063
FXUS63 KARX 252337
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
637 PM CDT FRI SEP 25 2026
KEY MESSAGES
- LIGHT RAIN CHANCES INCREASE FOR SATURDAY WITH THE HIGHEST
CHANCES (40-70%) FOR AREAS WEST OF THE MISSISSIPPI RIVER.
- DRY CONDITIONS ON MONDAY GIVE WAY TO THE POTENTIAL (40-70%
CHANCE) FOR RAIN ON TUESDAY.
- MILD TEMPERATURES PERSIST THIS WEEKEND AND INTO NEXT WEEK WITH
HIGHS IN THE 60S TO LOWER 70S.
DISCUSSION
ISSUED AT 246 PM CDT FRI SEP 25 2026
SATURDAY - SUNDAY: LIGHT RAIN CHANCES SATURDAY, DRIER SUNDAY
AS WE HEAD INTO THE AFTERNOON ON SATURDAY, A SHORTWAVE TROUGH WILL
PUSH THROUGH THE GREAT PLAINS AND INTO THE UPPER MIDWEST WITH AN
INCREASING SOUTHERLY MOISTURE FETCH. IN THE PRESENCE OF THIS WAVE,
850MB MOISTURE TRANSPORT INCREASING FAIRLY CONSIDERABLY WITH
PRECIPITABLE WATER VALUES INCREASING TO AROUND 1.5" IN THE VICINITY
OF THE I-35 CORRIDOR. AS A RESULT, MUCH OF THE CAMS GENERALLY AGREE
ON SHIFTING AN AXIS OF LIGHT PRECIPITATION WITH THE SHORTWAVE
THROUGH PORTIONS OF NORTHEAST IA AND SOUTHEAST MN DURING THE MORNING
HOURS ON FRIDAY WITH HIGH CONFIDENCE (OVER 80%) FOR MEASURABLE
PRECIPITATION IN THE NBM FOR AREAS NEAR I-35. HOWEVER, AS THIS AXIS
OF RAIN PUSHES EASTWARD, IT WILL BE MORE REMOVED FROM THE
AFOREMENTIONED 850MB MOISTURE PLUME AND THUS HAVE MORE DRY AIR TO
CONTEND WITH. CONSEQUENTLY, MUCH OF THE CAMS GENERALLY AGREE ON
WEAKENING THIS AREA OF PRECIPITATION AS IT MOVES EAST RESULTING IN
LOWER CHANCES FOR PRECIPITATION ONCE YOU GET EAST OF THE MISSISSIPPI
RIVER. AS FAR AS RAINFALL AMOUNTS ARE CONCERNED, THE HIGHEST
PROBABILITIES (20-50%) FOR AMOUNTS OVER 0.25" IN THE RECENT HREF
GENERALLY REMAINS ALONG US-52 AND WEST WHERE THE BETTER MOISTURE IS
LOCATED. IN THE WAKE OF THIS SHORTWAVE, UPPER-LEVEL RIDGING BUILDS
INTO THE REGION FOR SUNDAY RESULTING IN DRIER CONDITIONS FOR MUCH OF
THE DAYTIME HOURS.
MONDAY - FRIDAY: DRY MONDAY, RAIN POTENTIAL ON TUESDAY
THE AFOREMENTIONED RIDGING REMAINS IN PLACE FOR MONDAY RESULTING IN
CONTINUED DRY CONDITIONS. WITH THE RIDGING IN PLACE AND VERY WEAK
SOUTHERLY SURFACE FLOW, WOULD EXPECT SOME INCREASE IN TEMPERATURES
FOR MONDAY WITH MEDIAN HIGH TEMPERATURES IN THE NBM REACHING INTO
THE UPPER 60S TO LOWER 70S AREAWIDE. HOWEVER, AS WE HEAD INTO
TUESDAY A BROADER TROUGH SWINGS INTO THE AREA FROM THE CANADIAN
ROCKIES WITH AN ATTENDING COLD FRONT. AS THIS OCCURS, MUCH OF THE
GRAND ENSEMBLE (GEFS/EC/CANADIAN ENSEMBLE) AGREES ON BRINGING
MEASURABLE PRECIPITATION INTO THE REGION WITH HIGH PROBABILITIES (70-
90%) DURING THE TUESDAY TIMEFRAME. ONE NOTICEABLE DIFFERENCE FROM
YESTERDAY IS THAT PROBABILITIES FOR 0.25" AMOUNTS OR GREATER HAVE
DECREASED (20-50%) IN THE GRAND ENSEMBLE (GEFS/EC/CANADIAN
ENSEMBLE). WHEN LOOKING AT THE CLUSTER ANALYSIS OF THE GRAND
ENSEMBLE DURING THIS PERIOD, THE GENERAL TREND THAT IS NOTED IS THAT
THE MAJORITY OF MEMBERS (ROUGHLY 75%) KEEP A SECONDARY UPPER-LEVEL
TROUGH OVER THE SOUTHERN ROCKIES FOR A LONGER PERIOD WHICH DOES NOT
PHASE WITH THIS UPSTREAM WAVE. CONSEQUENTLY, THINKING OUR TUESDAY
WAVE MAY BE MORE PROGRESSIVE AND CUT OFF FROM THE BETTER
MOISTURE ASSOCIATED WITH THE SECONDARY WAVE WHICH WOULD IN TURN
LIMIT RAINFALL TOTALS.
THE DOWNSTREAM IMPLICATION OF THIS ENSEMBLE FAVORED SCENARIO IS THE
AFOREMENTIONED SOUTHERN ROCKIES UPPER-LEVEL TROUGH TAKES LONGER TO
EJECT INTO THE GREAT PLAINS DURING THE WEEK. AS A RESULT, QUESTIONS
LINGER AS TO HOW LONG IT WOULD TAKE BEFORE AND IF ANY PRECIPITATION
WOULD REACH THE REGION. CONSEQUENTLY, THE GRAND ENSEMBLE
(GEFS/EC/CANADIAN) GENERALLY KEEPS MEASURABLE PRECIPITATION MODEST
(30-50%) THROUGH FRIDAY DUE TO THIS UNCERTAINTY. REGARDLESS, STILL
SOMETHING TO WATCH AS THIS FEATURE WILL LIKELY HAVE A RESPECTABLE
AMOUNT OF MOISTURE WITH IT AS IT INTERACTS WITH THE REMNANTS OF
HURRICANE POLO, SO CERTAINLY COULD SEE SOME HEALTHY RAINFALL AMOUNTS
WHERE THIS SYSTEM TRACKS. IN ANY CASE, WITH RELATIVELY WEAK SURFACE
FLOW AND MINIMAL CHANGE TO THE SYNOPTIC STREAM FLOW ALOFT, THINKING
THAT TEMPERATURES WILL REMAIN RELATIVELY STEADY-STATE WITH HIGHS
GENERALLY IN THE 60S TO LOWER 70S THROUGHOUT THE WEEK, AS SUPPORTED
IN THE 50TH PERCENTILE NBM.
AVIATION /00Z TAFS THROUGH 00Z SUNDAY/
ISSUED AT 637 PM CDT FRI SEP 25 2026
A SHORTWAVE TROUGH WILL MOVE NORTHEAST INTO THE UPPER
MISSISSIPPI VALLEY ON SATURDAY. AS THIS OCCURS, SHOWERS WILL
AND MVFR CEILINGS WILL MOVE INTO THE REGION. THE SHOWERS WILL
MOVE INTO SOUTHEAST MINNESOTA AND NORTHEAST IOWA ON SATURDAY
MORNING AND WESTERN WISCONSIN ON SATURDAY AFTERNOON. THE MVFR
CEILINGS WILL MOVE INTO NORTHEAST IOWA AND SOUTHEAST MINNESOTA
ON SATURDAY MORNING AND THEY WILL BE PRIMARILY WEST OF HIGHWAY
52. THESE MVFR CEILINGS WILL PERSIST INTO THE AFTERNOON.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...NAYLOR
AVIATION...BOYNE
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