183
FXUS63 KMQT 210646
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
246 AM 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 LOW
CHANCE (15%) OF EXCEEDING FLASH FLOOD GUIDANCE ACROSS WESTERN
UPPER MICHIGAN. ISOLATED SEVERE STORMS ARE ALSO POSSIBLE.
- ADDITIONAL ROUNDS OF THUNDERSTORMS ARE POSSIBLE WEDNESDAY
THROUGH FRIDAY MORNING.
SHORT TERM /THROUGH TUESDAY/
ISSUED AT 245 AM EDT MON JUL 21 2025
SURFACE HIGH SITTING OVERHEAD HAS RESULTED IN A CALM NIGHT WITH
LIGHT WINDS. MID TO UPPER LEVEL CLOUDS HAVE BEEN OBSERVED ON GOES IR
IMAGERY STREAMING IN FROM THE WEST, BUT A MAJORITY OF THE FORECAST
AREA HAS REMAINED MOSTLY CLEAR. TEMPERATURES SO FAR HAVE FALLEN INTO
THE UPPER 40S AND 50S. WARMER TEMPERATURES ARE STILL BEING OBSERVED
IN MENOMINEE, WHICH IS CURRENTLY 61 DEGREES.
SURFACE RIDGING WILL CONTINUE TODAY OVER THE UPPER GREAT LAKES AS
THE RESPONSIBLE HIGH SHIFTS EASTWARD FROM EASTERN ONTARIO TO QUEBEC.
THIS WILL CONTINUE THE DRY CONDITIONS OVER THE REGION FOR THE
REMAINDER OF THE OVERNIGHT PERIOD AND TODAY. SOUTHEASTERLY FLOW AND
WARM AIR ADVECTION AT 850MB IN THE AFTERNOON WILL ALLOW SURFACE
TEMPERATURES TO WARM INTO THE MID TO UPPER 70S FOR MOST OF THE
FORECAST AREA. ALOFT, MID-TO-UPPER LEVEL RIDGE AXIS WILL MOVE
EASTWARD INTO THE FORECAST AREA LATE TODAY WITH NEAR-ZONAL FLOW FROM
THIS AXIS WESTWARD. MULTIPLE EMBEDDED IMPULSES IN THIS REGIME OVER
THE PLAINS/UPPER MIDWEST WILL SUPPORT VARIOUS CLUSTERS OF STORMS
THROUGH THE DAY. MODELS VARY ON THE PLACEMENT OF THESE FEATURES AND
ONLY A HANDFUL OF DETERMINISTIC CAMS/MEDIUM RANGE GUIDANCE PACKAGES
SUGGEST WEAKENING SHOWERS OR STORMS MAY MOVE INTO WESTERN/NORTHERN
LAKE SUPERIOR/ISLE ROYALE OR THE FAR WEST THIS EVENING. OUTSIDE OF
THIS LOW PROBABILITY FOR PRECIP, THE REGION IS ANTICIPATED TO REMAIN
MOSTLY DRY TODAY.
TUESDAY, MID-TO-UPPER LEVEL RIDGING WILL DOMINATE MOST OF THE
MISSISSIPPI RIVER VALLEY WITH WHAT APPEARS TO BE A STATIONARY
SURFACE BOUNDARY ACROSS THE CENTRAL PLAINS AHEAD OF A DEVELOPING
SURFACE LOW NEAR NEBRASKA/SOUTH DAKOTA. NORTHEAST OF THIS LOW,
SURFACE TROUGHING WITHIN A STRONGLY UNSTABLE REGION AND STRONG MID-
LEVEL SOUTHWESTERLY FLOW WILL PROVIDE FOR MULTIPLE IMPULSES/MCS
THROUGH THE DAY. THERE IS A GOOD BIT OF UNCERTAINTY IN WHERE THESE
WILL DEVELOP, BUT ONE SUCH CLUSTER COULD MOVE INTO THE WEST BY LATE
AFTERNOON. BETTER CHANCES THOUGH WILL BE TUESDAY EVENING AND
OVERNIGHT INTO WEDNESDAY. WITH PWATS PUSHING 2 INCHES, HEALTHY
EFFECTIVE SHEAR, AND SOMEWHAT STEEP MID-LEVEL LAPSE RATES IN THIS
ENVIRONMENT, ANY THUNDERSTORM WOULD HAVE THE POTENTIAL OF PRODUCING
HEAVY RAIN AND MAYBE HAIL.
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 /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1258 AM EDT MON JUL 21 2025
VFR CONDITIONS AND GENERALLY LIGHT AND VARIABLE WINDS PREVAIL AT THE
START OF THE 06Z TAF PERIOD AS HIGH PRESSURE SETTLES OVERHEAD THE
NORTHERN GREAT LAKES. S TO SE WINDS PICK UP THIS AFTERNOON AND ARE
EXPECTED TO REMAIN BELOW 15 KTS. SOME ELEVATED WILDFIRE SMOKE MAY BE
PRESENT HOWEVER NO VISIBILITY IMPACTS ARE EXPECTED AT ANY TERMINAL.
MARINE
ISSUED AT 250 PM EDT SUN JUL 20 2025
LIGHT WINDS OF GENERALLY 20 KNOTS OR LESS DOMINATE THIS WEEK AS HIGH
PRESSURE EARLY GIVES WAY TO A TROUGHING PATTERN AND MULTIPLE
SHORTWAVE IMPULSES FOR MOST OF THE REST OF THE WORK WEEK. THIS MEANS
THAT WE COULD SEE SHOWERS AND STORMS OVER LAKE SUPERIOR FROM LATE
MONDAY THROUGH THURSDAY, WITH SOME OF THE STORMS TUESDAY THROUGH
THURSDAY POTENTIALLY BEING STRONG.
MQT WATCHES/WARNINGS/ADVISORIES
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
SHORT TERM...JTP
LONG TERM...JTP/TAP
AVIATION...BW
MARINE...TAP
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