315
FXUS63 KARX 121043
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
543 AM CDT FRI SEP 12 2025
KEY MESSAGES
- SUMMERTIME WARMTH FOR THE END OF THE WEEK INTO EARLY NEXT WEEK
AS HIGHS SURGE BACK INTO THE 80S TO EVEN NEAR 90 DEGREES.
- SCATTERED STORMS TONIGHT (30-40%) AND POSSIBLY SUNDAY NIGHT
(10-20%) WITH PERIODIC RAIN CHANCES (20-30%) FROM WEDNESDAY TO
FRIDAY OF NEXT WEEK.
DISCUSSION
ISSUED AT 245 AM CDT FRI SEP 12 2025
RETURN OF SUMMERTIME WARMTH!
THE MAIN STORY FOR MUCH OF THE FORECAST WILL BE THE RETURN OF
SUMMERTIME HEAT. WARMER LOWER TO MID-TROPOSPHERIC AIR ADVECTS
NORTHEASTWARD FROM THE SIOUXLAND REGION TODAY AS 925-700-MB
MAXIMUM TEMPERATURES INCREASE FROM +12 AS OF MIDNIGHT TO +20C BY
THE END OF THE DAY. SOUTH TO SOUTHWESTERLY FLOW REMAINS IN
PLACE FOR THE WEEKEND AND INTO MUCH OF NEXT WEEK, KEEPING ABOVE
AVERAGE TEMPERATURES IN PLACE DURING THIS PERIOD.
THE WARMEST DAYS ARE SHAPING UP TO BE OVER THE WEEKEND WITH AN
AMPLIFIED MERIDIONAL UPPER TROPOSPHERIC RIDGE FIRMLY IN CONTROL.
THE NBM INPUTS ARE ALL TIGHTLY CLUSTERED IN THE MID TO UPPER
80S FOR SATURDAY AND SUNDAY WITH FAVORED VALLEY LOCALES SUCH AS
LA CROSSE MAKING A RUN AT 90 DEGREES. WHILE THE EC EXTREME
FORECAST INDEX HAS VALUES OF 70-80% FOR SAT-MON, OUR DAILY
RECORDS IN THE MIDDLE 90S (SET BACK IN THE 1930S) DO NOT APPEAR
TO BE WITHIN REACH.
MOVING INTO NEXT WEEK, THE AFOREMENTIONED RIDGE BUCKLES TO THE
EAST, BUT DOES NOT BREAK. THIS KEEPS THE WARMER AIR MORE OR LESS
IN PLACE, THOUGH TEMPERATURES SHOULD MODERATE SOMEWHAT OWING TO
AN INCREASED POTENTIAL FOR SHOWERS AND STORMS.
MOSTLY DRY THROUGH EARLY NEXT WEEK
A PASSING RIBBON OF 800-700-MB THETA-E ADVECTION ALONG AND
NORTH OF A SURFACE WARM FRONT LOOKS TO BE ENOUGH TO SPARK AT
LEAST SCATTERED SHOWERS AND STORMS LATER THIS EVENING INTO THE
OVERNIGHT HOURS. SHEAR PROFILES ARE WEAK/COMPLEX AND MUCAPE
VALUES TOP OUT AROUND 500-800 J/KG, THUS SEVERE WEATHER IS NOT
EXPECTED. THE 00Z HREF MEMBERS ALL SHOWED NOTABLE INCREASES IN
THEIR PRECIPITATION COVERAGE FOR THIS EVENT AND HAVE FOLLOWED
SUITE WITH INCREASING POPS TO AROUND 30-40%.
THE NEXT SHOT OF RAIN COMES SUNDAY NIGHT AS A SHARP UPPER LEVEL
WAVE LIFTS NORTHWARD THROUGH THE DAKOTAS. WITH THE REGION STILL
UNDER THE INFLUENCE OF THE GREAT LAKES RIDGE, PRECIPITATION
WILL STRUGGLE TO ADVANCE EASTWARD AND POPS ARE ONLY AROUND 10-20
PERCENT WEST OF THE MISSISSIPPI RIVER. THE RIDGE SHIFTS
EASTWARD JUST ENOUGH BY WEDNESDAY TO ALLOW THE NEXT SHORTWAVE TO
CUT DEEPER INTO THE UPPER MIDWEST, SERVING AS THE NEXT
POTENTIAL SOURCE OF RAINFALL.
ON THE WHOLE, GIVEN THE LIMITED FORCING, RAINFALL AMOUNTS FROM
ANY OF THESE EVENTS IN THE NEXT WEEK SHOULD BE LIMITED IN
INTENSITY AND SCOPE. THAT BEING SAID, GIVEN THE SUMMERTIME
MOISTURE IN PLACE--PWATS OF 1-1.5 INCHES AND DEEPER PACIFIC
MOISTURE WORKING INTO THE CENTRAL U.S.--LOCALIZED MESOSCALE
FORCING WITHIN THE WEAKER FLOW PATTERN COULD YIELD TARGETED
REGIONS OF HIGHER RAINFALL AMOUNTS OF OVER AN INCH (NOTED IN THE
00/06Z HRRR EAST OF THE MISSISSIPPI RIVER BY SATURDAY MORNING).
AVIATION /12Z TAFS THROUGH 12Z SATURDAY/
ISSUED AT 540 AM CDT FRI SEP 12 2025
LIFR FOG AND STRATUS CURRENTLY OVER CENTRAL WI AND THE
WISCONSIN RIVER VALLEY LIFTS BY MID-MORNING. PREDOMINANTLY VFR
CONDITIONS ARE THEN FORECAST FOR THE REMAINDER OF THE TAF PERIOD
OUTSIDE OF A 30-40% CHANCE OF HIGH-BASED SHOWERS MOVING IN FROM
THE WEST AFTER 22Z AND DEPARTING BY 12Z SAT. WINDS INCREASE OUT
OF THE SOUTHEAST AT 5-15G15-25 KTS TODAY, STRONGEST WEST OF THE
MISSISSIPPI RIVER THIS AFTERNOON. WINDS SUBSIDE SOMEWHAT AFTER
SUNSET BUT COULD STILL BE GUSTIER AT HIGHER ELEVATIONS.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...SKOW
AVIATION...SKOW
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