732
FXUS63 KARX 131830
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
130 PM CDT SAT SEP 13 2025
KEY MESSAGES
- A SUMMERY AIRMASS SETTLES IN THROUGH AT LEAST NEXT TUE WITH HIGHS
TOPPING OUT IN THE 80S. COOLER, MORE SEASONABLE CONDITIONS SET TO
RETURN BY THE END OF NEXT WEEK.
- SPOTTY RAIN CHANCES FOR THE START OF THE NEW WEEK (20%) WITH
INCREASED SHOWER/STORM CHANCES BY MID WEEK (40-50%).
DISCUSSION
ISSUED AT 130 PM CDT SAT SEP 13 2025
* WEEKEND INTO START OF NEXT WEEK: SUMMER HEAT!
THE UPPER LEVEL RIDGE AXIS SHIFTS EASTWARD FROM THE PLAINS TO ACROSS
THE UPPER MISSISSIPPI RIVER VALLEY TODAY, GRADUALLY EASING EAST
ACROSS THE GREAT LAKES AS AN UPPER LEVEL TROUGH SWINGS OVER THE
NORTHERN PLAINS. A FEW LOBES OF SHORTWAVE ENERGY MOVE THROUGH THE
TROUGH (FROM THE SOUTH AND NORTH), BUT GEFS AND EPS HOLD THE BULK OF
THAT UPPER LEVEL FORCING WEST/NORTH OF THE LOCAL AREA. WARM/MOIST
AIR POOLS UNDER THE RIDGE - MAKING IT FEEL A LOT MORE LIKE MID
SUMMER RATHER THAN THE START OF FALL.
> TEMPERATURES: THE CALENDAR SAYS SEPTEMBER BUT WALK OUTSIDE AND IT
FEELS LIKE JULY. 925 MB TEMPS IN THE NAM/GFS/EC ALL HOVER IN THE
LOW/MID 20S C THROUGH TUE. 850 MB TEMP ANOMALIES IN THE NAEFS AND EC
HOLD 1.5+ WHILE EFIS FOR HIGH TEMPS RUN FROM 0.5 TO 0.7 (HIGHEST TO
THE SOUTH). THE UPPER 75% OF THE GEFS AND EPS ENSEMBLE SUITES WARM
HIGHS INTO THE LOW TO MID 80S THROUGH TUE. THE GEFS REMAINS THE
WARMER OF THE GUIDANCE ALTHOUGH NOT QUITE AS WARM AS IT WAS A FEW
DAYS PRIOR. SOME UPPER 80S IN THE RIVER VALLEYS POSSIBLE AND CAN'T
COMPLETELY RULE OUT A LOCATION OR TWO FLIRTING WITH 90. NOT LOOKING
LIKE RECORD HEAT AT THIS TIME. ADD IN MID 60 DEWPOINTS AND THE HEAT-
HUMIDITY COMBO WILL HAVE MANY/MOST STARTING THEIR AC BACK UP.
> RAIN CHANCES: WHILE THE RIDGE LOOKS TO KEEP THE BULK OF THE
SHORTWAVE ACTIVITY TO THE WEST, THE LONG RANGE GUIDANCE REMAINS
ADAMANT THAT SOME RIPPLES IN THE FLOW WILL WORK ACROSS THE RIDGE,
SPINNING OVER THE REGION. WITH A SUMMERY AIRMASS IN PLACE, AMPLE
INSTABILITY (ESP FOR SEP) WILL BE ON HAND TO AID CONVECTIVE
POTENTIAL. SFC WARM FRONT MAY ALSO BE WAVERING ACROSS THE REGION.
HOWEVER, DIFFERENCES IN OPINION ON WHERE THESE SMALLER SCALE
"FORCERS" WILL BE, ALONG WITH TIMING, BETWEEN THE ENSEMBLE SUITES.
CONFIDENCE LOW IN THE DETAILS AS A RESULT. BECAUSE OF THE
DIFFERENCES, THE MODEL BLEND HOLDS POPS FROM 20-30% -
WHICH LOOK REASONABLE GIVEN THE CURRENT SETUP.
* MID NEXT WEEK INTO WEEKEND: COOLING DOWN, HIGHER RAIN CHANCES
THE UPPER LEVEL TROUGH GETS A PUSH EASTWARD BY MID WEEK, MARCHING A
COLD FRONT ACROSS THE MISSISSIPPI RIVER VALLEY. MUCH COOLER, LESS
HUMID (SEASONABLE) AIRMASS RETURNS. 75% OF THE GEFS AND EPS MEMBERS
FAVOR HIGHS IN THE UPPER 60S TO LOWER 70S BY THE FOLLOWING WEEKEND.
THE TROUGH WILL OFFER UP SOME SHOWER/STORM CHANCES WITH COLD
FRONT/SHORTWAVES ALL HAVING ROLES. HOW ORGANIZED ANY OF THESE RAIN
CHANCES WILL BE ISN'T CLEAR AT THIS TIME.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1235 PM CDT SAT SEP 13 2025
A 10-15K DECK OF CLOUDS WILL LINGER ALONG AND EAST OF THE
MISSISSIPPI RIVER THROUGH MUCH OF THE AFTERNOON. THESE CLOUDS ARE
ASSOCIATED WITH 700 MB FRONTOGENESIS.
THERE ARE MIXED SIGNALS FOR VALLEY FOG TONIGHT. WHILE THE NOCTURAL
INVERSION AND LONGER NIGHTS ARE FAVORABLE. THE WINDS ALOFT ARE NOT
LIGHT ALL NIGHT ARE NOT. AS A RESULT, THINKING THAT THERE WILL BE
SOME VALLEY FOG IN THE TRIBUTARIES AND WISCONSIN RIVER VALLEY.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...RIECK
AVIATION.....BOYNE
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