240
FXUS63 KARX 161058
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
558 AM CDT SAT MAY 16 2026
KEY MESSAGES
- LOW CONFIDENCE IN DAILY STORMS AND SEVERITY TONIGHT THROUGH
SUNDAY, INCREASING SOMEWHAT FOR MONDAY. SHOULD STORMS OCCUR
SUNDAY, LARGE HAIL AND DAMAGING WINDS WILL BE THE MAIN HAZARDS
WITH ALL SEVERE WEATHER HAZARDS POSSIBLE FOR MONDAY.
- HEAVY RAINFALL REPEATING OVER AREAS RAISES RIVER FLOODING
CONCERNS ON FLASHIER RIVERS WITH CURRENT, ALBEIT LOW (<30%),
LOCAL CONFIDENCE LIMITED TO THE TURKEY RIVER IN NORTHEAST
IOWA.
DISCUSSION
ISSUED AT 201 AM CDT SAT MAY 16 2026
COOLER & DRY TODAY:
THE MOISTURE BOUNDARY THAT CAUSED FRIDAY NIGHT STORMS HAS BEEN
SLOWLY SAGGING EAST-SOUTHEAST THROUGH THE FORECAST AREA OVERNIGHT,
AND IS EXPECTED TO SIT QUASI-STATIONARILY SOUTH OF THE FORECAST
AREA THROUGH CENTRAL IOWA TODAY. A RESULTANT MOSTLY CLEAR, DRY,
AND COOLER DAY FOR MUCH OF THE AREA WITH DAYTIME HIGH
TEMPERATURES FROM THE 70S TO MID 80S.
INITIAL STORM CHANCES THIS EVENING & TONIGHT:
THE DRY CONDITIONS CEASE THIS EVENING INTO TONIGHT INITIALLY ALONG
SOUTHWESTERN PERIPHERAL COUNTIES IN NORTHEAST IOWA AS STORMS
INITIATE ALONG THE BOUNDARY SOUTHWEST OF THE FORECAST AREA WHILE
ATTEMPTING TO TRUDGE NORTHEAST. MEAN WEST-SOUTHWEST FLOW WILL
TRY TO ADVECT STORMS NORTHEAST WHILE A LACK OF SYNOPTIC FORCING
AND LOW LEVEL EAST WINDS WEAKEN CONFIDENCE IN LOCAL STORM
ACTIVITY. SHOULD THE FRONTAL BOUNDARY BE REALIZED FARTHER
NORTHEAST, STRONG TO SEVERE STORM POTENTIAL COULD BRUSH CLOSER
TO THE LOCAL FORECAST AREA AND WILL REQUIRE ADDITIONAL FORECAST
UPDATES.
OVERNIGHT & SUNDAY STORM POTENTIAL:
EVENTUALLY, A WEAK MID LEVEL PERTURBATION ALONG SOUTHWEST FLOW
OVERNIGHT INTO EARLY SUNDAY MORNING ADVECTS THE FRONTAL
BOUNDARY THROUGH THE FORECAST AREA. ISENTROPIC UPGLIDE WITHIN
THE ADVECTING WARM SECTOR WILL PROVIDE SUFFICIENT FORCING WHILE
LAPSE RATES AND INSTABILITY REMAIN MINIMAL. THEREFORE,
CONFIDENCE IN STORMS THROUGH THE MORNING REMAINS LOW.
CONFIDENCE IN ADDITIONAL, SUBSEQUENT LOCAL STORM CHANCES
REMAINS LOW THROUGH THE DAYTIME AND EVENING HOURS AS LOW LEVEL
WARM, DRY AIR PLUME QUICKLY FOCUSES NORTH THROUGH THE FORECAST
AREA, CAUSING A STOUT, WIDESPREAD 850MB-700MB CAPPING INVERSION.
INCREASED MOISTURE AND ACCOMPANYING SATURATION WILL REMAIN TO
THE WEST, TIED CLOSER TO THE FRONTAL BOUNDARY THROUGH MINNESOTA,
VARYING FROM CENTRAL MINNESOTA IN THE COOLER, MORE MOIST ECMWF
TO THE DAKOTAS IN THE DRIER, WARMER NAM SOLUTION.
WHILE CONFIDENCE IN STORMS INCREASES SOMEWHAT THROUGH THE
NIGHTTIME HOURS, EASTERN ADVECTION OF ANY AVAILABLE FORCING
REMAINS IN QUESTION AS LREF MEMBERS SUGGESTS WEAK, ONLY SLIGHTLY
ZONAL MID LEVEL LOBE OF POSITIVE MID LEVEL VORTICITY SUFFICIENT
FOR STORM INITIATION THROUGH THE LOCAL FORECAST AREA. THEREFORE,
CONFIDENCE IN SEVERE STORMS REMAINS LOW, HIGHEST IN THE WESTERN
HALF OF THE FORECAST AREA FROM NORTHEAST IOWA INTO SOUTHEAST
MINNESOTA CLOSER TO THE FRONTAL BOUNDARY LOCATION. DAMAGING
WINDS AND LARGE HAIL WILL BE THE MAIN LOCAL SEVERE HAZARDS
SHOULD STORMS OCCUR.
INCREASED SEVERE STORM THREAT MONDAY:
HIGHEST THREAT FOR COLLOCATION OF SEVERE STORM PARAMETERS OVER
THE FORECAST AREA OCCURS MONDAY AS THE SYNOPTIC PATTERN
PROGRESSES EAST, LIFTING MID LEVEL POSITIVE VORTICITY
ASSOCIATED WITH THE MID LEVEL TROUGH ON WATER VAPOR IMAGERY OVER
THE PACIFIC WEST COAST EARLY THIS MORNING THROUGH THE UPPER
MIDWEST. LREF MEMBERS AGREE ON 1500+ J/KG OF ML/MU/SB CAPE FOR
MUCH OF THE FORECAST AREA WITH MOSTLY STRAIGHT LINE SW TO NE
HODOGRAPHS CAPABLE OF INITIALLY SPLITTING SUPERCELLS BEFORE
CONGEALING AND SHIFTING EAST WITH THE FRONTAL BOUNDARY SAGGING
EAST-SOUTHEAST INTO MONDAY NIGHT. WHILE SOME LONG RANGE
DETERMINISTIC AND ENSEMBLE MEMBERS SUGGEST THE LINGERING LOW TO
MID LEVEL DRY AIR ENTRAINMENT LIMITING COVERAGE, SATURATION IS
LIKELY SOMEWHERE OVER THE FORECAST AREA BEFORE THE BOUNDARY
TRAVERSES THE FORECAST AREA.
AVIATION /12Z TAFS THROUGH 12Z SUNDAY/
ISSUED AT 552 AM CDT SAT MAY 16 2026
AREAS OF SHALLOW, PATCHY MVFR-LIFR FG EXPECTED TO QUICKLY LIFT
THROUGH THE MORNING HOURS. VFR EXPECTED THROUGH MUCH OF THE
16.12Z TAF PERIOD OUTSIDE OF SMALLER AIRPORTS IN NORTHEAST IOWA
WHERE WEAKENING STORMS MAY GRAZE SITES THIS EVENING INTO
TONIGHT. EVENTUALLY, STORMS EXPECTED TO SHIFT NORTHEAST THROUGH
THE AREA THROUGH SUNDAY.
STORM POTENTIAL RETURNS THROUGH SUNDAY EVENING AND MONDAY.
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...JAR
AVIATION...JAR
HYDROLOGY...JAR
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