443
FXUS63 KARX 162301
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
601 PM CDT SAT MAY 16 2026
KEY MESSAGES
- HAIL THREAT LOWERS LATE TONIGHT AND SUNDAY MORNING.
- SEVERE WEATHER THREAT ON SUNDAY AND SUNDAY NIGHT SHIFTS WEST.
- SEVERE WEATHER THREAT FROM MONDAY INTO TUESDAY MORNING IS
BECOMING MORE UNCERTAIN.
DISCUSSION
ISSUED AT 124 PM CDT SAT MAY 16 2026
THIS AFTERNOON
A DRY LINE WILL CONTINUE TO SLIDE SOUTH THROUGH NORTHERN IOWA,
SOUTHERN WISCONSIN, AND NORTHERN ILLINOIS THIS AFTERNOON. SURFACE
DEW POINTS WILL FALL INTO THE 30S AND 40S NORTH OF THIS DRY LINE.
THIS WILL LOWER THE AFTERNOON RELATIVE HUMIDITIES INTO THE TEENS AND
20S FOR MUCH OF THE FORECAST AREA. THE DEW POINTS WERE LOWERED
CLOSER TO THE CONSHORT WHICH SEEMS TO BE HANDLING THIS DRY AIR THE
BEST. EVEN THEN, THE DEW POINTS ARE NOT LOW ENOUGH SOUTH OF
INTERSTATE 90.
FURTHER SOUTH ACROSS NORTHERN MISSOURI AND CENTRAL ILLINOIS IS
THE OUTFLOW BOUNDARY FROM THE STORMS THAT MOVED THROUGH OUR AREA
LAST EVENING. WITH CONVECTION CONTINUING ALONG THIS BOUNDARY,
IT WILL LIKELY REMAIN QUASI-STATIONARY.
TONIGHT AND SUNDAY
THE BOUNDARY ACROSS NORTHERN MISSOURI WILL MOVE SLOWLY NORTH AS A
WARM FRONT IN RESPONSE TO THE NOCTURNAL JET TONIGHT AND THE SURFACE
LOW LIFTING NORTHEAST OUT OF THE CENTRAL PLAINS ON SUNDAY. WHILE
THERE IS GOOD 1 TO 7 KM SHEAR LOCATED NORTH OF THE WARM FRONT, THE
INSTABILITY STAYS SOUTH OF THE WARM FRONT. AS A RESULT, WE HAVE SEEN
A SIGNIFICANT DROP IN THE PROBABILITIES OF SEEING ELEVATED HAIL FOR
TONIGHT AND SUNDAY MORNING.
IN AN INTERESTING DEVELOPMENT IN THE 16.16Z HRRR, A MCS DEVELOPS
OVER EASTERN NEBRASKA AND WESTERN IOWA TONIGHT. AS THIS SYSTEM MOVES
TOWARD OUR AREA, IT GRADUALLY WEAKENS. ONE THING THAT WILL HAVE TO
BE WATCHED IS WHETHER THE RAIN-COOLED AIR PRODUCED BY THIS MCS
WILL LIMIT THE NORTHERN EXTENT OF THE WARM FRONT ON SUNDAY. THIS
COULD POTENTIALLY KEEP THE HIGH TEMPERATURES IN THE LOWER TO
MID-60S NORTH OF INTERSTATE 94. THIS WOULD BE 10 TO 15 DEGREES
COOLER THAN THE NBM.
SUNDAY NIGHT
PLENTY OF UNCERTAINTY IS SHOWING UP IN THE CAMS. WHILE MANY ARE IN
GENERAL AGREEMENT THAT STORMS WILL INITIATE OVER WESTERN IOWA,
EASTERN NEBRASKA, SOUTHWEST MINNESOTA AND EASTERN SOUTH DAKOTA
DURING THE LATE AFTERNON/EVENING, THEY THEN DIVERGE ON THEIR
SOLUTIONS. SOME SHOW A LINE DEVELOPING AS THEIR COLD POOLS
COALESCE AND OTHERS SHOW CLUSTERS OF STORMS. IN EITHER SCENARIO,
THE STORMS ARE TRENDING TO WEAKEN AS THEY MOVE INTO THE UPPER
MISSISSIPPI RIVER VALLEY DUE TO WEAKENING INSTABILITY AND
SHEAR. AS A RESULT, THE DAY 2 SLIGHT RISK HAS BEEN SHIFTED WEST.
IT NOW IS LOCATED ALONG AND WEST OF THE MISSISSIPPI RIVER
MONDAY INTO TUESDAY MORNING
MUCH OF UNCERTAINTY EXISTS ON THE TIMING OF THE COLD FRONT MOVING
THROUGH THE AREA. THIS ULTIMATELY AFFECTS THE LOCATION OF THE WARM
SECTOR. THE GFS AND MANY OF ITS ENSEMBLE MEMBERS MOVE THE FRONT
ACROSS THE AREA ON SUNDAY NIGHT OR MONDAY. THE 16.12Z OPERATIONAL
GFS WAS FURTHER WEST THAN ITS 16.16Z RUN. IT HAS 1500 TO 3000
J/KG CAPES IN NORTHEAST IOWA, AND SOUTHWEST AND CENTRAL
WISCONSIN. WHILE THERE IS MORE INSTABILITY, THE BETTER DEEP
SHEAR IS POST FRONTAL. THE OPERATIONAL ECMWF AND MANY OF ITS
ENSEMBLES HAS ITS COLD FRONT MOVING THROUGH ON MONDAY NIGHT.
WITH THIS TIMING, THE INSTABILITY (UP TO 750 J/KG) IS MUCH LESS
AHEAD OF THIS COLD FRONT. ITS HAS DEEP SHEAR OVER 40 KNOTS NORTH
OF INTERSTATE 94, SO THERE MAY BE SOME SUPERCELLS IN THIS AREA
DURING THE EVENING.
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 600 PM CDT SAT MAY 16 2026
SHOWERS AND STORMS ARE EXPECTED TO DEVELOP BETWEEN 00Z-03Z
ACROSS PORTIONS OF EASTERN IOWA TONIGHT, SHIFTING NORTHWARD WITH
TIME. THOSE SITES SOUTH OF HIGHWAY 18 ARE MOST LIKELY TO SEE
IMPACTS FROM STORMS THAT DEVELOP. CAN'T RULE OUT A STRONGER
STORM DURING THIS PERIOD.
OVERNIGHT, THESE STORMS WEAKEN AND MOVE EASTWARD. THERE IS SOME
INDICATION SHOWERS MAY DEVELOP NORTH OF THEM AS THEY WEAKEN,
GENERALLY IN THE 06Z-09Z TIMEFRAME, WHICH COULD IMPACT THE TAF
SITES. CONFIDENCE IN THIS SCENARIO IS QUITE LOW SO HAVE LEFT
MENTIONS OUT OF THE TAFS. HIGHER CONFIDENCE IN SHOWERS AND
PERHAPS A THUNDERSTORM COMES AFTER 10Z AS AN AREA OF SHOWERS AND
STORMS LIFTS NORTHEASTWARD FROM CENTRAL IOWA (60-80%). WINDS
INCREASE AS THIS PRECIPITATION MOVES THROUGH THE REGION,
GENERALLY GUSTING TO 15-25KT FROM THE SOUTHEAST, BUT THOSE WEST
OF THE MISSISSIPPI RIVER MAY SEE GUSTS TO 30KT THROUGH SUNDAY
AFTERNOON. MVFR TO NEAR IFR CONDITIONS DEVELOP BEHIND THE
PRECIPITATION AS CEILINGS LOWER TO 1-3KFT BEFORE VFR CONDITIONS
RETURN FROM SOUTH TO NORTH TOWARDS THE END OF THE TAF PERIOD.
HYDROLOGY
ISSUED AT 440 AM CDT SAT MAY 16 2026
STORM CHANCES INCREASE DAILY, INITIALLY TONIGHT THROUGH SUNDAY
MORNING. THE ACCOMPANYING ANOMALOUSLY MOIST AIRMASS RAISES HEAVY
RAIN CONCERNS WITH A WIDESPREAD 1" TO 2" OF RAINFALL EXPECTED
THROUGH MONDAY. WHILE LOW LOWER CONFIDENCE IN SPECIFIC REPEAT
STORM LOCATIONS OVER THE NEXT 72 HOURS LIMITS OVERALL CONFIDENCE
IN LOCATION OF HIGHER RAINFALL AMOUNTS, 2" TO 3" WILL BE
POSSIBLE SHOULD STORMS REPEAT OVER SIMILAR AREAS.
RESULTANT CURRENTLY LOW CONFIDENCE (10-20%) FOR MINOR RIVER
FLOODING IMPACTS LIMITED TO FLASHIER CREEKS AND RIVERS IN
NORTHEAST IOWA SUCH AS THE TURKEY RIVER AT GARBER AND ELKADER.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...BOYNE
AVIATION...FALKINHAM
HYDROLOGY...JAR
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