438
FXUS63 KARX 041107
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
607 AM CDT THU SEP 4 2025
KEY MESSAGES
- RAIN AND WIND GUSTS OF 30-40 MPH LOOK ON TRACK FOR TONIGHT.
RAINFALL AMOUNTS OVER ONE-HALF INCH ARE MOST LIKELY IN
NORTHCENTRAL WI, NORTH OF HIGHWAY 29, LESS FURTHER SOUTH. WIND
GUSTS AROUND 40 MPH ARE MOST PROBABLE (40-50%) ALONG AND SOUTH
OF I-90 OVERNIGHT.
- POSSIBLY A RECORD COOL DAY ON FRIDAY IN SOME LOCATIONS WITH
HIGH TEMPERATURES OF 54-63F ACROSS THE AREA. WINDS WILL REMAIN
BREEZY 15-25 MPH FRIDAY.
- A SLOW WARMING TREND AFTER FRIDAY, WITH 70S BUILDING
NORTHEASTWARD NEXT WEEK.
DISCUSSION
ISSUED AT 258 AM CDT THU SEP 4 2025
RAIN STILL ON TRACK FOR TONIGHT, WITH WIND GUSTS OF 30-40 MPH
GOES WATER VAPOR IMAGERY IS SHOWING AN IMPRESSIVE WAVE RIPPING
SOUTHEAST ACROSS SASKATCHEWAN AT 08Z. THIS STRONG AND DYNAMICAL
SYSTEM IN NORTHWEST FLOW ARRIVES BY EARLY EVENING BRINGING RAIN
TO THE AREA. FORECAST CONFIDENCE IS HIGH IN A WIDESPREAD RAIN
WITH MULTIPLE CONSISTENT DAYS OF MODEL FORECASTS. STRONG
TROPOSPHERIC-DEEP FORCING AND ATTENDANT DEEPENING SURFACE LOW
PRESSURE SWEEP ACROSS THE AREA FROM WEST TO EAST, WITH THE
STRONGEST LIFT NORTH OF I-90 THIS EVENING. RAINFALL AMOUNT
TRENDS HAVE BEEN LOWER (HIGHER) SOUTH OF I-90 (NORTH OF I-94),
WITH AROUND 0.10" ACROSS SWRN WI, INCREASING TO 0.50-0.75" NORTH
OF HIGHWAY 29 IN WI BASED ON 04.00Z HREF LPMM. THIS SYSTEM AND
HIGHEST RAINFALL AMOUNTS HAVE TRENDED NORTH BY A COUNTY OR TWO
OVER THE LAST 24 HOURS. LIMITED INSTABILITY WILL KEEP THUNDER
CHANCES VERY LOW. THE QUICK MOTION OF THE SYSTEM, 6 HOURS OF
RAIN ROUGHLY, WILL ALSO BE A LIMITING FACTOR FOR RAINFALL
TOTALS.
WIND FORECASTS FOR TONIGHT CONTINUE TO TREND UPWARD ON AND BEHIND
THE COLD FRONT IN STRONG COLD AIR ADVECTION AND STEEPENING
LAPSE RATES. THE LATEST HRRR/RAP/NAMNEST SOUNDINGS SUGGEST
MIXING THROUGH ABOUT 2500 FEET WHERE NEARLY 40 KTS OF WIND IS
AVAILABLE TO TAP INTO, WITH A MEAN WIND IN THE LAYER JUST OVER
30 KTS AT ROCHESTER MN. THUS, 40 MPH GUSTS ARE ON THE TABLE NEAR
AND BEHIND THE COLD FRONT SWEEPING THROUGH FOR LOCATIONS NEAR/SOUTH
OF I-90, WITH THE 04.00Z SPC HREF IN THE 50-70% PROBABILITY
RANGE FROM ABOUT 10PM-6AM FOR 40 MPH+ WIND GUSTS. SOME DECREASE
IN THE LOW-LEVEL WIND FIELD THEN OCCURS FRIDAY MORNING, WITH
GUSTS TOPPING OUT AT 30 MPH FOR THE REMAINDER OF THE DAY. THIS
IS A LARGER MISS IT SEEMS FOR THE MUCH LOWER WIND GUST GUIDANCE
IN THE NBM. HAVE ADJUSTED THE WIND FORECAST UP TO INCLUDE GUSTS
TO NEAR 40 MPH.
FRIDAY IS THE COOLEST DAY, SOME WEEKEND SPRINKLES POSSIBLE
THE DEEP LONGWAVE TROUGH DOMINATING THE UPPER MIDWEST TO GREAT
LAKES WILL HOLD ITS INFLUENCE THROUGH ABOUT SUNDAY MORNING. WITH
STRONG COLD ADVECTION TONIGHT INTO FRIDAY, AND THE COLDEST
TEMPERATURES ALOFT OVERHEAD, WE ARE STILL FORECASTING RECORD
COOL HIGH TEMPERATURES ACROSS PARTS OF THE AREA. SOME AFTERNOON
SHOWERS MAY BE AROUND FRIDAY AND SATURDAY, ESPECIALLY INTO THE
COLDER AIR ALOFT NORTH OF I-90 WHERE THE INSTABILITY LAYER IS A
BIT DEEPER.
AFTER SUNDAY MORNING, HEIGHTS BEGIN TO RISE AS A HIGH AMPLITUDE
LARGE SCALE RIDGE BUILDS ACROSS THE HIGH PLAINS. PROLONGED
LOW-LEVEL SOUTHWESTERLY FLOW WILL YIELD SLOWLY WARMING
TEMPERATURES TO NEAR NORMALS (70-80F) BY MIDWEEK. PRECIPITATION
CHANCES LOOK LIMITED THROUGH NEXT THURSDAY.
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 603 AM CDT THU SEP 4 2025
MODERATE (60-80%) CONFIDENCE FOR AREA WIDE VFR THROUGH THE
04.12Z TAF PERIOD. NEAR SURFACE SMOKE CONCENTRATIONS OVER THE
MISSOURI RIVER VALLEY EARLY THIS MORNING CAUSING MVFR
VISIBILITIES ARE EXPECTED TO LESSEN, DECREASING OVERALL CONFIDENCE
FOR ANY LOCAL IMPACTS TODAY. MAIN CONCERN FOR AFTERNOON SMOKE
IMPACTS WILL LIE WEST OF THE MISSISSIPPI RIVER VALLEY WITH LOW
CONFIDENCE IN OVERALL EASTERN EXTENT, POTENTIALLY TONIGHT BEFORE
PRECIPITATION CHANCES INCREASE.
OTHER THAN RAINFALL ACCOMPANYING VISIBILITY IMPACTS, HIGH WINDS
WILL BE MAIN CONCERN WITH INCOMING PRECIPITATION CHANCES AS
WIDESPREAD 30+KT GUSTS ARE POSSIBLE. RAPID ROTATION EXPECTED TO
DIRECTION OF STRONGEST WINDS, FROM INITIALLY SOUTH NEAR 05.00Z,
WEST NEAR 05.03Z, TO WEST-NORTHWEST SHORTLY THEREAFTER. STRONGEST
WINDS SUBSIDE THROUGH FRIDAY MORNING ALBEIT REMAINING STRONG,
SUSTAINED 15+KT FROM THE NORTHWEST UNTIL FRIDAY NIGHT.
WHILE LLWS WASN'T ADDED AT THE CURRENT FORECAST DUE TO SURFACE
GUSTS INSTEAD CAUSING LOW LEVEL TURBULENCE, LLWS WILL NEED TO
BE REFINED IN COMING FORECAST(S) PRIMARILY AT INITIAL ONSET,
BEFORE SURFACE WINDS RESPOND TO STRONG LOW LEVEL JET.
SUBSEQUENT AVIATION IMPACTS POSSIBLE FRIDAY NIGHT THROUGH
SATURDAY WITH CURRENT CONFIDENCE PRIMARILY ALONG AND EAST OF THE
MISSISSIPPI RIVER IN CENTRAL WISCONSIN.
CLIMATE
ISSUED AT 258 AM CDT THU SEP 4 2025
RECORD COOL MAXIMUM TEMPERATURES AND THE CURRENT FORECAST.
LA CROSSE, WI
DATE RECORD COLD HIGH FORECAST HIGH
----- ----------- -----------
9/5 59F(1896) 62F
9/6 60F(1965) 63F
ROCHESTER, MN
DATE RECORD COLD HIGH FORECAST HIGH
----- ----------- -----------
9/5 59F(1956) 59F
9/6 58F(1965) 61F
ARX WATCHES/WARNINGS/ADVISORIES
WI...FROST ADVISORY UNTIL 8 AM CDT THIS MORNING FOR WIZ017-029.
MN...NONE.
IA...NONE.
DISCUSSION...BAUMGARDT
AVIATION...JAR
CLIMATE...BAUMGARDT
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