300
FXUS63 KMPX 170743
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
243 AM CDT THU SEP 17 2026
KEY MESSAGES
- WIDESPREAD HEAVY RAIN IS EXPECTED FRIDAY INTO EARLY SATURDAY,
WITH AMOUNTS IN EXCESS OF 2-4" LIKELY FROM THE SOUTHERN TWIN
CITIES METRO SOUTH TOWARDS THE MINNESOTA/IOWA BORDER.
- FLOODING IS POSSIBLE WHERE REPEATED ROUNDS OF HEAVY RAIN
OCCUR, WITH THE GREATEST CONCERN FRIDAY NIGHT INTO EARLY
SATURDAY MORNING.
DISCUSSION
ISSUED AT 243 AM CDT THU SEP 17 2026
AN AREA OF SHOWERS REMAINS ONGOING ACROSS EAST CENTRAL MN INTO
ALL OF WEST CENTRAL WI, DRIVEN BY SOUTHWESTERLY 850 MB MOISTURE
TRANSPORT ACROSS SOUTHERN MN. RAIN TOTALS HAVE BEEN PRETTY
IMPRESSIVE WITH MRMS SUGGESTING THREE STREAKS OF 3/4"+ AMOUNTS -
ST. CLOUD AND EAST, WILLMAR AND EAST, AND FROM LE SUEUR CO AND
EAST. ESTIMATES ARE EVEN HIGHER ACROSS CENTRAL MEEKER AND
SOUTHERN WRIGHT COUNTIES WHERE NEAR AN INCH AND HALF HAS LIKELY
FALLEN. THE MOISTURE TRANSPORT WILL VEER WITH TIME AND SHOULD
ALLOW THE SHOWERS TO FOCUS MORE IN WISCONSIN BEFORE THINGS DRY
OUT FOR THE REST OF THE DAY. LOW CLOUDS AND LIGHT FOG HAVE
DEVELOPED ACROSS SOUTHERN AND WESTERN MN. IT SHOULD TAKE SEVERAL
HOURS TO BEGIN CLEARING OUT TODAY, POSSIBLY NOT UNTIL LATE
AFTERNOON WITH A HEALTHY INVERSION ABOVE 5 KFT, BUT FORECAST
SOUNDINGS DO SHOW IT OCCURRING EVENTUALLY.
ATTENTION THEN TURNS TO THE HEAVY RAIN THREAT FRIDAY. THE SYSTEM
IS CURRENTLY OVER THE FOUR CORNERS/SOUTHERN ROCKIES AND IS
BEING DRIVEN NORTH BY AN UPPER LOW OVER THE WEST COAST AND THE
VERY LARGE AND INTENSE RIDGE ACROSS THE SOUTH. IT WILL BEGIN TO
CREST THE RIDGE AND REACH THE UPPER MIDWEST LATE TONIGHT AND
FRIDAY. NOT MUCH HAS CHANGED WITH RESPECT TO THE OVERALL IDEA OF
THIS SYSTEM'S EVOLUTION, BUT NOW THAT CAMS ARE BEGINNING TO
CAPTURE THE EVENT, SOME SMALLER SCALE DETAILS ARE BECOMING
CLEARER. BY EARLY FRIDAY MORNING, A LARGE SHIELD OF SHOWERS WILL
BE ADVANCING INTO CENTRAL AND SOUTHERN MN, WITH THE HEAVIEST
RATES OVER EASTERN SD. AS THE DAY PROGRESSES, THIS SHIELD WILL
PUSH EAST ACROSS THE AREA AND THEN WEAKEN LATE IN THE DAY.
HEAVY RAINFALL TOTALS (1-2+ INCHES) ARE LIKELY WHERE THE
ELONGATED SHIELD PERSISTS THE LONGEST. MOST MODELS HIGHLIGHT AN
AREA FROM WEST CENTRAL MN TOWARDS THE METRO AS THE HIGHEST
LIKELIHOOD. THAT ROUND WILL BE DRIVEN PRIMARILY BY MID LEVEL
FORCING. A SECOND ROUND TIED TO THE SURFACE WARM FRONT SHOULD
DEVELOP LATER IN THE DAY FARTHER SOUTH ACROSS SOUTH CENTRAL AND
SOUTHEAST MN INTO NORTHEAST IA. THERE WILL BE POTENTIAL FOR VERY
HEAVY TOTALS IN THIS AREA GIVEN THAT TRAINING THUNDERSTORMS IS
A POSSIBILITY WITH STORM MOTIONS PARALLEL TO THE SURFACE FRONT.
HOW FAR NORTH THIS DEVELOPS AND WHETHER IT WILL INTERSECT ANY
HARD HIT AREAS FROM THE FIRST ROUND IS THE MAIN QUESTION. GIVEN
LARGE SPREAD IN THE GUIDANCE WITH MEMBERS CONTINUALLY SHIFTING
AROUND, A BLENDED APPROACH FOR QPF REMAINS APPROPRIATE. NBM MAY
BE TOO HIGH IN SOME PLACES AND NOT HIGH ENOUGH IN OTHERS, BUT
IT DOES SUFFICIENTLY HIGHLIGHT THE AREAS OF MOST CONCERN - THE
SOUTHERN PORTION OF THE METRO AND SOUTH/EAST FROM THERE INTO
NORTHEAST IA AND SOUTHWEST WI.
THE FRONT WILL SETTLE SOUTH BEHIND THE FRIDAY SYSTEM, BRINGING
DRIER WEATHER SATURDAY. THE UPPER LOW OUT WEST WILL MAKE SLOW
PROGRESS EAST AND BRING ANOTHER CHANCE OF SHOWERS LATE SUNDAY
INTO MONDAY.
AVIATION /06Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 1236 AM CDT THU SEP 17 2026
SHIELD OF RAIN & THUNDERSTORMS IS DEPARTING EAST INTO CENTRAL WI
FOR THE START OF THE 6Z PERIOD. WE'LL HAVE A FEW HOURS OF
LINGERING SHOWERS AT THE EASTERN MN/WESTERN WI TERMINALS BEFORE
DRY WEATHER RETURNS. MVFR/IFR CONDITIONS ACROSS SOUTHERN MN WILL
EXPAND NORTHWARD IN THE COMING HOURS AND HAVE INCLUDED TEMPOS
FOR IFR (OR LOWER) CIGS AND VISIBILITY THAT WILL PREVAIL THROUGH
DAYBREAK BEFORE IMPROVEMENTS ARE OBSERVED MID-MORNING. RWF/MKT
WILL BE STUCK IN THE VERY LOWER CIGS/FOG THE LONGEST, BUT
EVENTUALLY ALL TERMINALS OBSERVE IMPROVEMENTS TO VFR BY EARLY
AFTERNOON. LIGHT WINDS BETWEEN 5-7KTS OUT OF THE ENE TODAY.
KMSP...HEAVIEST RAIN HAS MOVED EAST OF THE TERMINAL, THOUGH
WE'LL KEEP THE CHANCE FOR ADDITIONAL SHOWERS IN THE TAF UNTIL
8Z. BANK OF MVFR (AND LOWER) CEILINGS AND VISIBILITY IS CREEPING
NORTH INTO SOUTHERN MN. ANTICIPATE MVFR CEILINGS WILL REACH THE
TERMINAL AROUND 8Z AND WE'VE ALSO INCLUDED A TEMPO FOR IFR CIGS
WITH VISIBILITY REDUCTIONS THROUGH 12Z. MVFR CIGS WILL BE SLOW
TO CLEAR AFTER DAYBREAK, BUT VFR CONDITIONS WITH LIGHT EASTERLY
FLOW SHOULD RETURN BY LATE MORNING.
/OUTLOOK FOR KMSP/
FRI...MVFR/RA. CHC IFR W/-TSRA. WIND SE 10-15G30KTS.
SAT...VFR. WIND NE 5-10G20KTS.
SUN...VFR. WIND NE 5-10G20KTS.
MPX WATCHES/WARNINGS/ADVISORIES
MN...NONE.
WI...NONE.
DISCUSSION...BORGHOFF
AVIATION...STRUS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page