502
FXUS63 KARX 211905
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
205 PM CDT TUE APR 21 2026
KEY MESSAGES
- DRY CONDITIONS AND WARM TEMPERATURES THROUGH THURSDAY. DAYTIME HIGHS
WILL REACH INTO THE 70S FOR MOST WHILE OVERNIGHT LOWS FALL
INTO THE 40S AND 50S.
- SHOWERS AND STORMS ARE VERY LIKELY (70-90%) THURSDAY EVENING
INTO THE OVERNIGHT HOURS. A FEW STRONG TO SEVERE STORMS CAN'T
BE RULED OUT.
- TEMPERATURES COOL THIS WEEKEND INTO THE BEGINNING OF NEXT WEEK
WITH ANOTHER ROUND OF PRECIPITATION POSSIBLE (30-50%) SUNDAY
AFTERNOON INTO MONDAY.
DISCUSSION
ISSUED AT 205 PM CDT TUE APR 21 2026
TONIGHT - THURSDAY: DRY WITH A WARMING TREND
DRY AND WARMER WEATHER ARE IN STORE THROUGH MID-WEEK AS AN UPPER
LEVEL LONGWAVE RIDGE REMAINS THE DOMINANT FEATURE ACROSS THE CENTRAL
UNITED STATES. BROAD SUBSIDENCE AND A DRY ATMOSPHERE LIMIT ANY
PRECIPITATION AND RESULT IN ADIABATICALLY WARMING TEMPERATURES,
FURTHER INCREASED BY SOUTHERLY WINDS RETURNING WEDNESDAY. HIGH
TEMPERATURES CLIMB INTO THE 70S FOR MOST WITH SOME LOCATIONS
ALONG/WEST OF THE MISSISSIPPI RIVER POSSIBLY HITTING 80F ON
WEDNESDAY (30-40%) WITH LOWS FALLING INTO THE 40S AND 50S.
THURSDAY - FRIDAY: SHOWERS AND STORMS
A ROUND OF SHOWERS AND STORMS IS EXPECTED LATE THURSDAY THROUGH
EARLY FRIDAY MORNING ASSOCIATED WITH THE TROUGH SPINNING OFF THE
WEST COAST OF THE UNITED STATES TODAY MOVING ONSHORE, RESULTING IN A
DEEPENING SURFACE LOW OVER THE NORTHERN GREAT PLAINS ON WEDNESDAY.
THE COLD FRONT ASSOCIATED WITH THIS LOW IS EXPECTED TO BE THE
CATALYST FOR THESE SHOWERS AND STORMS WITH HIGH CONFIDENCE IN
PRECIPITATION (70-90%). STILL SOME CONCERN FOR STRONG/SEVERE STORM
POTENTIAL DURING THIS PERIOD, BUT THIS REMAINS THE POINT OF GREATEST
UNCERTAINTY IN THIS SCENARIO. GIVEN MUCAPE OF 1000-1250 J/KG, SOME
MORE POTENT UPDRAFTS MAY BE ABLE TO DEVELOP THOUGH WIND SHEAR
REMAINS THE BIGGEST LIMITING FACTOR TO STRONGER STORMS. THE MAJORITY
OF THE SHEAR IS LOCKED UP "DOWNSTAIRS" IN THE 0-3KM LAYER OWING TO
RATHER WEAK FLOW AT 500HPA. WHILE THE INSTABILITY WOULD SUPPORT A
MORE POTENT UPDRAFT, THE LACK OF STRONGER DEEP LAYER SHEAR WILL MAKE
IT DIFFICULT FOR THESE UPDRAFTS TO SUSTAIN THEMSELVES. IF THE UPPER
JET STREAK WERE TO MOVE EASTWARD, INCREASING 0-6KM SHEAR WOULD BE
SUPPORTIVE OF STRONGER STORMS OVER OUR AREA. ALL THIS SAID, WHILE A
STRONG TO SEVERE STORM CANNOT BE RULED OUT AT THIS TIME WITH WIND
BEING THE PRIMARY THREAT, THE BETTER ENVIRONMENT APPEARS TO BE WEST
OF OUR AREA AS DEPICTED BY THE SPC DAY 3 OUTLOOK.
REGARDING RAINFALL AMOUNTS DURING THIS PERIOD, THE 21.13Z NBM MEAN
SUGGESTS AROUND 0.5 INCHES ACROSS THE REGION WITH THE INTERQUARTILE
RANGE SITTING AROUND 0.3-0.8 INCHES. HOWEVER, THE MEAN IS LIKELY
INFLATED BY A FEW OUTLIER MEMBERS (ALSO NOTED IN THE 21.06Z
GEFS/EPS) LIKELY OWING TO CONVECTIVE ENHANCEMENT WHICH CAN BE
SEEN IN THE DETERMINISTIC GUIDANCE (21.06Z GFS/ECMWF) AS A
"STRIPEY" LOOK. LOOKING TO THE AIWP GUIDANCE, THE 21.06Z
AIFS/AIGEFS ARE LESS GUNG- HO ABOUT THE HIGHER END AMOUNTS,
LIMITING THE OUTLIERS TO AROUND 1 INCH. ALL THAT SAID, TEND
TOWARDS THE LOWER END FOR AMOUNTS TO AND THINKING 0.5 INCHES OR
LESS IS THE FAVORED SCENARIO AT THIS POINT, BUT AREAS WHERE
THUNDERSTORMS FREQUENT MAY SEE AMOUNTS AROUND 1 INCH.
FRIDAY - NEXT WEEK: COOLER, ANOTHER ROUND OF SHOWERS
AS WE HEAD INTO THE WEEKEND AND NEXT WEEK, A COOLER AIRMASS IS
USHERED INTO THE REGION BEHIND THE COLD FRONT THAT MOVES THROUGH
THURSDAY INTO FRIDAY. TEMPERATURES FALL TO NEAR NORMAL, BRINGING
HIGHS DOWN TO THE UPPER 50S TO LOW 60S AND LOWS TO PER THE 21.13Z
NBM MEAN ALTHOUGH THERE IS QUITE A BIT OF SPREAD NOTED IN THE 21.06Z
GEFS/EPS. ANOTHER 500HPA TROUGH SHIFTS THROUGH THE UNITED STATES
SUNDAY INTO MONDAY DEVELOPING ANOTHER DEEP SURFACE LOW AND
ASSOCIATED FRONTAL SYSTEM. THE 21.00Z LREF MEMBERSHIP IS IN GOOD
AGREEMENT REGARDING THE DEVELOPMENT OF THIS LOW, BUT THE CLUSTERS
DEPICT MORE VARIATION REGARDING THE FINER DETAILS PRIMARILY
REGARDING THE TRACK OF THE LOW, AS IS TO BE EXPECTED AT THIS RANGE.
HOWEVER, THE CONSENSUS OF THIS SURFACE WAVE DEVELOPING AND
MOVING THROUGH THE UPPER MIDWEST BRINGS A 30-50% PROBABILITY FOR
PRECIPITATION TO START THE NEW WEEK.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1219 PM CDT TUE APR 21 2026
VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. THE WEAK FRONT
CONTINUES TO SINK SOUTHWARD AND IS CLEAR OF RST AND LSE. FLOW
BEHIND THE FRONT IS CALM TO LIGHT AND HAVE PREVAILED THE
PREDOMINANT FORECAST WIND DIRECTION THROUGH THE AFTERNOON, WHICH
BECOMES MORE FROM THE NORTHEAST AND REMAINS VERY LIGHT THROUGH
SUNRISE WEDNESDAY. SOME INDICATIONS FOG MAY DEVELOP TOWARD THIS
LATTER TIME FRAME, BUT IS EXPECTED TO STAY SOUTH OF THE
FORECAST TERMINALS. WINDS WILL BECOME FROM THE EAST-SOUTHEAST
AND INCREASE TO BETWEEN 8 TO 12 KNOTS OVER SOUTHEAST MINNESOTA
TO 5 TO 10 KNOTS OVER SOUTHWEST WISCONSIN BY THE END OF THE
PERIOD.
HYDROLOGY
ISSUED AT 205 PM CDT TUE APR 21 2026
FLOODING ALONG THE YELLOW RIVER AT NECEDAH, WI CONTINUES TRENDING
DOWNWARD TODAY WITH PRECIPITATION NOT EXPECTED THROUGH THURSDAY.
WHILE STILL IN MINOR FLOOD STAGE AS OF THIS MORNING, THE RIVER IS
CURRENTLY FORECAST TO FALL BELOW FLOOD STAGE BY LATE WEDNESDAY. RAIN
RETURNS LATE THURSDAY INTO FRIDAY MORNING BUT OVERALL AMOUNTS ARE
EXPECTED TO REMAIN IN THE 0.3-0.8 INCH RANGE, LOCALLY AROUND 1 INCH
WHERE STORMS FREQUENT. THIS MAY RESULT IN SOME MINOR RISES ON AREA
RIVERS, BUT EXPECTING ANY RISES WOULD RESULT IN ACTION STAGE BEING
EXCEEDED AT MOST. DRY CONDITIONS RETURN THROUGH THE WEEKEND ALLOWING
ANY OF THESE RISES TO QUICKLY WORK THEIR WAY DOWNSTREAM.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...NAYLOR
AVIATION...ANSORGE
HYDROLOGY...NAYLOR
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