381
FXUS63 KARX 242358
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
658 PM CDT THU SEP 24 2026
KEY MESSAGES
- LIGHT RAIN CHANCES (30-60%) ACROSS PORTIONS OF SOUTHEAST MN
AND NORTHEAST IA THIS EVENING AND OVERNIGHT. ADDITIONAL LIGHT
RAIN CHANCES (20-60%) 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 137 PM CDT THU SEP 24 2026
REST OF TODAY - TONIGHT: LIGHT RAIN MOVES INTO THE REGION
INCREASING PRECIPITATION CHANCES ARE EXPECTED INTO THE EVENING AND
OVERNIGHT AS A MID-LEVEL SHORTWAVE DEPICTED ON GOES-19 WATER
VAPOR IMAGERY AND RAP 500MB HEIGHTS MOVES NORTH OF THE REGION
THIS EVENING. CONSEQUENTLY, MUCH OF THE CAMS PUSH PRECIPITATION
INTO PORTIONS OF SOUTHEAST MN AND NORTHEAST IA BY LATE AFTERNOON
AND INTO THE EVENING HOURS TODAY. OVERALL, THE FORCING REGIME
WITH THIS WAVE IS NOT OVERLY IMPRESSIVE WITH MUCH OF THE FORCING
BEING FROM MID-LEVEL Q-VECTOR CONVERGENCE LEADING AHEAD OF THE
WAVE. ADDITIONALLY, WITH A DECENT AMOUNT OF DRY AIR IN PLACE
EAST OF THIS FEATURE FROM NORTHEASTERLY FLOW, THINKING THAT THIS
SYSTEM WILL STRUGGLE TO PRECIPITATE EAST OF THE MISSISSIPPI
RIVER. CONSEQUENTLY, THE RECENT HREF HAS FAIRLY LOW
PROBABILITIES (10-30%) FOR RAINFALL AMOUNTS OVER 0.05" EAST OF
THE MISSISSIPPI RIVER. IN ANY CASE, GIVEN THE FAIRLY WEAK
FORCING REGIME AND DRY AIR, PROBABILITIES FOR RAINFALL AMOUNTS
OVER 0.25" ARE VERY LOW (UNDER 10% CHANCE) IN THE RECENT HREF.
FRIDAY - SUNDAY: STAYING MILD, ADDITIONAL RAIN CHANCES
AS WE HEAD INTO FRIDAY AND THE WEEKEND, UPPER-LEVEL RIDGING WILL
BUILD INTO THE REGION FOR FRIDAY, WHICH IN TURN SHOULD KEEP US
FAIRLY DRY DURING THE DAYTIME HOURS. WITH SOME WEAK SOUTHEASTERLY
FLOW IN PLACE, MAY SEE TEMPERATURES NUDGE UP A COUPLE OF DEGREES
WITH A FEW SPOTS TOPPING 70 DEGREES, HOWEVER GIVEN HOW WEAK THIS
SOUTHERLY PUSH IS, WOULD NOT EXPECT TOO MUCH MODIFICATION TO
THE AMBIENT AIRMASS THAT HAS BEEN IN PLACE. REGARDLESS, GOING
INTO SATURDAY WE SEE ANOTHER SHOT FOR RAIN AS A SECONDARY 500MB
SHORTWAVE PUSHES THROUGH THE GREAT PLAINS AND INTO THE UPPER
MIDWEST. OVERALL, THERE SEEMS TO BE A SIMILAR STORY WITH THIS
SYSTEM AS WELL AS MUCH OF THE BETTER MOISTURE REMAINS WEST OF
THE MISSISSIPPI RIVER WITH PRECIPITABLE WATERS OVER THE ONE INCH
MARK IN BOTH THE NAM/GFS, PARTICULARLY NEAR I-35. AS A RESULT,
THE GRAND ENSEMBLE (GEFS/EC/CANADIAN ENSEMBLE) KEEPS MUCH OF THE
HIGHER MEASURABLE PRECIPITATION PROBABILITIES (50-90%) WEST OF
THE MISSISSIPPI RIVER WITH LOW PROBABILITIES (20-50%) EAST OF
THE MISSISSIPPI RIVER. IN THE WAKE OF THIS SYSTEM FOR SUNDAY,
DETERMINISTIC GUIDANCE GENERALLY FAVORS CONTINUED WEAK
SOUTHEASTERLY FLOW, WHICH SHOULD ALLOW FOR SOME SLIGHT WARMING
IN TEMPERATURES. HOWEVER, GIVEN THAT MEDIAN HIGH TEMPERATURES
FOR SUNDAY REMAIN ONLY IN THE MIDDLE TO UPPER 60S, THINKING THAT
MINIMAL WARMING WILL OCCUR.
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 /00Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 641 PM CDT THU SEP 24 2026
LIGHT RAIN WILL LIKELY (50-70%) SPREAD EASTWARD OVER THE NEXT
FEW HOURS, AFFECTING BOTH RST/LSE. THIS SHOULD BE LIGHT ENOUGH
THAT VISIBILITY REDUCTIONS WILL NOT OCCUR. HOWEVER, WINDS OUT
OF THE SOUTHEAST ALONG WITH THE INCREASE IN SURFACE MOISTURE MAY
LEAD TO FOG SO HAVE INCLUDED MVFR FOR A FEW HOURS OVERNIGHT
AFTER THE LIGHT RAIN ENDS.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...NAYLOR
AVIATION...FERGUSON
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