607
FXUS63 KMPX 312318
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
618 PM CDT MON AUG 31 2026
KEY MESSAGES
- BEST CHANCE OF RAIN COMES LATE TUESDAY NIGHT, FOLLOWED BY A
LOW CONFIDENCE PRECIPITATION FORECAST WITH MULTIPLE LOW
CHANCES FOR RAIN THROUGH LABOR DAY WEEKEND.
- SUMMER-LIKE TEMPERATURES AND HUMIDITY CONTINUE THROUGH LABOR
DAY WEEKEND.
DISCUSSION
ISSUED AT 409 PM CDT MON AUG 31 2026
THERE'S AN IMPRESSIVE BOWLING BALL UPPER LOW OVER SOUTHERN
SASKATCHEWAN AND MANITOBA THIS AFTERNOON, WHICH IS DRIVING A
COLD ACROSS WESTERN WI AND FAR SOUTHEAST MN. OUR POSITION SOUTH
OF THIS UPPER LOW PUTS US IN ITS ZONE OF SUBSIDENCE AND MID-
LEVEL DRY AIR, WHICH MEANS WE GET YET ANOTHER DRY COLD FRONT,
WHICH SEEMS PAR FOR THE COURSE FOR AN AUGUST THAT WILL SEE MSP
FINISH THE MONTH WITH JUST 0.46" OF RAIN (WE AVERAGE 4.34"),
WHICH IS THE 4TH DRIEST AUGUST ON RECORD AND JUST THE 8TH OUT OF
156 YEARS WHERE THE TWIN CITIES FAILED TO GET AT LEAST 1" OF
RAIN IN THE MONTH OF AUGUST. WITH THAT SAID, WE CAN'T COMPLETELY
RULE OUT RAIN IN THE MPX AREA THIS EVENING, BUT THAT CHANCE IS
IN EAU CLAIRE AND CHIPPEWA COUNTIES, TO THE EAST OF CHIPPEWA
FALLS AND EAU CLAIRE. EAST OF THE COLD FRONT, IT'S OPPRESSIVE
FOR THE LAST DAY OF AUGUST, WITH TEMPERATURES IN THE UPPER 80S,
DEWPOINTS IN THE MID 70S, AND HEAT INDEX VALUES IN THE MID 90S.
ALL OF THIS HEAT AND HUMIDITY IS TRANSLATING INTO INSTABILITY,
WITH A POOL OF 3000+ J/KG OF MLCAPE FORECAST DEVELOP AHEAD OF
THE FRONT. ALTHOUGH ISOLATED STORM CHANCES LOOK BETTER EAST OF
THE MPX AREA, THE HRRR HAS BEEN INITIATING STORMS IN EASTERN EAU
CLAIRE COUNTY AROUND 23Z FROM THE 15Z RUN THROUGH ITS MOST
CURRENT RUN (19Z), SO WE WILL HAVE TO KEEP AN EYE ON THE STORM
POTENTIAL OUT AROUND STANLEY AND AUGUSTA. AFTER THAT, THE REST
OF THE NIGHT WILL BE QUIET, WITH DRIER AIR MOVING IN LIMITING
THE FOG POTENTIAL IN MN (WHERE DEWPOINTS ARE IN THE MID 50S
ACROSS CENTRAL MN). WI WILL STILL HAVE RADIATIONAL FOG POTENTIAL
AS THEY WILL HOLD ON TO DEWPOINTS IN THE 60S THROUGH THE NIGHT.
THIS DRIER AIRMASS MOVING IN TODAY WILL STAY WITH US THROUGH THE
DAY ON TUESDAY, WITH DEWPOINTS IN THE UPPER 40S TO LOWER 60S
MAKING HIGHS TUESDAY IN THE 80S MORE TOLERABLE.
TUESDAY NIGHT IS WHEN THINGS START TO TURN MORE ACTIVE AS A
SHORTWAVE COMING OUT OF THE SOUTHWEST MONSOON TRAVELS ACROSS
SOUTHERN MN. MOST GUIDANCE SHOWS STORMS DEVELOPING ON THE NOSE
OF THE LLJ AND RIDING THE ELEVATED CAPE GRADIENT EAST TUESDAY
NIGHT. LOOKING AT THE HREF/REFS, THE POOL OF HIGH MUCAPE (OVER
3000 J/KG) WILL REMAIN NEAR/NORTH OF THE I-80 CORRIDOR IN IOWA,
WITH THE LLJ NOSING UP INTO NORTHERN IOWA. THIS ALL POINTS TO
THE MN/IA BORDER BEING THE ZONE MOST CONDUCIVE TO SEEING
THUNDERSTORMS/HEAVY RAIN, WITH A LIGHTER OVERRUNNING
PRECIPITATION AREA GETTING ABOUT AS FAR NORTH AS THE TWIN CITIES
METRO, WHICH WILL LIKELY MEAN CENTRAL MN INTO NORTHWEST WI
MISSES OUT ON THIS ONE. BASED ON WHERE THE LARGE SCALE FORCING
IS FORECAST TO BE, THE NBM THIS MORNING LOOKED TO HAVE DISPLACED
IT'S HIGHER POPS/QPF A BIT TOO FAR NORTH, SO DID NUDGE POPS A
BIT SOUTH TUESDAY NIGHT TO GET CLOSER TO WHERE THE FORCING IS.
WEDNESDAY THROUGH LABOR DAY BEGINS A PERIOD OF HIGH CONFIDENCE
IN SUMMER-LIKE WARMTH AND HUMIDITY FOR THE FIRST WEEK OF
METEOROLOGICAL FALL, BUT LOW CONFIDENCE ON PRECIPITATION.
FIGURING OUT SEVERE WEATHER POTENTIAL COMES DOWN TO FIGURING OUT
WHERE MOISTURE (FOR SAID STORMS), FORCING (SOMETHING TO PROVIDE
LARGE SCALE ASCENT FOR THAT MOIST AIR), INSTABILITY (SO THAT
THE ASCENDING MOIST AIR GOES UP IN A CONVECTIVE UPDRAFT), AND
WIND SHEAR (LET'S ORGANIZE THOSE STORMS!) ALL COME TOGETHER. THE
LARGE SCALE WEATHER PATTERN THROUGH THE WEEKEND WILL BECOME
AMPLIFIED AS A TROUGH DIGS INTO THE PAC NW. AS IT DIGS INTO THE
PAC NW, WE SEE THE RIDGE OVER THE CENTRAL CONUS AMPLIFY, WITH A
WESTERLY TO SOUTHWEST FLOW DEVELOPING ALOFT LOCALLY. THIS SETUP
WILL PUMP DEEP MOISTURE INTO OUR REGION FROM THE GULF AND
SOUTHWEST MONSOON. LOOKING AT THE 4 INGREDIENTS, WE'LL HAVE
PLENTY OF MOISTURE (MEAN EPS PWATS ARE 150% TO 200% OF NORMAL
THROUGH THE WEEKEND), GIVEN THE HEAT AND HUMIDITY, INSTABILITY
WILL BE AMPLE, AND WITH THE UPPER JET ALWAYS OVERHEAD/NEARBY,
WE'LL HAVE AMPLE WIND SHEAR AS WELL. THE BIG UNCERTAINTY THROUGH
THE WEEKEND IS THE FORCING VARIABLE. WITH THE BUILDING UPPER
RIDGE, FORCING LOOKS SUBTLE, WITH PRECIPITATION CHANCES TIED TO
WHERE THE WARM FRONT IS ON A DAILY BASIS AND WHERE ANY WEAK
WAVES MOVE THROUGH IN THE UPPER FLOW. IN OTHER WORDS, IT'S
MESOSCALE FEATURES THAT WILL BE DRIVING OUR PRECIPITATIONS,
WHICH IS HARD TO PARSE OUT MORE THAN 48 HOURS IN ADVANCE. THE
RESULT IS WHAT YOU GET WITH THIS FORECAST, NUMEROUS LOW CHANCES
FOR PRECIPITATION THROUGH THE HOLIDAY WEEKEND. AT THIS POINT,
ABOUT THE BEST WE CAN SAY IS WHATEVER WE GET, IT LOOKS TO BE
PREDOMINATELY NOCTURNAL IN NATURE. WILL WE MANAGE TO FINALLY
CASH IN ON A POTENTIAL ACTIVE WEATHER PATTERN? MAYBE, BUT WHEN
IT COMES TO FORECASTING PRECIPITATION IN A DROUGHT, I LIKE TO
LIVE BE THE MAXIM OF WHEN IN DROUGHT, LEAVE IT OUT.
AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 545 PM CDT MON AUG 31 2026
VFR CONDITIONS EXPECTED THROUGHOUT THIS DURATION. BEHIND THE
DEPARTING COLD FRONT, WEAK HIGH PRESSURE WILL BREEZE ACROSS THE
REGION TONIGHT INTO TOMORROW, RESULTING IN DIMINISHING WINDS
FROM SUNSET THROUGH SUNRISE, ALONG WITH MOSTLY CLEAR SKIES ASIDE
FROM PASSING HIGH CLOUDS. HIGH CLOUDS WILL INCREASE IN COVERAGE
DURING THE DAY TUESDAY, RESULTING IN HIGH CEILINGS FROM THE
AFTERNOON ONWARDS. AFTER LIGHT/VARIABLE WINDS TONIGHT, WINDS
PICK UP FROM THE W TO NW UNDER 10KTS DURING THE DAY TOMORROW.
KMSP...NO ADDITIONAL CONCERNS.
/OUTLOOK FOR KMSP/
WED...VFR. EARLY AM -RA LIKELY. CHC -TSRA LATE NIGHT. WIND SE 5
KTS.
THU...VFR. CHC TSRA MORNING AND AGAIN OVERNIGHT. WIND SE
5-10 KTS.
FRI...VFR. WIND S 5-10 KTS.
MPX WATCHES/WARNINGS/ADVISORIES
MN...NONE.
WI...NONE.
DISCUSSION...MPG
AVIATION...JPC
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