438
FXUS63 KAPX 312346
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
746 PM EDT FRI JUL 31 2026
KEY MESSAGES
- WIDESPREAD RAIN TONIGHT/SATURDAY AS A COOL-SEASON CYCLONE PASSES
SOUTH OF THE GREAT LAKES. HEAVY RAIN THREAT PARTS OF EASTERN
UPPER/NORTHEAST LOWER THIS EVENING.
- DRYING OUT FROM NORTH TO SOUTH SUNDAY (THOUGH COULD BE A SLOWER PROCESS
THAN WE WOULD LIKE).
- RAIN CHANCES RETURN WEDNESDAY.
DISCUSSION
ISSUED AT 316 PM EDT FRI JUL 31 2026
PATTERN SYNOPSIS/FORECAST: BROAD UPPER RIDGE ENCOMPASSES ROUGHLY THE
SOUTHERN HALF OF THE CONUS...SAVE FOR A LONG WAVE TROUGH THAT RUNS
ALONG THE EAST COAST. A SHORT WAVE TROUGH COMING OVER THE TOP OF
THE RIDGE AND INTO THE MIDWEST TODAY WILL BE A FEATURE OF INTEREST
HEADING INTO THE WEEKEND...A COUPLE OF SMALLER PV ANOMALIES ALSO
COMING OVER THE TOP OF THE RIDGE ACROSS IDAHO/MONTANA. LOW
AMPLITUDE WESTERLY FLOW ACROSS MUCH OF CANADA...EMANATING FROM A
LONG WAVE TROUGH OFF THE BRITISH COLUMBIA COAST. ANTICYCLONIC UPPER
LEVEL FLOW ACROSS THE GREAT LAKES TODAY WITH BROADLY DIFLUENT FLOW
AHEAD OF THE MIDWEST SHORT WAVE TROUGH; ALSO AHEAD OF THIS TROUGH IS
A NARROW AXIS OF DEEP LAYER MOISTURE (PRECIPITABLE WATER AT OR ABOVE
2.00 INCHES SPANNING THE MISSISSIPPI VALLEY). MID LEVEL DEFORMATION
ZONE EXTENDS FROM EASTERN NORTH DAKOTA/NORTHERN MINNESOTA/NORTHWEST
ONTARIO. AT THE SURFACE...1006MB LOW ALONG THE IOWA/MINNESOTA
BORDER WITH A WARM FRONT EXTENDING SOUTHEAST ACROSS IOWA AND ALONG
THE MISSISSIPPI RIVER. COLD FRONT WAS NORTH OF LAKE SUPERIOR INTO
NORTHERN MINNESOTA. BROAD HIGH PRESSURE ACROSS THE OHIO VALLEY AND
MID ATLANTIC REGION WITH SEVERAL HIGH CENTERS INCLUDING A 1016M HIGH
BUBBLE OVER SOUTHERN LOWER MICHIGAN.
COLD ADVECTION INTO THE BACKSIDE OF THE UPPER MIDWEST SHORT WAVE
TROUGH SUGGESTS A CONTINUED DIGGING AND STRENGTHENING OVER THE NEXT
24 HOURS...APPROACHING A -3 SIGMA 500MB HEIGHT ANOMALY ACROSS THE
MID MISSISSIPPI VALLEY. THIS TROUGH WILL SLOWLY MEANDER ACROSS THE
OHIO VALLEY THIS WEEKEND...WHAT HAPPENS BEYOND THAT IS UNCERTAIN.
WILL THIS SYSTEM TRACK INTO THE MID ATLANTIC MONDAY...WILL IT HANG
ON LONGER (SLOWER IS USUALLY THE BETTER WAY TO GO)...OR DOES THE
TROUGH SPLIT AND A PIECE GETS LEFT BEHIND TO DRIFT INTO THE
SOUTHEAST STATES EARLY NEXT WEEK? QUESTIONS ABOUT THE EVOLUTION OF
THIS FEATURE MAY NOT HAVE MUCH IMPACT ON THE UPPER LAKES...PROVIDED
WE CAN GET SOME HEIGHT RISES/SURFACE HIGH PRESSURE INTO THE REGION
BY TUESDAY AND THE "PIECE GETS LEFT BEHIND TO DRIFT INTO THE
SOUTHEAST STATES" IDEA MENTIONED ABOVE GETS SLINGSHOTTED BACK IN OUR
DIRECTION INSTEAD. REGARDLESS...THE TREND SHOULD BE TOWARD MORE
UNSETTLE WEATHER BY MIDWEEK...AS THE TROUGH CURRENTLY OVER THE
NORTHEAST PACIFIC MOVES INLAND AND TAKES UP RESIDENCE ACROSS CENTRAL
CANADA. THIS SHOULD SEND HEIGHT FALLS AND A COLD FRONT INTO THE
GREAT LAKES AROUND WEDNESDAY.
PRIMARY FORECAST CONCERNS:
WIDESPREAD RAIN TONIGHT/SATURDAY AS A COOL-SEASON CYCLONE PASSES
SOUTH OF THE GREAT LAKES. HEAVY RAIN THREAT PARTS OF EASTERN
UPPER/NORTHEAST LOWER THIS EVENING: UPSTREAM SYSTEM OVER SOUTHERN
MINNESOTA MUCH MORE REMINISCENT OF SOMETHING WE WILL BE MORE
FAMILIAR WITH IN A COUPLE OF MONTHS RATHER THAN SOMETHING WE
TYPICALLY SEE IN LATE JULY. BUT IT IS THERE...WITH A NICE
DEFORMATION PRECIPITATION SHIELD ACROSS SOUTHERN MINNESOTA/NORTHERN
WISCONSIN...AND A WARM FRONTAL RAIN BAND SPREADING NORTHEAST ACROSS
SOUTHERN WISCONSIN. MEANWHILE...AT THE ONSET THIS AFTERNOON THINGS
ARE JUST STARTING TO BUBBLE UP ON THE CLOUD FRONT...WITH THE LAKE
HURON BREEZE HAVING KICKED IN NORTH OF THUNDER BAY. ACROSS EASTERN
UPPER AN UNCAPPED MLCAPE 1000+J/KG... WITH LAKE BREEZE CONVECTION
UNDERWAY FROM MARQUETTE TO THE SOO. COMBINATION OF AFTERNOON
CONVECTION...EASTWARD EXTENSION OF PRECIPITATION BAND ACROSS
NORTHERN WISCONSIN/WESTERN UPPER...AND THE MAIN PRECIPITATION SHIELD
WRAPPING AROUND THE UPPER MIDWEST CYCLONE WILL BE THE IMPETUS FOR
RAIN ACROSS NORTHERN MICHIGAN TONIGHT AND SATURDAY. GIVEN HIGH
PRECIPITABLE WATER...K INDICES ABOVE 35...AND LIGHT CLOUD LAYER FLOW
THERE IS CONCERN FOR SLOW MOVING HEAVY DOWNPOURS THROUGH MIDNIGHT
ACROSS EASTERN UPPER AND PARTS OF NORTHEAST LOWER AND MAY CARRY AN
EXPLICIT HEAVY RAIN WORDING TO COVER THIS. A LOT OF MOISTURE AROUND
SATURDAY BUT NOT A LOT OF FORCING...THOUGH SOUTHERN PORTIONS OF THE
FORECAST AREA WILL STILL BE CLOSE TO THE MAIN DEFORMATION ZONE.
DRYING OUT FROM NORTH TO SOUTH SUNDAY (THOUGH COULD BE A SLOWER
PROCESS THAN WE WOULD LIKE): RAIN CHANCES SHOULD START TO COME TO
AN END ACROSS EASTERN UPPER AND PARTS OF NORTHWEST LOWER SATURDAY
NIGHT...BUT WILL CONTINUE INTO SUNDAY FOR ABOUT THE SOUTHEAST THIRD
OF THE FORECAST AREA. SLOW MOVING DEFORMATION ZONES CAN BE STUBBORN
IN CLEARING OUT...SO LATER FORECASTS MAY TREND TOWARD HANGING ONTO
SOME RAIN CHANCES OVER (AT LEAST) NORTHEAST LOWER FOR A BIT LONGER.
BUT EXPECTING THINGS TO DRY OUT ALL AREAS BY MONDAY.
RAIN CHANCES RETURN WEDNESDAY: HEIGHT FALLS AND A RESULTANT COLD
FRONT LOOKS TO CROSS THE UPPER LAKES TUESDAY NIGHT/WEDNESDAY WHICH
WILL BRING THE NEXT CHANCE FOR SHOWERS AND THUNDERSTORMS. OUTLOOK
BEYOND WEDNESDAY IS A BIT MORE UNCERTAIN...BUT REMOVED A LOT OF
SPOTTY SLIGHT CHANCE POPS FOR THURSDAY/FRIDAY FOR THE TIME BEING.
AVIATION /00Z TAFS THROUGH 00Z SUNDAY/
ISSUED AT 746 PM EDT FRI JUL 31 2026
SHOWERS AND A FEW STORMS WILL INCREASINGLY PREVAIL TONIGHT INTO
SATURDAY. VSBYS AND ESPECIALLY CIGS WILL TEND TO LOWER WITH
TIME. MVFR DEVELOPS EVERYWHERE OVERNIGHT INTO SATURDAY, AND IFR
SHOULD DEVELOP AT CIU. LIGHT WINDS.
APX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...JPB
AVIATION...JZ
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