415
FXUS63 KMQT 212314
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
714 PM EDT MON SEP 21 2026
KEY MESSAGES
- WIDESPREAD FROST LIKELY (50-80%) IN THE INTERIOR UP TUESDAY
MORNING, AND A FREEZE POSSIBLE (20-40%) ACROSS PORTIONS OF THE
INTERIOR-WEST. FROST AND FREEZE HEADLINES ARE IN EFFECT LATE TONIGHT
THROUGH TUESDAY MORNING.
- DRY PATTERN WITH PERSISTENT HIGH PRESSURE SETS UP THROUGH MUCH OF
THIS WEEK. BELOW-AVERAGE TEMPERATURES THROUGH WEDNESDAY GIVE WAY TO
ABOVE-AVERAGE TEMPERATURES BY THE WEEKEND.
DISCUSSION
ISSUED AT 156 PM EDT MON SEP 21 2026
AFTERNOON WATER VAPOR IMAGERY REVEALS QUITE NICELY A COMPACT
MIDLEVEL LOW SPINNING OVER THE PLAINS, CENTERED NEAR SIOUX FALLS,
THOUGH HIGH PRESSURE CENTERED NORTH OF LAKE SUPERIOR IS HELPING TO
SUPPRESS THIS WELL SOUTH OF THE UP. CLOSER TO HOME, WE REMAIN UNDER
PATCHY HIGH CLOUD COVER, WITH TEMPERATURES SO FAR ONLY IN THE MID
AND UPPER 50S. WITH MORE BREAKS IN THE CLOUD COVER DEVELOPING, MOST
SPOTS SHOULD BE ABLE TO CLIMB SLIGHTLY HIGHER INTO THE LOWER 60S.
THE EXCEPTION WILL BE OVER THE KEWEENAW AND THE NORTH-CENTRAL UP,
WHERE NORTHEAST FLOW OFF OF SUPERIOR SHOULD LIMIT TEMPERATURES TO
THE MID/UPPER 50S. TONIGHT, SKIES GRADUALLY CLEAR FROM NORTH TO
SOUTH, AND WITH LIGHT WINDS ALLOWING FOR GOOD RADIATIONAL COOLING,
WE ARE LOOKING AT ANOTHER CHILLY NIGHT. TEMPERATURES THIS PAST NIGHT
BOTTOMED OUT IN THE MID 30S ACROSS MUCH OF THE INTERIOR-UP, WITH
SOME OF OUR TYPICALLY COOLER SPOTS BELOW FREEZING. GIVEN CLEARING
SKIES, WE STAND A BETTER CHANCE AT DROPPING EVEN FURTHER WITH LOWS
RANGING IN THE LOWER TO MID 30S FOR MOST OF THE UP AND POSSIBLY
FLIRTING WITH THE UPPER 20S. WILL BE ISSUING FROST/FREEZE HEADLINES
FOR MOST OF THE UP, EXCLUDING THE KEWEENAW, LATE TONIGHT INTO EARLY
TUESDAY.
THE ONTARIO HIGH PRESSURE CENTER STRENGTHENS AND TRACKS EAST
TOMORROW, SETTING UP A HUDSON BAY HIGH PATTERN TO THE NORTHEAST WITH
A PLAINS TROUGH IMMEDIATELY TO THE SOUTHWEST. AS THE SURFACE HIGH,
REINFORCED BY MID-LEVEL FLOW, STRENGTHENS INTO WEDNESDAY, THE PLAINS
TROUGH MOVES SOUTH TOWARD THE LOWER MIDWEST, AND CLEAR SKIES PREVAIL
BY THE SECOND HALF OF TOMORROW. MODELED SOUNDINGS SHOW DEEP-LAYER
DRY AIR WITH SUBSTANTIAL (>20C) SURFACE DEWPOINT DEPRESSIONS TUESDAY
AFTERNOON, YIELDING MINIMUM RHS IN THE HIGH 20S IN THE WESTERN
INTERIOR (WIDESPREAD 30S ELSEWHERE) TOMORROW AFTERNOON. DRY WEATHER
PERSISTS WEDNESDAY AND THURSDAY, THOUGH MORE MOISTURE SHOULD BE
WORKING INTO THE AREA AS THE SURFACE HIGH SHIFTS EASTWARD AND
SOUTHERLY FLOW DEVELOPS OVER THE UP; EXPECT RH TO BOTTOM OUT AROUND
35-40% IN THE DRIEST SPOTS WEDNESDAY, AND TO REMAIN ABOVE 40% AREA-
WIDE THURSDAY. STILL, EVEN TUESDAY, CRITICAL FIRE WEATHER CONDITIONS
WILL BE FAR FROM ACHIEVED GIVEN LIGHT WINDS <10 KNOTS IN THE DRIEST
SPOTS AND HIGH TEMPERATURES IN THE LOW 60S FOR THE NEXT FEW DAYS.
THE SPLIT FLOW PATTERN SLOWLY MOVES EAST OF THE GREAT LAKES REGION
INTO THURSDAY AS HIGH PRESSURE PERSISTS OVER ONTARIO/QUEBEC INTO THE
WEEKEND. SLIGHT VARIATIONS IN LREF CLUSTERS MAKE THEIR APPEARANCE
BEGINNING ON SATURDAY, GENERAL CONSENSUS EXISTS THAT SOME FORM OF
REGIONAL RIDGING IS LIKELY THROUGH SUNDAY. THUS, BELOW-AVERAGE HIGH
TEMPERATURES GRADUALLY WARM INTO ABOVE-AVERAGE HIGH TEMPERATURES (5-
10 ABOVE ON SATURDAY) BY THE WEEKEND WHILE CONDITIONS REMAIN DRY.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 713 PM EDT MON SEP 21 2026
VFR CONDITIONS WILL CONTINUE TO PREVAIL THROUGH THE TAF PERIOD AS
HIGH PRESSURE IN QUEBEC INFLUENCES THE UPPER GREAT LAKES. WINDS
BECOME CALM TONIGHT BEFORE PICKING UP (<15 KTS) OUT OF THE EAST
TOMORROW. A FEW 15-20 KTS GUSTS ARE POSSIBLE AT CMX.
MARINE
ISSUED AT 156 PM EDT MON SEP 21 2026
WINDS CONTINUE TO DIMINISH AS HIGH PRESSURE BUILDS IN FROM THE
NORTH. THE ROBUST ONTARIO HIGH WILL LEAD TO SLOWLY VEERING SURFACE
WINDS GENERALLY FROM THE NORTHEAST THIS AFTERNOON TO SOUTHERLY ON
THURSDAY. AS THE HIGH STRENGTHENS AND TRACKS EAST THROUGH THURSDAY
MORNING, BRIEF PERIODS OF HIGHER WIND SPEEDS WILL OCCUR AS THE
PRESSURE GRADIENT TIGHTENS AT TIMES. AFTER THURSDAY, WINDS GO VERY
LIGHT (GUSTS < 10 KNOTS) AND WAVES DIMINISH TO LESS THAN 1 FOOT.
FOR LAKE SUPERIOR: NE WIND GUSTS AROUND 20-25 KNOTS BECOME MORE
COMMON OVER THE WESTERN LAKE (JUST EAST OF THE APOSTLES) WHERE
FUNNELING OCCURS THROUGH THIS EVENING. WIND GUSTS UP TO 15-20KTS
WILL BE POSSIBLE OVER THE EAST-CENTRAL PORTIONS OF THE LAKE AND THE
NEARSHORES THROUGH THE FIRST HALF OF THE NIGHT. EXPECT LIGHT
EASTERLY WINDS THE SECOND HALF OF THE NIGHT TO INCREASE TO AROUND
20KTS AGAIN FOR THE AFTERNOON AND EVENING HOURS TUESDAY AND
WEDNESDAY. WAVE HEIGHTS FALL TO AROUND A FOOT TONIGHT, BUT PICK UP
TO 1-2FT AS WINDS INCREASE DURING THE AFTERNOON AND EVENING HOURS.
THURSDAY AND FRIDAY, WINDS COME IN GENERALLY FROM THE SOUTH TO
SOUTHEAST, AND WHILE GUSTS TO AROUND 20KTS WILL BE POSSIBLE OVER THE
EAST-CENTRAL PORTIONS OF THE LAKE THURSDAY, WINDS FALL BELOW 10KTS
ACROSS THE ENTIRE LAKE FRIDAY.
FOR THE BAY OF GREEN BAY AND NORTHERN LAKE MICHIGAN: NE WIND GUSTS
UP TO 15-20KTS BECOME MORE COMMON THIS EVENING THROUGH TONIGHT.
WHILE SUSTAINED WINDS REMAIN LIGHT (<10 KNOTS) THROUGH THE NEXT FEW
DAYS, GUSTS TO 15-20 KNOTS REMAIN POSSIBLE FOR THE MAJORITY OF
TUESDAY THROUGH WEDNESDAY MORNING. WINDS SHIFT OVER TO THE E/SE
THURSDAY AND FRIDAY, FALLING BELOW 15KTS. WAVES WILL GENERALLY BE
AROUND 1-2FT, BUT LATEST GUIDANCE SHOWS A POTENTIAL FOR HIGHER WAVE
HEIGHTS UP TO 2-3FT FOR A PERIOD TUESDAY EVENING.
MQT WATCHES/WARNINGS/ADVISORIES
UPPER MICHIGAN...
FROST ADVISORY FROM 2 AM EDT /1 AM CDT/ TO 9 AM EDT /8 AM CDT/
TUESDAY FOR MIZ002-005>007-009-011-013-014-085.
FREEZE WARNING FROM 2 AM EDT /1 AM CDT/ TO 9 AM EDT /8 AM CDT/
TUESDAY FOR MIZ004-010-084.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
DISCUSSION...RE/LC
AVIATION...BW
MARINE...RE/LC
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