917
FXUS63 KMQT 132257
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
657 PM EDT MON JUL 13 2026
KEY MESSAGES
- HOT CONDITIONS CONTINUE THROUGH TUESDAY WITH HIGHS WELL INTO
THE 90S AND HEAT INDEX VALUES OVER 100. EXTREME HEAT WARNING
NOW IN EFFECT UNTIL TUESDAY EVENING AS HIGH DEWPOINTS AND POOR
OVERNIGHT RECOVERIES WILL INCREASE CUMULATIVE IMPACTS. PEOPLE
ARE ENCOURAGED TO TAKE PRECAUTIONS TO MINIMIZE HEAT RELATED
IMPACTS WHEN POSSIBLE.
- TEMPERATURES MODERATE FROM WEDNESDAY ONWARD, WITH
PRECIPITATION CHANCES RETURNING LATE IN THE WEEK.
DISCUSSION
ISSUED AT 321 PM EDT MON JUL 13 2026
AFTERNOON GOES WATER VAPOR IMAGERY AND RAP ANALYSIS REVEAL A STRONG
UPPER LEVEL RIDGE OF HIGH PRESSURE ENCOMPASSING MUCH OF THE CONUS
FROM THE FOUR CORNERS REGION TO LAKE SUPERIOR, SUPPORTING THE
HOTTEST AIR MASS SO FAR THIS SEASON AND INDEED ONE OF THE HOTTEST ON
RECORD BY SOME METRICS FOR PORTIONS OF THE UPPER GREAT LAKES. RAP
ANALYSIS SHOWS 500 MB HEIGHTS RISING TO 600 DAM THIS AFTERNOON FROM
THE UPPER MISSISSIPPI RIVER VALLEY INTO THE UP, NEARING OR IN SOME
CASES EXCEEDING THE CLIMATOLOGICAL MAX FOR SEVERAL LOCATIONS AROUND
THE REGION. ADDITIONALLY, THIS MORNING'S 12Z ATMOSPHERIC SOUNDING
FROM INTERNATIONAL FALLS, MN REPORTED AN 850 MB TEMP OF 28.4 C,
WHICH IS THE SECOND HIGHEST READING ON RECORD DATING BACK TO 1948.
THIS UPSTREAM AIR MASS HAS CONTINUED TO ADVECT EASTWARD INTO THE UP
THIS AFTERNOON, CORRESPONDING TO WIDESPREAD TEMPERATURES IN THE 90S
AND HEAT INDEX VALUES IN THE 100S ACROSS THE UP AS OF MID AFTERNOON.
WILL HAVE TO KEEP A CLOSE EYE ON TEMPERATURE READINGS THROUGH THE
REST OF THE DAY AS SEVERAL TEMPERATURE RECORDS WILL BE IN JEOPARDY,
INCLUDING POTENTIALLY THE ALL TIME HIGH TEMPERATURE READING OF 99
DEGREES AT THE NWS FORECAST OFFICE IN NEGAUNEE TOWNSHIP. IN ADDITION
TO THE HOT WEATHER, STRONG LOW PRESSURE DEEPENING OVER HUDSON BAY IS
HELPING TO SQUEEZE THE SURFACE PRESSURE GRADIENT AND PRODUCE BREEZY
CONDITIONS OVER THE UP AND LAKE SUPERIOR INTO THIS EVENING.
FORTUNATELY, DEWPOINTS IN THE 60S ARE GENERALLY KEEPING RELATIVE
HUMIDITY VALUES ABOVE CRITICAL FIRE WEATHER THRESHOLDS, THOUGH SOME
LOCATIONS IN THE WESTERN UP MAY FLIRT WITH 30% RH THROUGH THIS
AFTERNOON.
TONIGHT WILL OFFER LITTLE RELIEF FROM THE HEAT AS MOST LOCATIONS
AROUND THE UP ONLY COOL INTO THE MID AND IN SOME CASES UPPER 70S,
AGAIN NEARING THE CLIMATOLOGICAL MAX IN TERMS OF WARM MINIMUM
TEMPERATURES. MID AND UPPER LEVEL CONDITIONS WILL BEGIN TO RETREAT
SOME FROM TODAY'S HISTORIC VALUES ON TUESDAY, BUT 500 MB HEIGHTS
ABOVE 590 DAM AND 850 MB TEMPS OF 22-25 C WILL STILL EASILY SUPPORT
HIGHS IN THE 90S ON TUESDAY, MAINTAINING A MAJOR HEAT RISK ACROSS
THE UP FOR ONE MORE DAY. GIVEN THE CUMULATIVE IMPACT OF WARM
OVERNIGHT LOWS AND MULTIPLE DAYS OF HIGHS IN THE 90S COUPLED WITH
60S DEWPOINTS AGAIN PUSHING THE HEAT INDEX ABOVE 100 DEGREES, HAVE
OPTED TO EXTEND THE EXTREME HEAT WARNING THROUGH TUESDAY EVENING
ACROSS THE AREA. BOTTOM LINE, PEOPLE SHOULD TAKE PRECAUTIONS TO
MITIGATE HEAT RELATED IMPACTS WHENEVER POSSIBLE THROUGH TUESDAY.
THIS INCLUDES STAYING HYDRATED, LIMITING OUTDOOR TIME, AND CHECKING
ON THOSE WHO ARE VULNERABLE TO THE HEAT INCLUDING THE ELDERLY,
CHILDREN, AND PETS.
SPC HAS NOTABLY INCLUDED THE UP IN THE DAY 2 GENERAL THUNDERSTORM
RISK FOR TUESDAY. CURRENTLY THINKING SHOWER AND THUNDERSTORM CHANCES
ARE LOW ENOUGH TO KEEP OUT OF THE FORECAST GIVEN CAPPING AND
SUBSIDENCE THAT WILL STILL BE IN PLACE UNDER HIGH PRESSURE, BUT WILL
KEEP AN EYE ON THIS POTENTIAL AS THERE WILL BE PLENTY OF CONDITIONAL
INSTABILITY AVAILABLE FOR AN CELL THAT DOES MANAGE TO FORM.
TEMPERATURES WILL MODERATE TOWARDS MORE "NORMAL" SUMMER HEAT FROM
WEDNESDAY ONWARD AS THE UPPER RIDGE IS FLATTENED OUT BY PERSISTENT
STRONG TROUGHING OVER EASTERN CANADA. THIS WILL YIELD HIGHS
GENERALLY IN THE LOW 80S NEAR LAKE SUPERIOR TO AROUND 90 OVER THE
SOUTH-CENTRAL UP FOR WEDNESDAY AND THURSDAY, COOLING FURTHER INTO
MID 70S TO MID 80S BY FRIDAY. OVERNIGHT LOWS WILL ALSO RETURN CLOSER
TO SEASONAL NORMS IN THE 50S BY WEDNESDAY NIGHT. THE FORECAST
REMAINS MOSTLY DRY THROUGH WEDNESDAY, BUT THE FLATTENING OF THE
UPPER LEVEL FLOW WILL PAVE THE WAY FOR THE NEXT SYSTEM BRINGING A
HIGHER CHANCE FOR WIDESPREAD RAIN AND THUNDERSTORMS BACK TO THE
AREA BY LATE THURSDAY INTO FRIDAY. DO NOT SEE SIGNALS FOR ANY
SIGNIFICANTLY IMPACTFUL WEATHER IN THE LONG TERM FORECAST AT THIS
TIME.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 657 PM EDT MON JUL 13 2026
VFR CONDITIONS PREVAIL THROUGH THE PERIOD AS UPPER-LEVEL HIGH
PRESSURE RIDGING KEEPS LOWER CIGS AWAY. MAINLY EXPECTING TO SEE LOW-
LEVEL TURBULENCE DEVELOP OVER IWD AND CMX TONIGHT, WITH WINDS UP AT
AROUND 2 KFT GETTING TO ABOUT 40 TO 45 KTS IN THE SAME (OR NEAR THE
SAME) DIRECTION AT THE SFC. BEST CHANCE FOR LLWS LOOKS TO BE OVER
SAW AFTER MIDNIGHT TONIGHT, WHERE THERE MAY BE ENOUGH DIRECTIONAL
SHEAR TO CREATE LLWS CONDITIONS THROUGH THE PRE-DAWN MORNING HOURS
ON TUESDAY. EXPECT WINDS TO DWINDLE WITH TIME ON TUESDAY, WITH THE
LAKE BREEZE FROM LAKE SUPERIOR POTENTIALLY IMPACTING SAW BY TUESDAY
AFTERNOON.
MARINE
ISSUED AT 321 PM EDT MON JUL 13 2026
SOUTHWESTERLY WINDS HAVE INCREASED TO 20 TO 25 KT ACROSS THE WESTERN
HALF OF LAKE SUPERIOR THIS AFTERNOON AS THE PRESSURE GRADIENT
TIGHTENS BETWEEN SURFACE HIGH PRESSURE TO THE SOUTH AND DEEPENING
LOW PRESSURE TO THE NORTH. LOOK FOR WINDS TO INCREASE HIGHER TONIGHT
INTO THE 25 TO 30 KT RANGE WHILE EXPANDING OVER THE CENTRAL PORTIONS
OF THE LAKE AS WELL. BOTH HREF AND NBM GUIDANCE HIGHLIGHT A 30-50%
CHANCE FOR SOME GALE FORCE GUSTS BETWEEN THE KEWEENAW AND ISLE
ROYALE THIS EVENING, BUT PROBABILITIES AND COVERAGE REMAIN LOW
ENOUGH TO FOREGO ANY GALE HEADLINES AT THIS TIME. SMALL CRAFT
CONDITIONS WILL IMPACT MANY OF THE NEARSHORE ZONES TONIGHT INTO
EARLY TUESDAY AS WAVE BUILD TO 4 TO 7 FEET ACROSS WESTERN AND
CENTRAL PORTIONS OF THE LAKE. WINDS THEN GRADUALLY DIMINISHING
THROUGH TUESDAY AND LOOK TO REMAIN BELOW 20 KT FOR MOST OF THEW
REST OF THE WEEK.
MQT WATCHES/WARNINGS/ADVISORIES
UPPER MICHIGAN...
EXTREME HEAT WARNING UNTIL 10 PM EDT /9 PM CDT/ TUESDAY FOR
MIZ001>007-009>014-084-085.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
DISCUSSION...CB
AVIATION...TAP
MARINE...CB
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