434
FXUS63 KARX 091040
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
540 AM CDT TUE SEP 9 2025
KEY MESSAGES
- POTENTIAL (15-50%) SHOWERS AND PERHAPS (10-20%) A RUMBLE OF
THUNDER TODAY AND TONIGHT, MAINLY FOR AREAS NORTH OF
INTERSTATE 90. NEITHER SEVERE STORMS NOR FLASH FLOODING ARE
EXPECTED.
- WARMING THROUGH SATURDAY WITH ABOVE NORMAL TEMPERATURES
EXPECTED THIS WEEKEND.
DISCUSSION
ISSUED AT 250 AM CDT TUE SEP 9 2025
SHOWERS AND STORMS TODAY/TONIGHT
A SHORTWAVE DISTURBANCE IS CURRENTLY TREKKING INTO WESTERN LAKE
SUPERIOR, CAUSING SHOWERS AND A FEW RUMBLES OF THUNDER WELL TO
OUR NORTH ACROSS THE NORTHWOODS. SECONDARY SHORTWAVES ARE
EXPECTED TO MOVE OUT OF THE DAKOTAS AND INTO THE THE REGION
THROUGH THE DAY, SETTING OFF CHANCES FOR SHOWERS AND STORMS.
OVERALL CHANCES LOOK TO BE BEST ACROSS THE CHIMNEY AND OUR
NORTHWESTERN COUNTIES, GENERALLY CORRELATED TO WHERE INSTABILITY
WILL BE MAXIMIZED AT AROUND 1000 J/KG MUCAPE. WARM TEMPERATURES
IN THE 850-700 MB LAYER LOOK TO LIMIT COVERAGE OF SHOWERS AND
STORMS OVERALL SO HAVE KEPT POPS IN THE 20-50% RANGE AREAWIDE
WITH THE HIGHEST CHANCES STILL ACROSS CLARK AND TAYLOR COUNTIES.
SHEAR IS VERY WEAK AT LESS THAN 20 KTS SO EVEN WITH MODEST
INSTABILITY, WE'RE NOT EXPECTING STORMS TO REACH STRONG TO
SEVERE THRESHOLDS. MOISTURE LOOKS TO BE MAXIMIZED IN THE SAME
REGION AS THE INSTABILITY WITH PWATS AROUND 1.5 INCHES. AS THIS
FALLS BELOW THE 90TH PERCENTILE IN SOUNDING CLIMATOLOGY, WE'RE
NOT EXPECTING A FLOODING THREAT WITH THESE SHOWERS AND STORMS,
EVEN WITH SOME TRAINING POSSIBLE. RAIN CHANCES PUSH EAST INTO
THE EVENING AND WANE INTO THE OVERNIGHT HOURS BETWEEN 06-12Z.
WARMING TREND THROUGH THE END OF THE WORK WEEK
AS WE MOVE INTO THE MID TO LATE PORTIONS OF THE WORK WEEK, AN
UPPER LEVEL RIDGE IS EXPECTED TO BUILD ACROSS THE PLAINS WITH
ITS AXIS GRADUALLY SHIFTING EAST INTO THE UPPER MISSISSIPPI
VALLEY THURSDAY AND FRIDAY. THIS WILL ALLOW HEIGHTS TO INCREASE
AND WARMER 850 MB TEMPERATURES TO SURGE NORTHWARD. BOTH OF THESE
FACTORS WILL BE AT THEIR PEAK FRIDAY AND SATURDAY WITH 850 MB
TEMPS AROUND 10 DEGREES ABOVE NORMAL FOR SEPTEMBER. HIGH
TEMPERATURES WEDNESDAY AND THURSDAY WILL BE ON AN UPWARD TREND
WITH 70S EXPECTED ON WEDNESDAY AND MID 70S TO LOW 80S ON
THURSDAY. THIS TREND WILL CONTINUE INTO FRIDAY AND SATURDAY
WITH 09.01Z NBM PROBABILITIES SHOWING A 60-90 PERCENT CHANCE OF
HIGH TEMPERATURES ABOVE 80 DEGREES FOR AREAS ALONG AND SOUTH OF
THE I-94 CORRIDOR. HIGHS WILL LIKELY BE LIMITED TO THE MID 80S
WITH ONLY A 10% CHANCE OF HIGHS REACHING THE 90 DEGREE THRESHOLD
IN THE RIVER VALLEYS. TEMPERATURES WILL COOL OFF SLIGHTLY
SUNDAY INTO EARLY PORTIONS OF NEXT WEEK BEHIND A WEAK COLD FRONT
WITH HIGHS IN THE MID 70S TO LOW 80S. THE ANOMALOUSLY WARM 850
MB TEMPERATURES ARE EXPECTED TO STAY THROUGH MID-NEXT WEEK WHICH
LOOKS TO PREVENT ANY SIGNIFICANT COOL-DOWN.
LOW RAIN CHANCES RETURN FOR THE WEEKEND
THE AFOREMENTIONED UPPER LEVEL RIDGE LOOKS TO WEAKEN BY THE
WEEKEND WITH UPPER LEVEL IMPULSES POTENTIALLY ROUNDING THE CREST
OF THE RIDGE ACROSS OUR AREA. SOUTHERLY LOW LEVEL FLOW WILL
HELP TO RETURN MOISTURE TO THE AREA WITH PWATS CLIMBING BACK TO
AROUND 1.25-1.5 INCHES. THE AFOREMENTIONED FRONT LOOKS TO
PROVIDE SOME KIND OF FOCUS FOR SHOWER AND STORM DEVELOPMENT BUT
GIVEN HOW WEAK IT'S EXPECTED TO BE, DEVELOPMENT LOOKS TO BE A
BIT MORE NEBULOUS IN NATURE. THE GFS AND EC ENSEMBLES TEND TO
HAVE DIFFERING SOLUTIONS IN HOW TO HANDLE THE UPPER LEVEL FLOW
SATURDAY ONWARDS. THE EC MEMBERS FAVOR AN OMEGA BLOCK TO OUR
NORTH AND SLIGHTLY INCREASED RAIN CHANCES FOR OUR AREA WITH THE
GFS MEMBERS FAVORING THE WEAK RIDGING TO CONTINUE AND EXTEND
NORTH INTO SOUTHERN CANADA. OVERALL, GIVEN THE LACK OF LARGE
SCALE FORCING AND LOWER THAN NORMAL CONFIDENCE IN THE UPPER
LEVEL PATTERN, HAVE CAPPED POPS SATURDAY THROUGH MONDAY AT
AROUND 30 PERCENT.
AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
ISSUED AT 537 AM CDT TUE SEP 9 2025
VFR CONDITIONS EXPECTED FOR THE NEXT 24 HOURS. SHOWERS AND
STORMS ARE EXPECTED TO MOVE INTO THE AREA LATER THIS MORNING
FROM THE NORTH AND WEST. DUE TO CONTINUED UNCERTAINTY IN HOW
THESE STORMS WILL EVOLVE INTO THE AFTERNOON, HAVE CONTINUED WITH
THE PROB30 GROUPS TO COVER CHANCES FOR PRECIPITATION AT THE
TERMINALS. SHOULD CONFIDENCE INCREASE IN EVOLUTION, AMENDMENTS
TO PREVAILING OR TEMPO GROUPS WILL LIKELY BE NEEDED. RAIN
CHANCES WILL WANE INTO THE EVENING BEFORE COMING TO AN END
OVERNIGHT. WIND GUSTS HAVE TAPERED OFF EARLY THIS MORNING BUT
SUSTAINED SPEEDS REMAIN IN THE 8-13 KT RANGE. GUSTS WILL BE
POSSIBLE AT THE RST TERMINAL LATER ON AND COULD PICK UP AGAIN IN
THE COMING HOURS. WINDS ARE EXPECTED TO DECREASE AREAWIDE THIS
EVENING, GENERALLY BECOMING LIGHT AND VARIABLE FOR THE OVERNIGHT
HOURS. FOG/MIST WILL BE POSSIBLE ACROSS SE MINNESOTA AND WEST
CENTRAL WISCONSIN TOMORROW MORNING BUT DUE TO ITS ANTICIPATED
PATCHY NATURE, HAVE LEFT IT OUT OF THIS PACKAGE; THOUGH IT MAY
NEED TO BE ADDED FOR RST IN FUTURE UPDATES.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...BARENDSE
AVIATION...BARENDSE
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