540
FXUS63 KAPX 030956
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
556 AM EDT THU SEP 3 2026
KEY MESSAGES
- RAIN/STORM CHANCES HANG OUT IN THE REGION THROUGH AT LEAST
FRIDAY/FRIDAY NIGHT...HEAVY RAIN AND A STRONGER STORM OR TWO
POSSIBLE AT TIMES, ESPECIALLY TODAY/TONIGHT.
DISCUSSION
ISSUED AT 353 AM EDT THU SEP 3 2026
PATTERN SYNOPSIS/FORECAST:
SW FLOW ALOFT ACROSS THE CENTRAL US, FEEDING PLUME OF VERY HOT AIR
(850MB TEMPS UP INTO THE 25C RANGE) AND STEEP MID-LEVEL LAPSE RATES
FROM THE SW US ACROSS THE CENTRAL AND NORTHERN PLAINS ATTM. BROAD
TROUGHING OVER THE W US, INCLUDING AN UPPER LOW AND ATTENDANT 100KT
UPPER JET POKING INTO THE PACNW...AND A PV MAX SWIRLING ALMOST DUE
NORTH THROUGH MT INTO ALBERTA. BROAD TROUGHING OVER EASTERN CANADA
WITH INFLUENCES ACROSS THE LOWER GREAT LAKES AND NEW ENGLAND WHERE
THE BULK OF THE CONVECTION HAS BEEN ONGOING AS OF 4Z. CONFLUENCE AND
ZONAL FLOW OVER THE GREAT LAKES BETWEEN UPPER RIDGE OVER THE SE AND
UPPER LOW NEAR JAMES BAY; A PLUME OF DEEPER MOISTURE (PWATS AT OR
ABOVE 1.5IN) STRETCHES ALONG THIS CONFLUENCE ZONE FROM THE PLAINS
EASTWARD THROUGH THE UPPER MS VALLEY AND INTO THE LOWER GREAT LAKES.
NOW THAT REMNANTS OF "EDOUARD" ARE TRACKING DEEPER INTO TX,
STARTING TO SEE BETTER GULF MOISTURE TRANSPORT NORTH UP THE MS
VALLEY. SW LLJ IS A BIT STRONGER TONIGHT ACROSS THE PLAINS AS
WELL...UPWARDS OF 40KTS OR BETTER AT 850MB, MORE OR LESS
ORTHOGONAL TO AFOREMENTIONED BOUNDARY FROM THE PLAINS TO LOWER
MI...BUT DOES TURN TO THE SE ACROSS THE NORTHERN PLAINS UP INTO
CANADA AHEAD OF THE OCCLUDED SURFACE LOW IN ALBERTA AHEAD OF
AFOREMENTIONED PV MAXIMUM. LOW-LEVEL COL REGION AND/OR
DEFORMATION AXIS OVER THE UPPER MIDWEST ATTM BETWEEN UPSTREAM
FEATURE AND LAST LOBES OF ENERGY SWIRLING AROUND THROUGH ONTARIO
ON THE BACKSIDE OF THE JAMES BAY AREA UPPER LOW. SLIGHTLY
COOLER AND SLIGHTLY LESS HUMID AIR AROUND ATTM, WITH TDS ACROSS
MOST OF NORTHERN LOWER IN THE UPPER 50S TO LOWER 60S, VS THE
JUICY UPPER 60S TO LOWER 70S WE HAD THE DAY BEFORE...THOUGH THAT
JUICY AIR MASS REMAINS ACROSS S. MI SOUTH OF AFOREMENTIONED
BOUNDARY.
PV OVER MT AND A LITTLE WIND OF PV AHEAD OF IT TRACK NORTHWARD
TOWARD CANADA TODAY...RESULTING IN THE BAROCLINIC ZONE BUCKLING
NORTHWARD AS UPPER LOW OVER JAMES BAY SLOWLY RELEASES ITS GRIP ON
OUR WEATHER...AND WILL ANTICIPATE AN INCREASED THREAT FOR
SHOWERS/STORMS TONIGHT INTO FRIDAY MORNING ALONG SAID BOUNDARY,
INCLUDING INTO NORTHERN MI. WILL NEED TO KEEP AN EYE OUT FOR
CONVECTION TO RIDE THE RIDGE AXIS INTO THE GREAT LAKES FRIDAY NIGHT
INTO SATURDAY, WHICH COULD LEAD TO A DAMPER START TO THE HOLIDAY
WEEKEND. IT ALSO APPEARS HIGH PRESSURE WILL ATTEMPT TO OOZE BACK
INTO NORTHERN MI FROM ONTARIO THIS WEEKEND AS THE RIDGE AXIS
STRENGTHENS JUST UPSTREAM; THIS WILL PUT A CONFLUENCE ZONE LIKELY
WELL TO OUR NORTH ACROSS CANADA, AND MAY NEED TO KEEP AN EYE OUT FOR
ANY OF THIS ACTIVITY TO TRY TO DRIFT DOWN THE THICKNESS GRADIENT
INTO THE GREAT LAKES. SIGNALS POINT TOWARD THE RIDGE AXIS BUILDING
INTO THE UPPER MIDWEST AND EVEN GREAT LAKES FOR LABOR DAY AND
PERHAPS BEYOND...WITH STRENGTHENING EASTERLY FLOW ACROSS SOUTHERN
CANADA AND PERHAPS PARTS OF THE UPPER MIDWEST...AS ENERGY EJECTS OUT
OF THE WESTERN TROUGH AND DRIVES PRESSURE FALLS ACROSS THE NORTHERN
PLAINS. THE OVERALL PATTERN GOING INTO MIDWEEK NEXT WEEK SUGGESTS WE
WILL REMAIN IN A WARM, MOIST, AND POTENTIALLY UNSETTLED ENVIRONMENT
(BARRING ANY MID-LEVEL STABILITY PROVIDED BY THE RIDGE)...THOUGH THE
EVOLUTION OF THE EJECTING ENERGY IS UNCLEAR AND WILL DETERMINE HOW
STRONG A SURFACE RESPONSE IS HAD IN THE GREAT LAKES NEXT WEEK.
INCREASING UNCERTAINTY IN THE PATTERN BEYOND THE MIDDLE OF NEXT
WEEK, PRIMARILY IN THE EVOLUTION/STRENGTH/POSITION OF UPSTREAM
TROUGHING, WHICH WILL IMPACT HOW MUCH OF AN INFLUENCE THE RIDGE AXIS
WILL CONTINUE TO EXERT ON OUR AREA GOING INTO THE SECOND WEEKEND OF
SEPTEMBER.
FORECAST DETAILS...
RAIN/STORM CHANCES TODAY/TONIGHT... CURRENT EXPECTATION IS FOR
UPSTREAM CONVECTION (CURRENTLY STRUGGLING TO DEVELOP OVER IA AS OF
6Z BUT FINALLY TAKING SHAPE AROUND 7Z OVER N. IA/S. MN) TO
EVENTUALLY DEVELOP ACROSS MN/WI THIS MORNING AS THE DEFORMATION AXIS
LIFTS NORTHEASTWARD. IF THIS EARLY MORNING BATCH DOES NOT HOLD
TOGETHER WELL, IT MAY TAKE TILL 12-15Z TO GET GOING, WHICH IS WHEN
THERE IS BETTER SYNOPTIC-LEVEL SUPPORT FOR ASCENT. EITHER WAY,
WILL LOOK FOR UPSTREAM CONVECTION TO TRACK GENERALLY EASTWARD INTO
LOWER MI WITH TIME THROUGH THE DAY. THINK THE GREATEST INSTABILITY
WILL REMAIN TO OUR SOUTH AND WEST...BUT WE WILL BE ON THE
INSTABILITY GRADIENT AS A PLUME OF STEEPER LAPSE RATES ALOFT SNEAKS
IN THIS MORNING AND THE BOUNDARY (AND JUICIER BOUNDARY LAYER) LIFTS
BACK NORTHWARD. STICKY WICKET FOR SPICIER STORMS IS MID-LEVEL
WARMTH, AS IT WOULD PUT SOMETHING OF A CAP ON DEEP MOIST CONVECTION
POTENTIAL THIS AFTERNOON, PARTICULARLY IF WE DO NOT MOISTEN/WARM
ENOUGH IN THE LOW LEVELS TO OVERCOME THIS CAP (AND THIS MAY BE
HARDER TO DO AS WE MAY END UP ON THE NORTH AND LIKELY, STRATIFORM-
RAIN-WITH-EMBEDDED-THUNDER SIDE OF THE BOUNDARY). JET MAX MOVING
THROUGH TODAY (AND REDEVELOPING UPSTREAM THIS AFTERNOON) SHOULD
SUPPORT SUFFICIENT DEEP-LAYER SHEAR FOR STORM ORGANIZATION FOR THOSE
STORMS THAT DO GET GOING...AND COULD SUPPORT UPSCALE GROWTH WITH
TIME. BETTER SHOT AT THIS WOULD BE TO OUR SOUTH OR TO OUR WEST, THE
LATTER IDEA PARTICULARLY THIS AFTERNOON/TONIGHT WITH LLJ-DRIVEN
CONVECTION AGAIN (THOUGH PROGGED THICKNESS GRADIENT ORIENTATION
COULD TREND IT JUST TO OUR SOUTHWEST).
THINK HEAVY RAIN WILL BE A THREAT AGAIN TODAY, GIVEN THE DEEP WARM
LAYER, POTENTIAL FOR SKINNIER CAPE, AND RELATIVELY WEAK FLOW IN THE
LOW-LEVELS THAT COULD ALLOW STORMS/RAIN TO MOVE SLOWLY ALONG THIS
EAST-WEST(ISH) BOUNDARY IN THE REGION...NOT TO MENTION PWATS AT OR
ABOVE 1.5IN AGAIN. IF WE END UP WITH SOME SORT OF DEFORMATION AXIS
FORCING GOING THIS AFTERNOON, WE COULD BE LOOKING AT A SWATH OF
RAINFALL IN EXCESS OF 0.75-1IN IN 6HRS OR LESS, PERHAPS NEAR THE M-
72/M-55 CORRIDOR...BUT ANY STORMS COULD CERTAINLY PUT DOWN OVER AN
INCH OF RAIN (HI-RES PROB GUIDANCE SUGGESTS A NON-ZERO THREAT OF
RAINFALL TOTALS IN EXCESS OF 2IN, ALBEIT A VERY SMALL PERCENTAGE).
CURRENT FORECAST DOES NOT REFLECT THIS HIGHER-QPF IDEA ATTM, GIVEN
LACK OF CONFIDENCE IN WHERE THE STORMS WILL FOCUS...AND CERTAINLY
POSSIBLE THE HEAVIER TOTALS COULD END UP JUST SOUTH OF OUR AREA.
WE REMAIN CLOSE TO THE BOUNDARY FRIDAY, AND DEPENDING ON WHAT
HAPPENS TONIGHT, MAY BE DEALING WITH SOME LEFTOVERS FROM TONIGHT
FRIDAY MORNING. IT MAY NOT BE OUT OF THE QUESTION TONIGHT'S ACTIVITY
COULD START FURTHER NORTH ALONG THE EDGE OF THE 700MB CAP OVER THE
PLAINS, WHICH, IF IT OCCURS, COULD LEAD TO SOME UPSTREAM CONVECTION
SNEAKING IN FURTHER NORTH THAN EXPECTED...BUT WE MAY NOT KNOW TILL
TONIGHT IF THIS IDEA WILL TAKE PLACE. IT ALSO APPEARS WE COULD
REMAIN UNDER THE DEFORMATION AXIS THROUGH MUCH OF FRIDAY, WHICH
COULD KEEP THE THREAT OF BETTER RAINFALL AROUND INTO FRIDAY AS WELL.
A SIMILAR RIDGE-RIDING PATTERN REMAINS IN PLACE FRIDAY NIGHT, AND
WHILE IT IS MORE LIKELY THE ACTION WILL STAY TO OUR WEST/SOUTH IN WI
AND SOUTHERN MI, IT IS WORTH KEEPING AN EYE ON INTO AT LEAST THE
FIRST HALF OF SATURDAY. AS MENTIONED IN THE PATTERN FORECAST ABOVE,
IT APPEARS HIGH PRESSURE WILL TRY TO OOZE IN FROM THE NORTHEAST
BEYOND SATURDAY, WHICH SHOULD SHUNT THE BULK OF THE ACTION FURTHER
TO OUR WEST FOR THE REMAINDER OF THE WEEKEND.
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 554 AM EDT THU SEP 3 2026
PATCHY FOG WILL DISSIPATE THROUGH THE MORNING, WITH CHANCES FOR
AFTERNOON SHOWERS/ THUNDERSTORMS, ESPECAILLY ACROSS MBL. MAINLY
VFR CONDITIONS EXPECTED WITH GENERALLY LIGHT WINDS THROUGH THE
PERIOD, WITH CHANCES FOR FG/BR DEVELOPMENT YET AGAIN TONIGHT
INTO FRIDAY MORNING, POTENTIALLY DROPPING CONDITIONS TO MVFR/
IFR.
APX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...FEF
AVIATION...NSC
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