932
FXUS63 KARX 071647
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1145 AM CDT SUN SEP 7 2025
KEY MESSAGES
- UNSEASONABLY COOL TEMPERATURES TODAY WITH HIGHS IN THE UPPER
50S TO MIDDLE TO 60S. THEN TEMPERATURES WARM INTO THE 70S BY
MIDDLE OF THIS WEEK.
- SHOWERS AND A FEW STORMS EXPECTED MONDAY AFTERNOON INTO
TUESDAY. THEN MAINLY DRY WEATHER FOR THE REST OF THE WEEK.
DISCUSSION
ISSUED AT 226 AM CDT SUN SEP 7 2025
TODAY THROUGH TONIGHT
LATEST SURFACE ANALYSIS SHOWS RIDGE OF HIGH PRESSURE EXTENDING FROM
NORTHERN MISSOURI INTO NORTHERN MINNESOTA. THE SURFACE RIDGE WILL BE
THE DOMINANT WEATHER FEATURE ACROSS THE FORECAST AREA TODAY.
SUBSIDENCE UNDER SURFACE WILL ALLOW FOR MOSTLY SUNNY SKIES...LIGHT
WINDS (LESS THAN 10 MILES PER HOUR) AND DRY WEATHER ACROSS THE
FORECAST AREA. TEMPERATURES WILL REMAIN UNSEASONABLY COOL AS LATEST
NAEFS SUGGEST STANDARD ANOMALIES OF MINUS 2 TO MINUS 4 DEGREE
CELSIUS OVER THE REGION. HIGH TEMPERATURES ARE EXPECTED TO BE IN THE
UPPER 50S TO MIDDLE 60S.
MONDAY INTO TUESDAY NIGHT
RIDGE AXIS BUILDS EAST OF THE AREA AND SOUTHERLY FLOW ALOFT DEVELOPS
OVER THE NORTHERN PLAINS/UPPER GREAT LAKES MONDAY. SHORTWAVE TROUGH
MOVES INTO NORTHERN PLAINS MONDAY AFTERNOON/NIGHT. THE LATEST 07.00Z
GFS/ECMWF/NAM SHOW DECENT MOISTURE CONVERGENCE WITH THE SHORTWAVE
TROUGH. THE AXIS OF MOISTURE CONVERGENCE IS OVER WEST CENTRAL
WISCONSIN/EASTERN PART OF MINNESOTA AND THE FAR NORTHWEST PORTIONS
OF THE FORECAST AREA WILL BE ON THE FRINGE OF THIS AXIS MONDAY
EVENING. AS SHORTWAVE TROUGH SLOWLY PUSHES EAST THIS MOISTURE AXIS
WILL TRACK OVER THE FORECAST AREA AND SPREAD CONVECTION INTO THE
AREA MONDAY NIGHT. FORCING/VERTICAL MOTION...MOISTURE CONVERGENCE
WANES ACROSS FORECAST AREA TUESDAY AND CONVECTION WILL DIMINISH
DURING THE DAY. CAPE IS LIMITED WITH THE SHORTWAVE TROUGH...AS
SUGGEST 0-6KM MOST UNSTABLE CAPE OF 100-200 J/KG OVER THE
NORTHWEST/WESTERN PARTS OF THE FORECAST AREA WITH THE MAIN AXIS OF
INSTABILITY WEST OF THE FORECAST AREA. COVERAGE OF STORMS SHOULD BE
ISOLATED TO SCATTERED ACROSS THE FORECAST AREA MONDAY EVENING INTO
TUESDAY MORNING. ANY STORMS THAT DEVELOP SHOULD REMAIN BELOW SEVERE
LIMITS...AS CAPE IS LIMITED BELOW 500 J/KG SURFACE/ELEVATED CAPE AND
0-3KM SHEAR IS LESS THAN 20 KNOTS.
WEDNESDAY THROUGH SATURDAY
THE LATEST DETERMINISTIC MODELS ARE IN DECENT AGREEMENT WEDNESDAY
THROUGH FRIDAY ON BUILDING UPPER LEVEL RIDGE OVER THE CENTRAL UNITED
STATES/NORTHERN PLAINS STATES. THEN...THE MODELS/ENSEMBLES ARE IN
DISAGREEMENT ON WHEN UPPER LEVEL RIDGE BREAKS DOWN AND PLACEMENT OF
UPPER LEVEL TROUGHS/LOWS. SUBSIDENCE UNDERNEATH UPPER LEVEL RIDGE
WILL PROVIDE MAINLY DRY WEATHER ACROSS THE FORECAST AREA WEDNESDAY
THROUGH FRIDAY. TEMPERATURES WILL BE WARMER...AS WARMER AIR ALOFT
ADVECTS INTO THE REGION. 07.00Z ECMWF/GFS INDICATE 925MB
TEMPERATURES WARMING TO PLUS 15 TO PLUS 18 DEGREES CELSIUS BY 12Z
FRIDAY. HIGH TEMPERATURES ARE EXPECTED TO CLIMB INTO THE 70S AND
POSSIBLY IN THE LOW 80S AT FEW LOCATIONS LATE IN THE WEEK. WITH
UPPER LEVEL RIDGE BREAKING DOWN FRIDAY NIGHT INTO SATURDAY THERE IS
THE POSSIBILITY OF SOME SHOWERS OR STORMS MOVING INTO THE AREA.
HOWEVER...CONFIDENCE IS LOW ON PRECIPITATION CHANCES...BASED ON HOW
FAST THE RIDGE BREAKS DOWN AND PLACEMENT OF UPPER LEVEL TROUGHS/LOWS
OVER THE NORTHERN TIER UNITED STATES.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1145 AM CDT SUN SEP 7 2025
CIGS: A FEW FAIR WEATHER CU THIS AFTERNOON FOLLOWED BY SKC
CONDITIONS THIS EVENING THROUGH MOST OF THE OVERNIGHT. LOW/MID LEVEL
WARM AIR ADVECTION FAVORS THE DEVELOPMENT OF A MID LEVEL VFR DECK OF
CLOUDS ACROSS IA OVERNIGHT, SHIFTING NORTHEAST ACROSS THE TAF SITES
AFTER 12Z. A FEW HOURS OF 4-5KFT CIGS LIKELY MON MORNING.
CAVEAT FOR KLSE - WHILE FOG IMPACTS OVERNIGHT ARE NOT ANTICIPATED
(SEE SECTION BELOW), A LAYER OF STRATUS COULD DEVELOP ACROSS THE
MISSISSIPPI RIVER WITH DECOUPLED WINDS POTENTIALLY BRINGING THOSE
ACROSS THE AIRPORT. A LOW PROBABILITY AT THIS TIME (<20%), BUT
SOMETHING TO MONITOR.
WX/VSBY: INITIAL LIGHT WIND FIELD IN THE VERTICAL WILL SEE INCREASES
IN SPEED AND LOWERING OVERNIGHT AT KLSE PER RAP/HRRR SOUNDINGS.
THIS, ALONG WITH A RELATIVELY LARGER SPREAD IN T/TD, WILL WORK
AGAINST FOG IMPACTS AT KLSE.
MID LEVEL CLOUDS MON MORNING MIGHT PRODUCE A SPRINKLE OR TWO, BUT
LOW PROBABILITIES (<15%) PRECLUDE INCLUDING MENTION IN THE FORECAST.
WINDS: NORTHWEST BECOME LIGHT SOUTH/SOUTHEAST TONIGHT. WILL PICK UP
FROM THE SOUTH MONDAY WITH AFTERNOON GUSTS IN THE LOW 20 KTS.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...DTJ
AVIATION...RIECK
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