710
FXUS63 KMPX 171100
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
600 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 /12Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 555 AM CDT THU SEP 17 2026
MESSY AVIATION SCENARIO TO OPEN THE 12Z PERIOD FOLLOWING THE
DEPARTURE OF EARLY MORNING SHOWERS. SATELLITE AND OBSERVATIONS
SHOW MVFR/IFR STRATUS ACROSS SOUTHERN MN AND INTO WESTERN WI.
THE WORST OF THE CONDITIONS ARE NEAR RWF, WHERE LIFR CIGS ARE
IN PLACE AT INITIATION. SATELLITE HAS CAPTURED SOME CLEARING
ACROSS CENTRAL MN, BUT THAT HAS ALLOWED FOR THE DEVELOPMENT OF
FOG AT STC AND SURROUNDING OBS. GENERAL THINKING IS THAT FOG
ERODES AFTER DAYBREAK, BUT THE LOW STRATUS LIKELY STICKS AROUND
FOR MUCH OF THE MORNING AND INTO THE AFTERNOON GIVEN A STRONG
INVERSION DISPLAYED ON FORECAST SOUNDINGS. HAVE DELAYED IMPROVEMENTS
TO VFR AT MOST TERMINALS AS A RESULT. AXN, STC, MSP, RNH & EAU
WILL LIKELY IMPROVE TO VFR BEFORE RWF & MKT. CIGS LOWER LATE
TONIGHT AHEAD OF HEAVY RAIN THAT IS FORECAST TO MOVE INTO
SOUTHWESTERN MN TOWARDS THE END OF THE 12Z PERIOD.
KMSP...LOW MVFR CEILING AT INITIATION, WITH A BRIEF DIP TO IFR
POSSIBLE THROUGH 14Z. LATEST TRENDS ARE SLOWER WITH DELAYING CIG
IMPROVEMENTS, SO THE 12Z TAF KEEPS MVFR CIGS IN PLACE UNTIL
20Z. SHOWER ARRIVE AROUND 12Z FRIDAY AND WILL BE FOLLOWED BY
HEAVIER RAIN AND VISIBILITY REDUCTIONS INTO THE 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
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