403
FXUS63 KARX 311829
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
129 PM CDT FRI JUL 31 2026
KEY MESSAGES
- RAIN EXITS THROUGHOUT THE OVERNIGHT HOURS AND INTO SATURDAY
MORNING. HIGHEST ADDITIONAL RAINFALL AMOUNTS WILL BE NEAR AND
SOUTH OF I-90 WHERE 1 TO 2 INCHES OF RAIN ARE LIKELY (50-90%
CHANCE).
- DRIER CONDITIONS EXPECTED FOR THE WEEKEND WITH HIGHS IN THE
UPPER 70S TO LOWER 80S.
- SHOWER AND STORM CHANCES (20-40%) RETURN TUESDAY INTO WEDNESDAY.
DISCUSSION
ISSUED AT 129 PM CDT FRI JUL 31 2026
REST OF TODAY - TONIGHT: RAIN CONTINUES THIS AFTERNOON AND
EVENING, EXITS TO THE EAST OVERNIGHT
RAIN WILL CONTINUE TO PIVOT THROUGH THE REGION THROUGHOUT THE
AFTERNOON AND INTO THE EVENING HOURS. EARLY THIS AFTERNOON THE
SURFACE CYCLONE RESPONSIBLE FOR OUR PRECIPITATION IS CURRENTLY
CENTERED OVER PORTIONS OF SOUTHWEST MN AND NORTHWEST IA WITH THE
DRY SLOT ASSOCIATED WITH IT PUSHING INTO PORTIONS OF NORTHEAST
IA AND SOUTHEAST MN. AS WE CONTINUE THROUGH THE AFTERNOON, THIS
SYSTEM IS EXPECTED TO MOVE GENERALLY TO THE SOUTHEAST THROUGH
IOWA WHICH WILL THEN ALLOW FOR THE DEFORMATION BAND ASSOCIATED
WITH THIS SURFACE LOW TO MOVE OVERHEAD. WITHIN THIS REGIME,
SLOPING FRONTOGENESIS AS A RESULT OF A TROWAL REGION WILL PIVOT
OVER THE REGION AND REINVIGORATE SHOWER DEVELOPMENT THROUGH THE
REMAINDER OF THE AFTERNOON AND EVENING, PARTICULARLY NEAR AND
SOUTH OF I-90. THE MAIN QUESTION THAT REMAINS IS IF ANY
INSTABILITY CAN PUSH NORTHWARD INTO THE LOCAL AREA AS THIS
STRONGER FORCING REGIME MOVES OVERHEAD. THERE IS SOME INDICATION
IN THE RECENT RAP THAT WE COULD BUILD IN 100-250 J/KG OF MUCAPE
IN PORTIONS OF SOUTHWEST WI AND NORTHEAST IA LATER THIS
AFTERNOON AND INTO THE EVENING. CONSEQUENTLY, HAVE NOTED THAT
SOME OF THE CAMS ARE A BIT MORE AGGRESSIVE WITH DEVELOPING
ROBUST CONVECTION IN THESE RESPECTIVE AREAS.
OVERALL, EXPECTED ADDITIONAL RAINFALL AMOUNTS WILL BE GREATEST NEAR
AND SOUTH OF I-90 WHERE THIS AFOREMENTIONED FORCING REGIME IS
PRESENT THIS AFTERNOON AND EVENING. CONSEQUENTLY, THE 31.12Z HREF
HAS AN INTER-QUARTILE RANGE OF ANYWHERE FROM 1 TO 2 INCHES OF
RAINFALL WHERE THIS FORCING IS PRESENT. THE 90TH PERCENTILE MEMBERS
OF THE HREF SUGGEST SOME POCKETS OF 3-4+" MAY BE POSSIBLE, MOST
LIKELY WITH ANY AREAS THAT SEE CONVECTION REPEAT OVER THE SAME
LOCATIONS. HOWEVER, SEEING THIS HIGHER AMOUNTS ARE YET AGAIN
CONTINGENT ON IF WE CAN MANAGE TO GET ANY INSTABILITY NORTHWARD INTO
THE REGION TO PROMOTE CONVECTION. IN THESE LOCALIZED CASES, CANNOT
RULE OUT SOME ISOLATED FLOODING, HOWEVER THIS WOULD BE
RELATIVELY SPARSE IN NATURE. EVENTUALLY, AS WE HEAD INTO THE
OVERNIGHT AND DAYBREAK ON SATURDAY, THE BROADER SURFACE LOW AND
ASSOCIATED UPPER-LEVEL TROUGH WILL CONTINUE TO PUSH EAST OF THE
LOCAL AREA, WHICH IN TURN WILL NOTE A WEST TO EAST PROGRESSION
OF THE BROADER PRECIPITATION SHIELD, LIKELY EXITING MUCH OF THE
LOCAL AREA BY LATE MORNING.
THIS WEEKEND: DRIER & SLIGHTLY COOLER THAN NORMAL
AS THE AFOREMENTIONED SURFACE LOW PRESSURE CENTER PUSHES EAST OF THE
AREA, UPPER-LEVEL RIDGING WILL BUILD IN BEHIND IT FOR THE WEEKEND
WITH ATTENDING SURFACE HIGH PRESSURE PUSHING INTO THE REGION LATER
SATURDAY AND INTO SUNDAY. CONSEQUENTLY, EXPECTING SKIES TO CLEAR
THROUGHOUT THE DAY ON SATURDAY WITH NO CHANCES FOR PRECIPITATION
AFTER THE MORNING HOURS. ADDITIONALLY, WITH FLOW SWITCHING TO
NORTHERLY OVER THE WEEKEND, EXPECTING TEMPERATURES TO REMAIN
SLIGHTLY COOLER THAN NORMAL WITH THE INTER-QUARTILE RANGE IN THE NBM
KEEPING HIGH TEMPERATURES ACROSS THE AREA IN THE MIDDLE 70S TO LOWER
80S.
EARLY NEXT WEEK: PRECIPITATION CHANCES RETURN TUESDAY & WEDNESDAY
BY THE TIME THE BEGINNING OF THE UPCOMING WORK WEEK ROLLS AROUND,
THE PREVIOUSLY MENTIONED UPPER-LEVEL RIDGING AND ATTENDING SURFACE
HIGH PRESSURE REMAINS IN PLACE FOR MONDAY. HOWEVER, LOW-LEVEL FLOW
EVENTUALLY SWITCHES TO SOUTHERLY WHICH WILL ALLOW FOR A WARMER
AIRMASS TO PUSH INTO THE REGION. CONSEQUENTLY, TEMPERATURES WILL
LIKELY NUDGE UPWARDS A FEW DEGREES ON MONDAY WITH HIGHS IN THE LOWER
TO MIDDLE 80S FOR MOST. GOING INTO TUESDAY, A PRONOUNCED UPPER-LEVEL
TROUGH PUSHES THROUGH THE DAKOTAS WITH AN ASSOCIATED BOUNDARY
PUSHING SOUTHEAST TOWARDS THE LOCAL AREA. CONSEQUENTLY, THE GRAND
ENSEMBLE (GEFS/EC/CANADIAN ENSEMBLE) HAS INCREASED
PROBABILITIES (30-70%) FOR MEASURABLE RAINFALL TUESDAY EVENING
THROUGH WEDNESDAY MORNING AS IT PROGRESSES THROUGH THE REGION.
OVERALL, PROBABILITIES FOR SEVERE WEATHER WITH THIS WAVE APPEAR
RELATIVELY LOW AS THE GRAND ENSEMBLE (GEFS/EC/CANADIAN ENSEMBLE)
ONLY HAS AROUND 5-10% CHANCE FOR AMPLE INSTABILITY AND BULK
SHEAR TO BE PRESENT OVER THE REGION FOR SEVERE WEATHER.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1246 PM CDT FRI JUL 31 2026
RAIN WILL CONTINUE TO ROTATE ACROSS THE REGION THIS AFTERNOON
AND EVENING AS AN AREA OF LOW PRESSURE PASSES BY JUST TO OUR
SOUTH. RATHER LOW PROBABILITY (15%) FOR A STRIKE OR TWO OF
LIGHTNING IN THE VICINITY OF RST/LSE, SO HAVE KEPT THUNDER
MENTION OUT OF TAFS. SLIGHTLY HIGHER CHANCES FOR A THUNDERSTORM
WILL BE FURTHER SOUTH OF I-90. MVFR VISIBILITY WITH ANY AREAS
OF HEAVIER RAIN. CEILINGS WILL LIKELY RANGE FROM MVFR TO IFR
THROUGH TONIGHT, LOWEST TO THE SOUTH OF INTERSTATE 90, BEFORE
EVENTUALLY RETURNING TO VFR AFTER DAYBREAK SATURDAY.
INCREASING WINDS THIS AFTERNOON OUT OF THE NORTHEAST WITH GUSTS
OF 20-30 KNOTS AS THE LOW PASSES BY, THEN DIMINISHING OUT OF
THE NORTH TONIGHT.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...NAYLOR
AVIATION...KURZ
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page