681
FXUS63 KARX 250538
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1238 AM CDT FRI SEP 25 2026
KEY MESSAGES
- CHANCES (30-60%) FOR VERY LIGHT RAIN OVERNIGHT THURSDAY NIGHT. ADDITIONAL
LIGHT RAIN CHANCES (30-70%) FOR SATURDAY INTO SATURDAY NIGHT.
- DRY CONDITIONS TO START THE UPCOMING WEEK GIVE WAY TO
WIDESPREAD RAIN POTENTIAL FOR TUESDAY AND ONWARD.
- TEMPERATURES REMAIN FAIRLY STEADY OVER THE NEXT WEEK WITH
HIGHS IN THE 60S TO LOWER 70S.
DISCUSSION
ISSUED AT 1015 PM CDT THU SEP 24 2026
VERY LIGHT RAIN OVERNIGHT, LIGHT AGAIN SATURDAY AFTERNOON INTO
SATURDAY NIGHT
BELT OF VERY LIGHT RAIN HAS BEEN SLIDING EASTWARD THIS EVENING AHEAD
OF A LONGWAVE UPPER TROUGH SEEN ON IR OVER MN AS OF 03Z. WEAK
FORCING OVERALL AND NO INSTABILITY TO SPEAK OF HAS LED TO VERY LOW
RAIN RATES WITH MANY SITES STRUGGLING TO GET TO 0.01". HAVE THUS
CONTINUED TO GO WITH A MODERATE POP BUT VERY LOW QPF FORECAST FOR
THE RAIN OVERNIGHT TONIGHT.
SHORT LIVED UPPER HEIGHT RISES WILL LEAD TO A DRY FRIDAY BUT, BY
SATURDAY, ANOTHER LONGWAVE RIDGE MOVES OVER THE UPPER MIDWEST WITH A
LEAD IMPULSE SLOWLY ROLLING EASTWARD AROUND MIDDAY AND A SECOND
WAVE DURING THE NIGHTTIME HOURS. PROGGED MOISTURE REMAINS AN ISSUE
EAST OF THE MISSISSIPPI DUE THE INFLUENCE OF A DRY HIGH PRESSURE
SYSTEM IN THE GREAT LAKES AND VERY DRY MID-LEVELS AND SOMEWHAT DRY
CONDITIONS NEAR THE SURFACE SHOULD EAT INTO RAIN TOTALS, IF ANY.
FARTHER WEST, ENOUGH MOISTURE SHOULD (70-80%) SNEAK AROUND THE
SOUTHWESTERN EDGE OF THE HIGH TO LEAD TO LIGHT RAIN WITH WEAK
FORCING AND LACK OF INSTABILITY ONCE AGAIN KEEPING RAIN INTENSITY
AND CONCERNS FOR HAZARDS FOR THOSE OUTDOORS LOOKING AHEAD TO OCTOBER
VERY LOW.
NEXT WEEK: MILD, WIDESPREAD RAIN LIKELY TUESDAY
CONTINUED SOUTHEASTERLY SURFACE FLOW WILL ALLOW FOR SOME EVER SO
SLIGHT WARMING INTO MONDAY WITH HIGHS POTENTIALLY REACHING INTO THE
70S FOR MORE OF THE AREA. HOWEVER, DRY CONDITIONS ON MONDAY WILL
GIVE WAY TO INCREASING PROBABILITIES FOR WIDESPREAD RAINFALL ON
TUESDAY AS A LONGWAVE TROUGH AND ASSOCIATED SURFACE COLD FRONT WILL
SWEEP THROUGH THE LOCAL AREA THROUGHOUT THE DAY ON TUESDAY WITH
ALREADY FAIRLY HIGH PROBABILITIES (50-70%) FOR RAINFALL AMOUNTS OVER
0.25" ACROSS MUCH OF THE AREA IN THE GRAND ENSEMBLE
(GEFS/EC/CANADIAN ENSEMBLE). MUCH OF THESE HIGHER PROBABILITIES ARE
IN PART DUE TO A STRONG AXIS OF 850MB MOISTURE TRANSPORT SURGING
NORTH OUT AHEAD OF THIS FRONT WITH ANOMALOUS PRECIPITABLE WATERS AS
SHOWN IN GRAND ENSEMBLE (GEFS/EC/CANADIAN ENSEMBLE) WITH RESPECTABLE
PROBABILITIES (40-70%) FOR PRECIPITABLE WATERS OVER 1.5" ON TUESDAY.
SO COULD CERTAINLY SEE SOME HEALTHY RAINFALL TOTALS FROM THIS
SYSTEM, PARTICULARLY IF WE CAN GET SOME ELEVATED INSTABILITY TO WORK
ITS WAY INTO THE REGION.
FORECAST CONFIDENCE BEGINS TO LESSEN AS WE HEAD INTO WEDNESDAY AND
BEYOND AS THIS MOISTURE FETCH WILL BATTLE AGAINST THE NORTHWESTERLY
COOLER AND DRIER AIR IN LIGHT OF THE AFOREMENTIONED FRONT. THE KEY
MECHANISMS FOR PRECIPITATION POTENTIAL MID-WEEK WILL BE TIED TO A
FAIRLY ROBUST UPPER-LEVEL TROUGH EJECTING INTO THE SOUTH-CENTRAL
GREAT PLAINS DURING THE SECOND HALF OF THE WORK WEEK. THIS SYSTEM
WILL LIKELY SEE A BIT OF A "BOOST" IN MOISTURE AS WELL GIVEN IT WILL
BE INGESTING MOISTURE FROM THE REMNANTS OF HURRICANE POLO IN THE
SOUTHWEST CONUS. AS A RESULT, NOTING A FOOTPRINT IN THE SHIFT OF
TAILS OF 0 IN THE EC EXTREME FORECAST INDEX QPF FOR WEDNESDAY,
SUGGESTING THERE ARE A FEW EC MEMBERS SHOWING QPF REACHING THE 99TH
PERCENTILE OF CLIMATOLOGY FOR THIS TIME OF YEAR. MUCH TOO EARLY TO
DEDUCE IF THE LOCAL AREA MAY SEE ADDITIONAL RAINFALL FROM THIS
FEATURE AS IT MAY REMAIN TOO OUR SOUTH, BUT SOMETHING TO MONITOR
NEVERTHELESS.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1238 AM CDT FRI SEP 25 2026
AS THE LIGHT RAIN SHOWERS CONTINUE MOVING EASTWARD OVER THE
NEXT FEW HOURS, MVFR MIST/FOG MAY DEVELOP ACROSS THE REGION. THE
MAIN UNCERTAINTY REGARDING MIST/FOG DEVELOPMENT IS THE
INFLUENCE OF LOW TO MID-LEVEL CLOUD COVER OBSERVED ACROSS THE
UPPER MISSISSIPPI RIVER VALLEY, BUT AMPLE LOW LEVEL MOISTURE AND
SOME BREAKS IN THE CLOUDS WOULD SUPPORT PATCHY MIST/FOG
DEVELOPMENT. THE 25.00Z HREF/REFS ALSO DEPICT A 20-40% CHANCE OF
VISIBILITIES LESS THAN 5SM, SO HAVE MAINTAINED MENTIONS IN THE
TAFS.
EVEN IF MIST/FOG FAILS TO DEVELOP, MVFR IMPACTS IN THE FORM OF
LOW CEILINGS AROUND 2-3KFT LOOK TO DEVELOP EARLY THIS MORNING
AND CONTINUE THROUGH THE EARLY AFTERNOON FOR THOSE SITES WEST
OF THE MISSISSIPPI RIVER AND SOUTH OF I-90 WHERE A STRAY LIGHT
SHOWER ALSO CAN'T BE RULED OUT THIS AFTERNOON. OUTSIDE OF THESE
AREAS, VFR CONDITIONS ARE EXPECTED TO PREVAIL DURING THE DAYTIME
HOURS.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...FERGUSON/NAYLOR
AVIATION...FALKINHAM
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