598
FXUS63 KMQT 271830
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
230 PM EDT SAT JUN 27 2026
KEY MESSAGES
- A WARMING TREND CONTINUES THROUGH THIS WEEKEND, BRINGING UNSEASONABLY
WARM TEMPERATURES AND HUMID CONDITIONS INTO NEXT WEEK. THIS
IS LEADING TO A POTENTIAL FOR HEAT-RELATED IMPACTS TO
VULNERABLE POPULATIONS.
- SHOWERS AND THUNDERSTORMS ARE LIKELY SUNDAY NIGHT, SOME OF
WHICH COULD BE STRONG TO SEVERE WITH DAMAGING WINDS AND LARGE
HAIL (5% CHANCE FOR SEVERE THUNDERSTORMS). THERE WILL BE THE
CHANCE FOR THUNDERSTORMS EVERY DAY NEXT WEEK.
DISCUSSION
ISSUED AT 216 PM EDT SAT JUN 27 2026
SURFACE HIGH PRESSURE OVER THE UPPER GREAT LAKES THIS AFTERNOON WAS
BRINGING PLEASANT WEATHER TO THE UP WITH SFC TEMPERATURE
OBSERVATIONS IN THE 70S. IT WAS COOLER ALONG THE SHORELINE OF LAKE
SUPERIOR AND LAKE MICHIGAN WHERE LAKE BREEZES HAD DEVELOPED AND
DROPPED TEMPERATURES BACK INTO THE 60S. GOES VISIBLE SATELLITE
IMAGERY SHOWED AREAS OF FAIR WEATHER CUMULUS. UPSTREAM LOW PRESSURE
WAS MOVING THROUGH THE PACIFIC NORTHWEST WITH RIDGING DEVELOPING
OVER THE PLAINS AND RELATIVELY ZONAL UPPER LEVEL FLOW OVER THE GREAT
LAKES.
THE UPPER LEVEL LOW WILL MOVE INTO THE NORTHERN ROCKIES THIS
WEEKEND, LINGERING INTO EARLY NEXT WEEK BEFORE SLOWLY PUSHING NORTH
AND EAST INTO CANADA. RIDGING WILL CONTINUE TO BUILD AHEAD OF THE
LOW PRESSURE OVER THE MIDWEST, BRINGING SOUTHERLY FLOW AND
INCREASING TEMPERATURES AND MOISTURE. BY TUESDAY AND WEDNESDAY 850MB
TEMPS WARM UP TO 22-24C WHICH WILL TRANSLATE TO HIGHS WELL INTO THE
80S TO MID 90S ACROSS MUCH OF THE UP. HUMIDITY ALSO BEGINS TO
INCREASE STARTING MONDAY WITH GULF MOISTURE SURGING NORTH, BRINGING
DEWPOINTS TO NEAR OR EXCEEDING 70F AT TIMES. HEAT IMPACTS ARE LIKELY
NEXT WEEK AS LOWS REMAIN WARM (60S TO LOW 70S) AND DAYTIME HIGHS
APPROACH OR BREAK THE 90F MARK, COMBINING WITH THE HUMID AIRMASS TO
BRING HEAT INDICES INTO THE 90-100F RANGE. ENS 850MB TEMPERATURE
ANOMALIES ARE NOT OVERLY IMPRESSIVE THOUGH RETURN INTERVALS ARE IN
THE 10-30 YR RANGE. THUS THE HEAT EVENT LOOKS IMPACTFUL BUT NOT
EXTREME FOR THE UP. NBM BIAS CORR COULD BE OVERDOING TEMPERATURES AS
IT HAS WITH PREVIOUS WARMER STRETCHES OVER THE LAST MONTH. DID KNOCK
HIGH TEMPERATURES DOWN A FEW DEGREES FROM THE NBM SUNDAY THROUGH
TUESDAY. HEAT ADVISORIES MAY BE NEEDED NEXT WEEK AND THOSE WHO WILL
BE EXPOSED TO THE HEAT FOR PROLONGED PERIODS AND THOSE WHO ARE
SENSITIVE TO THE HEAT SHOULD HAVE A PLAN TO STAY COOL AND HYDRATED.
IN ADDITION TO THE HEAT, THUNDERSTORMS WILL BE A POTENTIAL HAZARD
STARTING SUNDAY NIGHT WITH CONTINUED CHANCES THROUGH THE WEEK.
MOISTURE AND TEMPERATURE ADVECTION INCREASES AS A WARM FRONT PUSHES
THROUGH SUNDAY NIGHT. MOST UNSTABLE CAPE INCREASING TO 2000-3000
J/KG SUNDAY NIGHT WITH EFFECTIVE SHEAR OF 40+ KT, PROVIDING AN
ENVIRONMENT FAVORABLE FOR ORGANIZED CONVECTION AS LARGE SCALE ASCENT
PROVIDES LIFT FOR ELEVATED CONVECTION. THE STRONGEST UPPER LEVEL
SUPPORT REMAINS NORTH AND WEST OF THE UP IN AN AREA OF DIVERGENT
FLOW ALOFT, AHEAD OF THE UPPER LEVEL LOW PRESSURE OVER MONTANA.
HOWEVER, THUNDERSTORMS ARE STILL LIKELY SUNDAY NIGHT AND SPC HAS A
MARGINAL RISK FOR SEVERE THUNDERSTORMS OVER THE WESTERN 2/3 OF THE
UP, WITH THE MAIN HAZARDS BEING LARGE HAIL AND DAMAGING WINDS.
POTENTIAL INSTABILITY REMAINS MODERATE TO HIGH THROUGH THE REST OF
THE WEEK, HOWEVER, THE ATMOSPHERE LARGELY WILL REMAIN CAPPED AND
LARGE SCALE ASCENT MAY BE NEEDED TO TRIGGER CONVECTION. ECMWF CAPE
EFI IS HIGH ON MONDAY THROUGH WEDNESDAY WITH SHIFT-OF-TAILS OF 1
OVER THE GREAT LAKES TUE AND WED. VALUES ARE A BIT LOWER WITH
COMBINED CAPE/SHEAR BUT STILL NOTABLE. OVERALL, SHOULD CONVECTION
DEVELOP DURING THIS PERIOD IT COULD BE STRONG TO POTENTIALLY SEVERE
BUT IT IS TOO EARLY TO PIN DOWN DETAILS. SHOULD MSC ACTIVITY OCCUR,
OUTFLOW BOUNDARIES AND LINGERING CLOUD COVER WILL LIKELY IMPACT THE
EVOLUTION OF THE PROCEEDING CONVECTION AND HIGH TEMPERATURES.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 120 PM EDT SAT JUN 27 2026
HIGH PRESSURE WILL CONTINUE TO RESULT IN VFR CONDITIONS AND LIGHT
WINDS THROUGH MOST OF THE TAF PERIOD. SOUTHEASTERLY WIND GUSTS AT
IWD COULD APPROACH 20 KT BY LATE SUNDAY MORNING.
MARINE
ISSUED AT 216 PM EDT SAT JUN 27 2026
A LARGE AREA OF HIGH PRESSURE OVER THE GREAT LAKES AND EASTERN
CANADA WILL SLOWLY MOVE EAST THROUGH EARLY NEXT WEEK AS LOW PRESSURE
DEEPENS OVER THE CENTRAL U.S, AHEAD OF A UPPER LEVEL LOW PRESSURE
MOVING FROM THE PAC NW TO THE NORTHERN ROCKIES. THIS WILL RESULT IN
A TIGHTENING PRESSURE GRADIENT OVER LAKE SUPERIOR AND INCREASING
WINDS. EASTERLY WINDS OF 20-30KT CAN BE EXPECTED TO DEVELOP SUNDAY
AFTERNOON, TURNING SOUTH-SOUTHEAST ON MONDAY. WINDS WILL REMAIN
SOUTHERLY FOR TUESDAY AND WEDNESDAY BUT GENERALLY 20KT OR LESS.
THERE IS THE POTENTIAL FOR THUNDERSTORMS STARTING SUNDAY NIGHT, WITH
CHANCES EACH DAY THROUGH THE WEEK. SOME OF THE STORMS COULD BE
STRONG TO POTENTIALLY SEVERE SUNDAY NIGHT INTO MONDAY (5% CHANCE).
THEREAFTER PREDICTABILITY IS TOO LOW BUT THERE REMAINS A NON-ZERO
CHANCED FOR STRONG TO SEVERE THUNDERSTORMS AT TIME THROUGH THE WEEK.
MQT WATCHES/WARNINGS/ADVISORIES
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
DISCUSSION...NL
AVIATION...THOMPSON
MARINE...NL
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