155
FXUS63 KARX 312331
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
631 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 /00Z TAFS THROUGH 00Z SUNDAY/
ISSUED AT 630 PM CDT FRI JUL 31 2026
RAIN CONTINUES TO OVERSPREAD THE UPPER MISSISSIPPI VALLEY THIS
EVENING AS A SURFACE LOW PRESSURE SYSTEM PIVOTS TO THE SOUTHEAST
OVER NE IOWA. IFR/MVFR CIGS AND VISIBILITIES WILL CONTINUE AT THE
TERMINALS THROUGH THE EVENING HOURS WITH RAIN GRADUALLY ENDING FROM
NORTHWEST TO SOUTHEAST THROUGH THE OVERNIGHT HOURS. BOTH CIGS AND
VISIBILITIES SHOULD IMPROVE AT THE TERMINALS BEYOND 12Z AS SOME LOW
CLOUDS AND MIST/FOG MAY LINGER EVEN AS THE BULK OF THE RAIN HAS
MOVED OUT LATE OVERNIGHT. VFR CONDITIONS WILL PREVAIL FOR TOMORROW
WITH SKIES CLEARING BY THE AFTERNOON. GUSTY EAST/NORTHEASTERLY WINDS
WILL PIVOT TO A MORE NORTHERLY DIRECTION AS THE LOW PRESSURE SYSTEM
SLIDES SOUTHEAST TONIGHT WITH GUSTS TAPERING OFF AROUND MIDNIGHT.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...NAYLOR
AVIATION...BARENDSE
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