782
FXUS63 KARX 301720
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1220 PM CDT THU JUL 30 2026
KEY MESSAGES
- PRECIPITATION CHANCES INCREASE THROUGH FRIDAY FROM WEST TO
EAST WITH LOCAL CONFIDENCE DECREASING IN HIGHER RAINFALL
AMOUNTS (1-2"+) AND STRONGER STORMS (<5%).
- SEASONABLE TEMPERATURES AND MOSTLY DRY CONDITIONS ARE EXPECTED
SUNDAY THROUGH EARLY NEXT WEEK.
DISCUSSION
ISSUED AT 1243 AM CDT THU JUL 30 2026
INCOMING HEAVY RAINFALL OVERNIGHT & THROUGH FRIDAY:
THE AREA OF HIGHER PRESSURE AND ACCOMPANYING ANTICYCLONIC FLOW
WILL SLOWLY EXIT EAST/SOUTHEAST THROUGH THE END OF THE WORK WEEK
AS A DEEPENING MID/UPPER LEVEL PERTURBATION USHERS IN HEAVY
RAINFALL POTENTIAL ACROSS THE UPPER MIDWEST OVERNIGHT THURSDAY
THROUGH FRIDAY. THE RESPONSIBLE UPPER LEVEL JET STREAK SEEN ON
GOES18 DERIVED WIND LOOPS EXHIBITS SLIGHT TROUGHING WILL
STRENGTHEN AS IT CIRCUMNAVIGATES THE RIDGE PERIPHERY. RESULTANT
EASTERLY ADVECTION OF A VERY MOIST, WITH A DAILY MAXIMUM PWAT OF
1.63" OBSERVED AT INTERNATIONAL FALLS, MN 30.00Z RAOB TO 90TH
PERCENTILE AT OMAHA, NE (SPC CLIMATOLOGY), TRAVERSES THROUGH THE
UPPER MISSISSIPPI RIVER VALLEY. ACCOMPANYING LREF (EPS/GEFS)
100% PROBABILITIES FOR 1.5" TO 2" PWATS BIFURCATE AND GRAZE THE
LOCAL FORECAST AREA, RESPECTIVELY, THROUGH FRIDAY NIGHT.
HEAVY RAINFALL IMPACTS:
SIMILAR TO PREVIOUS FORECASTS, MAIN DIFFERENCES BETWEEN LREF
MEMBERS (EPS/GEFS) SURROUND LOCATION AND STRENGTH OF THE
DEEPENING EXTRATROPICAL CYCLONE. A SLIGHTLY MORE NORTHERN
SOLUTION BETWEEN EPS MEMBERS RESULTS IN HIGHER MEMBER CONSENSUS
FOR HEAVIER PRECIPITATION AMOUNTS COMPARED TO THE GEFS. CURRENT
FORECAST CONFIDENCE FOR 1" TO 2" OF RAINFALL THROUGH FRIDAY BUT
SHOULD THE MORE NORTHERN, DEEPER SOLUTION COME TO FRUITION
HIGHER AMOUNTS WILL NEED TO BE ACCOUNTED FOR IN THE FORECAST.
TIMING:
WHILE CONFIDENCE IS HIGH FOR INITIAL PRECIPITATION TO REACH THE
LOCAL FORECAST AREA OVERNIGHT INTO FRIDAY MORNING, EXIT
BEHAVIOR AND SUBSEQUENT DURATION REMAINS ADDITIONAL FORECAST
DETAIL TO REMAIN COGNIZANT OF. THE STRONGER EPS SOLUTION
SUGGESTS LINGERING LOW LEVEL FRONTOGENETICAL BANDS WITHIN THE
DEFORMATION ZONE PERPETUATING PRECIPITATION THROUGH SATURDAY.
CURRENT LREF CLUSTER ANALYSIS CONFIDENCE KEEPS POPS ABATED
THROUGH SATURDAY AFTERNOON ALTHOUGH ADDITIONAL SCRUTINY MAY NEED
TO BE SPENT ON SATURDAY AS FORECAST HOUR NEARS SHOULD HEAVY
RAINFALL IMPACTS PERSIST.
SEVERE STORM POTENTIAL:
WHILE OVERALL SEVERE STORM POTENTIAL APPEARS LOW (<5%),
RELATIVELY CLOSE PROXIMITY TO THE SURFACE LOW AMPLIFIES LOW
LEVEL VORTICITY MAXIMA RAISING SOME CONCERN AND QUESTIONS
SURROUNDING TORNADO POTENTIAL SHOULD SURFACE STRETCHING OCCUR.
SUNDAY - TUESDAY: SEASONABLE TEMPERATURES AND MOSTLY DRY
BEHIND THE LATE WEEK SHOWERS AND STORMS, SYNOPTIC SCALE RIDGING
BUILDS ACROSS THE CENTRAL UNITED STATES AND REMAINS IN PLACE
THROUGH EARLY NEXT WEEK WITH SEASONABLE TEMPERATURES EXPECTED
IN RESPONSE. STABILITY ASSOCIATED WITH THIS RIDGE LOOKS TO KEEP
SHOWERS/STORMS AT BAY THROUGH AT LEAST TUESDAY WHEN ENSEMBLE
GUIDANCE SUGGESTS A SHORTWAVE AT 500HPA SHIFTS EASTWARD ACROSS
THE UNITED STATES/CANADA BORDER, FORCING A WEAK SURFACE
BOUNDARY THROUGH THE UPPER MIDWEST. PRECIPITATION IS POSSIBLE
LATE TUESDAY ALONG THIS BOUNDARY, THOUGH VARIATIONS AMONGST THE
VARIOUS ENSEMBLE SUITES KEEPS PROBABILITIES ON THE LOWER END FOR
THE TIME BEING, SITTING AROUND 30-40% IN THE 29.12Z LREF.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1220 PM CDT THU JUL 30 2026
VFR CONDITIONS ARE EXPECTED THROUGH LATE THIS EVENING AND INTO THE
OVERNIGHT HOURS WITH THE MAIN AVIATION CONCERN BEING SHOWERS
THAT MOVE INTO THE REGION TOMORROW MORNING. OVERALL CONFIDENCE
IS FAIRLY HIGH (40-80%) IN THE RECENT HREF FOR MVFR CEILINGS
ACROSS PORTIONS OF SOUTHEAST MN AND NORTHEAST IA TOWARDS 18Z, SO
HAVE OPTED TO INCLUDE AN MVFR CIG GROUP AT KRST DURING THIS
PERIOD. OTHERWISE, MVFR VSBY REDUCTIONS WILL BE POSSIBLE WITH
HEAVIER SHOWERS DURING THE MORNING. GIVEN THE ABSENCE OF ROBUST
INSTABILITY, THE THREAT FOR THUNDERSTORMS IS FAIRLY LOW THROUGH
18Z ACROSS MUCH OF THE LOCAL AREA.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...FALKINHAM/JAR
AVIATION...NAYLOR
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