016
FXUS63 KMPX 171758
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1258 PM 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 /18Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 1240 PM CDT THU SEP 17 2026
IFR TO MVFR CIGS CONTINUE OVER THE NEXT FEW HOURS. HOWEVER, WE
ARE STARTING TO SEE MOVE SCT TO BKN CU MOVING NE TO SW ACROSS
THE REGION WITH CIGS INCREASING BACK TO VFR BY 19-20Z. WINDS
WILL BE LIGHT OUT OF THE NE/E THROUGH THE AFTERNOON AND EVENING.
BKN TO OVC RETURN TO THE REGION TONIGHT AS THE NEXT STORM SYSTEM
BRINGS WIDESPREAD LIGHT TO MODERATE SHOWERS THROUGH MOST OF
FRIDAY. TIMING FOR ONSET OF LIGHT SHRA IS BETWEEN 11-13Z WITH
CIGS AND VIS LOWERING SHORTLY AFTER FROM SW TO NE THROUGH THE
MORNING HOURS. MODERATE SHRA EXPECTED TO BEGIN AROUND 17-19Z
WITH FURTHER LOWERING OF CIGS AND VIS TO MVFR AND IFR
CATEGORIES. TEMPO GROUPS HAVE BEEN ADDED TO THIS TAF ISSUANCE,
INDICATING THE REDUCTIONS IN CIGS AND VIS. THREAT FOR TS IS VERY
LOW AS CONVECTIVE PARAMETERS DON'T SUPPORT MUCH IN TERMS OF
CONVECTION AND LIGHTNING. THAT SAID, EVEN THOUGH THE THREAT FOR
TS IS LOW, IT'S NOT ZERO. BUT FOR NOW, WITH LOW CONFIDENCE,
THERE'S NO MENTION IN TAF.
KMSP...MVFR CIGS WILL IMPROVE TO VFR BY 20Z WITH LIGHT E/NE
WINDS PREVAILING THROUGH THE EVENING AND OVERNIGHT. CLOUD
COVERAGE WILL INCREASE DURING THE OVERNIGHT BECOMING BKN TO
EVENTUALLY OVC AS THE NEXT STORM SYSTEM BRINGS WIDESPREAD LIGHT
TO MODERATE SHOWERS ON FRIDAY. ONSET OF LIGHT SHRA IS AROUND 12Z
WITH CIGS BEGINNING TO LOWER AND MINOR REDUCTIONS TO VIS.
MODERATE SHRA EXPECTED DURING THE LATE MORNING AND EARLY
AFTERNOON HOURS WITH MVFR TO IFR CIGS AND VIS LOOKING LIKELY,
ILLUSTRATED IN 18Z TAF. THREAT FOR TS IS VERY LOW AS CONVECTIVE
PARAMETERS DON'T SUPPORT MUCH IN TERMS OF CONVECTION AND
LIGHTNING. THAT SAID, EVEN THOUGH THE THREAT FOR TS IS LOW, IT'S
NOT ZERO. BUT FOR NOW, WITH LOW CONFIDENCE, THERE'S NO MENTION
OF TS IN TAF.
/OUTLOOK FOR KMSP/
SAT...VFR. WIND NE 5-10G20KTS.
SUN...VFR. WIND NE 5-10G20KTS.
MON...VFR. WIND E 5-10G15KTS.
MPX WATCHES/WARNINGS/ADVISORIES
MN...NONE.
WI...NONE.
DISCUSSION...BORGHOFF
AVIATION...LPR
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page