876
FXUS63 KARX 041756
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1156 AM CST WED MAR 4 2026
KEY MESSAGES
- FOG CONTINUES THIS MORNING, PRIMARILY WEST OF THE MISSISSIPPI
WHERE VISIBILITIES ARE 1/4 MILE OR LESS IN SPOTS. THE FOG WILL
BEGIN TO LIFT AFTER DAYBREAK THIS MORNING.
- RAIN CHANCES RETURN THURSDAY (20 TO 40%), MOSTLY IMPACTING
PORTIONS OF NORTHEAST IOWA AND SOUTHWESTERN WISCONSIN HOWEVER
AMOUNTS REMAIN BELOW 0.2".
- RAIN VERY LIKELY (95%) FOR FRIDAY MORNING AND THUNDERSTORMS -
PERHAPS SEVERE - FOR FRIDAY EVENING. THERE IS A 35 TO 85%
CHANCE (HIGHEST IN NE IA AND SW WI) FOR AT LEAST 1" OF RAIN TO
FALL FRIDAY INTO SATURDAY.
UPDATE
ISSUED AT 520 AM CST WED MAR 4 2026
AREAS OF DENSE FOG HAVE DEVELOPED ACROSS THE REGION RESULTING IN
1/4 MILE VISIBILITIES ACROSS PORTIONS OF SOUTHEAST MN AND
NORTHEAST IA. AS A RESULT, HAVE THE DENSE FOG ADVISORY
CONTINUING THROUGH 10AM ACROSS THESE AREAS. CURRENTLY, CALM
WINDS, CLEAR SKIES AND A PRESENT NOCTURNAL INVERSION WILL AID IN
MAINTAINING ONGOING FOG UNTIL SUNRISE WHERE DIURNAL MIXING
PROCESSES WILL ALLOW FOG TO DISPERSE BY MID-MORNING. BASED ON
THE CURRENT HREF PROBABILITIES FOR 1/4 MILE OR LOWER, CONFIDENCE
IS HIGH (70-90%) FOR CONTINUED 1/4 MILE VISIBILITIES WEST OF
THE MISSISSIPPI RIVER TOWARDS DAYBREAK BUT WITH MUCH LOWER
PROBABILITIES (20-40%) EAST OF THE MISSISSIPPI RIVER WHICH IS
BEING VERIFIED WITH CURRENT OBSERVATIONS. AS A RESULT, LIKELY
WILL NOT NEED TO EXPAND THE DENSE FOG ADVISORY FURTHER EAST.
WITH SOME LOCATIONS IN SOUTHEAST MN AND NORTHEAST IA SEEING
ONGOING DENSE FOG WITH BELOW FREEZING TEMPERATURES, SOME SLICK
SPOTS MAY DEVELOP ON ELEVATED SURFACES.
DISCUSSION
ISSUED AT 1214 AM CST WED MAR 4 2026
FOG OVERNIGHT
CLEAR SKIES AND LIGHT WINDS HAVE LED TO POTENTIAL FOR FOG OVERNIGHT
WITH CONCERNS FOR DENSE (AT OR UNDER 1/4 OF A MILE) FOG FOCUSING ON
LOCATIONS WEST OF THE MISSISSIPPI, PARTICULARLY LOCATIONS WITH
SNOWPACK. HAVE ISSUED A DENSE FOG ADVISORY FOR AREAS WITH SNOW PACK
AND FARTHER WEST TOWARD SOUTH CENTRAL MN AND NORTH CENTRAL IA, WHERE
OBSERVATIONS AT MULTIPLE LOCATIONS ARE AT A 1/4 OR LESS AS OF 10 PM.
LOW POTENTIAL FOR RAIN THURSDAY IN NORTHEAST IOWA AND SOUTHWEST
WISCONSIN
WEDNESDAY IN TO THURSDAY, WAVE CURRENTLY OVER COLORADO MOVES JUST TO
OUR SOUTH AS IT TREKS TOWARD SOUTHERN ONTARIO. WITH SURFACE RIDGING
PRESENT IN THE SOUTHEAST CONUS, SOUTHERLY MOIST FETCH AT THE SURFACE
AND 850MB SHOULD BRING ENOUGH NORTHWARD FOR WIDESPREAD PRECIP TO
DEVELOP ACROSS THE OH VALLEY WITH THE NORTHWESTERN EDGE OF THE
PRECIP SHIELD POTENTIALLY GRAZING NE IA AND SW WI. 04.00Z HREF AND
04.01Z NBM CONTINUE TO MAINTAIN A 20-40% CHANCE FOR PRECIP SO HAVE
CONTINUED TO MAINTAIN THIS IN THE FORECAST. SHOULD RAIN OCCUR,
AMOUNTS WILL BE LOW WITH 04.00Z HREF MAX VALUES UP TO ONLY 0.2".
RAIN VERY LIKELY FRIDAY MORNING, POTENTIAL FOR SEVERE STORMS
EVENING, UNCERTAIN NIGHTTIME INTO SATURDAY
STRONG UPPER WAVE CURRENTLY HEADING FOR THE PACIFIC NORTHWEST LOOKS
TO BREAK OVER THE FOUR CORNERS FRIDAY AND BARRELS TOWARD LAKE
SUPERIOR. WITH SURFACE RIDGING STILL FIRMLY IN PLACE IN THE SE
CONUS, CONTINUE SOUTHERLY MOIST ADVECTION ACROSS THE CENTRAL CONUS
WILL SET THE STAGE FOR WIDESPREAD RAIN WITH VIRTUALLY ALL GUIDANCE
DEPICTING THIS OCCURRING FRIDAY MORNING IN THE DRIFTLESS REGION WITH
ADDITIONAL RAIN LIKELY DURING THE EVENING INTO SATURDAY. 04.12Z MEAN
PWAT VALUES CLIMB TO AROUND 1" BEFORE THE RAIN ARRIVES, JUST BELOW
MODEL CLIMATOLOGY MAXIMUMS FOR THIS TIME OF YEAR. 04.01Z NBM
PROBABILITIES GENERALLY DEPICT A 35 TO 85% CHANCE FOR 1" OF RAIN
ACROSS FRIDAY AND SATURDAY WITH CHANCES TOWARD THE HIGH END OF THAT
RANGE IN NE IA AND SW WI. GIVEN POTENTIAL FOR FROZEN GROUND
- 6 TO 17 INCHES OF FROST DEPTH WERE OBSERVED MONDAY AND TUESDAY -
ADDITIONAL RUNOFF COULD LEAD TO RISES ON CREEKS AND STREAMS.
HOWEVER, AFTERNOON HIGHS IN THE 40S AND 50S WEDNESDAY AND THURSDAY
MAY HELP THAW THINGS BEFORE THE RAIN ARRIVES.
ASIDE FROM RISES ON RIVERS, OTHER POTENTIAL HAZARD LOOKS TO BE
SEVERE THUNDERSTORMS. WITH STRONG WINDS EXPECTED ALOFT, FOCUS WILL
BE ON WHERE SUFFICIENT INSTABILITY IS PRESENT FOR THUNDERSTORMS TO
DEVELOP AND POTENTIALLY TAP INTO SAID SEASONABLY STRONG SHEAR. IN
SHORTER TERMS, MUCH DEPENDS ON HOW FAR NORTH THE WARM FRONT ADVANCES
AND GUIDANCE CONTINUES TO DIFFER QUITE A BIT ON THIS. ILLUSTRATIVE
ARE THE 04.00Z OPERATIONAL RUNS OF THE GFS AND NAM WHICH BRING THE
WARM SECTOR TO ENCOMPASS MOST OF THE CWA AND JUST
FAYETTE/CLAYTON/GRANT COUNTIES, RESPECTIVELY. CSU-ML PROBABILITIES
BASED ON THE GEFS SUGGEST SOME CHANCE ACROSS VIRTUALLY THE WHOLE CWA
WHILE 03.12Z ECENS JOINT MUCAPE-SHEAR PROBABILITY VALUES SUFFICIENT
FOR ORGANIZED CONVECTION ARE AROUND 15% IN TAYLOR COUNTY INCREASING
TO NEAR 60% IN OUR SOUTH. WILL NEED TO CLOSELY MONITOR THIS PERIOD
AS, GIVEN DEEP SHEAR VALUES UPWARDS OF 50 KNOTS AND SEASONABLY COLD
TEMPS ALOFT, SEVERE HAIL SEEMS PLAUSIBLE SHOULD THE WARM FRONT REACH
OUR CWA AND THUNDERSTORMS DEVELOP.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1155 AM CST WED MAR 4 2026
LITTLE TO NO IMPACTS TO AVIATION ARE EXPECTED THROUGH THE
AFTERNOON AND EVENING. OVERNIGHT, THERE IS AN INCREASING SIGNAL
FOR ANOTHER ROUND OF DENSE FOG DEVELOPING WEST OF THE
MISSISSIPPI RIVER AFTER 06Z AS LOW LEVEL SATURATION INCREASES.
SOME UNCERTAINTY WHETHER OR NOT THIS IS REALIZED AS AN IFR/LIFR
STRATUS DECK INSTEAD EXISTS, BUT HAVE INTRODUCED VISIBILITY
REDUCTIONS TO THE KRST TAF TO ACCOUNT FOR THE POTENTIAL (30-60%
PER THE 04.12Z HREF/REFS). VISIBILITY RESTRICTIONS SHOULD
DISSIPATE AFTER 15Z, BUT LINGERING MVFR CEILINGS ARE EXPECTED
INTO THURSDAY AFTERNOON.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
UPDATE...NAYLOR
DISCUSSION...FERGUSON
AVIATION...FALKINHAM
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