324
FXUS63 KMQT 211933
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
333 PM EDT MON JUL 21 2025
KEY MESSAGES
- SHOWERS AND THUNDERSTORMS ARE EXPECTED LATE TUESDAY INTO EARLY
WEDNESDAY. STRONGER STORMS COULD PRODUCE HEAVY RAIN. THERE IS
A SLIGHT CHANCE (15%) OF EXCEEDING FLASH FLOOD GUIDANCE ACROSS
FAR WESTERN UPPER MICHIGAN. ISOLATED SEVERE STORMS ARE ALSO
POSSIBLE (5%).
- ADDITIONAL ROUNDS OF THUNDERSTORMS ARE POSSIBLE WEDNESDAY
THROUGH FRIDAY MORNING. STORMS ON WEDNESDAY BRING ADDITIONAL
CHANCES FOR STRONG TO SEVERE STORMS (15%) AND HEAVY RAIN
EXCEEDING FLASH FLOOD GUIDANCE.
SHORT TERM /THROUGH TUESDAY NIGHT/
ISSUED AT 332 PM EDT MON JUL 21 2025
A SFC HIGH EXTENDING SW INTO THE GREAT LAKES FROM N ONTARIO SHOULD
CONTINUE MOSTLY DRY WEATHER THROUGH TONIGHT AS IT SHIFTS SE TOWARD
THE LOWER GREAT LAKES. SOME TRANSIENT -SHRA CAN'T BE RULED OUT OVER
THE W THIS EVENING INTO TONIGHT, CURRENTLY LINGERING OVER NW WI THIS
AFTERNOON AFTER A MCS THIS MORNING TRACKED ESE OVER MN. THIS PRECIP
WILL HAVE TO ERODE THROUGH A FAIRLY DRY RESIDENT AIR MASS, BUT WILL
HAVE SOME HELP FROM A MID LEVEL SHORTWAVE. QPF WILL BE SPARSE AND
LOW, IF ANY, SO NO IMPACTS ARE EXPECTED IN THE NEAR TERM. OTHERWISE,
TEMPS HOLD IN THE LOW TO MID 70S OUTSIDE AREAS WHERE LAKE BREEZES
OFF BOTH LAKES HAVE MODERATED TEMPS DOWN INTO THE 60S. LOWS BY TUE
MORNING WILL BE IN THE 50S TO LOW 60S.
AN ACTIVE PERIOD THEN BEGINS ON TUE. INCREASING S FLOW WITH THE HIGH
PRESSURE SHIFTING SE BRINGS A WARM AND MOIST AIRMASS IN. THIS BRINGS
TEMPS INTO THE MID 70S TO MID 80S AND TDS IN THE 60S, RESULTING IN
MUCAPE INCREASING TO 1000-1500J/KG OVER THE W. WHERE UNCERTAINTY
STILL REMAINS IN THE FCST IS THE TIMING OF TSRA. TONIGHT, TWO
SHORTWAVES ALONG THE FAR W PERIPHERY OF THE CENTRAL/N PLAINS QUICKLY
TRACK NE TOWARD THE GREAT LAKES FOR LATE IN THE DAY TUE. THIS SHOULD
SUPPORT CONVECTIVE ACTIVITY WITHIN THE UNSTABLE ENVIRONMENT IT
PROGRESS THROUGH. IF THIS WAVE IS ON THE PROGRESSIVE SIDE AND
ARRIVES IN THE FAR W BY 17/19Z ON TUE LIKE THE 12Z HRRR/ARW/FV3,
INSTABILITY MAY NOT BE QUITE AS HIGH AS A LATER ARRIVAL LIKE THE
NAMNEST/RAP. REGARDLESS, BULK SHEAR SHOULD BE SUFFICIENT FOR
ORGANIZED CONVECTION ~30 KTS OR HIGHER. MID LEVEL LAPSE RATES
APPROACH 7C/KM, LOW LEVEL LAPSE RATES WILL STRUGGLE, AND A FEW
HUNDRED J/KG OF DCAPE (LIKELY 900J/KG OR LESS) WILL BE PRESENT LATE
IN THE AFTERNOON/EVENING HOURS. THIS SHOULD BE SUPPORTIVE FOR SOME
GUSTY WINDS AND HAIL, ESPECIALLY WITHIN STRONG UPDRAFTS. WITH
PWATS/SPECIFIC HUMIDITY INCREASING ABOVE THE NAEFS 99TH PERCENTILE
TUE NIGHT INTO WED AND A STRONG LLJ MOVING IN OVER THE W, HEAVY
DOWNPOURS AND RESULTING FLOODING RISKS ARE INCREASED FOR LATER WAVES
AND MCS DEVELOPMENT FOR TUE NIGHT INTO WED. OTHERWISE TEMPS ONLY
SETTLE INTO THE 60S TUE NIGHT.
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/
ISSUED AT 245 AM EDT MON JUL 21 2025
THE EXTENDED PERIOD LOOKS TO BE FAIRLY ACTIVE FOR THE MOST PART THIS
WEEK. AS THE HIGH PRESSURE OVER US TODAY GIVES WAY TO TROUGHING THIS
WEEK, EXPECT SEVERAL SHORTWAVES TO POTENTIALLY BRING MULTIPLE ROUNDS
OF SHOWERS AND STORMS OVER US. RAIN CHANCES AND AMOUNTS LOOK TO
INCREASE BEGINNING TUESDAY NIGHT AS A HEAVY SUPPLY OF GULF MOISTURE
INTERACTS WITH A LOWER-LEVEL SHORTWAVE MOVING INTO OUR REGION, A JET
STREAK OVER THE NORTHERN PLAINS AND NORTHERN ONTARIO, AND ZONAL FLOW
IN THE MID LEVELS. BECAUSE OF THIS, BOTH THE GFS AND EUROPEAN
ENSEMBLE GUIDANCE HAS PWATS GETTING TO AROUND 2 INCHES, WHICH IS
NEAR THE MAX OF MODELED CLIMATOLOGY (!). WITH ENSEMBLE GUIDANCE
SHOWING ABUNDANT CAPE AND A MARGINAL BULK SHEAR ENVIRONMENT TO WORK
WITH TUESDAY NIGHT THROUGH THURSDAY, WE COULD SEE SEVERAL ROUNDS OF
HEAVY RAIN SHOWERS AND THUNDERSTORMS ROLLING THROUGH THE AREA FOR
THE MIDDLE OF THE WEEK AS EACH WEAK ATMOSPHERIC IMPULSE MOVES
THROUGH THE REGION. THUS, WE HAVE THE POTENTIAL FOR FLASH FLOODING
AND FLOODING ACROSS THE AREA FOR THE MIDDLE OF THIS WEEK; IT'S
UNSURPRISING THEN THAT WPC HAS PUT THE WESTERN U.P. AND COPPER
COUNTRY UNDER A SLIGHT RISK FOR EXCESSIVE RAINFALL, AND A MARGINAL
RISK FOR THE REST OF THE WEST AND CENTRAL TUESDAY NIGHT (MOST OF THE
RAINFALL IS EXPECTED TUESDAY NIGHT). IN ADDITION, GIVEN THE ENERGY
EXPECTED AND STRONG SHEAR ENVIRONMENT, SOME SEVERE WEATHER COULD BE
SEEN IN SOME OF THE THUNDERSTORMS, NAMELY SEVERE HAIL AND WINDS; SPC
HAS OUTLINED THIS FOR TUESDAY NIGHT BY PUTTING THE MARGINAL SEVERE
RISK OVER THE SAME AREAS AS WPC'S SLIGHT EXCESSIVE RAINFALL RISK.
IT APPEARS THAT THE RAIN CHANCES WILL CEASE OVER OUR AREA BY NEXT
WEEKEND AS ADDITIONAL HIGH PRESSURE RIDGING FINALLY BUILDS BACK INTO
THE REGION AS THE TROUGHING PATTERN FINALLY WEAKENS AND LIFTS
TOWARDS NEW ENGLAND. ABOVE TO AROUND NORMAL HIGH TEMPERATURES
DOMINATE FROM MONDAY ONWARDS THIS WEEK, EVEN AFTER WE TRANSITION
FROM A WETTER TO DRIER PATTERN BY THIS NEXT WEEKEND.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 142 PM EDT MON JUL 21 2025
HIGH LEVEL CLOUDS ARE STREAMING OVER THE REGION, BUT VFR FLIGHT
CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE DURATION OF THE 18Z
TAF PERIOD WITH HIGH PRESSURE EXTENDING OVER THE GREAT LAKES. THIS
WILL ALSO SUPPORT LIGHT S/SE WINDS AT IWD/SAW AND E/SE WINDS AT CMX,
GENERALLY LESS THAN 10 KTS DURING THE PERIOD. WHILE A FEW TRANSIENT -
SHRA MAY IMPACT IWD AND POSSIBLY CMX THIS EVENING AND TONIGHT,
CONFIDENCE WAS TOO LOW TO INCLUDE AND IMPACTS ARE NOT EXPECTED
REGARDLESS.
MARINE
ISSUED AT 332 PM EDT MON JUL 21 2025
LIGHT WINDS OF GENERALLY 20 KNOTS OR LESS ARE EXPECTED TO DOMINATE
THE REST OF THIS WEEK, ALTHOUGH SOME SOUTHERLY WINDS OF 20 TO 25
KNOTS ARE POSSIBLE OVER THE EASTERN HALF OF THE LAKE TUESDAY NIGHT
AS THE SFC LOW MOVES THROUGH LAKE SUPERIOR. SOME SHOWERS AND
THUNDERSTORMS ARE EXPECTED ACROSS THE LAKE THIS EVENING AND ONCE
AGAIN TUESDAY THROUGH THURSDAY. SOME THE STORMS MAY BE STRONG TO
SEVERE TUESDAY THROUGH THURSDAY, BRINGING ERRATIC/DAMAGING WINDS AND
LARGE HAIL TO THE SFC.
MQT WATCHES/WARNINGS/ADVISORIES
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
SHORT TERM...JABLONSKI
LONG TERM...JTP/TAP
AVIATION...JABLONSKI
MARINE...TAP
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