STRONGER STORMS WOULD BE LARGE HAIL AND
DAMAGING WIND GUSTS.
THE THREAT FOR STRONG THUNDERSTORMS WILL DIMINISH MONDAY EVENING,
BUT SCATTERED SHOWERS AND A FEW GENERAL THUNDERSTORMS WILL PERSIST
OVERNIGHT AND INTO TUESDAY, MAINLY FOCUSED ALONG AND EAST OF THE
I-35 CORRIDOR. THE AIR MASS WILL BE QUITE MOIST, WITH PRECIPITABLE
WATER VALUES OF 1.0 TO 1.5 ADVECTING IN WHICH WILL SUPPORT EFFICIENT
RAINFALL PROCESSES AND COULD LEAD TO LOCALIZED RAINFALL AMOUNTS OVER
ONE INCH. WIDESPREAD FLOODING IS NOT A CONCERN. THIS ACTIVITY WILL
GRADUALLY END FROM WEST TO EAST THROUGH THE DAY TUESDAY. HIGHS ON
TUESDAY WILL RANGE FROM THE MID 60S TO MID 70S, WITH THE WARMEST
READINGS EXPECTED IN THOSE AREAS THAT SEE CLOUDS CLEAR OUT SOONER
ACROSS NORTH-CENTRAL AND NORTHEAST MINNESOTA.
LOOKING AHEAD TO THE MIDDLE OF THE WEEK, LINGERING CYCLONIC FLOW
ON THE BACKSIDE OF THE DEPARTING TROUGH COULD SUPPORT AN ISOLATED
SHOWER ON WEDNESDAY, BUT DRY AIR IN THE MID-LEVELS MAKES THIS A LOW
PROBABILITY, AND THE FORECAST REMAINS DRY FOR NOW. TEMPERATURES ARE
EXPECTED TO REMAIN NEAR-NORMAL THROUGH THE END OF THE WEEK AND INTO
THE WEEKEND AS UPPER-LEVEL RIDGING BUILDS OVER THE CENTRAL U.S. A
POSSIBLE RETURN TO A SOUTHERLY FLOW PATTERN LATE IN THE WEEK
WILL INCREASE THE CHANCES FOR SCATTERED SHOWERS AND
THUNDERSTORMS ACROSS THE NORTHLAND FOR FRIDAY AND THE WEEKEND.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1226 PM CDT SUN SEP 7 2025
EXPECT VFR CONDITIONS FOR MOST OF THE TAF PERIOD WITH LIGHT
WINDS. DIURNAL CUMULUS DIMINISHES TOWARDS SUNSET WITH THE LOSS
OF DAYTIME HEATING. MID/HIGH-LEVEL CLOUD COVER STARTS TO MOVE IN
LATER TODAY AND THEN INCREASES MONDAY MORNING AHEAD OF SHOWER
AND THUNDERSTORM CHANCES LATER ON MONDAY. A SMALL CHANCE FOR
FOG OVERNIGHT, SO HINTED AT IT IN TAFS. WINDS MAY BE STRONG
ENOUGH TO KEEP THE BOUNDARY LAYER MIXY AND THEREFORE LESS PRONE
TO FOG COMPARED TO LAST NIGHT.
MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/
ISSUED AT 135 PM CDT SUN SEP 7 2025
FAVORABLE BOATING CONDITIONS TODAY EXCEPT ALONG THE NORTH SHORE
EAST OF GRAND MARAIS WHERE WINDS MAY APPROACH 20 TO 25 KNOTS
THOUGH THE HREF ONLY GIVES ABOUT A 20% CHANCE OF HITTING THAT
UPPER LIMIT. CONDITIONS WILL DETERIORATE SLIGHTLY MONDAY WITH
SOUTHERLY WINDS BUILDING WAVES EAST OF GRAND MARAIS.
THUNDERSTORMS ARE POSSIBLE MONDAY AFTERNOON AND EVENING.
CONDITIONS WILL GRADUALLY IMPROVE ON TUESDAY, WITH TRANQUIL
WEATHER RETURNING FOR THE MIDDLE OF THE WEEK.
FOR THE OPEN WATER DISCUSSION, REFER TO THE NWS MARQUETTE AREA
FORECAST DISCUSSION AT WEATHER.GOV/MQT.
DLH WATCHES/WARNINGS/ADVISORIES
MN...FROST ADVISORY FROM 1 AM TO 8 AM CDT MONDAY FOR MNZ010-011-019-
037.
WI...FROST ADVISORY FROM 1 AM TO 8 AM CDT MONDAY FOR WIZ001>004-008-
009.
MARINE...NONE.
DISCUSSION...WOLFE
AVIATION...WOLFE
MARINE...WOLFE
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