612
FXUS63 KARX 151110
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
610 AM CDT FRI AUG 15 2025
KEY MESSAGES
- MULTIPLE ROUNDS OF STORMS, INITIALLY THIS EVENING, CONTINUE THROUGH
MONDAY. STORMS WILL BE CAPABLE OF HEAVY RAINFALL, POTENTIALLY
LEADING TO LOCALIZED FLASH FLOODING OVER THE WEEKEND
PRIMARILY ALONG AND NORTH OF INTERSTATE 90.
- STRONG TO SEVERE STORMS POSSIBLE LATE THIS AFTERNOON INTO THE
OVERNIGHT PRIMARILY ALONG AND NORTH OF INTERSTATE 90. LARGE
HAIL AND DAMAGING WINDS WILL BE THE PRIMARY THREATS.
ADDITIONAL SEVERE STORM POTENTIAL FROM SATURDAY THROUGH
MONDAY.
- SATURDAY HEAT INDICES FROM THE MIDDLE 90S TO AROUND 100F SOUTH
OF INTERSTATE 94.
DISCUSSION
ISSUED AT 330 AM CDT FRI AUG 15 2025
TODAY - TONIGHT: STORMS MOVE IN NORTH OF I-90 BY EVENING, SCATTERED
STRONG TO SEVERE STORMS POSSIBLE
GOES-19 WATER VAPOR IMAGERY AND 15.06Z RAP 500MB HEIGHTS DEPICTS OUR
REGION BEING SUBJECTED TO QUASI-ZONAL FLOW EARLY THIS MORNING WITH
SMALL RIPPLES IN THE FLOW BEING NOTED. AS WE CONTINUE INTO THE
MIDDLE OF THE MORNING, SOME OF THE CAMS DEVELOP SOME SHOWER ACTIVITY
ON THE NOSE OF SOME LOW-LEVEL WARM ADVECTION AND ISENTROPIC UPGLIDE
ACROSS SOUTHEAST MN AND WEST-CENTRAL WI. CANNOT RULE OUT SOME
EMBEDDED THUNDER WITH THIS AS THE 15.03Z RAP HAS MUCAPE VALUES
ROUGHLY AROUND 1000-1500 J/KG. HOWEVER, THIS WILL QUICKLY PUSH EAST
AND HAVE MINIMAL SHEAR TO SUPPORT THEM SO WOULD LIKELY STRUGGLE AS
DEPICTED IN THE CAMS. OTHERWISE, WILL LIKELY BE RELATIVELY RAIN FREE
FOR THE LATE MORNING AND EARLY AFTERNOON TODAY PER MUCH OF THE CAMS.
EYES THEN TURN TO LATER THIS AFTERNOON AND EVENING AS AN AXIS OF
850MB MOISTURE TRANSPORT ASSOCIATED WITH AN ENHANCING LOW-LEVEL JET
BRINGS STRONG ISENTROPIC ASCENT INTO PORTIONS OF EASTERN MN AND
WEST/NORTH-CENTRAL WI DURING THIS TIMEFRAME. AS A RESULT, MUCH OF
THE CAMS AGREE ON DEVELOPING CONVECTION DURING THIS 4-8PM WINDOW
JUST NORTHWEST OF THE LOCAL AREA IN NORTHWESTERN WI AND SOUTH/EAST-
CENTRAL MN. INITIALLY, CONVECTION WILL FAVOR A DISCRETE MODE, PERHAPS
EVEN SUPERCELLULAR, WITH THE 15.03Z RAP FAVORING 0-6KM BULK
SHEAR VALUES OF 30-50 KTS AND ELONGATED HODOGRAPHS AROUND 6-8PM
IN THE 15.03Z RAP SOUNDINGS NEAR THE TWIN CITIES. AS THESE
STORMS SLIDE ALONG AND NORTH OF I-90 DURING THE EVENING,
UNCERTAINTY ON IF THEY WILL REMAIN DISCRETE OR TREND LINEAR. IF
STORMS REMAIN QUASI-DISCRETE, MID-LEVEL LAPSE RATES OF 7-8
C/KM, MUCAPE VALUES APPROACHING 3500- 4000 J/KG AND "RELATIVELY
LOW" WARM CLOUD DEPTHS OF 3500-4000M WOULD FAVOR A LARGE HAIL
THREAT. THAT SAID WITH THE BORDERLINE SHEAR IN PLACE, STORMS MAY
ORGANIZE IN A LINEAR FASHION ON THEIR COLD POOLS LATER INTO THE
EVENING AND OVERNIGHT WHICH WOULD THEN TREND TO MORE OF A
DAMAGING WIND THREAT. ALSO, CANNOT FULLY RULE OUT A TORNADO OR
TWO IN THIS ENVIRONMENT WITH AROUND 100-150 0-1KM SRH AND 0-3KM
SHEAR OF UP TO 30 KTS AT TIMES THIS EVENING, HOWEVER WITH SOME
CAPPING TO POTENTIALLY WORK AGAINST, CONFIDENCE IN THIS THREAT
IS QUITE LOW.
SATURDAY: MULTIPLE ROUNDS OF STORMS WITH HEAVY RAIN, LOCALIZED FLASH
FLOODING POSSIBLE NORTH OF I-90
THE FORECAST BECOMES SIGNIFICANTLY MORE CHALLENGING BEGINNING
SATURDAY AS AN UPPER-LEVEL RIDGE NUDGES INTO THE AREA FROM THE
SOUTH, ESTABLISHING A QUASI-STATIONARY FRONT OVER THE LOCAL AREA.
GET USED TO HEARING ABOUT THIS QUASI-STATIONARY FRONT AS IT WILL BE
VITAL FACTOR FOR OUR WEATHER FOR THE NEXT FEW DAYS. THE PRE-DAWN
HOURS ON SATURDAY WILL FEATURE AN AXIS OF ROBUST 850MB MOISTURE
TRANSPORT SITUATED RIGHT OVER THE LOCAL AREA WHICH WILL TRANSVERSE
THIS BOUNDARY AND CONTINUE TO INVIGORATE CONVECTION INTO THE MORNING
HOURS ON SATURDAY, ALBEIT WITH SOME DRAMATIC LOCATION DIFFERENCES
AMONGST THE CAMS. THIS WILL LIKELY PERSIST THROUGHOUT MUCH OF THE
DAY ON SATURDAY AS EACH ROUND OF STORMS WILL MODIFY THE POSITION OF
THE QUASI-STATIONARY BOUNDARY WHICH IN TURN WILL AFFECT WHERE THE
NEXT ROUND OF STORMS DEVELOPS, ETC. AS A RESULT, CONFIDENCE REMAINS
ON THE LOW SIDE AS TO WHERE CONVECTION WILL DEVELOP AT ANY
PARTICULAR PLACE AND TIME ON SATURDAY.
HOWEVER, THIS BRINGS US TO THE PRIMARY CONCERN FOR SATURDAY WHICH
WILL BE THE HEAVY RAIN AND LOCALIZED FLASH FLOODING RISK, PRIMARILY
NORTH OF I-90 AS THIS IS WHERE THE INSTABILITY GRADIENT AND ASCENT
IS CURRENTLY SITUATED AMONGST SHORT-RANGE GUIDANCE. OVERALL, THE
ENVIRONMENT IS FAVORABLE FOR EFFICIENT RAIN PRODUCERS ON SATURDAY
WITH WARM CLOUD DEPTHS IN THE 15.00Z NAM/GFS BEING OVER 4000 METERS
AND PRECIPITABLE WATERS OF 1.75-2", WHICH IS APPROACHING THE SPC
CLIMATOLOGICAL MAXIMUM AT KDVN OF AROUND 2" FOR THIS TIME OF YEAR.
ADDITIONALLY, CURRENT RFC 3-HR FLASH FLOOD GUIDANCE DEPICTS
AROUND 2-2.5" FROM A LINE EXTEND FROM ROUGHLY ROCHESTER, MN
NORTHEAST THRU CLARK COUNTY, WISCONSIN WHERE AROUND 2-6" OF
RAINFALL FELL LAST WEEKEND.
THERE REMAINS SOME SEVERE POTENTIAL ON SATURDAY AS WELL WITH ROBUST
INSTABILITY STILL IN PLACE WITH MUCAPE VALUES PUSHING 3000-4000
J/KG. SHEAR DURING THIS PERIOD APPEARS SLIGHTLY MORE NEBULOUS WITH
FAIRLY WEAK FLOW ALOFT DURING THIS PERIOD. OVERALL THE PRIMARY
THREAT DURING THIS PERIOD WOULD LIKELY BE ASSOCIATED WITH DAMAGING
WINDS IF ANY MCS CAN ORGANIZE INTO A LINEAR COMPLEX THROUGHOUT THE
DAY. OTHERWISE, LARGE HAIL SEEMS FAR LESS LIKELY WITH THE
AFOREMENTIONED WARM CLOUD DEPTHS.
ASIDE FROM THE STORM POTENTIAL, WARM AND MUGGY CONDITIONS ARE
ANTICIPATED SOUTH OF THE QUASI-STATIONARY BOUNDARY WITH HEAT INDICES
REACHING INTO THE MIDDLE 90S TO AROUND 100 DEGREES SOUTH OF
INTERSTATE 94. STILL SOME QUESTIONS EXACTLY HOW WARM IT WILL GET
WITH THE AFOREMENTIONED CONVECTION AROUND SO HAVE HELD OFF ON ANY
HEAT ADVISORY ISSUANCE AT THIS TIME, ESPECIALLY CONSIDERING THAT THE
GRAND ENSEMBLE (GEFS/EC/CANADIAN ENSEMBLE) ONLY HAS LOW TO MEDIUM
PROBABILITIES (20-50%) TO HIT 100 FOR HEAT INDEX SOUTH OF THE MN/IA
STATE LINE.
SUNDAY - MONDAY: POTENTIAL FOR ADDITIONAL ROUNDS OF HEAVY RAIN
THE OVERALL PATTERN REALLY DOES NOT CHANGE GOING INTO SUNDAY AND
MONDAY AS THE AFOREMENTIONED STATIONARY FRONT SIMPLY WOBBLES
SLIGHTLY OVER THIS PERIOD AS CONVECTION PUSHES IT SOUTHWARD AND
DIURNAL RECOVERY PUSHES IT NORTHWARD. AS A RESULT, ADDITIONAL ROUNDS
OF STORMS WOULD SEEM FEASIBLE WITH ANY RIPPLES IN THE MID-LEVEL FLOW
AND 850MB MOISTURE TRANSPORT TRAVERSE THIS BOUNDARY. OVERALL, THE
PRECIPITABLE WATERS AND WARM CLOUD DEPTHS CHANGE VERY LITTLE OVER
THE WEEKEND AND INTO MONDAY WITH THE 15.00Z NAM/GFS KEEPING WARM
CLOUD DEPTHS OF 4000 METERS THROUGH MONDAY. CONSEQUENTLY, WILL HAVE
TO CLOSELY MONITOR HOW THIS BOUNDARY BEHAVES OVER THE SUBSEQUENT
DAYS AS AREAS COULD RECEIVE MULTIPLE ROUNDS OF EFFICIENT RAINFALL
THROUGH MONDAY WHICH MAY LEAD TO FLOODING ISSUES. OVERALL CONFIDENCE
IS FAIRLY HIGH FOR WIDESPREAD QPF TOTALS THROUGH MONDAY OF 2" OR
GREATER ALONG AND NORTH OF I-90. THIS IS REFLECTED IN THE GRAND
ENSEMBLE (GEFS/EC/CANADIAN ENSEMBLE) WHICH HAS RESPECTABLE
PROBABILITIES (30-60%) FOR THESE AMOUNTS BUT THE TRUE PROBABILITY IS
LIKELY HIGHER THAN THIS GIVEN THE ENVIRONMENT. ADDITIONALLY, IF
STORMS MOVE OVER THE SAME LOCATIONS MULTIPLE TIMES, WOULD EXPECT
THAT LOCALIZED AMOUNTS WELL IN EXCESS OF THIS WOULD BE POSSIBLE.
AS FAR AS SEVERE POTENTIAL, CONFIDENCE FOR STRONG TO SEVERE STORMS
IS FAIRLY LOW ON SUNDAY AND MONDAY AS THIS WILL BE HEAVILY
CONTINGENT ON HOW PREVIOUS CONVECTION MANIFESTS AND INFLUENCES THE
BOUNDARY. THAT BEING SAID, FAIRLY ROBUST DCAPE AND STEEP LOW-LEVEL
LAPSE RATES OF 7-8 C/KM IN THE 15.00Z NAM ON SUNDAY NEAR THE
BOUNDARY WOULD SUGGEST AT LEAST SOME POTENTIAL FOR SOME DAMAGING
WIND GUSTS DEPENDING ON HOW STORMS ORGANIZE GIVEN THAT DEEP-LAYER
SHEAR PROFILES ARE FAIRLY LACKLUSTER ON SUNDAY.
TUESDAY - NEXT FRIDAY: COOLER, SOME RAIN CHANCES TUESDAY
AS WE HEAD TOWARDS THE MIDDLE OF THE UPCOMING WORK WEEK, WE FINALLY
BEGIN TO EXIT THIS PATTERN OF HEAVY RAIN AS AN UPPER-LEVEL RIDGE
DEVELOPS OVER THE EASTERN ROCKIES. WHILE THIS OCCURS, OUR REGION
BEGINS TO BECOME SUBJECT TO NORTHWESTERLY FLOW WHICH EJECTS ONE
FINAL SHORTWAVE TOWARDS THE AREA DURING THE DAY ON TUESDAY. OVERALL
THE GRAND ENSEMBLE (GEFS/EC/CANADIAN ENSEMBLE) IS NOT OVERLY
IMPRESSED WITH THIS WAVE AND ATTENDANT COLD FRONT WITH ONLY MEDIUM
PROBABILITIES (30-60%) FOR OVER 0.1" OF QPF. HOWEVER, AS THIS WAVE
EXITS THE AREA, A COOLER AND DRIER AIRMASS WILL BE ADVECTED INTO THE
AREA ALLOWING OUR TEMPERATURES TO TREND SEASONABLE FOR THE ENTIRE
LOCAL AREA AND KEEPING PRECIPITATION CHANCES AT BAY FOR WEDNESDAY
AND INTO THE END OF THE UPCOMING WORK WEEK.
AVIATION /12Z TAFS THROUGH 12Z SATURDAY/
ISSUED AT 555 AM CDT FRI AUG 15 2025
IMMEDIATE TERM IMPACT IS SINGLE CELL STORM OVER KLSE TAF SITE,
SLOWLY SHIFTING SOUTHEAST DOWN THE MISSISSIPPI RIVER VALLEY.
EXPECT ACCOMPANYING IMPACTS TO DEPART SHORTLY AFTER TAF
ISSUANCE.
SUBSEQUENT IMPACTS EXPECTED TOWARDS THE END OF THE TAF PERIOD
WITH INCREASING STORM COVERAGE FROM WEST TO EAST ALONG WESTERN
PERIPHERY WITH POTENTIALLY CELLULAR STORMS. LIMITED INITIAL
COVERAGE AND CONFIDENCE LEAVES MENTION OUT OF EITHER TAF SITE
UNTIL THE OVERNIGHT HOURS WHEN STORMS ARE EXPECTED TO CONGEAL
INTO A LINE WHILE PROGRESSING EAST. WHERE STORMS DO FORM, STRONG
TO SEVERE WINDS AND HAIL WITH HEAVY RAIN ARE EXPECTED, CAUSING
LIFR-IFR CONDITIONS WHERE THEY IMPACT. WIND GUSTS IN EXCESS OF
60KTS ALSO EXPECTED.
STORM COVERAGE INCREASES OVERNIGHT THROUGH SATURDAY MORNING
PRIMARILY ALONG AND NORTH OF INTERSTATE 90 LOCALLY IN SOUTHEAST
MINNESOTA AND WESTERN INTO CENTRAL WISCONSIN. STRONG TO SEVERE STORMS
WILL BE POSSIBLE CAUSING LIFR-IFR CONDITIONS WHERE THEY IMPACT.
STORM CHANCES CONTINUE THROUGH TUESDAY.
HYDROLOGY
ISSUED AT 555 AM CDT FRI AUG 15 2025
SEVERAL ROUNDS OF STORMS ARE ANTICIPATED TO MOVE THROUGH THE REGION
BEGINNING THIS EVENING AND CONTINUING THROUGH EARLY NEXT WEEK.
A VERY MOIST AIRMASS IN PLACE WILL BE CONDUCIVE FOR HEAVY
RAINFALL WITH PRECIPITABLE WATERS OF 1.75" TO 2", NEARING THE
SPC CLIMATOLOGICAL MAXIMUM AT KDVN. AS A RESULT, WIDESPREAD
RAINFALL AMOUNTS OF 1-3", WITH LOCALLY HIGHER AMOUNTS WHERE
STORMS FREQUENT ARE ANTICIPATED THROUGH SUNDAY. ADDITIONALLY,
GIVEN THE MOISTURE-RICH AIRMASS, RAINFALL RATES WITHIN HEAVIER
STORMS OF 1-2"/HR OR GREATER WILL BE POSSIBLE WHICH MAY
CONTRIBUTE TO LOCALIZED FLASH FLOODING. RECENT HEFS GUIDANCE HAS
SOME LOW-END PROBABILITIES (5-25% CHANCE) TO REACH FLOOD STAGE
ON MANY AREA RIVERS, HOWEVER THIS IS LIKELY A RESULT OF LOWER
CONFIDENCE ON WHERE STORMS WILL DEVELOP AND WHICH BASINS WILL BE
IMPACTED.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...NAYLOR
AVIATION...JAR
HYDROLOGY...NAYLOR
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page