989
FXUS63 KARX 120450
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1150 PM CDT THU SEP 11 2025
KEY MESSAGES
- WARMER TEMPERATURES EXPECTED FOR THE WEEKEND AND EARLY NEXT
WEEK WITH HIGHS IN THE MIDDLE TO UPPER 80S FOR MOST.
- SMALL CHANCES (10-30%) FOR SHOWERS AND STORMS LATE FRIDAY AND
AGAIN SUNDAY NIGHT.
DISCUSSION
ISSUED AT 125 PM CDT THU SEP 11 2025
REST OF TODAY - FRIDAY: SEASONABLE, SMALL RAIN CHANCES LATE FRIDAY
EAST OF MISSISSIPPI RIVER
GOES-19 WATER VAPOR IMAGERY AND 11.15Z RAP 500MB HEIGHTS THIS
AFTERNOON DEPICT UPPER-LEVEL RIDGING THAT IS BEGINNING TO
AMPLIFY INTO THE REGION. AS THIS OCCURS, THIS WILL ALLOW BOTH
850MB TEMPERATURES TO INCREASE WITH CLEAR SKIES AND EFFICIENT
DIURNAL MIXING ALLOWING OUR SFC TEMPERATURES TO WARM INTO THE
UPPER 70S AND LOWER 80S TO END THE WORK WEEK. CANNOT RULE OUT
SOME FOG POTENTIAL AGAIN TONIGHT, ESPECIALLY EAST OF THE
MISSISSIPPI RIVER, WITH MINIMAL SKY COVER OVERHEAD AND LIGHT
SURFACE WINDS. HOWEVER, FAIRLY STRONG WINDS JUST OFF THE SURFACE AT
2KFT TO AROUND 20-30 KTS IN THE RAP/HRRR GIVES SOME PAUSE TO
FOG POTENTIAL. HIGHEST CONFIDENCE FOR ANY FOG WOULD BE NEAR AND
EAST OF I-90/94 IN WEST-CENTRAL WI AS THE 11.12Z HREF HAS
RESPECTABLE PROBABILITIES (30-60%) FOR 1/4 MILE VISIBILITIES BUT
VIRTUALLY NONE FURTHER WEST TOWARDS THE MISSISSIPPI RIVER.
AS WE HEAD INTO FRIDAY NIGHT, THE RIDGE WILL CONTINUE TO
AMPLIFY BUT WILL OBSERVE SOME WEAK THETA-E ADVECTION ALONG THE
EASTERN PERIPHERY OF THIS RIDGE. AS A RESULT, NOTING SOME
INCREASE IN PRECIPITATION CHANCES IN THE 11.12Z HREF WITH LOW-
END PROBABILITIES (10-30%) FOR MEASURABLE PRECIPITATION ACROSS
WEST-CENTRAL AND NORTH-CENTRAL WI ON FRIDAY EVENING THROUGH THE
OVERNIGHT. REGARDLESS, LIMITED INSTABILITY (UNDER 500 J/KG OF
MLCAPE) IN THE 11.15Z RAP WOULD SUGGEST ANY UPDRAFTS THAT DO GET
GOING DURING THE OVERNIGHT PERIOD WOULD LIKELY BE ON THE WEAKER
SIDE AND THUS WOULD KEEP QPF TO A MINIMUM AS SHOWN IN THE VERY
LOW (UNDER 20%) PROBABILITIES FOR AMOUNTS OVER 0.1" IN THE
11.12Z HREF.
SATURDAY - TUESDAY: WARM WITH ADDITIONAL SMALL SHOWER/STORM CHANCES
LOOKING INTO SATURDAY, THE AFOREMENTIONED UPPER-LEVEL RIDGE AMPLIFIES
EVEN FURTHER AND PUSHES A FAIRLY WARM AIRMASS INTO THE REGION FOR
THE WEEKEND WITH MINIMAL PRECIPITATION CHANCES AFTER SATURDAY
MORNING. ADDITIONALLY, 850MB TEMPERATURES ALMOST CERTAINLY
EXCEED 20C FOR MUCH OF THE LOCAL AREA AS SHOWN IN THE GRAND
ENSEMBLE (GEFS/EC/CANADIAN ENSEMBLE). WHILE THERE HAS BEEN
FAIRLY LARGE DISAGREEMENT BETWEEN THE GEFS AND EC ENSEMBLE OVER
THE PAST FEW DAYS, THE MOST RECENT ENSEMBLE GUIDANCE HAS TRENDED
THE EC CLOSER TO THE GEFS SOLUTION WHICH WOULD FAVOR A WARMER
SCENARIO. GIVEN THAT THERE IS LITTLE DEVIATION BETWEEN THESE TWO
ENSEMBLE GROUPS IN THEIR INTER-QUARTILE SPREAD FOR HIGH
TEMPERATURES THIS WEEKEND, THINKING THAT HIGHS IN THE MIDDLE 80S
TO NEAR 90 IN THE NBM ARE FEASIBLE AND THUS HAVE MAINTAINED
THEM IN THIS FORECAST ITERATION.
AS WE START THE UPCOMING WORK WEEK, AN UPPER-LEVEL TROUGH WILL PIVOT
WEST OF THE LOCAL AREA THROUGH THE DAKOTAS AND WESTERN MN. AS THIS
OCCURS, SHOWER AND STORM CHANCES INCREASE. PARTICULARLY WEST OF THE
MISSISSIPPI RIVER, WITH MEDIUM TO HIGH PROBABILITIES (50-75%) IN THE
GRAND ENSEMBLE (GEFS/EC/CANADIAN ENSEMBLE) FOR MEASURABLE RAINFALL
OVERNIGHT SUNDAY. OVERALL, MINIMAL PROBABILITIES FOR ANY SEVERE
WEATHER POTENTIAL ARE PRESENT IN MACHINE LEARNING GUIDANCE AT
THIS TIME WITH THE FENGWU/PANGU AI SEVERE OUTLOOK GUIDANCE ONLY
HAVING SOME SPORADIC 5% PROBABILITIES FROM SUNDAY THROUGH
TUESDAY. IN ADDITION TO THE INCREASED SHOWER AND STORM CHANCES
WITH THIS WAVE, THE AFOREMENTIONED UPPER-LEVEL RIDGE WILL NUDGE
SLIGHTLY EASTWARD WHICH WILL ALLOW FOR TEMPERATURES TO MODERATE
SOME BUT WILL LIKELY REMAIN NEAR TO SLIGHTLY ABOVE NORMAL WITH
HIGHS IN THE LOWER TO MIDDLE 80S THROUGH TUESDAY.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1150 PM CDT THU SEP 11 2025
IFR TO LIFR FOG IS EXPECTED TO DEVELOP ACROSS CENTRAL WI AND
WITHIN THE WISCONSIN RIVER VALLEY LATER TONIGHT, LIFTING BY
MID-MORNING. VFR CONDITIONS ARE THEN FORECAST FOR THE REMAINDER
OF THE TAF PERIOD WITH A 30-40% CHANCE OF HIGH-BASED SHOWERS
MOVING IN FROM THE WEST AFTER 00Z. WINDS AFTER SUNRISE INCREASE
OUT OF THE SOUTHEAST AT 5-15G15-20 KTS, STRONGEST WEST OF THE
MISSISSIPPI RIVER THIS AFTERNOON.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...NAYLOR
AVIATION...SKOW
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